Instead of trying to figure out what the noise is (since it can't be take off config if you're already airborne. A lot of training is on take offs and landings (which is of no surprise) and one tends to immediately realize what the noise is telling you!
This is somewhat baffling, as you only get takeoff warning on the ground, and only get cabin altitude warning in flight (excepting very high altitude airports, which wasn't the case here).Īnd one would be amazed at how many crew made the mistake (although all but Helios) and only eventually realizing that it was the cabin pressure. Quoting tdscanuck ( Reply 3): However, the cabin altitude warning and the takeoff config warning use the same horn.apparently, the crew mistook one for the other. Quoting tdscanuck ( Reply 6): This isn't a new problem from the Helios accident
This was just a particularly egregious example. This isn't a new problem from the Helios accident.pilots have flown aircraft into the ground while fixated on troubleshooting a different problem, or on torubleshooting what they think is the problem instead of what's actually the problem. There's obviously a human factors issues there, but it's an open question as to exactly how much misinterpretation can you assume on the behalf of the flight crew. However, they got task focussed and misinterpreted the warning. The crew had all the information necessary (including the great big cabin pressure readout on the overhead panel) to understand what was happening. If you get the horn on the ground, it's takeoff config. If you get the horn in air, it's the cabin altitude. The argument that this was an acceptable thing to do is that the two modes are mutually exclusive (except very high altitude airports, which is a corner case with special planning anyway). The FCOM is very specific that the takeoff config warning and cabin altitude warning use the same horn (same sound). Quoting rolfen ( Reply 4): The second question I was asking myself is: even if there is no warning light, don't they have a reference at hand for understanding different warning sounds.? They misinterpreted the warning, for reasons unknown, and didn't take the appropriate corrective action. This is somewhat baffling, as you only get takeoff warning on the ground, and only get cabin altitude warning in flight (excepting very high altitude airports, which wasn't the case here).īasically, the plane correctly told the flight crew exactly what was wrong. However, the cabin altitude warning and the takeoff config warning use the same horn.apparently, the crew mistook one for the other. The warning system worked just fine, and correctly annunciated to the crew that the cabin altitude was becoming too high. The maintenance crew didn't put the pressurization system back in the mode the flight crew expected. Quoting Fly2HMO ( Reply 1): Also, while I haven't seen that documentary, I seem to recall reading that the warning system was defective. You should get a master warning and illumination of the AIR COND six-pack light, which directs the flight crew to look up at the air conditioning panel where you would see the actual cabin altitude, the AUTO FAIL light, etc. Been a while since my 737 training though so take that with a grain of salt. It will go off when the cabin pressure goes above 14000ft.
Quoting Fly2HMO ( Reply 1): IIRC, a master warning annunciation will go off directing attention to the pressurization panel, which will have yet another warning displayed. There can be a "CABIN ALTITUDE" light right next to the TAKEOFF CONFIG light (center console) but I'm not sure if the Helios flight had that, there's always a warning horn, and (assuming you were in auto mode when the failure happened), you'll get an AUTO FAIL light on the pressurization panel. Quoting rolfen ( Thread starter): Isn't there a "cabin pressure" warning light somewhere in a visible place in the cockpit?