Plane Crashes

Factual Questions
21

After one of the plane crashes into water last year (can’t recall which one), one of the divers let out with a statement that his bosses were quick to try to hush up, as it was the most graphic description I’ve heard.

He said it was difficult trying to recover the bodies from the ocean floor, because what was in the wreckage looked so much like “seat cushions” that it was hard to tell the difference.

THAT’S a mental image I have been unable to dislodge, and kindly thought I’d share with y’all . . .

—Madame DeFarge

22

My question was with regards to planes that are going down quickly. I often thought about that feeling - being on a plane in a steep dive and all of screaming and stuff flying around. It’s a terrifying thought.

I’ve also heard that the TWA flight that blew up over long island actualy broke in two and those two pieces fell to the ground relatively “slowly”. What’s more, the authorities say nothing had happened at that point that would have killed everyone on board. A few people got sucked out or blown up, but the vast majority of people on board were alive in the back half of the plane. JESUS! Imagine sitting on the plane, the front falls off, and you can see the plane falling out of the sky in front of you. That’s horrible. I certainly wish many of those people either died or passed out quickly from the shock… (And before you mention it, I know Cecil has already addressed the similar Challenger explosion)

Now back to the another point: Why did the Japanaese 747 crash? You say it lost the rudder, which I guess would cause a crash (I don’t know enough about planes…), but if someone had time to write a 20 page letter, wouldn’t the pilots have had time to either ditch the plane in the water or glide in for an emergency landing?

23

I find it hard to believe that somebody had time to write a twenty page letter, unless it was, in very big letters, one to a page, something like ‘fuck me we’re going to die’. I also doubt that these size of aircraft really have much ability to ‘glide’ as such. Do they really have sufficient wing area to glide? I suspect that ‘drop like a stone’ would be a more apt description of the aeronautical shennanigans undertaken by a jumbo with no thrust available. Of course, this could be utter nonsense. Where the hell is the rocket scientist when we need him? At a frat party i guess…

24

I’m no rocket scientist, but I am a pilot.

Actually, airliners have very good glide ratios. I can think of one case where this came in handy.

Several years ago a pilot landed his airliner on an abandoned drag strip after it ran out of fuel. IIRC, there was a mixup with pounds/U.S. gallons/Imerial gallons/litres of fuel or something like that. In any case, the tanks became filled with air and the engines starved. The pilot, who held a glider rating, made a beautiful dead-stick landing.

While we’re talking about gliding, people say I’m nuts to fly a helicopter. “What if the engine quits? Won’t you fall out of the sky?” Helicopters have a “free-wheeling unit”. This disengages the engine from the rotor system in the event of a power loss. By reducing the pitch of the rotors, rotor RPM is maintained and the helicopter can be flown in a glide to a safe touchdown. The procedure is called “autorotation”. :slight_smile:

25

Johnny, re: autorotation…

I’ve heard that helicopter pilots have to ignore their instinct to “pull pitch” when faced with a loss of power. Rather, they should dump pitch until the last minute, then pull like hell.

Is that anything near correct?

26

Autorotation.

I’ve never had the “instinct” to pull pitch. As a result of my training, my instinct is to reduce it.

Here’s how it works: You’re flying happily along and there’s a BANG! and your engine is dead (I put the “bang” in for effect). The first thing you do is lower your collective to the bottom (i.e., go to minimum pitch). At the same time, pull back slightly on the cyclic and step on the anti-torque pedal (you no longer have torque, so you need to stop counteracting it or you will spiral). Pulling the cyclic back will increase your rotor RPM because of aerodynamic forces acting upon it, so now you need to pull your collective up to prevent the rotor from overspeeding. Use the collective to maintain rotor RPM within the green arc. Okay, now you’re descending and you’re under control. Set up a glide at the recommended airspeed (not groundspeed) for the helicopter. Say, 70 knots. Maneuver as needed to reach a suitable landing site, maintaining rotor RPM (notice how I keep saying “maintain rotor RPM”? It’s important) and airspeed. When you’re, say 40 feet from the ground, start to flare the aircraft. This will cause your rotor RPM to rise, so counteract it by lowering the collective. Level out at about 8-10 feet and raise the collective to cushion your landing. Land skids-level with the nose pointed in the direction of travel.

Piece of cake! And rather fun to practice, to! :slight_smile:

27

Before I read the definition, I thought this was a euphemism for “shit your pants.”

28

They should put parachutes in planes…

That Challenger ship? I read the people on it were probbaly still alive when it hit the water.

29

Okay, I’m sure it’s not scientifically accurate, but there’s a truly harrowing description of what happens to the victims in a plane crash towards the end of Bret Easton Ellis’ Glamorama.

I coped alright with his more infamous early read, but this one nearly turned my stomach. It pretty much runs the gamut of the injuries already mentioned in this thread.

I never touched him, ref, honest!

30

It lost basically all control surfaces in the tail. Years earlier it dragged its tail on landing and was not repaired correctly (although it took years to finally fail). After the crash, when this was found out, the Japanese official who approved the repair work committed suicide.

The pilots had some control, but not enough to land or ditch into the sea. For nearly 45 minutes the plane essential flew itself, going up and down like a roller coaster, gradually losing altitude, until it hit a mountain.

Amazingly, one person survived, but over 500 died making it the 2[sup]nd[/sup] worst plane crash ever (the worst was the two 747s that collided on the runway in the Canary Islands in the 70s).

