The phrases
En-route, phrase by phrase
ADS Out of Service
When your automatic position reporting stops reaching the controller, they lose the picture they had been using instead of your voice reports. They tell you to start reporting again, and you answer WILCO.
ATC
[Callsign], ADS CONTACT LOST, RESUME POSITION REPORTING
ATC
VT-AIR, ADS-B contact lost, resume position reporting
Pilot
Mumbai Control, VT-AIR, IGOBA 1018, FL350, estimating LUMBO 1049, next PARAR
- WILCO is the right answer because you are being asked to do something from now on, not just told a fact.
- Go back to the full compulsory position report format, with the fix, the time, the level, the next estimate and the point after that.
- Expect procedural separation to come back with it, which usually means larger spacing and less flexibility on levels and direct routings.
Reference: ICAO Doc 9432
Airborne SELCAL check
Use this procedure after take-off when preparing for a long oceanic or remote-area sector and both assigned HF frequencies must be checked. The crew contacts the relevant radio station, tests the alert on the primary frequency, tunes the HF receiver to the backup frequency for another test, and then returns to the primary net. Once the station accepts the SELCAL watch, HF audio may be reduced because a call carrying the registered code will activate the cockpit chime.
Pilot
[station], [callsign], TRANSMITTING ON [primary frequency]
ATC
[callsign], [station], PASS YOUR MESSAGE
one, Opening contact and primary test, eight eight seven five kilohertz
Pilot
Chennai Radio, Vistara 815, transmitting on eight eight seven five.
ATC
Vistara 815, Chennai Radio, pass your message.
Pilot
Chennai Radio, Vistara 815, request SELCAL check, code bravo hotel delta kilo, on primary eight eight seven five.
ATC
Vistara 815, Chennai Radio, standby for SELCAL code bravo hotel delta kilo on eight eight seven five.
System
Chennai Radio sends the assigned four-tone sequence. The cockpit SELCAL lamp illuminates and the chime sounds.
Pilot
Chennai Radio, Vistara 815, SELCAL check complete on eight eight seven five.
two, Change to secondary five six four five kilohertz
Pilot
Chennai Radio, Vistara 815, request SELCAL check on secondary five six four five.
ATC
Vistara 815, Chennai Radio, change to secondary frequency five six four five for SELCAL check.
Pilot
Changing to secondary five six four five, Vistara 815.
System
A crew member tunes the HF receiver to five six four five kilohertz.
Pilot
Chennai Radio, Vistara 815, on five six four five, request SELCAL check, code bravo hotel delta kilo.
ATC
Vistara 815, Chennai Radio, standby for SELCAL on five six four five.
The matching four-tone sequence activates the cockpit SELCAL light and audible alert.
Pilot
Chennai Radio, Vistara 815, SELCAL check complete on five six four five.
three, Back to primary and SELCAL watch
Pilot
Chennai Radio, Vistara 815, going back to primary eight eight seven five.
ATC
Vistara 815, Chennai Radio, roger, primary eight eight seven five.
System
The crew retunes the HF receiver to eight eight seven five kilohertz.
Pilot
Chennai Radio, Vistara 815, on primary eight eight seven five, request SELCAL watch.
ATC
Vistara 815, Chennai Radio, roger, SELCAL watch on eight eight seven five and five six four five.
Pilot
SELCAL watch on eight eight seven five and five six four five, Vistara 815.
- SELCAL stands for Selective Calling System. A ground station alerts the registered aircraft by sending its assigned four-tone sequence. The decoder activates a cockpit light and audible alert. During extended overwater sectors, the crew can lower HF volume while remaining aware of calls for that aircraft, reducing fatigue caused by persistent static.
- Always pronounce each selected letter with the ICAO phonetic alphabet, for example BRAVO HOTEL DELTA KILO. Bare letters are not suitable for an R/T transmission. A SELCAL code uses only the letters A to S, leaving out I, N and O. The same careful pronunciation is used whenever the crew or controller passes the code, and this is a common DGCA examination point.
- After a new aircraft contacts an HF station, the station may invite the crew to PASS YOUR MESSAGE. An HF channel works simplex, so both ends cannot transmit simultaneously. This short invitation allows the ground station to prepare to receive the longer SELCAL request.
- The backup test is not valid until the aircraft receiver has been tuned away from primary. A crew member changes to the assigned secondary frequency, confirms reception there, and requests another code transmission. Ground transmission alone cannot test an aircraft receiver that remains on the primary setting.
- After the backup test, tell Chennai Radio that you are going back to primary before you retune. This announced step prevents the ground station from assuming that the aircraft remains on the backup net.
- The closing exchange identifies both guarded frequencies and confirms that SELCAL watch is active. Following that confirmation, the crew may reduce the HF speaker level. Any cockpit SELCAL alert must still receive immediate attention.
- OUT is customary on HF when the sender has finished and expects no answer. It is seldom used in routine VHF traffic. The final watch confirmation and readback in this example complete the exchange, so a separate OUT call is not required.
- Chennai Radio is shown on primary eight eight seven five and secondary five six four five kilohertz. Learn the pair assigned to the station relevant to the route because another station may use different frequencies. Current aeronautical publications and company documents take precedence over this example.
Reference: ICAO Doc 9432
Answering Traffic Information
When ATC passes traffic information, there are only three honest answers. LOOKING OUT while you search, TRAFFIC IN SIGHT once you have identified it, and NEGATIVE CONTACT if you cannot find it. Each one tells the controller something different about what they can now do with you.
Pilot
LOOKING OUT, [Callsign] / TRAFFIC IN SIGHT, [Callsign] / NEGATIVE CONTACT, [Callsign]
ATC
[Callsign], TRAFFIC [clock position] [distance] MILES, [direction], [level]
ATC
VT-AIR, traffic 11 o'clock 5 miles, opposite direction, FL280
ATC
VT-AIR, traffic 1 o'clock 8 miles, eastbound FL270
Pilot
Traffic in sight, VT-AIR
ATC
VT-AIR, maintain visual separation
Pilot
Maintaining visual separation, VT-AIR
- ROGER is not one of the three answers. It tells the controller you heard the words but nothing about whether you can see the aircraft.
- Move from LOOKING OUT to one of the other two as soon as you know. Leaving the controller with LOOKING OUT for a minute is leaving them with nothing.
- Once you report the traffic in sight you may be asked to maintain visual separation. Accepting that puts the separation on you, so only accept it if you are sure you have the right aircraft.
- Clock positions are relative to your track, not your heading. In a strong crosswind the traffic will not be where the clock code suggests.
Reference: ICAO Doc 9432
Ask for Climb
Use this exchange when an aircraft is climbing towards an interim level and seeks a higher cruising level while opposite direction traffic is descending towards the same corridor. ATC can limit the current clearance to the interim level, state the other aircraft's level and expected crossing point, and request a report at a DME beyond that point. Once the opposing aircraft has passed the relevant track and adequate separation exists, the controller may clear the aircraft to the higher level. The interim restriction remains in force until that new clearance is issued.
Pilot
[station], [callsign], REQUEST CLIMB [level], PASSING [level] FOR [level]
ATC
[callsign], CLIMB TO [level] AND MAINTAIN, REPORT PASSING [reference point], DUE TO [reason]: [conflicting traffic details]
Pilot
Hyderabad Control, Vistara 815, request climb flight level three nine zero, passing flight level two nine zero for flight level three one zero.
ATC
Vistara 815, climb flight level three one zero and maintain, report passing DME three two, due traffic, opposite direction, descending to flight level three two zero, expected to cross your track before DME three two.
Pilot
Climb to flight level three one zero and maintain, report passing DME three two, Vistara 815.
Pilot
Hyderabad Control, Vistara 815, passing DME three two.
ATC
Vistara 815, climb to flight level three nine zero.
Pilot
Climb to flight level three nine zero, Vistara 815.
