AF447

[stezam65]

To swedish steve:


A pilot always try to fly at OPTIMUM altitude, which is the altitude where you have the best kilometric endurance and you have a good margin to the low and high stall speed.

In Europe is always quite easy to fly at that altitude because, even if there are many planes flying around, the separation in height between planes are reduced (1000 feet between converging flights). The longitudinal and lateral separation between planes is also reduced because Air Traffic Controllers use the radar.

Across the Atlantic Ocean the longitudinal separations are very big (planes that follow the same route is 10 minutes of separation, i.e.80 nautical miles) and the vertical separation is double (2000 feet between converging flights).

So, at the start of Atlantic crossing if the pilot take the altitude which is not the optimum but nearly the maximum at that moment, is very happy because if there is bad weather in front of him, he will have more chance to overfly it (anyway the pilot, in the evaluation of the chosen flight level always have to think about ahead forecast turbulence).

If there is bad weather, the pilot has to use the weather radar, scans the sky in order to understand if he is able to overfly it or he has to change route in order to circumnavigate thunderstorm cells.

The job of the pilot is to evaluate and mainly take the decisions which are not the ideal but a compromise.

Anyway if the plane enters in a permissible cloud, pilot knows that the plane has a protection against ice built-up using airworthiness antice devices.


After this accident I know that Airbus had some troubles concerning the anticing of the pitots. If there is ice build-up in the pitot the airspeed indicated to the pilot (the speed that show the margin to the low and high stall speed) is unreliable.
See also this link
http://alphasite.airfrance.com/s01/?L=2

Anyway, there is a procedure called: flying with “UNRELIABLE SPEED INDICATION”.
In this procedure the pilot has to fly the plane with precalculated attitude showed to the PFD’s (primary flight displays through IR1, IR2, IR3 and ISIS) related to the phase of flight and applied the correct power to the engines in order to fly predetermined speed.

This emergency procedure is very difficult but I think that the Air France crew was able and well trained to follow, to manage and apply it.

This is the time to do again the question:BUT DID THE PILOTS HAVE THE ATTITUDE INDICATIONS ON PFD’s?

Answering this question will also answer the other: why the rudder could be detached? Without airspeed they didn’t have the Rudder Travel Limiter.
And without attitude indication, the flight could be so unstabilized that if not using the rudder with care the rudder could be damaged and detached
loosing, may be, the pressurization.


Now Swedish Steve, I ask you again to explain me better what you answer me using simple and comprehensive English (sorry, English is not my native language)


I ask again to other professionist people to clarify the line written in the Acars messages: did the AF447 flight also have IR’s failure?

Thanks
Stef