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CX-3 flight computer online

The CX-3 below is the official web version, running inside this page, and the rest of the page explains what each of its functions is for.

The CX-3 flight computer, provided by Sporty’s, running inside Ready Aviator

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What the CX-3 is

The CX-3 is an electronic flight computer. It does everything the circular slide rule E6-B does, and it adds the things a slide rule cannot: holding pattern entries, rhumb line navigation, weight and balance, and a multi leg trip planner. The version below is the official web build, running inside this page. It is not ours, we have not modified it, and it is free to use here with no account.

Everything the device computes, our own worked solutions compute too, from the same reference material. If a number here and a number in a solution ever disagree, the solution is the one that shows its working.

The sixteen flight functions, and what each one is for

Unit conversions

Converts across twelve categories: distance, speed, duration, temperature, pressure, volume, fuel rate, weight, rate and angle of climb, torque and angle. This is the function most DGCA papers actually need, because a question routinely gives you one unit and wants the answer in another.

Altitude

Indicated altitude and QNH to pressure altitude, then pressure altitude and temperature to density altitude and true altitude. It is a two step calculation and the device treats it as one.

Cloud base

Temperature and dew point to the height of the convective cloud base.

Standard atmosphere

The ISA pressure, temperature and density at any altitude, which is the reference every performance question is measured against.

Airspeed

CAS, TAS and Mach against pressure altitude and temperature, including the true and total air temperature relationship.

Fuel

Fuel quantity, flow and endurance, any one from the other two.

Ground speed

Distance, time and groundspeed, any one from the other two. This is speed, distance and time, not the wind triangle.

Glide

Glide ratio, height lost and distance covered.

Climb and descent

Rate, gradient, time and distance for a climb or a descent, including the top of descent question.

Wind component

A wind split into its headwind and crosswind components against a runway. The runway limit question.

Estimated time of arrival

Departure time and elapsed time to an arrival time, in clock time.

To and from a station

Time and distance to a station from a bearing change, which is the classic ADF and VOR fix question.

Compass heading

True, magnetic and compass heading through variation and deviation. East is positive on the device.

Wind correction

The wind triangle itself: track, TAS and wind to heading, groundspeed and drift.

Rhumb line

Rhumb line track and distance between two positions.

Holding pattern

The entry sector for a hold, from the track over the fix, the holding radial and the turn direction.

Press FLT to reach this list on the device, the up and down arrows to move through it, and the tick to choose one. Every function solves for whichever field you leave empty, so you enter what you know and press equals for what you do not.

Five things that go wrong on the device

Set your default units before you start, not per question. Knots, nautical miles, feet, degrees Celsius, hectopascals and hours and minutes. Most wrong answers on this device are right answers in the wrong unit.
The colon key is how you enter a time. 1:45 is one hour forty five minutes. Typing 1.45 gives you one and forty five hundredths of an hour, which is one hour twenty seven minutes, and the device will not warn you.
Wind direction is the direction the wind is coming FROM, as it is everywhere else in aviation.
Variation is positive East and negative West. West variation needs the plus or minus key, and forgetting it is a two times variation error, not a one times one.
Density altitude is two steps. Indicated altitude and QNH give pressure altitude, and only then do pressure altitude and temperature give density altitude. Skipping the first step is the most common single mistake on this function.

Carrying one into the exam

Our own reference guide to this device records that the CX-3 is approved for use in FAA and DGCA pilot examinations. That sentence comes from the manufacturer, not from a DGCA publication, and we are not going to dress it up as more than it is.

What is permitted in the hall is set by the DGCA, it is stated on the examination notice and on your admit card for the session you have booked, and it can change between sessions. Read that notice rather than any website, including this one, and if it is unclear, ask before the day rather than at the door.

The DGCA publishes its examination notices on the Pariksha portal at pariksha.dgca.gov.in. Our guide to the Pariksha portal explains where the notices appear and what else the portal is for.

The same calculations, worked rather than computed

A flight computer gives you a number. It does not give you the method, and the DGCA paper is testing the method. These are the same calculations with the working shown, and they are free too.

Wind correctionThe wind triangle the device solves in one press, drawn to scale with the drift and the heading worked through.Open AltitudeThe two step pressure altitude then density altitude calculation, with both steps written out.Open Holding patternThe entry sector, with the sector diagram drawn and the leg against radial trap named.Open Wind componentThe runway split, with the sine and cosine on one line.Open FuelEndurance and range, and the two the device does not do at all: the point of no return and the critical point.Open Air Navigation question bankEvery chapter of the paper these functions are examined in, with a worked solution behind each question and five free samples in every chapter.Open

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Groundspeed and wind

Track, TAS and wind solved as a triangle, with the triangle drawn to scale.

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Five question mock

Real DGCA questions under a clock, marked, with no account.

Ready Aviator

Now do it under exam conditions

Air Navigation has 1,929 practice questions, every one worked through. Free to start.