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Flagship 3701

June 15th, 2005 · 1 Comment

USA Today Article

Lots of people have been asking me about this accident over the past several days. I have some thoughts about the above article, and this accident. Before you read any further, I’d like it to be understood that in no way am I passing judgment upon dead crewmembers. I am merely relating my operational experiences in the CRJ-200 to the factors cited by the NTSB in preliminary reports.

The CRJ-200 is certified to FL410 (41,000 feet above mean-sea-level), and can attain that altitude relatively easily when the ISA temperature deviation is near-zero and the aircraft is at relatively light flight weights. I’ve flown the CRJ-200 at FL410 only a handful of times (when empty), and the performance was poor enough that I didn’t care to stay there very long.

The problem is three-fold, I believe. These problems are not unique to the CRJ by any means. Every swept-wing jet aircraft has similar limitations. Aerodynamicists can feel free to correct me if I’m off here.

First, even though the CRJ-200 might be able to attain it’s maximum certified ceiling, it’s engines may not be able to produce sufficient thrust at that altitude to allow it to accelerated past .70 Mach. My experience has showed a tendency for the aircraft to just sort of mush along at a relatively high deck angle without accelerating appreciably.

Second, if you climb to FL410 while flying within a cold(er) air mass, you might be in for a rude awakening when you cross that cold front into an air mass where the ISA temperature deviation is six-to-ten degrees above standard. All-of-a-sudden, the maximum altitude for your current weight ends up being 4,000 feet below you, and the plane starts to sink in that nose-high mushing area of the flight envelope, and at the very worst, comes dangerously close to an aerodynamic stall.

Third, the buffer any aircraft has between it’s angle-of-attack for a given speed and it’s stalling angle of attack is decreased the higher the aircraft goes. So any increase in load (as little as 1.3g’s due to turbulence) could result in aerodynamic stall at extreme altitudes.

I haven’t seen all the information regarding the Pinnacle wreck, but from what I’ve been told, they stalled the aircraft and departed from controlled flight temporarily, which flamed out both engines. Relight attempts were unsuccessful due to the fact that minimum windmilling start speeds (which if I remember correctly was in the range of 300 knots) were never attained. The relight attempts resulted in several hot-starts (an engine start where inter-turbine temperatures run extremely high due partially to a lack of airflow through the engine) that were severe enough to melt burner cans and turbine blades within the engine, which of course rendered at least one of the engines inoperative.

The cockpit voice recorder transcripts help corroborate the theory.

Flagship 3701 CVR transcript

All-in-all, a bad deal.

What we have in the article is the media sensationalizing the issue now with the whole “Small jet pilots don’t get enough training” thing. It wouldn’t be a glamorous-enough story if they didn’t put that spin on it. The fact is that the two pilots who were involved in this accident were trained to the guidelines established by the FAA for all FAR Part 121 Air Carriers (which includes the likes of United, American, Delta, and Southwest). The amount of training required is significant, and the course of training quite rigorous. It is definitely not “less than what should be required.”

And as far as David Stempler’s comments at the end of the article. Well…I’m just going to say that he doesn’t know his rudder from his aileron. To say that they were “experimenting” is a gross misinterpretation. FL410 is a certified altitude for that aircraft, meaning that under some circumstances it should perform well enough to attain that altitude and remain there. Had they taken it to FL450, then we could start talking about them being test-pilots. Ultimately, whether they should have been where they were or not is up to the judgment of the NTSB.

ABC News doesn’t get it either. Read my buddy Sam’s thoughts about their hatchet-job on this story that, when it actually occurred over a year ago, didn’t seem to garner much attention at all.

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1 response so far ↓

  • 1 Greybeard // Jun 15, 2005 at 10:18 pm

    I have commented more than once in my blog about my frustration with the news media not getting stories right. Since we know they get aviation related stories wrong all the time, is it an indication they get ALL their stories wrong this frequently?
    The recent crash of the Bell LongRanger in NY is a prime example:
    Fox news did the best job, but even they fell back on a retired Army General as their “expert”, and he made statements that weren’t 100% true.
    They also initially reported all passengers safely escaped, but today we find that one is hospitalized and was put into a “chemically induced” coma.

    If the public doesn’t check several sources, including experts in the field, they are sadly misinformed!

    I enjoy your blog, my friend!
    GB

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