- By giving the level being passed, the next level and the final level sought, the crew combines a progress report with a request. This saves a separate call at the intermediate flight level and allows ATC to see the complete intent.
- The reply sets flight level three one zero as the upper limit of the current clearance. The crew may climb to that level, but must level off there unless a further clearance removes the restriction. A definite interim instruction is more useful than merely saying that the higher climb must wait.
- The opposite direction aircraft is expected to cross the route at flight level three two zero before DME three two. At flight level three one zero, this gives one thousand feet of vertical separation at the crossing. The DME lies beyond the expected conflict point, so reaching it provides a practical coordination position.
- A complete readback includes the level to be reached, the requirement to MAINTAIN it and the instruction to REPORT PASSING the DME. The traffic explanation need not be copied word for word, but every operational restriction must be acknowledged.
- An estimated crossing time may help the crew anticipate the sequence, but it does not satisfy a request to REPORT PASSING a DME. The named point should be reported when actually reached, with level information added only if ATC asks for it.
- The call at DME three two is a position report, not a request for the higher level. It follows the required sequence of station, aircraft identity and position reached, allowing the controller to decide whether separation permits the next clearance.
- After confirming that the opposing aircraft has passed, the controller clears the aircraft to flight level three nine zero. The pilot repeats CLIMB TO and the destination level, so the amended clearance is complete and unambiguous.
- The difference between flight level three one zero and flight level three nine zero is eight thousand feet. A large segment is not automatically acceptable merely because one clearance covers it; performance, airspace, traffic and other restrictions still govern the climb.
- The technique offers a practical plan: climb only as cleared, report at the agreed point and await a new instruction. The crew must continue to honour the maintained level until an amended or additional clearance is issued, rather than acting on an assumption about traffic.
Reference: ICAO Doc 9432
Ask for Lower FL Due Weather
Use this exchange during en route level flight when turbulence, icing, or cloud makes the present flight level unsuitable and a lower cruising level is needed. A descent request may be delayed if reciprocal traffic occupies an intermediate level. In the example, the pilot seeks flight level three five zero from flight level three seven zero. ATC holds the higher level until opposing traffic passes DME zero eight five, then authorises the descent.
Pilot
[station], [callsign], [reference point], AT [level], REQUEST [level] DUE [reason]
ATC
[callsign], [station], MAINTAIN [level], EXPECT [level] AFTER TRAFFIC, [traffic information]
Pilot
Bengaluru Control, Air India 447, DME one one five, maintaining flight level three seven zero, request flight level three five zero due weather.
ATC
Air India 447, Bengaluru Control, maintain flight level three seven zero, expect three five zero after traffic, reciprocal traffic VT-SKL, Boeing 737, flight level three six zero, crossing your track at DME zero eight five.
Pilot
Maintain flight level three seven zero, expect three five zero after traffic, looking out for VT-SKL, Air India 447.
Pilot
Bengaluru Control, Air India 447, DME zero seven five, request flight level three five zero.
ATC
Air India 447, descend flight level three five zero.
Pilot
Descend flight level three five zero, Air India 447.
- The opening report places Air India 447 at flight level three seven zero, so the requested flight level three five zero is plainly a descent. Do not combine this request with a report of climbing through the present level toward a higher one. Each position report should describe only the level change actually being made.
- Weather is the stated basis for this request, rather than a desire to improve fuel use or exploit a favourable wind. ATC may still need to coordinate the descent with nearby traffic. The controller either issues the requested level or explains what separation must first be achieved.
- The reply does two jobs. MAINTAIN flight level three seven zero is the limit that applies right now, and EXPECT three five zero AFTER TRAFFIC tells the crew the request is parked, not refused. An expectation is never a clearance, so the aircraft stays level.
- VT-SKL occupies flight level three six zero, which lies between flight level three seven zero and the requested flight level three five zero. Air India 447 would therefore pass through the other aircraft's level during descent. The crossing point provides a reference for sequencing the two aircraft safely.
- VT-SKL is an aircraft registration used as that flight's callsign. The controller names it so the crew can pick out the traffic on TCAS or visually. The information is not addressed to the other aircraft.
- The readback repeats the restriction that applies now, MAINTAIN flight level three seven zero, and the expected level. Traffic information itself is not a readback item; acknowledging it and saying you are looking out is enough. The callsign goes last.
- At DME zero seven five, Air India 447 has moved ten nautical miles past the position marked by DME zero eight five. This update allows the controller to reassess separation before the pilot renews the lower level request. Passing a DME figure does not by itself provide clearance to descend.
- Once the conflict is gone, DESCEND flight level three five zero becomes the operative clearance and cancels the earlier hold at flight level three seven zero. The pilot reads back the newly assigned level. A position report alone never substitutes for an ATC descent clearance.
- Keep your own callsign identical in every call. On a busy frequency a similar callsign, or a digit that could be heard as part of a level, is a classic source of confusion, so say it clearly and check that each clearance is really meant for you.
Reference: ICAO Doc 9432
ATC Initiated Weather Warning - CB Activity Re-route
Apply this exchange when a controller opens contact to pass hazardous weather that intersects an aircraft's filed airway and obtain its planned avoidance action. Here, intense cumulonimbus development near Pune and Goa prevents safe continuation. The crew offers a bypass through Bengaluru and Kochi, receives approval, and states revised estimates for the amended sequence.
Pilot
[station] [callsign] GO AHEAD
ATC
Air India 447, Hyderabad Control.
Pilot
Hyderabad Control, Air India 447, go ahead.
ATC
Air India 447, Hyderabad Control, weather warning, heavy CB activity over Pune and Goa, advise intentions.
Pilot
Air India 447, request re-route via Bengaluru and Kochi.
ATC
Air India 447, Hyderabad Control, cleared to re-route via Bengaluru and Kochi.
Pilot
Cleared to re-route via Bengaluru and Kochi, estimating Bengaluru zero five one zero, Kochi zero five four five, Air India 447.
- This is a controller-initiated contact. A controller may call an aircraft already monitoring the frequency when weather could affect its filed route, so the crew does not need to make the opening transmission.
- GO AHEAD means the aircraft is ready to receive the controller's message. It confirms that two-way communication is established and is not an instruction to continue flight or enter controlled airspace.
- The abbreviation CB denotes cumulonimbus, a deep convective cloud that may contain thunderstorms, icing, hail, lightning, violent winds, and severe turbulence. A heavy CB report requires an early avoidance decision.
- Cells reported near Pune and Goa affect the area intended for use by the aircraft. The crew should consider the latest weather information, the movement of the cells, and any traffic or airspace constraints before accepting an avoidance route.
- ADVISE INTENTIONS asks the crew to state its proposed handling of the weather. The captain must assess the conditions, aircraft capability, fuel state, and suitable avoidance options before requesting an amended route.
- REQUEST RE-ROUTE VIA Bengaluru and Kochi identifies the path the crew wishes to use. The proposed points should be stated clearly so that ATC can verify the clearance and coordinate it with other sectors.
- The pilot must read back CLEARED TO RE-ROUTE VIA Bengaluru and Kochi without changing any point. If the controller approves a different route, that amended routing becomes the clearance that must be repeated.
- Giving updated estimates allows the controller to revise traffic sequencing and coordination with neighbouring units. Include the revised arrival times for the amended points in the readback, then finish with the aircraft callsign.
Reference: ICAO Doc 9432
Climbing, descending and maintaining levels
When ATC issues or confirms a climb, descent or cruise level.
Pilot
[callsign], leaving [present level], climbing or descending to [cleared level].
ATC
[callsign], climb or descend to [cleared level].
ATC
Skyline 345, descend to flight level one five zero.
Pilot
Descend to flight level one five zero, Skyline 345.
ATC
Skyline 345, report passing flight level one eight zero.
Pilot
Skyline 345, passing flight level one eight zero, descending flight level one five zero.
- Always read back the complete level instruction. If ATC changes any part, expect the whole level clearance to be restated.
