MD-90
Topic Author
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Can A 747 Fly On Just 2 Engines?

Sat Mar 11, 2000 6:43 am

I was reading a book the other day about a reborn Pan Am struggling to survive. There was some really cutthroat competition because supposedly they had introduced a new "bunk bed" type of cabin for their international flights. (full coach fare, I guess). Someone apparently wanted them to fail, and one of the things they did was plant a bomb on a 747 and tried to blow it up. Unfortunately, Boeing builds very strong airplanes, and the aircraft stayed together. But two engines were lost (on the same side), and the hydraulics were sluggish. They descended down to about 50 feet over the San Francisco Bay area. They had to fly around ships, otherwise they would have hit them! They made, but just barely. Of course, this is fiction, but I'm wondering if it could really happen?

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Photo © Urs Guettinger

 
747-600X
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Well...

Sat Mar 11, 2000 6:59 am

A few things:
A 747 can fly on just 2 engines. A 757 can fly on 1. A 747 cannot takeoff with just two engines because the time it would take to pick up enough speed would have it half way there, but once its in the air, they'll keep it moving.
2. If these two engines were on the same side, it would take everything but the galley sink to keep the airplane from turning.
3. At 50 feet above anything, a 747 is a risky story. Keep in mind that while in flight an aircraft doesn't remain at one absolute altitude. If turning with any degree of severity, the wings would drop a distance, getting pretty close to the water, but I can't see any reason a 747 couldn't fly at 50 feet as well as any other altitude (except over the Great Lakes or somewheres like that where it'd be 550 feet under water).
If you want a taste of what 50 feet is, go take a look at that picture you posted, the top of the blue circle on the vertical stabalizer is about 50' up.
4. I'm not sure how a bomb would take out the engines, and the last time someone bombed a Pan Am 747 - or any 747 at all - it, eh, didn't quite get where it was going.
 
Ilyushin96M
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RE: Can A 747 Fly On Just 2 Engines?

Sat Mar 11, 2000 7:00 am

That story about the bomb sounds like a big crock of s*** to me. It's never been reported anywhere, I certainly haven't heard it before now.

I think 747s can fly on two engines, but not for long. Having only two out of four powerplants operating would allow the plane to make an emergency landing relatively safely, but probably not allow it to remain airborne for very long.
 
747-600X
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Ilyushin96M

Sat Mar 11, 2000 7:06 am

MD-90 clearly stated that it was fiction. So yes, it's a crock of, well, shall we say you might try lightening up a little?
 
Trident
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Joined: Sun Feb 27, 2000 4:49 am

RE: Can A 747 Fly On Just 2 Engines?

Sat Mar 11, 2000 7:17 am

In 1982 Captain Eric Moody showed that a 747 can fly on NO engines (for a while at least) when all four stopped after swallowing great clouds of volcanic ash over Indonesia. However, he had the two things most precious to an airman, altitude and time. He set the aeroplane up for a long glide and eventually got three of the four engines running again and made an emergeny landing at Jakarta.

I think the fate of the El Al cargo 747 at Amsterdam in 1992 showed the more likely outcome of losing (literally) two engines off the same wing. When an engine falls off an aircraft, other damage occurs, often mortally wounding the plane (loss of flight controls, rupturing of hydraulic lines etc.).This was what happened to the American Airlines DC-10 at Chicago in 1979. The engine falling off the aircraft was not the main cause of the crash, but the loss of control caused by the haudralic pressure dropping and the leading edge slats retracting.
 
Boeing727
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Joined: Sat May 22, 1999 1:32 am

RE: Can A 747 Fly On Just 2 Engines?

Sat Mar 11, 2000 8:34 am

In level flight a B747 can actually fly on one engine, if necessary. A friend of mine is a UPS B747 pilot and I have asked him that question before, so there you go.

Ciao

Boeing727
 
dnalor
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RE: Can A 747 Fly On Just 2 Engines?

Sat Mar 11, 2000 8:42 am

Yes Capt Eric moody glided the 747 for 29 minutes from memory and some of that time was with the speed brakes deployed in a steeper than required dive due to the first officers oxygen mask falling apart, requiring him to get down fast !

The DC10 Chigaco incident was survivable (read report from NTSB) but the training given for one engine out stated a climb speed which the pilots stuck to, instead of lowering the nose when the left wing lost lift due to the damage/retraction of the slats etc. That was a great shame and I must state the pilots werent at fault, they did the best with what they thought they had.

The United 747 shut down engines 3 and 4, had a huge hole in the fuselage, control surface problems etc but was ladned successfully, but I'm sure it was only just.

Evergreen had an engine fall off on a 747 too and just made it back to the airport.

And there was a cargo707 that had both 3 and 4 fall off, wing on fire and it used its altitude and a little known airport and just made it in, great team work got those guys home.

The Amsterdam 747 had litle or no hope, it didnt have anything in its favour, it had massive control problems, two engines missing, no altitude and heavy.

cheers  
 
dnalor
Posts: 346
Joined: Fri Mar 10, 2000 7:58 pm

RE: Can A 747 Fly On Just 2 Engines?

Sat Mar 11, 2000 8:45 am

Thanks for that info, I wasnt sure if they could maintain level on one engine or could just use it to aid in landing.
 
Starship
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Pic Of 3-engined DC-8

Sat Mar 11, 2000 8:29 pm

This cargo DC8 lost an engine and part of the wing as a result of severe clear air turbulence at 31 000 ft over the Colorado Rockies in December 1992. Fortunately it landed safely.



Nick
Behind every "no" is a "yes"
 
VH-OJO
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KLM Incident

Sat Mar 11, 2000 11:00 pm

A KLM 747-400, PH-BFC has lost power to all 4 engines while flying over volcanic ash clound back in 1989. It had to drop and glide several thousand feet before the pilot successfully restarted 3 out of 4 engines, and performed a safe emergency landing in Anchorage. All four engines had to be replaced in ANC.
 
MD-90
Topic Author
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Joined: Mon Jan 17, 2000 12:45 pm

Thanks

Sun Mar 12, 2000 1:21 am

The bomb was supposedly planted in the aircraft while it was at a maintainence center. It was in the fuselage, and when it exploded it severed the controls to the engines; they didn't actually depart the aircraft or anything. I've gotta admit that it was pretty farfetched, but it made for great reading.