Microphone technique

Microphone Technique

Correct microphone technique is decisive for intelligible radio calls. Even the best radios cannot compensate for poor technique.

Microphone types in the cockpit

1. Hand microphone

• External unit on a coiled cable.
• PTT button on the microphone.
• Common: older Cessna 152/172, some PA-28.

2. Headset-mounted boom microphone

• Headset-integrated: microphone on the headset boom.
• PTT button on yoke or boom.
• Modern standard equipment.

3. Active noise-reducing headset (ANR)

• Active noise reduction: electronic noise cancelling.
• Examples: Bose A20, David Clark DC ONE-X, Lightspeed Zulu 3.
• Best speech intelligibility, expensive (€800-1200).

Microphone position

Optimum distance: 2-4 cm from the mouth.

• Too close: boomy sound, "pop" from B/P consonants.
• Too far: weak signal, ATC squelch closes.

Microphone in front of the mouth, NOT to the side:

• Best speech intelligibility.
• Breathing noise minimal.

Speaking technique

Speed

• 100 words per minute target.
• For critical content (altitude, heading, frequency): slightly slower for clarity.
• Don't rush — rather two short calls than one rushed and unintelligible.

Volume

• Normal speaking pace, normal volume.
• Don't shout — distorts signal (overdrive).
• Don't whisper — intelligibility suffers.

Pronunciation

• Clear articulation of consonants.
• Phonetic alphabet for letters (Alpha, Bravo, ...).
• Niner instead of nine for digit 9.
• Tree instead of three in some ICAO recommendations (to distinguish "tree" vs "three" on phone).

Push-to-talk (PTT) procedure

Correct sequence

1. Press PTT.
2. Brief wait (~0.5 s) — transmitter starts up, network "listens".
3. Speak — clear articulation.
4. End of message — keep PTT briefly held.
5. Release PTT — transmitter off.

Errors

• Press and speak immediately: first syllables cut off.
• Release PTT immediately after speaking: last syllable can be lost.
• Hold PTT too long (after speech): blocks the frequency.

Stuck mic / hot mic

Stuck mic: PTT switch physically stays pressed → transmitter sends continuously → blocks the frequency for everyone.

Recognition:

• ATC calls repeatedly with no answer.
• "Aircraft on XXX.XX, stuck mic" — other pilots or ATC report.

Resolution:

• Inspect PTT switch mechanically (jammed?).
• Repeated stuck: turn off radio or change frequency.
• Emergency: in distress Mayday on 121.500.

Common errors

• Microphone too far → ATC hears weak.
• PTT released too late → breath or chatter transmitted afterward.
• Background noise too loud (cockpit noise, pax chat).
• Hectic speech on approach or under stress.

Headset recommendation

• Active headset if budget allows: better intelligibility, long-term ergonomics (avoiding hearing damage, Subject 040).
• Earplug headsets: lighter, cheaper, less comfortable on long flights.

Emergency radio

Handheld radio as backup:

• Examples: Yaesu FTA-450, ICOM IC-A16.
• Important: separate power supply, often battery-powered.
• On total avionics loss: handheld can save communication with ATC.

Audio panel operation

• COM1 or COM2 selected for transmit.
• MIC select switch: ensures the chosen COM transmits when PTT is pressed.
• NAV1/NAV2 to listen to Morse identifiers on VOR / NDB / LOC.