- Report leaving, passing and reaching levels when asked, or when standard practice requires it.
- Distinguish altitude, height and flight level. Flight level is based on the standard pressure setting.
Reference: ICAO Doc 9432, 3.3
Compulsory position report
At compulsory reporting points, file this report unless the published procedure or an ATC instruction removes the requirement.
Pilot
[station], [callsign], [position] AT [time], [level], ESTIMATING [next position] AT [time], NEXT [following point]
ATC
[callsign], [station], ROGER, [information or next report]
Pilot
Nagpur Control, IndiGo 5231, Bhopal at zero three five zero, flight level two eight zero, estimating Nagpur at zero four three five, next Hyderabad.
ATC
IndiGo 5231, Nagpur Control, roger, report Nagpur.
- State the flight identity, present position, UTC time, current level, the following reporting point with its estimate, and the next significant point.
- If a climb or descent is still in progress, also provide the level being passed and the level already cleared.
- Use UTC for estimates, and pronounce every digit separately.
Reference: ICAO Doc 9432, 3.4
Confirm Altimeter Setting and Level
The controller asks for this when the level shown on radar does not agree with the level you should be at. You answer with the setting in the subscale and the level you are indicating, in that order.
Pilot
ALTIMETER [setting], FLIGHT LEVEL [number], [Callsign]
ATC
[Callsign], CONFIRM ALTIMETER SETTING AND LEVEL
ATC
VT-AIR, confirm altimeter setting and level
Pilot
Altimeter 1013, flight level 280, VT-AIR
- Above the transition altitude the subscale is on the standard setting of 1013 hectopascals and the level is a flight level. Below the transition level the subscale is on QNH and the level is an altitude in feet.
- Read what the subscale actually shows. This question is usually asked because a setting is wrong, and quoting the setting you meant to use hides it.
- A wrong subscale is one of the commonest level busts. If you find one, say so and correct it rather than quietly resetting.
Reference: ICAO Doc 9432
Confirm Squawk Code
The controller asks you to confirm the code you are transmitting when the radar label does not match what they expect. Read the code back digit by digit from what is actually set in the transponder, not from what you remember setting.
Pilot
SQUAWKING [code], [Callsign]
ATC
[Callsign], CONFIRM SQUAWKING [code]
ATC
VT-AIR, confirm squawking 4521
Pilot
Squawking 4521, VT-AIR
- Look at the transponder before you answer. This question is usually asked because something does not match, and answering from memory hides the very error the controller is chasing.
- Codes are spoken digit by digit. 4521 is four five two one, never forty five twenty one. Only a whole thousand uses THOUSAND: 2000 is two thousand (AAI MATS Part 1, paragraph 12.5.1, Table 12-3).
- If the transponder has failed, say TRANSPONDER UNSERVICEABLE. The controller will change to procedural separation and may have to refuse you entry to some airspace.
Reference: ICAO Doc 9432
Cross a Fix at a Specified Time
ATC asks whether you can be over a named fix at a given time when they are building a sequence or coordinating with the next unit. Answer from your groundspeed and your fuel, not from hope.
Pilot
AFFIRM, [Callsign] / NEGATIVE, [reason], [Callsign]
ATC
[Callsign], CAN YOU CROSS [fix] AT [time]
ATC
VT-AIR, can you cross PARAR at 1130
ATC
VT-AIR, cross PARAR at 1130
Pilot
Cross PARAR at 1130, VT-AIR
- The question and the instruction are two separate transmissions. AFFIRM is not a clearance, and you are only committed once you have read back CROSS PARAR AT 1130.
- Give a short reason when you answer NEGATIVE. Fuel, performance or turbulence each lead the controller to a different alternative.
- You may be asked to cross AT OR AFTER or AT OR BEFORE a time. Read the qualifier back with the time, because it changes what you are agreeing to.
Reference: ICAO Doc 9432
Crossing Reporting Point
For a compulsory reporting point, or when ATC requests a report over a named fix, make the transmission as you pass that point.
Pilot
[station], [callsign], [reporting point] AT [time], FLIGHT LEVEL [level], ESTIMATING [next point] AT [time]
ATC
[callsign], [station], ROGER
Pilot
Kolkata Control, Vistara 815, PUMMA at one four four five, flight level three five zero, estimating BUBKO at one five one two
ATC
Vistara 815, Kolkata Control, ROGER
- State the time when you actually cross the fix, rather than a time that was previously planned.
- Whenever the revised time has moved by at least three minutes, also state your latest estimate for the following reporting point.
Reference: ICAO Doc 9432
Descent Clearance
En-route or approach control issues this clearance to move an aircraft from cruise into the arrival descent. It may specify a target level, require that level by a named fix, or permit the pilot to begin descending when ready.
Pilot
[clearance readback] [callsign]
ATC
[callsign], DESCEND TO [level] / DESCEND TO REACH [level] BY [fix] / WHEN READY DESCEND TO [level]
ATC
Vistara 815, Chennai Control, descend to reach flight level one two zero by SASAN, contact Chennai Approach one one nine decimal seven
Pilot
Descend to reach flight level one two zero by SASAN, Chennai Approach one one nine decimal seven, Vistara 815
- A fix-based deadline is mandatory. Plan speed, descent rate and intermediate levels so the aircraft reaches the assigned level no later than the fix.
- If weather, traffic or a holding pattern makes compliance impossible, notify control without delay and request a workable revised clearance.
- The phrase WHEN READY DESCEND lets the crew choose where descent begins. This normally improves fuel efficiency, although traffic separation remains the priority.
Reference: ICAO Doc 9432
En-route frequency change
Whenever ATC transfers you from one controlled airspace frequency to another.
Pilot
[callsign], monitoring [current frequency]. Contact [next unit] on [frequency].
ATC
[callsign], contact [next unit] on [frequency].
ATC
Skyline 345, contact Chennai Control, one two seven decimal niner.
Pilot
Contact Chennai Control, one two seven decimal niner, Skyline 345.
ATC
Skyline 345, readback correct.
Pilot
Chennai Control, Skyline 345, flight level two four zero.
ATC
Skyline 345, Chennai Control, radar contact.
- If told MONITOR a frequency, listen there without making a routine initial call unless required.
- If told STAND BY, wait. It is neither an approval nor a refusal.
- If no advice to change frequency is received, notify the controlling station before making the change.
Reference: ICAO Doc 9432, 2.8.2
Expedite Climb or Descent
EXPEDITE asks you for the best rate the aircraft can safely give, usually to clear a level before crossing traffic. It changes your rate, never your cleared level.
Pilot
EXPEDITING DESCENT THROUGH [level], [Callsign]
ATC
[Callsign], EXPEDITE DESCENT THROUGH [level]
ATC
VT-AIR, expedite descent through FL200
Pilot
Expediting descent through FL200, VT-AIR
- Repeat the level in your read-back. EXPEDITING on its own does not tell the controller which level you understood.
- If the aircraft cannot give a better rate, say UNABLE TO EXPEDITE with your callsign straight away. The controller then has time to move the other traffic instead.
- Expedite means the best practical rate consistent with safety. It is not an instruction to exceed a limit or to make the aircraft uncomfortable.
Reference: ICAO Doc 9432
Fly a Parallel Offset
A parallel offset moves you a set distance left or right of your cleared route while you keep the same track. It is used to build lateral spacing, most often on oceanic and remote routes, and it needs area navigation equipment to fly accurately.
Pilot
AFFIRM, [Callsign] / NEGATIVE, [reason], [Callsign]
ATC
[Callsign], OFFSET [number] MILES [LEFT or RIGHT] OF ROUTE
ATC
VT-AIR, can you fly a 2 mile parallel offset right of route
ATC
VT-AIR, offset 2 miles right of route
Pilot
Offset 2 miles right of route, VT-AIR
- The distance and the side are both read-back items. Two miles right and two miles left put you on opposite sides of the traffic the offset was meant to separate you from.
