saunders111

It wasn't an "all engines out" failure on a twin, but would the Lauda Air thrust reversal deployment have been survivable by a four-engine aircraft?
Wikipedia entry on Lauda Air crash

saunders111

jredknapp11

The above situation is easily one of the greatest pieces of piloting in aiviation history. The story behind this flight is simply fascinating as the main pilot managed to bring that plane in by using a mathematic system. I believe there was low budget movie made about this experience. Also, it was the ground crew who didn't fuel the plane properly as the Canadian ground crew didn't convert their metric numbers properly.

As with the story above, it's not all about the mechanics of the plane but also the pilot himself. The majority of our pilots are simply world class and are very, very well trained for situations like the ones we are discussing.

Jenbel

it was, but it did actually have enough fuel to continue the flight to LHR - the pilots were unsure if it did so rightly declared a fuel emergency. And one example is all that is needed to prove it can do it - just as one incident with a double IFSD on a twin would raise a lot of eyebrows.
Well the official acceptable failure rate for engines IFSD is 1 x10-9 That's what the rule-making and certification standards are intended to achieve. Less than that, and the safety case may have to be re-examined. At the same time, if you read the techie boards, IFSD do probably occur about as commonly as security related diversions. But most of them happen on short-haul a/c where the don't get much press coverage, as it's generally an easy divert.

Jenbel

Actually, I do know of one. 737 in the US took birds down both engines at around 4-5000 ft. Had to shut down one engine immediately - it simply couldn't continue. In any other situation, would have shut down the other too, as it was in extreme distress - but of course, they've just shut down one, they did everything they could to keep the other going, and managed not to lose it too, making a one-engined emergency diversion. If that plane had been a 3 or 4 engined plane, it's likely not all engines would have been affected - and I bet the pilots would have loved to have some more engines, when faced with trying to nurse a poorly engine which they would normally have shut down, to continue flying.

alanh

However, the problem with environmental issues is they tend to affect all engines. Four engine planes have been brought down by birdstrikes, too.

Oxb

Rational or not, I have felt that since I have traveled to the airport in an automobile where, statistically, my chances of survival are a good bit less than on the commercial airliner, I will not worry about how many engines the plane has.

Jenbel

That's not true actually for birdstrikes. The vast majority of birdstrikes which involve engines only involve one. To involve all four is actually pretty rare, because it needs to be a pretty big flock of birds to cover the distance between a 747's no. 1 and no. 4 engine - involving both on a twin is actually a lot more common, as a smaller flock can straddle both engines. Modelling has shown that <10% of occasions of a four engined-plane passing through a flock of geese will all four engines be involved, and real life data supported the model when analysed. The mode was 1, and the median was between 1 and 2 I think).

There's never been a modern day commercial four engined jet taken down by birds - the last four engined jet to be lost was an AWACs (modified 707), and that did not involve all engines, but rather occured at a critical phase of flight. The data shows that generally, four-engined aircraft are safer from birdstrike risk, such that at some airports with extreme hazards, airlines have adopted policy of only using 4-engined aircraft.

Where it isn't a factor is in transpacific ETOPs - the highest recorded birdstrike was at 39000 (with a rumour of one at 48000! ) - but the vast majority of strikes occur below 2000. Out over the Pacific, you'd need a minor miracle to hit anything at cruise altitude, because it is not a migratory route (strikes above 2000 feet tend to involve birds which are on migration). At the same time, I used the incident to show that there have been incidents when a couple of extra engines on the plane would have been nice to have!

muskoka

WestJet also flies 737-700s from Vancouver to HNL & OGG
daily as well.

Tango

I thought the 767-300 also has lots of power.

JDiver

Though Aloha has had ETOPS-certified 737-200s; I have flown on one HNL-MDY and return, and they flew them to Kiribati.

(MDY has a hospital with a physician, and when I was there the largest income stream earned by Midway Phoenix Corp. was from aircraft and fuel fees. They also had a hyperbaric chamber, of interest to those of us who were there for the diving. One more problem with MDY is that daytime ops can be, er, disrupted by Laysan albatross, or "Gooney Bird," strikes.)

As to twin or quad-engine, I'll stick with a twin with ETOPS 180 certified (or 207) as plenty safe enough.

YVR Cockroach

On thrust:weight ratio, the high-thrust Rolls-Royce-powered 757-200s apparently have no peer among commercial a/c. Looks like it's 17% of maximum takeoff weight (and I doubt most 757s are loaded to this weight). Looks like it's 15.3-16% for the 767-300ERs and -200ERs. The newer 777s are in the 14-3-14.8% range.

Braniff

That's a very important comment. Yes, there may be a landing field for a 2-engine a/c within the time limits, but there may be no emergency infrastructure available to deal with it...

DrMaturin

Hey, I thought I was the only one who did that. I continue to do it every flight, though. After all, it's worked so far

jwillett13

During the enroute the phrase "heavy" is normally dropped from the callsign as all aircraft require the same amount of spacing from one another. During the approach phase more room is required behind larger aircraft due to wake turbulence. The 757 is not a true heavy because it weighs in under 255,000lbs but the wing puts of as much wake as "heavy" aircraft

woodway

I recalled and dug up an interesting thread on airliners.net on the topic of 777 engine in-flight shutdown. The most relevant post is about 1/3 of the way down:

"The following information is extracted from the 777 ETOPS database. Since it was introduced in 1995, all versions of the 777, including all engine types, have had 60+ Inflight Shutdowns (IFSD). This equates to an IFSD rate of .005 per 1000 engine hours. The requirement for 180 min. ETOPS is .02 per 1000 engine hours. One additional engine failure will not drive the IFSD rate high enough to violate the minimum requirement.

These data are for IFSD's on the worldwide 777 fleet. An IFSD will result in complaint to Boeing and the engine maker. Both are required to report these to the ETOPS database, so the information contained there is comprehensive."

How authorative? You decide. But it is interesting data.

http://www1.airliners.net/discussion...d.main/128872/