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Topic: Need help from my pilot friends on here...

Bruce Hansen
Jedi Master Film Handler

Posts: 847
From: Stone Mountain, GA, USA
Registered: Dec 1999

posted 06-11-2012 06:18 PM

I only fly small planes, but here is a guess. Durring taxeing, the pilots will be testing things. It may be that one of the pilots hit a wrong button, while proforming a test.

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Louis Bornwasser
Film God

Posts: 4441
From: prospect ky usa
Registered: Mar 2005

posted 06-11-2012 06:29 PM

Sounds like the FA wrote you a "feel good" letter. Louis

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Paul Mayer
Oh get out of it Melvin, before it pulls you under!

Posts: 3836
From: Albuquerque, NM
Registered: Feb 2000

posted 06-11-2012 09:02 PM

There have been cases of the wrong buttons being pressed causing engines to shutdown, like hitting the fuel cutoff instead of the auto-throttle engage right after takeoff (the incident at LAX is famous but I can't remember the aircraft type - the control layout did have those two controls right next to each other).

But to get a total shutdown as described here would (to me at least) require several buttons/switches to be actuated. Now we get into looking at crew actions. Hmmm. Wish I still had access to a B-757 systems trainer - could try to recreate this shutdown! [Big Grin]

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Sam D. Chavez
Film God

Posts: 2153
From: Martinez, CA USA
Registered: Aug 2003

posted 06-11-2012 09:53 PM

I believe Paul is referring to an early 767 where the pilots shut off the engines leaving LAX and by the time they sorted it out they were only at 500 Feet.

I remember they continued on to the destination without coming back for a change of underwear.

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Leo Enticknap
Film God

Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000

posted 06-12-2012 11:38 AM

quote: Paul Mayer
There have been cases of the wrong buttons being pressed causing engines to shutdown, like hitting the fuel cutoff instead of the auto-throttle engage right after takeoff (the incident at LAX is famous but I can't remember the aircraft type - the control layout did have those two controls right next to each other).

And one accident caused by an engine fire followed by the pilot mistakenly cutting the fuel supply to the one that was still OK.

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Paul Mayer
Oh get out of it Melvin, before it pulls you under!

Posts: 3836
From: Albuquerque, NM
Registered: Feb 2000

posted 06-12-2012 03:51 PM

No need for new underwear Sam. I'm sure the pucker factor was high enough that those guys were wearing the sheepskin seat covers that Boeing installs on their flight decks.

And for Leo, interesting read. That's why 'differences training' on a given type is so important. Those poor guys were proly used to flying 737-300s (maybe even -200s) and didn't have a whole lot of experience on -400s - not that anyone at that time practiced fire drills to the level of IDing burning engines by smelling the cabin air feeding the flight deck and the cabin. I'd wager such fire drills are a part of the 'recurrent training' for the type nowadays. Lessons learned the hard way for everyone.

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Leo Enticknap
Film God

Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000

posted 06-12-2012 05:55 PM

I remembered that one because it was a big news story when I was growing up in south London (near to where the plane left) at the time. There was a big "almost, but not quite" aspect to it, but I think the real reason is that it had been the first crash in Britain to cause significant loss of life for almost two decades, since this one (a year to the day before I was born!). By the late '80s, everyone believed that unless your plane was attacked by criminals in some way, flying had become totally safe.

From the stuff I've read, AF447 was a similar scenario, but with a lot more factors in the cascading sequence that led to the disaster: the pitot tube freezing up, the plane being close to the q-corner at the time, the pilots (allegedly) not having been trained properly as to what functions on the A330 remain under computer control and what drop out to manual control when the system enters alternate law, the captain being on a break and asleep when the emergency began, etc. etc. It's a paradox - these things are designed so that any one failure shouldn't be able to bring down the plane, but you still want to prevent failure #1 from happening, because if failure #2 does, then its consequences are that much more serious.

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Paul Mayer
Oh get out of it Melvin, before it pulls you under!