- Answer NEGATIVE if the aircraft cannot fly an accurate offset. Flying it by eye defeats the purpose, because the controller is now using that distance as separation.
- Return to the centre line only when ATC instructs it, and read that instruction back too.
Reference: ICAO Doc 9432
Frequency Change
Use this procedure for routine transfers between adjacent en-route control sectors. After the current controller directs you to another frequency, tune it and contact the receiving controller using your aircraft callsign and present flight level.
Pilot
[unit], [callsign], [level], [request]
ATC
[callsign], CONTACT [unit] [frequency]
ATC
IndiGo 5231, contact Kolkata Control one two seven decimal three.
Pilot
One two seven decimal three, IndiGo 5231.
Pilot
Kolkata Control, IndiGo 5231, maintaining flight level three five zero.
ATC
IndiGo 5231, Kolkata Control, identified.
- State the frequency digit by digit before selecting it, followed by the callsign, for example, "one two seven decimal three, IndiGo 5231".
- For initial contact, give the unit, aircraft callsign and current level in that sequence. Add a full position report only when the receiving sector's procedure calls for it.
Reference: ICAO Doc 9432
Holding Instructions
Use this instruction when an aircraft must wait before continuing, for example to sequence arrivals, avoid unsuitable weather at the destination or wait for a different runway. It identifies the fix and pattern to be flown, the level to maintain and, when supplied, the expected time of further clearance.
Pilot
[fix] AS PUBLISHED or [specified holding pattern], [level], EXPECT FURTHER CLEARANCE AT [time], [callsign]
ATC
[callsign], HOLD AT [fix] AS PUBLISHED or [specified holding pattern], [level], EXPECT FURTHER CLEARANCE AT [time]
ATC
IndiGo 5231, Chennai Control, hold at MMV as published, flight level one two zero, expect further clearance at one two four zero
Pilot
Hold at MMV as published, flight level one two zero, expect further clearance at one two four zero, IndiGo 5231
- "AS PUBLISHED" means using the pattern shown on the applicable chart. If no pattern is charted for the fix, ATC must state the inbound course, turn direction, and time or DME distance for each leg.
- EFC tells the crew when to anticipate the next clearance and helps with fuel planning. If contact is lost, the crew follows the approved procedure and, if no new clearance arrives, leaves the hold when the EFC time is reached.
- Do not assume one leg length or turn direction for every hold. Follow the timing or DME distance stated by ATC or, where available, shown on the applicable chart.
Reference: ICAO Doc 9432
Initial Contact with Area Control
Your first call to an area control centre after handover from departure or from the previous sector. Give the station, your callsign and your current level, then the level you are climbing or descending to. Add routing only if the new sector has not had your details.
Pilot
[Station], [Callsign], PASSING [level] CLIMBING [level], ROUTE [fix] TO [fix]
ATC
[Callsign], [Station], IDENTIFIED, CLIMB [level]
Pilot
Delhi Control, VT-AIR, passing FL150 climbing FL280, route RIXEN to BBB
ATC
VT-AIR, Delhi Control, identified, climb FL280
- Always include the level you are passing. It is the one item the new controller cannot get from the strip with any certainty.
- IDENTIFIED means the controller has radar or surveillance contact with you. It is not a clearance and it does not change anything you were told before.
- Read back the level instruction. IDENTIFIED itself is not a read-back item.
- If the new sector is non-radar, expect to be asked for a position report instead of being identified.
Reference: ICAO Doc 9432
Leave Airway Clearance
ATC issues this when you are departing the airway system at a named fix. The level restriction attached to it applies only while you remain inside controlled airspace.
Pilot
CLEARED TO LEAVE [designator] VIA [fix], MAINTAINING [level] WHILE IN CONTROLLED AIRSPACE, [Callsign]
ATC
[Callsign], CLEARED TO LEAVE AIRWAY [designator] VIA [fix], MAINTAIN [level] WHILE IN CONTROLLED AIRSPACE
ATC
VT-AIR, cleared to leave airway A464 via GANDH, maintain FL130 while in controlled airspace
Pilot
Cleared to leave A464 via GANDH, maintaining FL130 while in controlled airspace, VT-AIR
- Read back the words WHILE IN CONTROLLED AIRSPACE. They are the condition on the level, and dropping them turns a conditional restriction into an open one.
- Once you are outside controlled airspace you choose a level appropriate to your track and the semi-circular rule. Until then FL130 is a hard clearance.
- The exit fix is a read-back item. Leaving the airway anywhere else is leaving without a clearance.
Reference: ICAO Doc 9432
Leave Controlled Airspace by Descent
Use this when you want to drop out of the bottom of controlled airspace and continue outside it, typically on a VFR leg or a training sortie. ATC gives you a level to descend below and a code to squawk once you are out.
Pilot
[Station], [Callsign], REQUEST TO LEAVE CONTROLLED AIRSPACE BY DESCENT
ATC
[Callsign], DESCEND BELOW [level], LEAVE CONTROLLED AIRSPACE BY DESCENT, SQUAWK [code]
Pilot
Delhi Control, VT-AIR, request to leave controlled airspace by descent
ATC
VT-AIR, descend below FL75, leave controlled airspace by descent, squawk 2000
Pilot
Descend below FL75 leaving controlled airspace, squawk 2000, VT-AIR
- The level and the squawk code are both read-back items. Codes are spoken digit by digit, except a whole thousand, so 2000 is two thousand (AAI MATS Part 1, paragraph 12.5.1, Table 12-3).
- In India the conspicuity code is 2000, not the 7000 used in Europe. The Indian AIP ENR 1.6 paragraph 13.7.1 says an aircraft not assigned an SSR code operates Mode A3 code 2000 in the Chennai, Delhi, Kolkata and Mumbai FIRs and keeps that setting until told otherwise. Answer 2000 in an Indian exam.
- Squawk only what ATC gives you. If ATC gives you a code on leaving, that code wins over the standing conspicuity code.
- You are outside controlled airspace once you are below the level given, so your own terrain clearance and lookout start there.
Reference: ICAO Doc 9432
Line Squall approaching
Use this report when a crew spots a line squall near an aerodrome and needs the controller to know that it may disrupt arrivals, departures, or runway conditions. Supply the weather type, range from the aerodrome, travel direction, and dependable signs of severity. This is a pilot weather report, or PIREP. The controller can pass relevant information to other units, meteorological services, and affected aircraft as required.
Pilot
[station], [callsign], [intensity] [weather] [distance] MILES [direction] OF [aerodrome], MOVING [direction], [surface effects]
ATC
[callsign], [station], ROGER
Pilot
Jaipur Approach, Vistara 815, severe line squall one five miles southwest of Jaipur, moving northeast towards the field, surface gusts about three zero knots, heavy dust.
ATC
Vistara 815, Jaipur Approach, ROGER.
- A line squall is a narrow, fast-moving weather system that may bring abrupt wind shifts, very strong gusts, intense rainfall, hail, and a rapid loss of visibility. It can contain severe wind shear and leave a wet runway, making arrival or departure hazardous.
- R/T speech normally leaves out ordinary articles. Say SEVERE LINE SQUALL APPROACHING without placing A before the weather description.
- The stated range is measured from the aerodrome, not the reporting aircraft. It gives the controller an indication of the time available before the weather reaches the field, which can affect sequencing and runway planning.
- Movement direction shows whether the aerodrome lies along the squall's path. This helps tactical coordination with nearby units and may call for a change in traffic flow.
- SEVERE supplies the intensity in this example. Follow it with dependable details such as a measured gust, visible damage, or a rapid visibility change. SIGMET and AIREP each use a defined format.
- Observed ground effects help the controller judge the squall's actual consequences when the aerodrome has no usable wind reading. Bent structures, blowing dust, hail, or a sudden visibility loss may be reported if directly observed.
- The controller reply shown acknowledges receipt of the PIREP only. Any additional notice to nearby sectors, other controllers, meteorological services, or inbound aircraft is coordinated separately under the applicable local procedure.
