I'm watching video RV 10 N783V My 1st Emergency
At 8:45 a stall alarm goes off and is a horrible piercing whistle. Why? Surely the pilot has enough distractions without also being deafened while trying to talk to ATC.
Isn't there a better way of indicating a continuing alert, and why can't pilots switch the the thing off when they need to?
EDIT: The video shows that it is a false-positive warning. The pilot eventually manages to switch it off by resetting all his electronics.
A stall condition needs to be handled now, and once it's handled, the alarm will go away. What you don't want to happen is you are in an approaching stall condition, the pilot hits a "silence" button while the situation gets worse without the plane telling them.
An emergency is "AVIATE, NAVIGATE, COMMUNICATE" in that order. Fly the plane first, point it where you want to go second, and third, only if you have time/resources, is to talk to ATC about it. The pilot should be fixing the problem first, focus on flying the plane, ATC can wait.
They can't be turned off for that reason. Deal with the problem and the alarm goes away, you don't want to silence the alarm and forget about it. There is some merit to "overloading", where multiple alarms are happening at the same time, or when the pilot focuses on a low priority item and forgets to fly the airplane (Eastern Air 401).
Things may be different for small airplanes, but for the transport-category, i.e. Part 25 certification, your concern is taken into account:*
(d) The alert function must be designed to minimize the effects of false and nuisance alerts. In particular, it must be designed to:
...
(2) Provide a means to suppress an attention-getting component of an alert caused by a failure of the alerting function that interferes with the flightcrew's ability to safely operate the airplane. This means must not be readily available to the flightcrew so that it could be operated inadvertently or by habitual reflexive action. When an alert is suppressed, there must be a clear and unmistakable annunciation to the flightcrew that the alert has been suppressed.
As the text shows, suppressing alerts must not be readily available, but the means to suppress must be provided – once the crew for example confirms the false-positive. In the linked video the pilot reset a few circuit breakers and the warning was gone.
* Thanks to @Gerry for his insight and @Bianfable for tracking down the similar European rule, that regulation applies to aircraft made since 2011. It may be worth mentioning that at least the Airbus A320 have had the ability to suppress spurious alerts since the mid-80s.
A Stall horn will tell you, you are (close to) no longer flying, but actually falling.
Since this is of paramount importance for every airplane, it will sound until recovery is completed. Often it is only the silencing of the stall horn that can give a pilot certainty about that. Sometimes even this is ignored, because pilots treat it as just as alarming as any other device, which it isn't. Gear malfunction, terrain alert, traffic alert, burning engine, a hijacker holding you at gun point, all these things are of minor importance compared to a stall.
As dictated by law, a stall horn works on every winged aircraft, even if all power is lost and all other instruments are dead. (EDIT: this is not correct. It should be, but it ain't. See comments)
A winged aircraft with a continuously sounding stall horn is in the process of crashing. It is not going there, it is there. Its falling, like a brick.
Tell me, why would anybody in his right mind ever want to even just be able to shut that down?