Posts: 3836
From: Albuquerque, NM
Registered: Feb 2000

posted 06-14-2012 11:43 AM

Nova, the science show on PBS here, just did a show last night (in this market) on Air France 447. Not to knock a dead flight crew, but sadly it looks like those guys were seriously lacking in basic airmanship skills at the time, for whatever reasons. Basic "pitch & power" works every time, no matter how many computers or pitots, or ASIs one may have, or not have. Very sad.

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Sam D. Chavez
Film God

Posts: 2153
From: Martinez, CA USA
Registered: Aug 2003

posted 06-14-2012 01:09 PM

I've done a lot of reading on this crash and it had a lot of information as to why the co-pilot did not know the plane was pitched up at an angle of attack of 15 degrees which stalled the plane until the ground speed was less than 125 MPH. It fell all the way down to the water in 4 minutes or less and only at the last minute or so were they even aware they were in a stall.

What none of the reports I have seen touch on is whether or not you can recover from a stall in this plane no matter what the skill of the pilot.

The idea in pilot training was to avoid a stall in the first place.

They may have been doomed from the moment the pilot raised the nose and climbed 8,000 feet or so in response to the pitot tubes freezing and the computers handing the controls back to the crew.

Paul no doubt has access to forums I do not. I's love to know more about this.

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Ron Funderburg
Jedi Master Film Handler

Posts: 814
From: Chickasha, Oklahoma, USA
Registered: Nov 2007

posted 06-14-2012 01:19 PM

There was the tragic crash in Florida of the L10-11 back in the 70's. There was a bad bulb on indicator for down and locked for the nose gear. This caused them to wonder if the nose gear was down or not. The engineer and some other crew member went down in the hell hole to check it out. It was so dark out they couldn't really see anything. You look though some little scope to see the gear. Meanwhile, the pilot and co-pilot got the bright idea to change the bulb and one or the other bumped the yoke which put them in a slow constant descent like you were coming in for a landing. In fact the L10 was designed to do just that minimal pilot effort for landing. Well they landed at 175 to 200 miles an hour in the everglades.

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Paul Mayer
Oh get out of it Melvin, before it pulls you under!

Posts: 3836
From: Albuquerque, NM
Registered: Feb 2000

posted 06-14-2012 10:59 PM

Sam, I doubt that the A.330 would have been certified to carry pax if it was that difficult to recover from a stall. It is true that some airfoils with laminar flow wings can use up more altitude in order to recover, since some designs would require an aggressive pitch down (nose below the horizon) in order to initiate recovery. But still, all anyone generally has to do in a stalling transport-category aircraft, is lower the nose to approx. level while ensuring the power is set appropriately, especially at when high altitude since the difference between over-speed (Mmo) and stall speed may only be a few dozen knots (the so-called "coffin corner" of the aircraft's flight envelope). Pitch and power. That's all there should be to it.

Iced-over pitot tubes and/or static ports can produce very confusing airspeed indications. That's why all airliners have heated pitots. It takes a lot of concentration to ignore airspeed in favor of pitch and power indications only, since normally one uses airspeed as the primary indicator for pitch. There have been several airliner losses over the years that were traced to iced-over pitot tubes or blocked static ports (as in tape covering the ports while the aircraft was being washed prior to the flight). It looks like iced-over pitot tubes were one of the major factors in the loss of AF447.

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Lyle Romer
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Posts: 1400
From: Davie, FL, USA
Registered: May 2002

posted 06-15-2012 07:51 PM

Going back to the original post (and I'm not a pilot or aviation expert) but it almost sounds like they begun to taxi with one engine (I've been on plenty of flights that do this to save fuel) and when it was time to start the other one they accidentally shut down the first one.

If this was the case then the solution would just be to re-start the APU and start both engines.

Having both engines shut down during taxi due to any kind of problem would be nearly impossible. The engines are independent of each other. If something that unlikely had happened there is no way the captain would have elected to take off without having mechanics look at the plane. As far as I know there has NEVER been a case of more than one engine shutting down on a multi engine aircraft due to independent reasons. Running out of fuel or flying through volcanic ash clouds has caused multi engine shutdowns but neigher of those happened on your flight.

