Communications - Radiotelephony and Emergencies
Radiotelephony discipline
Good RT is standard, brief and unambiguous. Learn the phonetic alphabet, the standard words - roger, wilco, affirmative, negative, say again, standby, unable, request - and use the standard call sequence: who you are calling, who you are, position and level, and your request. Read back all safety-related clearances: route clearances, runway in use, altitudes and flight levels, headings, frequencies and transponder codes.
Distress and urgency
MAYDAY is for grave and imminent danger; PAN PAN is for urgency without immediate danger. Use 121.5 for emergency communications and know the distress call: MAYDAY three times, callsign, nature of distress, intentions, position, level, fuel and persons on board. Squawk 7700 for an emergency, 7600 for radio failure and 7500 for unlawful interference.
Radio failure and range
Know the lost-communication procedure: squawk 7600, try alternate frequencies including approach, tower and 121.5, and follow the published procedure for your flight rules. VHF is line of sight, so range increases with the square root of height.
Common traps
Saying 'roger' when a readback is required; confusing 'wilco' with 'affirm'; using the word 'take-off' outside a clearance; and omitting the callsign.
Worked example
An aircraft at 4,000 ft has roughly 1.23 × √4000 ≈ 78 NM of VHF range to a station at sea level, so a distant station that cannot be raised may simply be out of range rather than off frequency.