How often has an airliner failed at cruising altitude?

Has anything disastrous ever happened to a commercial airliner at cruising altitude that was not caused by a deliberate human act? I can’t think of very many at all. I remember reading about a case in which a large portion of the top of a passenger liner’s fuselage tore off in mid-flight, basically giving the plane a sunroof, but the pilot simply reduced altitude to compensate and the aircraft landed safely. I don’t think anybody was killed or even seriously injured, but I could be wrong. There must have been at least a few other cases of something bad happening to a plane at cruise elevation, but for all intents and purposes, large passenger liners never seem to just fall out of the sky. How often does this happen, and what are some notable examples?

There’s a few I’m aware of off the top of my head:

Alaska Airlines Flight 261 first noticed problems that ultimately resulted in the loss of the aircraft and all onboard while at cruising altitude.

There’s another one I couldn’t find the name of on google, but I believe it was from the late 80s and a piece of one of the jet engines actually ripped off mid flight and hit a key weak point of the plane where all three redundant hydraulic lines met, taking out all hydraulics on the plane. The two pilots (and an instructor for that model aircraft who was by coincidence on the flight) were able to land it by using differential speeds for the plane’s engines to bring it down but were not able to extend the landing gear and the crash landing killed a good number (but not all) of the passengers.

The Gimli Glider ran out of fuel at 41,000 feet but was safely landed.

That was United Flight 232 which crashed at Sioux City, Iowa.

British Airways flight 9 (aka Speedbird 9) lost all four engines due to volcanic ash. They were eventually able to restart the engines but couldn’t keep them all running. They managed to land the plane safely.

This incident was featured in one episode of the show Mayday (Air Crash Investigations).

In Aloha Flight 243 (the incident I believe the OP is talking about where the top of the plane’s fuselage came off) one flight attendant was sucked out of the plane during the decompression/failure and plummeted to her death. There were no other fatalities.

ETA: There was a similar failure to the Sioux City crash that occurred in Japan, but that plane was unable to reach the airport and crashed on a high mountain top.

The De Havilland Comet is also probably worthy of mention. It was the first commercial jetliner, and metal fatigue wasn’t as well understood back then. They had several break up in mid-flight, and the investigation of those incidents led to a lot of the modern methods for air crash investigations. Pressurization tests eventually found that the fuselage would develop stress fractures and would fail at altitude.

The plane was eventually redesigned with smaller windows and other changes, but its reputation never recovered.

TWA Flight 800. Probable cause was the center fuel tank exploded.

Only 12 minutes after takeoff, so not sure if that would be close enough to cruising altitude.

I would count that, yes. I’m looking for anything that didn’t happen while taxiing, or immediately after takeoff or immediately before landing.

If we take the OP’s definition liberally to mean if a flight cruising at altitude has ended in disaster, then Air France 447 would also qualify. Granted, pilot error was at play, but this was a flight that was basically cruising without much significant problems (except the faulty pitot tubes) one minute, crash into the ocean the next.

Air France Flight 447 crashed in the middle of the Atlantic.

ETA: ninjaed by two darn minutes grumble

There was actually one fatality in the incident you’re thinking of (Aloha Airlines 243) when the flight attendant was sucked out of the open section of the fuselage.

Japan Airlines 123 lost the vertical stabilizer and all hydraulic systems due to an explosive decompression due to an improper repair. They amazingly managed to more or less control it for a time but unlike the United 232 they lost control and it fell out of they sky before they could line it up with a runway.

Lauda Air 004 the crew lost control due to an uncommanded deployment of a thrust reverser in mid flight.

Going in the wayback machine we have Pan-Am flight 6.

It’s certainly not the most common situation for an airline accident, but it’s happened plenty of times without being caused by a deliberate human act.

The same failure caused Aeroflot FLight 8641 to crash

Aeroflot doesn’t count. There was a joke going around during the Gulf War:

Q. What’s the difference between Aeroflot and an Iraqi Scud?

A: Aeroflot has killed more people.

A China Airlines 747 broke apart at altitude due to metal fatigue on a poor repair job from a tail strike 22 years earlier.

In the late 1950’s, theLockheed L-188 Electra, a four engine turboprop, suffered from “whirl mode flutter.” Because of a poor engine mount design, the outboard propellers could induce oscillation and flutter through the engines to the wings. This would cause the wing to depart the aircraft while at cruise.

There are also the ever popular pressurization system failures, be they mechanical or human, that result in “Flying Dutchman” aircraft cruising along with dead or otherwise incapacitated crew and passengers until they run out of fuel and crash. The crash of the Learjet carrying golfer Payne Stewart was perhaps the best known at the time as the aircraft flew for some 4 hours before fuel exhaustion, but there are several similar incidents, including a 737.

The important re-design was that the metal failed at the corners of the square windows. The change made them round, but as you say, it was the end of De Havilland. Boeing bought the technology and leapfrogged into the lead with the 707.

From a current news story about the missing Air Malaysia plane:

> Just 9 percent of fatal accidents happen when a plane is at cruising altitude,
> according to a statistical summary of commercial jet accidents done by Boeing.

Airline pilot here …

The folks above have covered most of the well known climb / cruise / descent mishaps over the years. Except for the midair collisions. There have been a few.

Jets have crashed after engines fall off, or cargo doors open, or a big hunk of fuselage structure fails. They’ve crashed from failure of hydraulics, engines, pressurization, electrics, or instrumentation. They’ve crashed because they were flown into severe weather, volcanic ash, the sea, or solid mountains.

Overall aircraft are more reliable every year. As are the crews and the ground support ATC, operating procedures, international standards, etc. OTOH, at one time almost all airline aviation was first world people operating in first world conditions. Nowadays a lot bigger percentage of the industry is from the rest of the world. The safety record of second tier operators today compares very favorably with the relatively poor safety record of first tier folks in the 1960s. But there is still a significant safety difference between the various “layers” of today’s airline industry.
Bottom line: The OP’s apparent assumption that sabotage or on-board violence is the most likely cause is fundamentally faulty. Is sabotage/violence on the list of things to consider? Yes. Should it be the default assumption? No.