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Leo Enticknap
Film God

Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000

posted 06-16-2012 09:23 AM

quote: Lyle Romer
If this was the case then the solution would just be to re-start the APU and start both engines.

Unless the APU was NFG.

I was on an MD-11 from Atlanta to Amsterdam earlier this year that left an hour and a half late thanks to this. When we boarded, the temperature in the cabin was in the '90s, which the flight attendant in a PA explained was because "there's a piece of equipment on the plane that isn't working, and the air conditioning will be back on once we've started the engines". When boarding was complete, the captain announced a delay "because we need a truck to come and start one of the engines", and it took the truck over an hour to get there. I asked a flight attendant if the APU was the problem and she replied that it was, and that it routine, though inconvenient, for a plane to operate in service without a working APU. She guessed that it was cheaper and/or easier to fix it in Amsterdam (which made sense, given that this was a KLM plane and it was away from home in Atlanta), hence flying without it. Once engine #1 has been started by external power, its bleed air can then be used to start #2 and #3, and with all of them running, their generators can provide all the power needed, including for the air conditioning.

Apparently the APU is normally shut down during routine flight anyway. This strikes me as very inefficient, hauling such a dead weight around through the sky. You'd have thought that all airports would provide ground power facilities as routine so that APUs were unnecessary, but I'm guessing there's some safety reason I haven't thought of why you might need one in mid-air (generator failure in all engines?). But if so, why is it permissible for an airliner to fly with the APU out of service?

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Lyle Romer
Phenomenal Film Handler

Posts: 1400
From: Davie, FL, USA
Registered: May 2002

posted 06-16-2012 11:34 AM

quote: Leo Enticknap
Apparently the APU is normally shut down during routine flight anyway. This strikes me as very inefficient, hauling such a dead weight around through the sky. You'd have thought that all airports would provide ground power facilities as routine so that APUs were unnecessary, but I'm guessing there's some safety reason I haven't thought of why you might need one in mid-air (generator failure in all engines?). But if so, why is it permissible for an airliner to fly with the APU out of service?

From a safety perspective the APU is required to be functioning for the aircraft to fly an ETOPS (Extended Twin Engine Operations) route as a backup in case of single engine failure.

From a practical perspective it would probably not be cost effective to need all of those start carts at each airport plus ground crew to start the engines all the time. Typically they'll be starting the engines during push back. The start cart takes extra time as you have to get the engine started, disconnect the cart and then push back.

Most of the time at major airports the aircraft is connected to ground power and air conditioning while parked at the gate.

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Leo Enticknap
Film God

Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000

posted 06-16-2012 12:18 PM

quote: Lyle Romer
From a safety perspective the APU is required to be functioning for the aircraft to fly an ETOPS (Extended Twin Engine Operations) route as a backup in case of single engine failure.

So I'm guessing that my flight was allowed go to with a dead APU because the plane had three engines and thus did not have to comply with ETOPS rules. In that case it was very good luck - almost all the transatlantic flights I've taken in the last few years have been on either 767s or A330s. I was surprised to end up on an MD-11 that night: given the oil price increases of the last few years, I'd have thought that they'd have disappeared in the mid-00s, just as the DC-10s did. If KLM had decided to use a twinjet for that trip, the APU failure would have meant that my flight would have been cancelled.

quote: Lyle Romer
Most of the time at major airports the aircraft is connected to ground power and air conditioning while parked at the gate.

So why can't you start the first engine using "mainline" ground power (rather than a cart), and then push back? I'm guessing that having an engine running so close to the terminal building with people milling around it is a safety issue, and that if you don't even begin the engine start procedure until the plane has been pushed back and is in the middle of a sea of tarmac with no-one standing within 100ft of it, that's a much safer option.

Even so, I'd make a wild guess that an APU on a long-haul airliner must weigh at least as much as 5 passengers or 15 suitcases, and you'd have thought that plane designers would do everything they could to avoid the need to haul one through the air doing nothing if there were any other viable solution.

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