Radio Communication Fail • Communications

SYS

ConditionCondition

Perte radio / lost-comm — timer, re-établissements, squawk, isolation RTP/ASP, procédures ICAO/FAR.Radio loss / lost-comm — timer, re-establish attempts, squawk, RTP/ASP isolation, ICAO/FAR procedures.

ObjectifObjective

Démarrer un timer (RVSM), tenter fréquences / 121.50, squawk 7600 (USA 7700→7600), isoler panneau/mic.Start a timer (RVSM), try frequencies / 121.50, squawk 7600 (USA 7700→7600), isolate panel/mic.

◈ LIVE RTP ◈ LIVE ASP

In FLT

INITIAL ACTIONS

Démarrer un timer — beaucoup de procédures lost-comm sont time-based ; pertinent RVSM.Start a timer — many lost-comm procedures are time-based; relevant to RVSM.
Re-établir : radio check ATC freq actuelle ; autres aéronefs sur freq ; freq précédente ; 121.50.Re-establish: radio check ATC on current freq; other aircraft on freq; try previous freq; try 121.50.
Squawk 7600. USA : 7700 pendant 1 min puis 7600 pendant 15 min.Squawk 7600. USA: 7700 for 1 min then 7600 for 15 min.
Speakers : volume up ; PTT pas locké INT ; Service Interphone Switch OFF.Speakers: volume up; PTT not locked INT; Service Interphone Switch OFF.
RTP erratique ? Isoler en tunant freqs différentes sur chaque panneau VHF ; essayer VHF-2, VHF-3, HF.RTP erratic? Isolate by tuning different freqs on each VHF panel; try VHF-2, VHF-3, HF.

7600 général · séquence USA 7700→7600.General 7600 · USA 7700→7600 sequence.

MIC / HEADSET / ASP

6 mics : Capt boom+hand ; F/O boom+hand ; OBS hand ; PA hand (aft stand). Unplug/replug un par un.6 mics: Capt boom+hand; F/O boom+hand; OBS hand; PA hand (aft stand). Unplug/replug one-by-one.
ASP R/T–I/C non coincé ; 3 headsets unplug/replug. Cross-link Continuous TX / ALT mode.ASP R/T–I/C not stuck; unplug/replug 3 headsets. Cross-link Continuous TX / ALT mode.

APPLY PROCEDURES

ICAO Doc 4444 §12.4.1.9 ; lost-comm aérodrome-spécifique ; cruise → règles RVSM / oceanic.ICAO Doc 4444 §12.4.1.9; aerodrome-specific lost-comm; cruise → RVSM / oceanic rules.
ACARS (as installed) : envoyer POSITION ou DIVERSION à la compagnie.ACARS (as installed): send POSITION or DIVERSION to company.
CPDLC (as installed) : contacter ATC via page CPDLC ATC MSG.CPDLC (as installed): contact ATC via CPDLC ATC MSG page.
Diversion cue : DIVTO + code IATA dans FLT NO. sur FMS RTE (ex. DIVTOSYD).Diversion cue: put DIVTO + IATA code in FLT NO. on FMS RTE (e.g. DIVTOSYD).
FAR 91.185 [Two-way radio communications failure].FAR 91.185 [Two-way radio communications failure].

CHECKLIST ISOLATIONISOLATION CHECKLIST

#	Item
1	Timer ON (RVSM)
2	ATC / other a/c / prev freq / 121.50
3	Squawk 7600 (USA 7700→7600)
4	Speakers up · PTT ≠ INT · SERV INT OFF
5	Isolate RTP · try VHF-2/3/HF
6	Mics / headsets / ASP R/T–I/C
7	ACARS POSITION/DIVERSION · CPDLC · DIVTO+IATA
8	Doc 4444 · FAR 91.185 · aerodrome/RVSM

ASP ALT : pull P6-2B/C pour tester path dégradé — détails Audio Panel ALT.ASP ALT: pull P6-2B/C to test degraded path — details on Audio Panel ALT.
Stuck mic possible cause de « lost RX » perçu — Stuck Mic.Stuck mic can cause perceived “lost RX” — Stuck Mic.
LIVE : RTP + ASP/PTT + XPDR 7600/7700 + Service Interphone Switch.LIVE: RTP + ASP/PTT + XPDR 7600/7700 + Service Interphone Switch.

RVSM / oceanic lost-comm = time-based — d’où le timer dès le début. DIVTO+IATA alerte ATC via plan de vol.RVSM / oceanic lost-comm is time-based — hence timer from the start. DIVTO+IATA alerts ATC via flight plan.

Normal teaching + refs réglementaires. Urgence QRH séparée. LIVE XPDR 7600/7700.Normal teaching + regulatory refs. Separate QRH emergency. LIVE XPDR 7600/7700.