flashheatingand

O.k., this isn't totally hvac related, but in regards to the Air France plane crash recently. Based on the news report from NBC, they were speculating that the speed sensors were getting crazy eratic readings.

But, they were flying through a crazy storm. Wouldn't that storm cause crazy readings on a pitot tube as well? I am not pretending to know about reasons for plane crashes. But at this point in time, I doubt that the pitot tubes were the reason. I think flying through a major storm played a major role.

joasis

As an experienced pilot and licensed A&P, I would doubt seriously the frozen pitot tube idea, mainly because while they could encounter the conditions needed to make this happen, they also would have had the pitot heat system on, plus, the aircraft has other instruments that cross check speed sensing.

My guess is they literally flew into extreme turbulence that broke the aircraft up in flight, plain and simple. Inside of thunderstorms, there can be vertical air velocities exceeding 5000 feet per minute, and that, combined with an airspeed of 400+ knots probably spelled disaster.

If you consider what we learned about storms in the last 20 years, and the L-1011 that went down in Dallas on final, literally "pushed" into the ground by a vertical shear wind, the best course of action, even for Chuck Yeager types, is storm avoidance.

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nEighter

crazy they wouldn't go around or above it to begin with. How long did it take you to get your A&P?? I want to do that.

joasis

2 years, back 20 years ago.

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flashheatingand

The reason for bringing this topic here as opposed to the Off Topic section was because I thought that most people don't know exactly what a pitot tube is (other than pilots). As you and most hvac guys here know, it's used to get air velocity & static pressure readings.

As a technician, if I were taking duct s/p,v/p readings and the pitot tube froze while inserted in the duct work (Theoretically), I would get abnormally low readings. The report claimed they were getting readings of high speeds. So that would tell me that the pitot tubes were indeed "open" and not frozen.

As I am writing this, I realize there is the possibility that The pitot tubes were "jumpered" as they froze up. As a result, the pilots thought they were traveling at a rate of X knots, when they were really going Y knots. I don'k know sqwat about plane crashes or instruments. Just an Hvac Geek thats merely speculating as to the whole Pitot tube explanation.

beenthere

Tp-Sp=Vp.

So, if the pitot tube froze at the static point only. The reading would be high.

joasis

I don't buy the the analysts story yet because:

Every commercial aircraft system has backups. There is more then one, and probably 3 complete and separate pitot/static systems on the aircraft.

All heavy transport aircraft have GPS and navigation systems coupled with the auto pilot that would indicate speed, as well as flight profile.

And finally, most of the guesses at what happened are just that, a guess. What I do believe is the most accurate scenario is they knowingly flew into a major thunderstorm with cloud tops exceeding 50,000 feet.

I have been a pilot since I was 16, and taught from day one that thunderstorms and airplanes do not mix.

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beenthere

Not trying to say that icing of the pitot happened. Just how it could give a false higher velocity then they were doing.

While your thought of what happened may be correct.
I don't want to blame the pilots. if it was not their error.

Their families will have this tradegy on their minds for the rest of their lives withut me(not a pilot) pointing a finger.

Darwin

Uhh... Oh,... nevermind..

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Property Repair Specialists in Southeast Michigan

flashheatingand

Once again, b.t. you got me on the pressure reading thing. I was thinking s/p + v/p =t/p. So the readings would give false high speed ratings. Having explained that part, the pilots would slow down the plane. But word is the plane went too fast and disintegrated. I think the storm was a major factor, and the reporters should focus on why the plane got into a storm in the first place, should be asked.

The families deserve a better explanation of what happened. Perhaps not today, but if this is going to be the final report, that would compound the tragedy.

beenthere

The reporters should keep their noses ouot of it.
And let the investigators complete their investigation. And then report the findings. Instead of spreading speculation.

skymaster

nEighter : go around it or run away from it is correct, There is NO commercial or private aircraft that can ever hope to climb out or over a thunderstorm. In theory some of our fighters may be able to but I dont want to go along for the test ride.
When entering an area of nasty turbulance one is supposed to slow down to a specific airspeed based on type and load called " Manuvering Speed" simply put it is a speed where the aircraft will stall before doing structural damage. NO this isnt a bad thing, it is simply lowering the nose to gain speed anf you fly on.
Joasis: You can clarify that better than I can.
As to why they flew into it only them and God will ever know the real answer.
One fact that isnt clear to most people; Weather Radar DOES NOT show turbulence. Radar only :paints" precipatition, the "presumption" is the heavier the precip the worst the turb.
Precip is shown in varying colors from black to red. IE black the least, red the worst. NOW there is an interesting phenomena that occurs in really bad storms where there will be an area of black between to really really bad cells and it APPEARS to be the safe way out, what it really turns out to be is an area so severe that the radar cant penetrate it, so it has no returns.
This is where experience really kick in to be able to interpret what the screen is showing and what it REALLY is saying.
Again Joasis can clarify much better than I can.
Not being morbid here at all but believe this or not the finding of the bodies is actually a good thing. The autopsies will determine if the dies of drowning which meant they we alive when they went into the water or they died from the aircraft breaking up at high altitude. To me I believe it is the later, it broke up inside the cell.
A couple of years ago Scott Crossfield, Chuck Yeagers friend went flying and flew into a series of storms that were severe, they found him still strapped to his seat in what was left of his 210.
I totally agree that these news reporters should just button it and let NTSB and the others do their thing. Of this I am sure, there is one of our nuke subs is sniffin around as we speak to try and locate those data recorders, you will know when they find it, :}:} cause a civilian submersible will make a startling discovery.

joasis

I didn't go "technical" simply because if you are not a pilot, it doesn't make sense.

I have a minute, so story time:

Long ago, when I was 18, I went on a body run...that is, when a funeral home chartered a plane to pick up a body. We flew to Acron, Ohio, and loaded up the basket, flying a Piper Aztec. On the return, we flew at 12,500, and on an instrument flight plan (I was an instrument student, jumped at the chance for real "wet time", the term for real IFR conditions), and my instructor said I could lift the hood, no point. I looked out and was looking at a solid black wall....ATC (air traffic center) would not give us another altitude, or clear us to deviate, and said it was a localized storm. I flew on, and it got black, bumpy, and wild. To slow down, I added 20 degree flaps, gear down, and high prop rpm....just to make certain we did not get above maneuvering speed. (maneuvering speed is, as Skymaster pointed out, the maximum speed an aircraft can withstand the loads imposed on the airframe....like maximum G's, wing loading without failure, etc., )

Less then 4 minutes later, we popped out of the other side, beat up and bruised from the ride, nearly 20,000 feet up, or 8000 over assigned altitude, and guys, this was a little storm....I have never been so close to tearing an airplane up in the sky as that day, and that was the very last time I ever knowingly flew into a thunderstorm. The tops (vertical height of the cloud, can determine how intense the storm is) was probably no more then 25,000.....a baby storm compared to the equatorial storms seen down south, or for that matter, the average storms down here in Oklahoma.

It is a folly to fly into storms....even the hurricane hunters avoid the imbedded thunderstorms when flying to the eye to take readings. And those planes fly slow, and relatively low.

I doubt this really makes sense....it is kind of like how we contractors talk to each other and people outside the trade don't have a clue of what we are talking about, but simply, it was simply a bad call, and probably the pilots did not have any pireps (other pilot reports) about weather activity, and the plane was destroyed by extreme turbulence.

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