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This question focus on airliners but is not restricted to Airbus and Boeing.

In aircraft, there are a lot of audible warning (usually working along with visible warning). This include auto-pilot disengaged, stall, GPWS, wrong flaps configuration, low energy, ... (I'm not aware of all audible warning that are implemented)

Given one of this warning, is the sound associated to this warning the same in different aircraft? For example, does a GPWS warning sound the same in Boeing, Airbus, Embraer,...?

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General alerting sounds are chosen by the manufacturer of the cockpit systems. Stall warnings, autopilot disconnect alerts, fire alarms etc. are all not standardised, with the exception of the words spoken by the GPWS/TAW and TCAS system.

Whilst the exact sounds of these two systems are not standardised in the sense that a standard .wav file is to used by all manufacturers, the phraseology in their aural alerts is standard.

The Ground Proximity Warning System (GPWS)/ Terrain Awareness Warning System (TAWS) will have to issue an aural warning 'PULL UP, PULL UP' if the aircraft is approaching terrain, and 'GLIDESLOPE' when the aircraft is deviating far below the glideslope. Also the cautions ('SINKRATE.', 'TERRAIN.', 'DON'T SINK.', 'TOO LOW, GEAR.', 'TOO LOW, FLAPS.', 'TOO LOW, TERRAIN.' and 'FIVE HUNDRED.')1 are standardised. Whether it is a male, female or robotic voice is up to the manufacturer of the system, but the words are uniform across all systems. Additional cautions and aural alerts are allowed as long as they are clear and unambiguous.

The same holds for TCAS; 'TRAFFIC, TRAFFIC.', 'CLIMB, CLIMB.', 'DESCEND, DESCEND.', 'INCREASE CLIMB,', 'INCREASE DESCENT,', 'REDUCE CLIMB,', 'REDUCE DESCENT.', 'CLIMB, CLIMB NOW.', 'MAINTAIN VERTICAL SPEED, MAINTAIN.', 'LEVEL OFF, LEVEL OFF.' (supersedes "ADJUST VERTICAL SPEED, ADJUST), 'MONITOR VERTICAL SPEED.', 'CROSSING.' and 'CLEAR OF CONFLICT' are all standard phrases which have to be implemented in this exact wording(2).


1FAA TSO C151c Table 4-1 (pages 16 -- 18)

2 RTCA DO-185B, Minimum Operational Performance Standards for Traffic Alert and Collision Avoidance System II (TCAS II) Version 7.1, Volume I section, 2.2.6.3: Aural annunciations)

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    $\begingroup$ "standard phrases which have to be implemented in this exact wording" Do you have any citation for (particularly) this? Your answer would be much better IMO if it provided references for the claims made. $\endgroup$ – a CVn May 26 '15 at 14:14
  • $\begingroup$ @deltalima OK for phrases, but what of the sound that are not words (e.g. stall, auto-pilot disengaged,...) $\endgroup$ – Manu H May 26 '15 at 14:15
  • $\begingroup$ @MichaelKjörling reference included. $\endgroup$ – DeltaLima May 26 '15 at 15:40
  • $\begingroup$ @DeltaLima Much, much better, thank you! $\endgroup$ – a CVn May 27 '15 at 7:25
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No, the exact sound of a warning is not regulated across aircrafts. (By the way, "normalize a sound" refer to a special process in audio mixing.)

For example, the autopilot disengage sound in Airbus is very distinct. Airbus and Boeing has different altitude callout sounds as well (500, 400, 300, 200, 100, 50, 20, 10. retard. retard.)

Even sounds within planes from the same manufacturer are different. The fire warning in a Boeing 737 sounds like a physical fire bell, while that on a Boeing 777 is an electronic "beep beep beep" sound. The same applies to other sounds like takeoff configuration warning and Master Caution.

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