This crash happened a couple of years ago.
It appears that the pitot tubes clogged with ice.
The airspeed indicator measures the difference between static pressure (from static ports) and ram air pressure from the pitot tube. If the pitot tube clogs then the airspeed indicator becomes an altimeter.
Pilots are taught to raise the nose in the event airspeed is too high. So if it is not detected that the pitot tube is clogged the pilots might think the airspeed is climbing so they raise the nose which inexplicably makes the airspeed climb higher and so on. Apparently the Air France pilots went so far as to put the power levers down all the way.
If they would look at the attitude indicators then they would see the nose up condition. I know from experience it is easy to sit here and say that but when the pilot is experiencing the sensations of flight and focus on one instrument it can be very difficult to overcome that mentally. Vertigo is very hard to explain, you have to experience.
They lost situational awareness and lost control of the airplane and crashed into the ocean. Detecting malfunctioning instruments is a big problem for pilots. You have to teach yourself to trust the instruments over the sensations in the seat then when they lie to you, you have to detect it. If the gyros fail on the attitude indicator fail they wind down slowly so it's not like in training where the instructor covers the instrument and you know it has failed. This is a very difficult problem to teach. Now we've seen some of the most highly trained pilots fail at a critical moment.
It seems that they could obtain airspeed from GPS also.
Dave, if you have not already read "FATE IS THE HUNTER", you may enjoy it. Written by Ernest Kellog Gann, an early aviator, who tells vividly of icing while flying.
Don't pitot tubes in larger aircraft have redundancy? I would question the determination of the cause of the crash. Pilot error seems to be a catch all. During take off once in a small aircraft with my cousin doing the flying the air speed indicator did not register anything, a quick shutdown and return to the hanger. Found that a bee had taken up residence in the darn thing.
jud
GPS would indicate ground speed which is not necessarily useful in instrument flight.
Jud-spatial disorientation is very compelling.
This is not the first time. Our chief pilot related the story of a cargo jet that did the same thing many years ago. It was over water at night with no visual horizon evident.
GPS would offer some redundancy. If the pitot tube was icing, it is likely the wing form was being affected by icing also.
a look at the attitude indicator and the vertical speed indicator would tell the story but the pilot's have to recognize what is going on.
In high winds at altitude ground speed is not very useful. Airspeed is what matters. GPS does not do airspeed.
correct me if I'm wrong, but didn't the same thing (vertigo) doom JFK jr.?
Yes but for a different reason.
JFK, Jr was not an instrument trained pilot. As far as I know he didn't have any instrument malfunctions.
But Surely
the GPS velocity data would at least tell them if they were about to stall ?
But Surely
no it would not.
A wing stalls when it exceeds the critical angle of attack. The so-called stalling speed is an airspeed at which the wing reaches critical angle of attack at 1G. If the wing is loaded at 2Gs (such as in a level turn at a 60° bank) the wing will stall at a higher speed. I think the square root of the G factor times the 1G stalling speed gives the accelerated stalling speed.
An airplane can fly at 0 ground speed and not stall. If the wind speed aloft is at or above the stalling speed then the airplane will appear to stand still relative to the ground if the airspeed is matched to the ground speed.
But Surely
Yep...I've heard of DC-3's taking off backwards on the Aleutian airbases during high winds.
They dropped at 10,000 ft per minute... that's a ride I never want to experience. I wonder if it impacted or tore apart from forces. At least for me if something catastrophic happens in a helicopter it's usually low level and I wont have time to think about it for too long.
In 1979 a TWA 727 dropped 34,000 feet in 63 seconds, went supersonic, lost parts, pulled out at 5,000 feet, and landed safely. I flew on that plane- after it had been rebuilt.
At cruising altitude (say 38,000 feet) there may only be a few knots difference between normal cruising speed and a stall. As Dave points out, GPS is not going to reliably fill in for malfunctions elsewhere in the avionics.
I forgot about that, I never flew big airplanes.
They have to stay above stall and below Mach 1 which gets to be a narrower window the higher they go.
The Coffin Corner
Event as revealed by the recovered "black box"
http://www.flightglobal.com/blogs/learmount/2011/05/air_france_447_the_facts_and_w.html
Modern Aircraft
Have maximized the wing surface for maximum lift(carrying capacity) while minimizing tail surface to reduce drag (reducing fuel consumption) and reduced tailwing downforce as a part of the maximizing lift. This makes the aircraft inherently less self controlling and more dependant on computers. Aircrafts now fly much closer to very narrow limits.
In the past only U-2s and SR-70s flew in this condition, but those over stressed military pilots were also well overtained.
The fly by wire airliners are so computerized that airlines fail to see the need for adequate advanced pilot training. These computers then fly the aircraft to the brink of failure and the computer gives up, just plain quits and dumps the whole load unto the pilots. Learning on the job, while losing 10,000 feet per minute in altitude while thinkng all is well does not go well.
The flight recorder says that all the way down to the ocean Fight 447 maintained a controlled nose up attitude, while losing altitude and the pilots were not panicked. The computer while not in control monitored the situation. To a computer the monitored information can lead to only one final result, but since the computer has no senses of it's own worth or life it remained fairly unconcerned. At a minimum when the aircraft passed 20,000 feet it should have shouted out,
"Do something else, STUPID! This is not working."
Paul in PA
Modern Aircraft
This is basic piloting failure and it has happened before computers. This is a failure to recognize an airspeed indicator failure. If they would have simply flown the aircraft by basic attention to pitch attitude then this would not have happened.
Pilots are taught that pitch controls airspeed. If airspeed is too high then you increase pitch. Clogged pitot tubes cause the airspeed indicator to indicate high speed at that altitude so they raised the nose which caused higher airspeed indication etc.
It has happened before, long before computers came into the picture.
Just speculating but I think it may have to do with the pilots becoming over dependent on automation. I've flown with autopilot a few times and it is really nice because when it works it does a really nice job of following it's instructions. It lulls you into getting lazy. GPS navigation does that too; it's so nice, it flies you right to the airport. It is a lot less mentally taxing in a busy environment. It looks like the pilot flying failed to transition mentally to the instruments. At one point after things went seriously wrong he pulled the side stick back and towards himself. I think by then he had no idea what was going on.
Unless you have flown under instruments it is really hard to understand that this is not like sitting at a desk completely relaxed and able to think clearly. When the forces are on you and everything you do seems wrong your brain goes into overload.
Having the stall horn go off below 60kt.s is crazy. I can hold the wheel all the way back on any single engine Cessna (the most common primary training aircraft) and the horn will wail the entire time. That is conflicting with the pilots most basic early training which will stick best.
Dave Karoly ?
How much cockpit time do you have above 30,000 feet?
It is my understanding that above that altitude stall can occur at 600+ knots.
Paul in PA
