I was going through Helios crash and learned that Boeing was blamed for having similar sounding alarms for different alarm conditions.

  • On a given aircraft, can two different warning alarms have the same sound?
  • If so, what other aircraft have the same sound for different kinds of alarms?
  • Has Boeing changed their alarm systems post that incident?
  • 1
    $\begingroup$ Possible duplicate of Are the audible warning standardized? $\endgroup$
    – Manu H
    Commented Oct 12, 2015 at 9:58
  • $\begingroup$ @Manu H That question says are audible warning systems are standards across different aircrafts like Boeing/Airbus etc but my question is more like do they creates similar type of sound for every alarm or have different kind of beep sounds for different kind of alarms? $\endgroup$
    – NitinG
    Commented Oct 12, 2015 at 11:27
  • $\begingroup$ quoted from this answer: "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.". I think your question as it is written now already has great pieces of answers in the answers of the question Are the audible warning standardized? and I encourage you to be more specific. $\endgroup$
    – Manu H
    Commented Oct 12, 2015 at 11:52
  • $\begingroup$ @NitinG I rephrased your answer based on your comment. Feel free to revert the edit if I didn't understand what you meant. $\endgroup$
    – usernumber
    Commented Oct 12, 2015 at 12:16

2 Answers 2


Has boeing changed their alarm systems post that incident?

The story of Helios Airways flight 522 is complicated. It is not clear that a misidentified alarm was the cause of the crash.


If you are talking about the cabin altitude warning horn, that was allegedly misidentified as a take-off configuration, then nothing has been changed, at least up to May 2015 (see: The Boeing 737 Technical Guide, Version 70, May 2015, bottom of the page 50).

"As the aircraft climbed, the pressure inside the cabin gradually decreased. As it passed through an altitude of 12,040 feet (3,670 m), the cabin altitude warning horn sounded. The warning should have prompted the crew to stop climbing, but it was misidentified by the crew as a take-off configuration warning, which signals that the aircraft is not ready for take-off, and can only sound on the ground. In the next few minutes, several warning lights on the overhead panel in the cockpit illuminated. One or both of the equipment cooling warning lights came on to indicate low airflow through the cooling fans (a result of the decreased air density), accompanied by the master caution light. The passenger oxygen light illuminated when, at an altitude of approximately 18,000 feet (5,500 m), the oxygen masks in the passenger cabin automatically deployed."m, Source: Helios Airways Flight 522.

  • 2
    $\begingroup$ and this would answer the question how? $\endgroup$
    – Federico
    Commented Oct 12, 2015 at 9:13
  • $\begingroup$ Ur answer dont answer the question. This question doesnt say that what happened to Helios but asks if there are similar alarming alarms still in the cockpit? $\endgroup$
    – NitinG
    Commented Oct 12, 2015 at 9:20

If so, what other aircraft have the same sound for different kinds of alarms?

On older LR-JET typed learjets (31, 35, etc) the overspeed and cabin altitude warning sounds are eerily similar. It hard to tell which one it is without verifying both airspeed indicators.


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