Human error

One of my minor interests is the investigations of airplane accidents. Mostly civilian airliners, as that is what is easiest to find, and the investigations are public (unlike most military investigations).

It's amazing how many perfectly good planes have gone down due to seemingly tiny mistakes. Often the mistakes are made by the pilots, but there are many examples of mistakes by controllers and, mechanics. I don't know where to categorize bad design.

It's also amazing how many damaged planes have been saved, and nearly saved, by competent pilots. Sullenberger's landing on the Hudson is the latest, and thus best known, but there are others.

One which involved a good dose of luck was Air Canada 143, a brand new 767. Long before even being close to its destination, the plane ran out of fuel. According to the flight computer, they should have had plenty. But the computer merely calculates how much has been burned and compares that to how much was input into it. The plane had actual fuel gauges, but these were broken and couldn't be repaired in Montreal, where the flight originated.

To spare a lot of details, the captain had to improvise a glider maneuver near the landing strip in order to lose enough air speed while maintaining altitude. But then it turned out the abandoned air force base they were aiming for had been converted to a drag strip. The runway was clear, but there were lots of people around, including two teenagers riding bicycles on the runway. Not to mention the runway now sported a concrete and steel divider along a part of it.

The plane landed safely, even though the nose gear collapsed. It embedded itself in the divider, which caused a fire in some insulation under the nose cone. No one was killed, and passengers and crew escaped with only a few minor injuries sustained while using the emergency exit slides.

The cause of the accident came down to a ground crew person who fueled 20,000+ pounds on the plane, when it should have been 20,000 kilos. Sot he plane had about half the fuel it needed. Due to the physics of flight, this doesn't mean it can only go half as far. Takeoff consumes a great deal of fuel compared to the rest of the trip.

There were other issues, though, like the broken fuel gauges. The change from a 3-man crew to a 2-man one left unclear who was responsible for checking the fuel load. Previously the flight engineer had the job, but the 767 does not provide for a flight engineer. The bottom line is the airline screwed up their procedures, and the pilots lacked the initiative to double check the fuel load. Plus the guy in the fuel truck effed up big time.

teh famed gimli glider incident to which you refer is really a "politically correct" incident. It was the first MetrIc plane and all the support personnel were used to dealing in pounds of fuel, not kilos. even the manual fuel gauge was in milimeters when the crew thought it was in inches.

the pilot flew gliders for fun and knew
to make s turns toward your landing point not away from it
and that a 360 to lose altitude may mean you won't acquire your target again.

but for the collapsed nose gear those two brats on their bikes would have been toast.

the canadian controllers should have been lined up and shot.

As for Air Canada 143-- if they knew the fuel guage was broken and it couldn't be repaired before the flight, why not just fill up the tank entirely? It's 1,900 miles from Montreal to Edmonton, and a 767 can fly about 3,700 miles on a full tank. No stress, no worries, no complicated calculations.

Yes, yes, I know fuel is heavy and the goal of every airline is to save money, but c'mon! Worse case scenario-- they lose a few thousand dollars needlessly carrying excess weight. What's the alternative-- making a mistake in the calculations and crashing the plane??? That one's a no-brainer.

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My personal favorite airline emergency story is Japan Airlines Flight 1628 from Paris to Tokyo back in November 1986. I'd preface it by saying I'm a bit of a weirdo, but you guys already knew that.

Quote: reno

Yes, yes, I know fuel is heavy and the goal of every airline is to save money, but c'mon! Worse case scenario-- they lose a few thousand dollars needlessly carrying excess weight.

I don't think any civilian airliner ever takes off with full tanks, other than on manufacturer tests. If then.

Military planes get full tanks, and strap-on additional tanks, almost all the time. Many even refuel in mid-air shortly after take off to top off. that's how come they can fly such long distances.

Quote:

What's the alternative-- making a mistake in the calculations and crashing the plane???

I know of exactly two crashes involving running out of fuel. The Air Canada I mentioned, and one where a Colombian airliner crashed after much delay near landing. I don't know if there have been others.

A jet with max fuel and max passengers might be too heavy to take off.

Looks like airlines make less than $6 per passenger per flight, so 200 people on a 767 would profit them less than $1200.

I didn't try to figure out how much it would cost to fly the extra fuel in full tanks, but you can see if it costs them a couple thousand per flight, they would lose money.

I think it is ryan air that aggressively punishes pilots who land with too much fuel and controllers get sick of ryan air planes squaking about 'sucking fumes' as they ask priority for landing.

Of course the worst ground accident in history would never have happened but for klm's captain taking on too much fuel.

the columbian one that crashed but did not burn in Oyster bay NY had made several missed approaches and had complained of low fuel but had never used the magic words of "minimum fuel" which would have brought it near the head of the line or the magic word "mayday" which would have made it "number one for landing".

some thought it was a "latin" or "macho" thing ... all men lining up for the porcelain at a base ball game have a need, but it requires a very frank confession to be allowed to go to the head of the line.... and the Macho pilot may not have been willing to express his predicament to controllers or he may not have known that "low fuel" was meaningless to teh controllers but "minimum fuel" packed much more of a meaning.

Quote: Dalex64

Looks like airlines make less than $6 per passenger per flight, so 200 people on a 767 would profit them less than $1200.

I've heard many times airlines operate on razor-thin margins, but $6 per passenger simply makes "razor-thin" seem as thin as the containing walls of a concrete dam.

Quote:

I didn't try to figure out how much it would cost to fly the extra fuel in full tanks, but you can see if it costs them a couple thousand per flight, they would lose money.

In a car, fuel makes up about 3% of the mass when the tank is full. Less if you're hauling a lot of stuff. In a rocket launched into Earth orbit, the payload can be as little as 3% of the total mass of the rocket, while the fuel is over 90%. For a jet liner the ratio is better than a rocket, but much worse than a car's. Depending on range, cargo, design and even flight plan, I suppose it could be as much as 75% fuel. Every additional pound of fuel requires more fuel to lift that additional fuel.

Confused? Me too. What it amounts to is an airliner carrying full tanks of fuel, and all other things being equal, will burn off more fuel than one carrying partially full tanks. This doesn't just cost more, but much more.

It is difficult to believe that someone would look at 7700 liters and think that it would weigh 13,600 kg. The basic conversion is that 7700 liters of water weighs 7700 kg. Minimal comprehension of metric is that they are by definition liters of water and kilograms are 1:1 relationship. Jet fuel is less dense than water, it isn't soup.

But, it is surprising how many people don't even think about rough order of magnitude.

Quote: reno

Yes, yes, I know fuel is heavy and the goal of every airline is to save money, but c'mon! Worse case scenario-- they lose a few thousand dollars needlessly carrying excess weight. What's the alternative-- making a mistake in the calculations and crashing the plane??? That one's a no-brainer.

Instead of transferring 16,131 kg they would have transferred 44,420 kg to fill the tank. That would have meant landing with over 400 kg per person still in the tank. Besides costing a fortune, I don't think you can land with that much fuel.


Fascinating story Nareed.

Quote: Pacomartin

Fascinating story Nareed.

For most incomprehensible error, I think It's a tie between the Air France crash over the Atlantic, and the Varig flight which crash-landed in the Amazon jungle.

The first involved a pilot trying to climb while in a stall. In the Varig incident, the plane flew in a completely different direction. They were supposed to fly north in a heading of 027, but flew west on a heading of 270.

There were additional errors in both cases, but those stand out and were the main causes of the accidents.