Phrase 1 of 15General procedures
Numbers and callsign conventions
Every number you say on the radio follows one set of rules: most numbers digit by digit, a few groups in hundreds and thousands. Callsigns have short rules of their own.
The pattern
You say
station, callsign, message, numbers said as mats 12.5 gives them
ATC says
callsign, station, message, numbers said as mats 12.5 gives them
Example
- ATC
IFLY 160, Delhi Approach, turn left heading one zero zero, descend to five thousand feet, QNH one thousand, squawk two four zero zero
- You
Left heading one zero zero, descend to five thousand feet, QNH one thousand, squawk two four zero zero, IFLY 160
- ATC
IFLY 160, correct
Remember
- ✓Transmit most numbers digit by digit: runway two seven, heading zero eight zero, squawk four two one three. Use HUNDRED for whole-hundred flight levels: flight level one hundred, flight level two hundred and flight level three hundred. Say other levels digit by digit, for example flight level one eight zero. Use THOUSAND for an altimeter setting or squawk code that is a whole thousand: QNH one thousand, squawk two thousand. Other settings and codes stay digit by digit, for example QNH one zero zero niner and squawk two four zero zero. A heading stays digit by digit even when it is a whole hundred: heading one zero zero. AAI MATS Part 1, Edition 7 (May 2025), paragraph 12.5.1 gives this rule. Do not say "three zero zero" for flight level three hundred: it is marked wrong.
- ✓Altitude, cloud height, visibility and RVR in whole hundreds and thousands take HUNDRED and THOUSAND: eight hundred, three thousand four hundred, one two thousand for 12,000, visibility seven hundred, RVR one thousand seven hundred (MATS 12.5.2).
- ✓Say DECIMAL in a frequency and leave out a zero at the end: 121.750 is one two one decimal seven five, and 118.100 is one one eight decimal one.
- ✓A callsign is the registration (VTEJP), the operator's telephony designator and the last four characters of the registration (INDAIR TEJP), or the designator and the flight number (INDAIR 809). Its digits are said one by one: Air India 1229 is Air India one two two niner (MATS 12.7.2.1, Table 12-3).
- ✓Once contact is made and no confusion is likely, a registration callsign may be shortened, for example VJP or INDAIR JP. A designator and flight number, such as Air India 1229, is never shortened (MATS 12.7.2.2).
Now say it out loud, with the examiner playing ATC.
Practise in the simulator