CRJ. First, toy. Then, glider.

[Gabriel]

Third (and last) in a series.

A CRJ was being ferry flown by a pair of young pilots. The airplane was light in weight because it was carrying no passengers or cargo and it wasn't a very long flight that required a lot of fuel.

They decided they would test-fly the airplane and see if they could reach the certified ceiling of 41,000 ft. But they did everything wrong:
- They climbed in vertical speed mode.
- They let the speed go below the best-glide speed.
- They leveled at 41,000ft at a speed that was on the wrong side of the thrust curve.
- They didn't stop plying when they saw the speed was still decaying and approaching the stall speed.
- They let the airplane stall.
- They didn't promptly and aggressively recover from the stall, which lead to both engines flaming out.
- They lied to the ATC saying that they suffered a single engine failure and requested lower to attempt a restart, instead of declaring the truth and aim for an airport within gliding range (of which there were several) in case the relight would fail.
- They screwed up the relight attempting it outside the windmilling envelope, which fatally damaged the engines that would never turn again.

Did I forget something?

A subject that was of theoretical interest to me was: Did the coffin corner has something to do? I say no and asked Flyboy (or whatever was his screen-name at the time) for some numbers for the airplane he knows so well (Mmo, Vmo, Vs). We are still waiting. I promise I will get some numbers from somewhere to support my thesis.

[3WE]

Gabe:

It all comes down to a broad concept, vs. nit-picky details.

An aircraft that is "very high" has reduced margins of stall speed, max speed, and reduced power.

Then we have "Coffin corner" which is the altitude where stall speed and max speed comes together.

If you are "at coffin corner" and you speed up, you exceed your max speed and are likely to experience something like a aft-shift in lift, and perhaps an uncontrolled dive.

If you slow down, you will stall and may tumble out of the sky, out of control for a while.

(Now, there is a tendency for uncontrollable dives or stalls where sometimes you break up and die, and of course in this incident, it was stall, flamout, failed restart, failed 50 mile glide to an airport, break up and die too).

So, the guys were up pretty high in the area where margins between stall, max speed and available power were reduced, and I argue that this was a factor in this accident.

When you are flying up high near coffin corner you should be aware that you have reduced stall, overspeed and power margins.

Now, technically, coffin corner is about stall and max speed, but not about reduced power, or "the backside of the drag curve". Therefore, Gabe is right, these guys never dealt with problems of "being boxed in by their max speed". Therefore technically, this accident is not about coffin corner. Gabe is also right that you would think that thier lighter weight would have given them a little extra buffer on the stall-speed side of coffin corner.

And let's be clear that Max Certified Altitude is not truly related to coffin corner either, except to say at high altitudes, all sorts of "margins" become thinner....could even be turbine inlet temp setting FL410 as max???

But, I restate, when you are flying up high, near coffin corner you should be aware that you have several reduced margins.

I am still amazed at the pilot's mentality who sat there, up high in the region of reduced power and speed margins, and noted signficantly-nose-high attitudes and decaying airspeed, and operating stick shakers, yet, allowed the plane to stall, fall and flameout. (And again, I think it's halfway common knowledge that rear-engined planes tend to flameout in stalls due to disrupted intake airflows).

Regarding your question of what was a max speed for them- have you asked Screamo Emo over at JP.net....I think he is a CRJ driver.

[Schorsch]

Third (and last) in a series.

A CRJ was being ferry flown by a pair of young pilots. The airplane was light in weight because it was carrying no passengers or cargo and it wasn't a very long flight that required a lot of fuel.

They decided they would test-fly the airplane and see if they could reach the certified ceiling of 41,000 ft. But they did everything wrong:
- They climbed in vertical speed mode.
- They let the speed go below the best-glide speed.
- They leveled at 41,000ft at a speed that was on the wrong side of the thrust curve.
- They didn't stop plying when they saw the speed was still decaying and approaching the stall speed.
- They let the airplane stall.
- They didn't promptly and aggressively recover from the stall, which lead to both engines flaming out.
- They lied to the ATC saying that they suffered a single engine failure and requested lower to attempt a restart, instead of declaring the truth and aim for an airport within gliding range (of which there were several) in case the relight would fail.
- They screwed up the relight attempting it outside the windmilling envelope, which fatally damaged the engines that would never turn again.

Did I forget something?

A subject that was of theoretical interest to me was: Did the coffin corner has something to do? I say no and asked Flyboy (or whatever was his screen-name at the time) for some numbers for the airplane he knows so well (Mmo, Vmo, Vs). We are still waiting. I promise I will get some numbers from somewhere to support my thesis.

I guess when they flew at the maximum operational ceiling the coffin corner was of no primary importance.
Very nice list though, classic example of swiss cheese.

[3WE]

......classic example of swiss cheese.

One might argue that this one was not swiss cheese hole alignment as much as a drill boring straight through a big thick block of cheese

[Gabriel]

One might argue that this one was not Swiss cheese hole alignment as much as a drill boring straight through a big thick block of cheese

Concur 100%.
Oh, and I'll still run the numbers just to satisfy my curiosity.