Intense read! What Really Happened Aboard Air France 447

What I have learned from this post is exactly this:

Leave your seatbelt unbuckled as much as you possibly can.

Nobody died in this incident, and the ones who weren't buckled in got a pretty serious knock on the head, but will each be getting multi-million dollar payouts as a result.

The lawsuit should be considered frivolous if the claimants happen to be the ones who were not wearing their seatbelts. Some people need to realize that they are sitting inside a pressurized aluminum tube traveling through the air at M0.8 (80% of the speed of sound). At that speed, even small air pockets and updrafts/downdrafts impart amplified loads on the fuselage of the aircraft. Why anyone but the cabin crew wouldn't be voluntarily buckled in (even loosely) at all times is beyond me. If a driver/passenger fastens his/her seatbelt when riding in a car traveling at 80 mph, why the hell does he/she feel that buckling up in an airplane traveling nearly 10 times as fast is not a necessity?


People are looking for a scapegoat for their own oversight.

I'm still trying, and failing, to learn more about how a stall could be caused by excessive speed at a flat angle of attack. I must have misunderstood something at some point because that doesn't seem possible.

Thank you for taking the time to post all of this Wayne, it was really interesting.

I don't understand this part:

5.) Stall Warning. What most people don't realize is that an airplane can stall because it's going too slow OR because it's going too fast.

I tried to do some research and I still don't get it. I understand how you can stall a plane at an speed with a sharp enough maneuver, or with an angle of attack that's too high, but how do you stall a plane with a good angle of attack by going too fast?

I grew up in airplanes on skydiving drop zones, but all propeller planes. Have I never heard of this because it's not possible for a propeller plane to go that fast?

The lawsuit should be considered frivolous if the claimants happen to be the ones who were not wearing their seatbelts.

I agree with you about always wearing your seatbelt, but they already won the lawsuit. It wasn't an air pocket, it was a documented malfunction. There is no law against getting up to go to the bathroom.

I'm still trying, and failing, to learn more about how a stall could be caused by excessive speed at a flat angle of attack. I must have misunderstood something at some point because that doesn't seem possible.

A stall is when airflow separates from the wing. Jet aircraft (and some WWII fighters) also have what's called a "critical Mach number," which, for stall discussion purposes, refers to the speed where the shockwave ahead of the wing moves back onto the wing and begins to disrupt the airflow, and eventually, if speed continues to increase, will cause airflow to separate from the wing.

If you look at the bottom wing in this graphic, you see that the aircraft is only doing M.80, but the airflow over the top of the wing is moving as high as M1.0 and starting to separate from the wing.

If you want to know WHY the airflow separates, there's some pretty serious JPL-level Fluid dynamics behind it that are way over my head.

It can happen at a very low or even a zero angle of attack. The approach to both conditions (low-speed and high-speed stall) feels exactly the same to the pilot. It begins as very light ripples of turbulence, then increasingly larger bumps...then, depending on the aircraft, very violent shaking and loss of control.



The WWII Hawker Tempest, Typhoon, and the Lockheed P-38 all had problems with this because pilots would roll into a steep dive and their speed would increase to the point that the tail surfaces would stall out and there was no way for them to pull out of the dive. The P-38 would get "control reversal," which means exactly what it says...you turn the wheel to the left, you go right. Not what you want to see when you're screaming toward the Earth at 500kts. They lost a bunch of aircraft before they figured out what was happening.

Modern transport category aircraft are required to not exhibit any violent reactions during a stall, but that requires engineers to design a wing that is less fuel efficient than it otherwise could be. So, as you might guess, they are designed to meet the regulations, but not much more. I don't really recall if they are required to meet the "no violent reaction" standard on the high-speed side though. They might, I just don't remember.

In this Air France accident, the guy apparently thought he was facing a high-speed stall situation since he was getting "the onset of boundary layer separation" which is engineering terminology for "shaking like hell," AND his indicated airspeed was steadily increasing (assuming this pitot system failure was like every other one I've ever seen), even though in fact his speed was decreasing due to his own actions.

So that's why I assume he keep trying to pull the nose up to stop the speed increase he was seeing and prevent an impending loss of control...so he thought.

...The The B-777 I flew would throw up an alert on the ICAS screen...

That's nice and all but the acronym EICAS stands for Engine Indication & Crew Alerting System and you should not have omitted the E.

You are definitely management material...

The whole transonic regime was extremely difficult for engineers to deal with initially. One solution was actually variable-geometry configurations for fighter aircraft.

In this Air France accident, the guy apparently thought he was facing a high-speed stall situation since he was getting "the onset of boundary layer separation" which is engineering terminology for "shaking like hell," AND his indicated airspeed was steadily increasing (assuming this pitot system failure was like every other one I've ever seen), even though in fact his speed was decreasing due to his own actions.

So that's why I assume he keep trying to pull the nose up to stop the speed increase he was seeing and prevent an impending loss of control...so he thought.

What I was wondering is this: the less experienced of the two F/Os was continuously pulling back on the joystick. This basically means that the elevators (and possibly even trim tabs) were close to the full up position. Why did the stick-shaker and then the stick-pusher NOT initiate on both joysticks when the airspeed dropped below stall speed (once the computers were reading from unblocked pitot tubes)? The stick shaker control system logic is (or is supposed to to be) completely oblivious to the flight mode of the autopilot (TO/GA, AUTOLAND, MAN, etc.).

No idea. I never checked-out on any of Airbus' newer models, so I'm not sure how they work. What I've HEARD is that more than a few crews over the years have had serious problems with the AirBus Flight Management System. For example...

The whole transonic regime was extremely difficult for engineers to deal with initially. One solution was actually variable-geometry configurations for fighter aircraft.

Not just initially; numerous wind tunnel tests on scale models of Boeing's sonic cruiser revealed many shortcomings of the special airfoil that was designed for the aircraft. In hindsight, and based on the current economic climate (and even as far back as 2008), I think Boeing made the right decision to can the sonic cruiser.

More cracks found in Airbus A380 wings

Airbus (EAD.PA) said on Thursday it had discovered more cracks in the wings of two A380 superjumbo aircraft but insisted the world's largest jetliner remained safe to fly.

The announcement comes two weeks after tiny cracks were first reported in the wings of the 525-seat, double-decker aircraft, which entered service just over four years ago.