Well. Case pretty, much clear now. They forgot the Pitot heaters and lost control after they entered icing conditions… Very stupid mistake.
The rest will be to find out if there was no warning. And if not, why.
But a frozen pitot doesn’t make the plane fall down.
@Urs, you seem to have better info than mine – which was very early, anyway. Thanks!
@mod: My original title for this thread has been shown to be little to the point, feel free to update.
But a frozen pitot doesn’t make the plane fall down.
A frozen pitot has made lots of planes fall down 
IIRC, a good number of fatal PA46 loss of control crashes were due to pilots forgetting to turn on the pitot heat.
EuroFlyer wrote:
But a frozen pitot doesn’t make the plane fall down.
It has before. AF447 for starters was triggered by one intermittendly frozen pitot. The resulting mayhem in the flight deck lead to the crash.
Here, all 3 pitots were off. The moment they got into IMC, the speed indications started to go wrong, with differential speed warnings and all that. A bit later, the speed indications of the various systems started predictably to disagree even more, with one going towards zero and the other increasing. They then disconnected the AP and started to “recover” what appears they thought was a stall. Once the airplane came out of IMC, speed indication increased to 800 km/h just before impact.
For now, the MAK concludes:
“A preliminary analysis of the recorded information, as well as an analysis of similar cases that occurred in the past, suggest that the development of a special situation in the flight could be caused by incorrect data on the flight speed on the pilots indicators, which in turn was apparently due to icing of the pitot probes when the heating systems are off.”
Why don’t they wire the pitot heat to the gear doors? I think Jason C said that you can run into problems with the pitot if there’s no airflow for a while, but once the plane is in the air I don’t see why they wouldn’t just leave them on? Obviously you would still need a manual switch for takeoff in inclement weather, and it would not help with mud daubers or waps, but it would help prevent these tragedies.
Would, on this aircraft, loss of pitot data, cause the pitch info and the engine power indications to be incorrect?
On the AF447 Airbus both of these remained correct, so doing the most basic thing – pitch+power=speed – would enable them to fly. And there is always a standby altimeter.
This isn’t like the Aspen EFD1000 (and others) where if the pitot gets iced up you lose the whole lot and have to use a backup AI if you have one.
Why don’t they wire the pitot heat to the gear doors?
A super idea. Or to the squat switch (“weight on wheels”) circuit. For some reason this isn’t done. Maybe partly to allow the pitot heater to be checked on the preflight walkaround. And probably to keep things very simple.
redRover wrote:
Why don’t they wire the pitot heat to the gear doors? I think Jason C said that you can run into problems with the pitot if there’s no airflow for a while, but once the plane is in the air I don’t see why they wouldn’t just leave them on? Obviously you would still need a manual switch for takeoff in inclement weather, and it would not help with mud daubers or waps, but it would help prevent these tragedies.
Most aircraft with good pitot heaters particularly pressurised aircraft have ground limits on use. I am actually not aware of a big PA46 issue with pitot heat leading to loss of control but I personally always use pitot heat when cleared for take off.
It was one of the recommandations from the PA46 FAA review I think, but much lower down the list than alternate air and proper autopilot use (VS, CSW being identified as particularly confusing/dangerous)
Pilot heat comes on every time one enters a runway, according to the PA46 POH. Unlike the PA28, pitot heat in the PA46 will leave a mark on your hand, Indiana Jones style, so it makes sense that you should not have it on all the time.
I would be surprised if the AN-148 does not have an warning annunciator going off if airborne without pitot heat on. In the US FAR’s has that as a certification requirement for all turbine aircraft and I believe EASA CS is the same.
The Russians are great designers of aircraft. If missing airspeed information is really the main issue here, I would look for crash causes in their CRM first, maintenance second and the aircraft design a distant third.
