PPRuNe Forums - View Single Post - Why use only pitot-static system for altimeter/airspeed
Old 3rd Feb 2014, 16:40
  #19 (permalink)  
Desert185
 
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Gouli
Mirkoni
The pitot system is cheap, simple and well understood. The AF447 system iced up due to the pitot heating system not being powerful enough to cope with the prevailing conditions at the time.

As usual, it was a combination of factors that lead to the aircraft crashing. The crew apparently chose to fly through a storm system rather than route around it which made the situation worse due to extreme turbulence while trying to recover the aircraft to stable flight. The sidestick controls didn't provide visual feedback to other cockpit members that the aircraft was being held stalled in a nose up attitude by the pilot flying. The crew were over reliant on automated systems and apparently unable to fly the aircraft manually without an accurate indication of airspeed.

A tragic accident where an otherwise perfectly serviceable aircraft crashed because the pilots were basically incapable of flying the aircraft manually - just one of an increasing number of such incidents.
I fly an atmospheric research DC-8. It is normal when entering heavy precip for the airspeed indicators to go to zero, which is most noticeable in the ITCZ. The autopilot will not trip off and we all know about pitch/power. The INS/GPS continues to chug along with groundspeed, etc. We (science) even have a radio altimeter in the back that accurately reads much higher than the standard 2,500' reading on the pilot's panels.

Not even going out on a limb here, I have to say had AF447 been a DC-8 everyone would still be alive, provided the "pilots" didn't touch anything while the airspeeds read zero. Of course, the pilots wouldn't have had those "cool" little tables in front of them. Oh, and no autothrottles or magenta lines (except for the magenta lines on the pilot's iPads, of course).

Sorry. Had to say it. Them's the facts. Period.
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