No fault of the pilots? The aircraft slowed to 150knots at FL410. Does that sound ok to you in a 40000 pound aircraft?
Indicated airspeed is not the same as true airspeed, and decreases with altitude until you stall. Speed up, and you get Mach buffet. You only have a limited range of airspeeds at which you can stay airborne at high altitudes. That's why they call it Coffin Corner.
They were flying at 180kts IAS, but making Mach 0.64 TAS (64% of the speed of sound). Read the transcript again.
The U-2 used to fly at 80 kts IAS at FL800.
-ccm
"The aircraft slowed to 150knots at FL410. Does that sound ok to you in a 40000 pound aircraft?"
The weight of the aircraft has nothing to do with airspeed at any given attitude. I assume the 150kts is what the pilot saw on his airspeed indicator and or was recorded on the flight recorder box at that attitude. And that sounds about right assuming they where climbing within the allowed Angle of attack at given speed and altitude which seems they would since they are commercial pilots.
True airspeed is the indicated airspeed corrected for air density altitude. As altitude and temperature increase, air pressure is reduced. Because this instrument measures dynamic pressure, true airspeed drops as altitude and pressure increase. Generally, true airspeed is 2% higher than indicated airspeed for each 1000 ft. of altitude.
So at 40K feet roughly: 2% (40) = 80% reduction in what you would see on the airspeed indicator as to what the speed would be at lets say sea level. Put another way. The aircraft was flying at about 270 knots. Well within it's flight envelope. If they actually had leveled out as they reached the intended altitude, then their angle of attack was not exceeding the envelope, therefore the plane would fly just fine at that altitude. OK. What I just wrote was taken verbatim from a Pro Pilot flight manual, and could as well have been taken out of any aircraft manual or other book on aviation. I am not a pilot but have flown literally thousands of hours in Microsoft Flight Simulator as well as other flight simulators using many different type aircraft, that yes, drop like a rock when not flown within their respective flight models.
I sense the final verdict is not in with all the facts, and perhaps some of us are jumping the gun. Plus let us remember that most all these small commerical aircraft such as the Lear Jets, Cessna Citation jets etc., all can safely operate at 40K plus and surely many do for long flights where they want to fly smooth fuel efficient flights.
I for one am not going to side on this issue until the facts are in. And once the facts are assembled and analyzed what the FAA comes up with should satisfy all.
For all we know, they may have experienced engine problems due to a myriad of reasons, lack of sufficient fuel etc., and this tragedy was just that. I sense something really went wrong this time. They should have been able to spin up the turbines as they decended and forced the nose down gaining more airspeed then relite the engines. Another thing, one can stall an aircraft while moving at a great rate of speed as any fighter pilot will attest to. These two pilots may have not done anything wrong from an operational standpoint. A general statement to all, we don't seem to have all the facts at this point.