I have read that in an emergency (example, when the plane is stalling), a pilot must always rely on his flight instruments and not on his own instincts. Is this true?
What if it were like in the case of Air France Flight 447? Due to the blocked pitot tubes, the altitude indicators displayed a false drop in altitude, so the pilot, relying on the wrong information, pulled up the plane to a higher altitude. This (added on with other errors) led to the plane stalling and the Airbus crashing. - Source: Air Crash Investigation.
So how can a pilot know when to trust his flight instruments and when to ignore them?
Hi Sean Yew,
Your first statement is only true if the flight instruments are reliable. There are times when the instruments become unreliable as in the case of the Air France Flight 447. In this case, the flight instruments were rendered unreliable because the pitot tubes were iced up.
In this scenario, the pilot must clearly identify this predicament as an “unreliable speed” condition.
This is a documented emergency drill and all pilots are trained to recognise and handle it accordingly. In fact this is, one of the 10 Airbus Memory Items (checklists) that a pilot must have on his fingertips. He forgets it at his peril!
A pilot must know when his main flight instruments are unreliable. For example, during the cruise with normal power settings, the plane should fly at a particular airspeed. If it indicates too high or too low a speed (because the pitot tubes are blocked) the pilot can then crosscheck it with the speeds on the standby instrument as well as from the GPS. It they are grossly in error, the pilot must ignore the readings and carry out the memory drills immediately to prevent the plane from crashing.
The memory drill at the cruise above 10,000 feet is to fly at an attitude of around 5 degrees pitch up with climb power then fine tune it with more information from the checklist (not part of the memory drill) when the danger is averted (follow the first Golden Rule – Aviate (fly), Navigate, Communicate). Generally, the Check List would guide the pilots out of this “Unreliable Speed” condition.
Apparently, the (BEA) investigation report of AF447 was of the view that this was not adhered to and came to the conclusion that one of the causes of the crash is due to human (pilot) error.
Air France 447: Final report on what brought airliner down
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