Phraseology & callsigns

090 CommunicationsChapter 2

Number pronunciation

Key fact

Uses the NATO phonetic alphabet. Numbers are always spoken as separate digits, except altitudes, cloud heights, visibility, and RVR may use the whole number. For numbers over 9,999, the number of thousands should be stated — e.g. 12,000 ft = “One Two Thousand”.

Key fact

Decimal points are transmitted as “decimal” — always used when giving a frequency. All six digits of a frequency should be used; if the last two digits are zero, these may be omitted.

Key fact

Times use the 24-hour clock with four digits in UTC. Minutes only if no confusion about the hour. Time checks are to the nearest half minute — e.g. “Time Check Two Three Three Zero”.

Callsign formats

Registration number

Form	Example
Full	”HB-XYJ”
Abbreviated	”H-YJ” (first and last two letters)

Key fact

The type/manufacturer of aircraft may be used instead of the first letter — e.g. “Citation BXYJ”. If so, abbreviation is just the last two letters — “Citation XJ”.

Operator + registration

Form	Example
Full	”FlyKeys PVMA”
Abbreviated	”FlyKeys MA”

Operator + flight number

Form	Example
Full	”Jersey 1234”
Abbreviated	May NOT be abbreviated

Key fact

Full callsigns are used until addressed by ATC in abbreviated form. ATC may temporarily change a callsign. “Heavy” is added on the first call if in the heavy wake turbulence category (over 136,000 kg) — e.g. “Speedbird 123 Heavy”.

Exam trap

Flight number callsigns may NOT be abbreviated. Registration and operator+registration callsigns may be shortened after the first call if no confusion.

Callsign shortening

Key fact

Callsigns are shortened by removing location/suffix after the first call, provided there will be no confusion.

Standard call formats

Situation	Format
First call	”Station callsign, your (full) callsign”
New information	”Aircraft callsign, then request”
Reply	”Information, then callsign”

Readback requirements

Key fact

Readback is required for: level, heading and speed instructions; clearances; runway in use; VDF information; frequency changes (only the frequency); SSR; radar service; altimetry; and anything with numbers involved.

Message priority

Messages are prioritised in this order:

1. Distress — “MAYDAY”
2. Urgency — “PAN PAN”
3. Direction finding — Q codes for directions
4. Flight safety — of immediate concern (normal ATC messages, including PIREPs)
5. Meteorological — reports, forecasts, warnings (METARs etc.)
6. Flight regularity — schedule changes, servicing, operations

Radio check

Key fact

Include station, callsign, “radio check” and frequency in use. Replies will not include the frequency. Transmission should be under 10 seconds long. “1, 2, 3, 4, Station” is a test call.

Readability categories

Category	Meaning
1	Unreadable
2	Readable now and then
3	Readable with difficulty
4	Readable
5	Perfectly readable

Exam trap

“TO” is allowed if preceding an altitude, height, or flight level — EASA only. Do not assume this applies outside EASA airspace.