- If the squall will reach the field before you land, report that separately with your intentions, such as holding clear or diverting. The weather report and your own plan are two different messages.
Reference: ICAO Doc 9432
Lose Time En Route
The controller asks you to absorb a few minutes when your arrival is early for its slot. You can do it with speed, with vectors or with a hold, and the aircraft's fuel decides whether you can do it at all.
Pilot
AFFIRM, [Callsign] / NEGATIVE, [Callsign]
ATC
[Callsign], CAN YOU LOSE [number] MINUTES EN ROUTE
ATC
VT-AIR, can you lose 5 minutes en route
ATC
VT-AIR, lose 5 minutes by reducing speed
Pilot
Reducing speed to lose 5 minutes, VT-AIR
- Check the fuel before you answer. Losing time costs fuel whichever way you do it, and taking it on and then asking for direct routing later helps nobody.
- Read back both the time and the method. REDUCING SPEED TO LOSE 5 MINUTES tells the controller which of the three tools you are using.
- If you can only lose part of the time, say the number you can actually manage rather than answering NEGATIVE. Three minutes of the five is still useful to the controller.
Reference: ICAO Doc 9432
Omit Position Reports
Under radar or surveillance cover the controller can see you, so they will tell you to stop making the compulsory reporting point calls. You acknowledge with WILCO, which says you have understood and you will comply.
ATC
[Callsign], OMIT POSITION REPORTS
ATC
VT-AIR, omit position reports
- WILCO is the correct answer here, not ROGER. ROGER only says you heard it. WILCO says you heard it and you will do it.
- Start reporting again on your own initiative if identification is lost or you enter non-radar airspace. The instruction was tied to the controller being able to see you.
- The instruction applies to routine position reports only. Level reports, revised estimates and anything ATC asked you to report specifically still stand.
Reference: ICAO Doc 9432
PIREP (Pilot Report)
Pilots use a PIREP to pass significant weather observations to ATC. Details of turbulence, icing, wind shear, cloud or visibility support the SIGMET picture and broader weather information for crews ahead.
Pilot
[station], [callsign], PIREP [position], [time], [level], [intensity] [phenomenon]
ATC
[callsign], [station], ROGER, [thanks or follow-up request]
Pilot
Hyderabad Control, IndiGo 5231, PIREP overhead VEMNU at one four two five Zulu, flight level three five zero, severe turbulence
ATC
IndiGo 5231, Hyderabad Control, roger, thank you, I will pass it to following traffic
- Choose the intensity term that applies to the phenomenon. Common ICAO descriptors include light, moderate, severe and extreme.
- Keep a radio PIREP concise but include position, time, level, phenomenon and intensity. MODERATE TURBULENCE AT FLIGHT LEVEL THREE FOUR ZERO is a useful minimum.
Reference: ICAO Doc 9432
Report Heading
ATC asks for your heading to help identify you on radar, or to confirm what you are flying before issuing a turn. Answer with the magnetic heading in three digits and nothing else.
Pilot
HEADING [three digits], [Callsign]
ATC
[Callsign], REPORT HEADING
ATC
VT-AIR, report heading
ATC
VT-AIR, identified, turn left heading 250
Pilot
Left heading 250, VT-AIR
- Headings are always three digits, so a heading of ninety degrees is spoken as zero nine zero.
- Give the heading you are flying, not the track you are making good. The controller is comparing your heading with what the radar shows.
- The turn that usually follows is a read-back item, and the direction goes into the read-back with it.
Reference: ICAO Doc 9432
Report Revised Estimate
Pass a revised estimate whenever your estimate for the next compulsory reporting point changes materially from what ATC already has. In non-radar airspace the controller separates traffic on these times, so an old estimate is a real hazard.
Pilot
[Station], [Callsign], REVISED ESTIMATE [fix] [time]
Pilot
Mumbai Control, VT-AIR, revised estimate IGOBA 1018
- The trigger is three minutes. If your estimate for the next reporting point, the FIR boundary or the destination is out by more than three minutes against what ATS already holds, pass a revised estimate as soon as you can.
- Three minutes is the ICAO figure, set in Annex 2 Rules of the Air under inadvertent changes to a flight plan, time variation, and repeated in the position reporting and flight planning material of the Indian AIP. Answer three minutes in the exam unless the question quotes a local figure of its own.
- The rule reads more than three minutes, so exactly three minutes is not yet a trigger. Pass it anyway if you know it is still growing.
- Times are in UTC and are spoken as four digits when there is any chance of confusion, minutes only when the hour is not in doubt.
- You can also be asked for a revised estimate directly. Then you answer with ESTIMATE, the fix and the time, without repeating the whole position report.
Reference: ICAO Doc 9432
Request a QDM or Direction Finding Bearing
Ask for a QDM when you are unsure of your position and want a magnetic heading to steer towards the station. The ground station measures your transmission and gives you the figure, so you keep your microphone keyed long enough for them to take it.
Pilot
[Station], [Callsign], REQUEST QDM
ATC
[Callsign], QDM [three digits]
Pilot
Delhi Tower, VT-AIR, request QDM
- QDM is the magnetic heading to steer to reach the station in zero wind. QDR is the magnetic bearing from the station, and QTE is the true bearing from the station. Examiners ask for all three.
- QDM and QDR are reciprocals of each other. A QDM of 095 is a QDR of 275.
- Read the bearing back in three digits. The reply is only good for the moment it was taken, so ask again if you have been drifting.
- Direction finding is a station by station service, not something every tower has. A ground station provides it only where the aerodrome's AIP entry AD 2.19 lists a VDF, and the large Indian aerodromes list VOR, DME, ILS and NDB rather than VDF. Treat a QDM as a service to ask for and be told about, not one to plan on.
- The procedure is still examinable, because it is standard ICAO phraseology and the fallback when you are lost with a working radio. Learn the call and the read-back even at an aerodrome that cannot give you one.
- Source: ICAO Doc 9432 Manual of Radiotelephony, direction finding, and the AD 2.19 radio navigation and landing aids table of each aerodrome in the Indian AIP.
Reference: ICAO Doc 9432
Request Clearance to Cross an Airway
Use this when your track cuts across a published airway and you need permission to pass through it. The clearance is needed even when you are not changing level, because the controller has to separate you from traffic on the airway.
Pilot
[Station], [Callsign], [position], [level], REQUEST CLEARANCE TO CROSS AIRWAY [designator] AT [fix]
ATC
[Callsign], CLEARED TO CROSS [designator] AT [fix], [level]
Pilot
Mumbai Control, VT-AIR, 30 miles north of Mumbai, FL150, request clearance to cross airway W20 at PARAR
ATC
VT-AIR, cleared to cross W20 at PARAR FL150
Pilot
Cleared to cross W20 at PARAR FL150, VT-AIR
- Give your position and level in the request. The controller cannot judge the crossing without knowing where you are and how high.
- The crossing is needed even in level flight. Being at a level nobody on the airway is using does not make the clearance optional.
- Read back the airway, the fix and the level together. Cross at the fix and the level cleared, not near them.
Reference: ICAO Doc 9432
Request Clearance to Join an Airway
Use this when you are flying outside a route structure and want to join a published airway at a named fix. Ask early enough for the controller to build the join into the traffic flow.
Pilot
[Station], [Callsign], REQUEST CLEARANCE TO JOIN AIRWAY [designator] AT [fix]
ATC
[Callsign], CLEARED TO JOIN [designator] AT [fix], CLIMB [level]
Pilot
Delhi Control, VT-AIR, request clearance to join airway A464 at GULAB
ATC
VT-AIR, cleared to join A464 at GULAB, climb FL230
Pilot
Cleared to join A464 at GULAB, climb FL230, VT-AIR
- The airway designator, the joining fix and the level are all read-back items. This is a route clearance, so nothing in it can be summarised.