31

For what it’s worth, if an airliner loses all engines at cruise altitude, it can glide over 100 miles.

32

Airliner being defined as what? Any passenger carrying aircraft? All can glide for 100 miles?

33

Johnny L.A.,

i think you’re thinking of the Air Canada jet that had to land on an abandoned WWII airstrip at Gimli, Manitoba, now used as a drag race-strip by the Gimlians. There actually was a race in progress when the plane came in for a landing.

It’s been a while since it happened (early 80s), but I think the plane was flying from Toronto to points west, and when the fuel ran out, it glided for quite some time. Not like a glider, obviously - it was going down steadily - but the pilot made a perfect landing, to much applause.

Then, he got disciplined by Air Canada because it turned out he was the one who made the conversion error at fuelling that caused the crisis in the first place. The pilots’ union grieved, in light of the fact that he saved the plane, and the employer replied that he’d endangered the plane in the first place. Not sure how it all got sorted out.

and the stars o’erhead were dancing heel to toe

34

I know next to nothing about flying and aircraft but it would seem to me that if a plane is going …say 600 miles per hour or 10 miles/minute and its at an altitude of 17000 feet or about 3 1/2 miles, wouldn’t it take only about 20 seconds or so to impact?

Also, if many of us feel horrible when there is turbulence and an aircraft “drops” say 100 feet or so, I would think that most if not all the passengers would become comatose from the rapid pressure changes and inability to breathe before impact. Am I right or way out in right field?

35

Airplanes don’t *descend that fast. An airplane’s gliding ability is measured by its glide ratio, which is a measure of how many feet it will move forward for each foot that it descends. An airplane with a 20:1 glide ratio will glide 20 miles for each mile of altitude it loses.

Large airliners typically cruise at altitudes between 30,000 and 40,000 ft. And surprisingly, most airliners have very good glide ratios, and 20:1 or better is not uncommon.

In comparison, a high-performance sailplane will have a glide ratio of perhaps 30:1 or 40:1. But there is one more factor, and that’s how fast the thing comes down. An airplane with a 20:1 glide ratio, gliding at 300 mph will come down at about 15 miles per hour, or 1300 fpm, meaning it will hit the ground from a normal cruise altitude in about 20-30 minutes. A high-performance sailplane will have maybe a 40:1 glide ratio, but at a glide speed of 70-80 mph or so. So it’s only coming down at the rate of maybe 150-200 fpm. So it can stay in the air for almost 10 times longer as a large jet can, and that’s important when you trying to win endurance contests or looking for thermals that will let you climb back up again. If a glider can ride a column of air rising faster than its descend rate, it can stay up indefinitely.

However, what matters when you lose your engines in a passenger jet is mainly how far you can get, and not how long it takes to get there. And jets are pretty good at this, because they are built aerodynamically clean, and they have long, high-aspect ratio wings for high altitude flight, which also helps them glide. The “Gimli Glider” which some other guys mentioned already glided something like 80 miles after it lost its engines. Coincidentally, the pilot happened to be an avid sailplane pilot, and his hobby served him well.

In comparison, your typical light Cessna will have a glide ratio somewhere around 12:1, albeit at a much slower 75 mph or so. My old Grumman AA1 had a glide ratio of about 9:1, at 90mph. It glided like a homesick brick.

The Lockheed U2 spy plane may have had a glide ratio as high as 35:1 or so, as I recall. And since it cruised up around 80,000 ft, the thing could glide over 500 miles if it lost its engines. But if it could manage to get a good tailwind in the jetstream or something, its glide ratio could double or triple.

36

jti:
Thanx! I thought it was an Air Canada DC-9 but I wasn’t sure so I didn’t post it.

dhanson:
Good explanation of glide ratios. You think your Grumman glided like a brick? Try a helicopter! :wink:

37

dhanson, thanks for the info, cool stuff. It’s curious how often one’s gut feeling can be totally wrong (see any thread on probability/chance). I’d always imagined that the large heavy jets really had to use large amounts of thrust to drag themselves through the air, my thinking being that the wings would be designed for lift and therefore, i thought, poor for gliding. My ignorance overcome, I feel safer now :cool:

38

Reminds me of our old discussions where we thought they should make planes out of the stuff they make black boxes.

39

Nah, black planes are for secret government agencies only. Or would they be orange?

40

JLA: The “Gimli Glider” was a Boeing 767. The chain of errors that led to the flameout was a one-in-a-million shot. The proper blame for the whole thing can be placed at the feet of the government, which was trying to use political pressure to force the country to change to metric. As a result it mandated that Air Canada use Metric in all its calculations, even though the tools on hand were still calibrated in English measure. That meant that conversions had to be done at every step in the fueling process, and during fuel management in the air. Dangerous and stupid.

Essentially, there are checks and cross/checks, all of which failed in this case. The pilot orders how much fuel he’ll need for the flight, and this is pumped into the aircraft. Someone screwed up here, and didn’t pump enough in. Next, a ground member physically dips the tanks to measure the fuel quantity. This guy screwed up too. Then, the fuel gauges should indicate how much was left, but they were inoperative, or at least the main ones were. They flew without it (allowed). Finally, the pilot does fuel calculations along the way, based on how much he thinks are in the tanks. If that number is wrong, then nothing the pilot does will fix the problem. But ultimately, the pilot is responsible for the safety of the flight.

The government was probably looking for someone to blame to cover the fact that the whole problem was created by politicians involving themselves in the daily operation of an airline.