- Airway letters are spoken with the phonetic alphabet and the numbers digit by digit. A464 is Alpha four six four.
- You are not cleared to join until you hear CLEARED TO JOIN. Continue on your present routing until then.
Reference: ICAO Doc 9432
Request Direct
Use this request to bypass published intermediate fixes and proceed straight to a later point when traffic and airspace permit. It can reduce track mileage, fuel burn and journey time.
Pilot
[station], [callsign], REQUEST DIRECT [fix]
ATC
[callsign], CLEARED DIRECT [fix] / [callsign], UNABLE [reason]
Pilot
Kochi Control, Vistara 815, request direct PGO
ATC
Vistara 815, cleared direct PGO
Pilot
Cleared direct PGO, Vistara 815
- Repeat the clearance with DIRECT and the complete fix identifier. Do not alter or shorten the fix name.
- A denial is given as UNABLE when the requested route cannot be accepted. ATC may then issue routing via suitable intermediate fixes.
Reference: ICAO Doc 9432
Request Fuel Dumping
Ask for fuel dumping when you have to return or divert soon after departure and the aircraft is above its maximum landing weight. ATC needs to clear the airspace below you and keep you away from populated ground before you start.
Pilot
[Station], [Callsign], REQUEST FUEL DUMPING, [reason]
ATC
[Callsign], FUEL DUMPING APPROVED, CLIMB [level], AREA CLEARED BELOW
Pilot
Mumbai Control, VT-AIR, request fuel dumping, returning due to engine problem
ATC
VT-AIR, fuel dumping approved, climb FL200, area cleared below
Pilot
Fuel dumping approved, climbing FL200, VT-AIR
- Say why you are dumping. The reason is usually an emergency or an urgency, and it should already have been declared with MAYDAY or PAN PAN.
- Read back the level and any routing. ATC has to keep other traffic well clear below and behind you while the dump runs.
- Tell the controller when you start and when you finish. The airspace stays restricted until you report the dumping complete.
Reference: ICAO Doc 9432
Request Level Change
Use during cruise to seek improved fuel efficiency, greater passenger comfort, or avoidance of hazardous weather. Give a concise reason so ATC can assess traffic and select a suitable level.
Pilot
[station], [callsign], REQUEST [climb or descent] FLIGHT LEVEL [level] DUE [reason]
ATC
[callsign], CLIMB (or DESCEND) FLIGHT LEVEL [level], REPORT REACHING / STANDBY / UNABLE
Pilot
Kolkata Control, IndiGo 5231, request climb to flight level three eight zero due weather
ATC
IndiGo 5231, climb flight level three eight zero, report reaching
Pilot
Climb flight level three eight zero, wilco, IndiGo 5231
- Typical reasons are "due performance" for fuel economy, "due turbulence" for comfort, "due weather" for hazardous weather avoidance, and "due icing" when icing is a concern.
- On STANDBY, do not begin the level change. Maintain the current assignment until a revised clearance is received.
Reference: ICAO Doc 9432
Request METAR
Request the latest routine weather report while airborne for a planned destination, chosen alternate, or airport close to a revised route.
Pilot
[station], [callsign], REQUEST [airport] METAR
ATC
[callsign], [airport] METAR AT [time], [report]
Pilot
Hyderabad Control, Alliance 912, request Hyderabad METAR
ATC
Alliance 912, Hyderabad METAR at one four three zero, wind two nine zero degrees six knots, visibility nine kilometres, few clouds two thousand five hundred feet, temperature three four, dew point two two, QNH one zero zero eight
Pilot
QNH one zero zero eight, Alliance 912
- On the radio, name the airport in plain words, for example Hyderabad. Its four-letter indicator, VOHY, is what appears in the written report. Read back the QNH; the rest of the report is information and only needs acknowledging.
- A routine METAR is issued every half hour, both on the hour and thirty minutes past it. A SPECI is issued when weather meets the reporting criteria for a significant change between routine reports.
Reference: ICAO Doc 9432
Request Radar Vectors
Ask for vectors when you want the controller to navigate you for a while, for example after you have lost sight of traffic, when a navigation aid has failed, or when you want to be taken round weather.
Pilot
[Station], [Callsign], NEGATIVE CONTACT, REQUEST VECTORS
ATC
[Callsign], TURN [LEFT or RIGHT] HEADING [three digits]
Pilot
Delhi Approach, VT-AIR, negative contact, request vectors
ATC
VT-AIR, turn left heading 240 for traffic
Pilot
Left heading 240, VT-AIR
- Say why you want vectors. Traffic, weather and a failed aid all lead the controller to a different heading.
- Read back the direction of turn as well as the heading. LEFT HEADING 240 and 240 are not the same read-back.
- While you are on vectors the controller owns your navigation, but you still own your terrain clearance below the minimum vectoring altitude and you still own your own weather avoidance.
Reference: ICAO Doc 9432
Request TAF
Use this request during flight or prior to departure when the destination, an alternate or an en-route station needs updated weather information. TAFs are normally issued every six hours and cover twenty-four or thirty hours.
Pilot
[station], [callsign], REQUEST [airport] TAF
ATC
[callsign], TAF [airport], [validity], [forecast]
Pilot
Kolkata Control, Vistara 815, request Kochi TAF
ATC
Vistara 815, Kochi TAF valid from one two zero zero to one two zero zero, wind zero nine zero degrees one zero knots, visibility eight kilometres, scattered two thousand feet, becoming between one three zero zero and one five zero zero, wind zero nine zero degrees one five knots gusting two five, visibility four kilometres, broken one thousand feet
Pilot
Kochi TAF copied, Vistara 815
- A TAF opens with its validity period, from one time to another. Note both ends: a forecast that expires before your arrival time says nothing about the weather you will actually meet.
- The groups BECMG, TEMPO and FM identify forecast changes. Give particular attention to any group overlapping your ETA, especially where cloud, visibility, wind or weather could influence fuel, alternate or diversion choices.
- If several hours have passed and conditions have changed, ask whether a newer TAF is available. Do not rely on a superseded forecast for fuel, alternate or diversion decisions.
Reference: ICAO Doc 9432
Request Temperature
Ask for the temperature when you need it for a performance calculation, for a density altitude check or to judge the icing risk, and it is not already on the ATIS.
Pilot
[Station], [Callsign], REQUEST TEMPERATURE
ATC
[Callsign], TEMPERATURE [PLUS or MINUS] [value]
Pilot
Delhi Tower, VT-AIR, request temperature
ATC
VT-AIR, temperature plus 24
- Temperature is in degrees Celsius, and the word PLUS or MINUS is spoken so a negative value cannot be lost in a poor transmission.
- Ask for the dew point in the same call when you are judging icing or fog, because the gap between the two is what matters.
- At a Delhi or Chennai style aerodrome in summer the temperature drives your take-off performance directly. It is worth having a current figure rather than an ATIS one that is half an hour old.
Reference: ICAO Doc 9432
Request VMC Descent
Ask for a VMC descent when you are in visual conditions and want to come down faster than the instrument procedure allows, accepting responsibility for seeing and avoiding other traffic while you do it.
Pilot
[Station], [Callsign], REQUEST VMC DESCENT TO [level]
ATC
[Callsign], DESCEND VMC [level], QNH [value]
Pilot
Delhi Control, VT-AIR, request VMC descent to 9000 feet
ATC
VT-AIR, descend VMC 9000 feet, QNH 1013
Pilot
Descend VMC 9000 feet, QNH 1013, VT-AIR
- Accepting a VMC descent puts see and avoid on you. You must stay in visual conditions for the whole descent, and you tell ATC at once if you cannot.
- The level and the QNH are both read-back items. Repeating the word VMC shows the controller you know which kind of descent you have.
- ATC still separates you from the IFR traffic it knows about. Your responsibility is the traffic it cannot separate you from.
Reference: ICAO Doc 9432
Request VOLMET
VOLMET provides scheduled weather for several aerodromes on one broadcast channel during its published operating hours. Tune the frequency shown in the AIP and listen for the destination or alternate. The pilot does not transmit on this channel; any request or follow-up is made to ATC.
Pilot
[station], [callsign], REQUEST [aerodrome] VOLMET
ATC
[callsign], [aerodrome] VOLMET ON [frequency], REPORT BACK ON [frequency]
Pilot
Kolkata Control, IndiGo 5231, request Chennai VOLMET
ATC
IndiGo 5231, Chennai VOLMET on one two six decimal four, report back on this frequency
Pilot
VOLMET one two six decimal four, will report back, IndiGo 5231
- Each VOLMET cycle covers the aerodromes listed for that provider in a planned order. Begin monitoring early enough to hear the destination and alternate reports in full.
- The VOLMET channel carries broadcasts only. After copying the required information, select the assigned ATC frequency again and make a report-back there only if the controller requested it.
Reference: ICAO Doc 9432
Resume Own Navigation
The controller hands navigation back to you at the end of a vectoring sequence. Your read-back names the point you are now going to, so both of you agree on where the aircraft is headed.
Pilot
DIRECT [waypoint], [Callsign]
ATC
[Callsign], RESUME OWN NAVIGATION DIRECT [waypoint]
ATC
VT-AIR, resume own navigation direct IGOBA
Pilot
Direct IGOBA, VT-AIR
- Name the waypoint in the read-back. WILCO alone leaves the controller guessing which point you have set up.
- If you are not sure where you are relative to the route, say so and ask for a position or a track. Resuming own navigation into the wrong fix is worse than admitting the doubt.
- You may also be given a track and distance, for example TRACK 090, 20 MILES, DIRECT AGRA. Read back what you were given.
Reference: ICAO Doc 9432
Resume Own Navigation After Identification is Lost
When the controller loses radar identification of you, they hand navigation back straight away. From that moment you navigate on your own aids, you own your terrain clearance, and you go back to making the position reports you had been told to omit.
Pilot
ROGER, RESUMING OWN NAVIGATION TO [fix], [Callsign]
ATC
[Callsign], RADAR CONTACT LOST, RESUME OWN NAVIGATION TO [fix]
ATC
VT-AIR, radar contact lost, resume own navigation to Agra
Pilot
Roger, resuming own navigation to Agra, VT-AIR
Pilot
Delhi Control, VT-AIR, Agra 1042, FL150, estimating GULAB 1058
- Position reporting starts again by itself. The earlier OMIT POSITION REPORTS was tied to the controller being able to see you, and they no longer can.
- Terrain clearance is yours from this point. Check your minimum safe altitude for the sector before you accept any descent.
- Continue on the last clearance you were given unless the controller replaces it. Losing radar contact does not cancel a clearance.
Reference: ICAO Doc 9432
SELCAL Alert
This is the everyday use of SELCAL on a long oceanic or remote sector. The crew has set up a SELCAL watch and turned the HF volume down. When the ground station wants the aircraft, it sends the aircraft's code, the chime sounds and the light comes on. The crew turns the HF volume back up and answers GO AHEAD, and the station then gives its message straight away. Compare this with a call the crew starts, where the station answers PASS YOUR MESSAGE.
Pilot
[station], [callsign], GO AHEAD
ATC
[callsign], [station], [message, for example REPORT POSITION]
System
Chennai Radio sends SELCAL code Bravo Delta Foxtrot Lima on eight eight seven nine kilohertz. The chime sounds, the SELCAL light comes on, and the crew turns the HF volume up.
Pilot
Chennai Radio, Air India 312, go ahead.
ATC
Air India 312, Chennai Radio, report position.
Pilot
Chennai Radio, Air India 312, position OPAMO at one one four two, flight level three six zero, estimating LULDA at one two one five, next PAGEM, true airspeed four eight five knots.
ATC
Air India 312, Chennai Radio, roger, out.
- When the SELCAL chime sounds, the only right answer is GO AHEAD. The crew has no idea yet what the station wants; the reply just says you are on frequency and listening.
- Because the station started this contact, it goes straight into its message after GO AHEAD. PASS YOUR MESSAGE belongs to the opposite case, when the crew calls first and the station invites them to talk. Mixing up the two is a favourite exam trap.
- The station might want a position report, give a new clearance or pass weather. The opening is the same every time; only the message and the reply that follows change.
- OUT closes the exchange on HF: the speaker has finished and expects no answer. The crew then turns the HF volume down again and goes back to SELCAL watch.
- A clearance that reaches you after a SELCAL call is just as binding as one heard on VHF, and it must be read back in full. Being over the ocean does not relax readback rules.
- Weather passed this way is information, not an instruction. Acknowledge it; what you do about it is your decision.
Reference: ICAO Doc 9432
SELCAL check not received
Use this procedure while airborne if the cockpit shows neither a SELCAL chime nor a lamp response during the test on the assigned primary frequency. Ask the controller to send the code again before reporting SELCAL unserviceable. If that attempt also fails, inform the controller that continuous listening will be maintained on the primary frequency and guard one two one decimal five megahertz, providing an ordinary voice-contact fallback while the decoder remains unavailable.
Pilot
[station], [callsign], NO SELCAL RESPONSE ON [frequency], REQUEST SECOND CHECK
ATC
[callsign], [station], ROGER, SENDING SELCAL [code] AGAIN, STANDBY
Pilot
Chennai Control, Vistara 815, request SELCAL check on one three two decimal six five, code Alfa Golf Kilo Mike.
ATC
Vistara 815, Chennai Control, standby for SELCAL check Alfa Golf Kilo Mike on one three two decimal six five.
SELCAL tone
The controller sends the assigned sequence. Neither a cockpit chime nor a SELCAL lamp indication is observed.
Pilot
Chennai Control, Vistara 815, no SELCAL response, request second check.
ATC
Vistara 815, roger, sending SELCAL Alfa Golf Kilo Mike again, standby.
Cockpit result
The repeated sequence is transmitted once more, but no audible or visual alert appears in the cockpit.
Pilot
Chennai Control, Vistara 815, negative SELCAL on second check, SELCAL unserviceable, will maintain listening watch on one three two decimal six five and one two one decimal five.
ATC
Vistara 815, roger, maintain listening watch on one three two decimal six five and one two one decimal five.
Pilot
Listening watch one three two decimal six five and one two one decimal five, Vistara 815.
- A missed first tone is not enough to label the decoder defective. Interference, a temporary signal fade, an incorrect code selection, or a cockpit setting error may explain the absent alert. Request a repeat test before reporting SELCAL unserviceable.
- During the repeat, the controller should use the exact four-letter SELCAL code assigned to that aircraft. The crew can compare the code heard with the selector setting, helping to identify a configuration mistake before declaring a failure.
- Use the report 'SELCAL unserviceable' only after both the initial transmission and the confirmed repeat fail to activate the system. This formally alerts the controller that selective calling is unavailable and ordinary voice watch will take its place.
- Guard one two one decimal five megahertz serves as the worldwide aeronautical distress and calling frequency. Monitoring it provides a backup means of voice contact and emergency calling when SELCAL cannot alert the crew.
- The controller's final instruction covers both the assigned primary frequency and guard. It keeps ordinary traffic available while preserving a dedicated watch on the emergency frequency for the remainder of the flight.
- A serviceable SELCAL lets the crew keep selector audio low because the unit announces an incoming call. After two failed tests, normal receiver audio must stay audible, which can increase fatigue on a long sector.
- Do not add 'OUT' to close this exchange. Once the controller has confirmed the listening arrangement, the pilot reads back the watch instruction and finishes with the aircraft callsign, as in the final example.
Reference: ICAO Doc 9432
SIGMET Information
ATC broadcasts a SIGMET for hazardous weather observed or predicted, including thunderstorms, severe icing, turbulence and volcanic ash. To acknowledge the advisory, state its SIGMET number and repeat any information specifically requested by the controller.
Pilot
[station], [callsign], SIGMET [number] COPIED
ATC
ALL STATIONS, [station], SIGMET [number]: [phenomenon] [area], valid [validity]
ATC
All stations, Guwahati Control, SIGMET two one, severe icing forecast between flight level one seven zero and flight level two six zero within five zero miles of Guwahati, valid from zero eight zero zero to one zero zero zero
Pilot
Guwahati Control, IndiGo 5231, SIGMET two one copied
- A SIGMET normally remains valid for no more than four hours. The limit may be extended to six hours for volcanic ash or tropical cyclone events.
- State the identifier when acknowledging a SIGMET. This tells the controller which advisory has been received, particularly when more than one is in force.
Reference: ICAO Doc 9432
Speed Control
ATC assigns speeds to preserve required separation during en route flight and within terminal areas. Below flight level two five zero, the instruction gives IAS in knots; at flight level two five zero and above, it gives a Mach value. The pilot should read back the speed together with any flight level or heading connected to the clearance.
Pilot
[assigned speed readback], [callsign]
ATC
[callsign], MAINTAIN [speed] [or REDUCE SPEED TO [speed] / INCREASE SPEED TO [speed]]
ATC
Vistara 815, Hyderabad Control, descend flight level one eight zero, maintain two three zero knots
Pilot
Descend flight level one eight zero, maintain two three zero knots, Vistara 815
ATC
Vistara 815, reduce speed to two one zero knots
Pilot
Reduce speed to two one zero knots, Vistara 815
- A Mach value is spoken using 'point', for example, 'Mach point seven four'. The word 'point' replaces the decimal mark in speech.
- If turbulence, traffic, aircraft performance, weight, or configuration prevents compliance, notify ATC without delay and state the reason and your actual speed.
- Obey a release to resume normal speed only when it can be done safely. After the aircraft is back at its normal value, inform ATC.
Reference: ICAO Doc 9432
Stop Descent or Continue Climb
ATC will stop you at an intermediate level when traffic appears below you or a level becomes unavailable. Your read-back has to carry the level, because that level is now the whole clearance.
Pilot
STOPPING DESCENT AT [level], [Callsign]
ATC
[Callsign], STOP DESCENT AT [level]
ATC
VT-AIR, stop descent at FL150
Pilot
Stopping descent at FL150, VT-AIR
- Never answer with ROGER or WILCO alone. The level is the read-back item and leaving it out is a standard exam fail.
- The same shape is used to reverse a descent into a climb. CLIMBING TO FL190 tells the controller which way you are now going and where you will stop.
- Stop the aircraft at the new level even if it means an abrupt change of rate. The controller has issued it because separation depends on it.
Reference: ICAO Doc 9432
Three-Sixty Turn or Orbit En Route
ATC uses a three-sixty turn or an orbit to buy time or spacing without changing your route. You hold the assigned level throughout and report when you are back on track.
Pilot
THREE SIXTY TURN LEFT, [Callsign]
ATC
[Callsign], MAKE A THREE SIXTY TURN LEFT FOR SPACING
ATC
VT-AIR, make a 360 turn left for spacing
Pilot
Three sixty turn left, VT-AIR
Pilot
VT-AIR, back on track
- Read back the direction of turn. A three sixty in the wrong direction can take you into the traffic the turn was meant to space you from.
- The cleared level does not change during the turn. Hold it and hold the assigned track once you roll out.
- Report back on track when the turn is complete. The controller is waiting for that call before resequencing you.
Reference: ICAO Doc 9432
Transponder Mode Instructions
ATC uses short standard words to change what your transponder is doing. IDENT sends a special return that makes your label flash, STANDBY stops the transponder replying, CHARLIE turns the altitude reporting back on, and RESET makes you re-enter the code.
Pilot
SQUAWKING IDENT, [Callsign] / STANDING BY, [Callsign] / SQUAWKING CHARLIE, [Callsign]
ATC
[Callsign], SQUAWK IDENT / SQUAWK STANDBY / SQUAWK CHARLIE / RESET SQUAWK [code]
Pilot
Squawking ident, VT-AIR
ATC
VT-AIR, squawk charlie
Pilot
Squawking charlie, VT-AIR
- Say what you are doing, not just ROGER. SQUAWKING IDENT and STANDING BY tell the controller which mode the box is now in.
- SQUAWK CHARLIE means switch on the pressure altitude reporting. Mode C is the reason the controller can see your level at all.
- Press IDENT once and only when asked. Pressing it unasked puts a flashing label on a screen the controller is trying to read.
- Never select STANDBY on your own while airborne in controlled airspace. You disappear from the radar picture as far as the code and the level are concerned.
Reference: ICAO Doc 9432
Visibility falls below AOM during taxi
Use this when fog or haze drops the visibility below the aerodrome operating minima while you are taxiing out, so continuing to the runway serves no purpose. Tell ATC where you are and that visibility is below minima, and ask how it is expected to change. If the controller says it will get worse and asks your intentions, ask to go back to the stand and wait. ATC then gives a new taxi clearance back to the apron.
Pilot
[station], [callsign], TAXIWAY [taxiway], VISIBILITY BELOW AERODROME OPERATING MINIMA, REQUEST TREND
ATC
[callsign], [station], [visibility trend], ADVISE INTENTIONS
Pilot
Lucknow Tower, Alliance 912, taxiway Charlie, visibility below our minima, request trend.
ATC
Alliance 912, Lucknow Tower, RVR runway two seven now three five zero metres and falling, fog expected to thicken, advise intentions.
Pilot
Lucknow Tower, Alliance 912, request return to the apron to wait for improvement.
ATC
Alliance 912, taxi to stand five via Charlie and Alfa.
Pilot
Stand five via Charlie and Alfa, Alliance 912.
- Giving your taxiway tells the controller exactly where you are, so a route back to the apron can be planned without conflicting with other movements.
- Aerodrome operating minima are the lowest visibility or RVR at which your aircraft and crew may legally take off or land at that aerodrome. Below them, the departure cannot go ahead.
- REQUEST TREND asks whether the visibility is expected to improve, stay the same or get worse. The answer helps the crew decide between a short wait on the taxiway and going back to the stand.
- A falling trend means holding near the runway is pointless, which is what prompts the crew to return.
- ADVISE INTENTIONS leaves the decision to the pilot in command. ATC does not tell the crew what to do; it helps with whatever the crew decides.
- Asking to wait at the apron is a sensible choice when improvement is expected within a reasonable time. Other options, such as cancelling the flight, are company decisions.
- The controller gives a definite stand and route so the return is orderly. Taxiway letters are said with the ICAO alphabet.
- The readback leaves out the station name and gives the stand and route, then the callsign. That is all a ground readback needs.
Reference: ICAO Doc 9432
Weather Deviation
Use this to ask for a temporary turn off track around weather such as a thunderstorm cell, icing or turbulence. Say which side and how far you need to go, how long you expect to be off track, and that you will come back.
Pilot
[station], [callsign], REQUEST DEVIATION [distance] MILES [left or right] OF TRACK DUE WEATHER, [expected duration]
ATC
[callsign], DEVIATION [distance] MILES [left or right] OF TRACK APPROVED, [level or other restriction], REPORT BACK ON TRACK
Pilot
Kolkata Control, Vistara 815, request deviation one five miles left of track due weather, for about eight minutes
ATC
Vistara 815, deviation one five miles left of track approved, maintain flight level three six zero, report back on track
Pilot
One five miles left of track approved, maintain flight level three six zero, wilco, Vistara 815
- Put the side and distance first, such as one five miles left, so the controller can check the airspace you will use against other traffic straight away.
- Call when you are back on track. Until then the controller keeps the deviation area protected, and your report lets it be released.
- If the weather leaves no time to ask, turn first and tell ATC, for example "deviating left of track due weather". That is a notification of what you are doing, not a request.
Reference: ICAO Doc 9432