Human error

Quote: Pacomartin

I didn't notice that. But my point was that you could design the winch with a slip ring and try and develop a complex locking mechanism. But the designer simply figured there was more than enough force from the friction around the drum. All the crew had to do was to keep enough wraps on the roll.

Yep, I was just being a pedantic git :)

Quote:

Everything goes along fine until someone loses count, and all the equipment slides off and drops to the bottom.

Which was not a failure mode I had ever considered ;)

Quote: Nareed

Oh, but they do!

Often pilots try to restart engines rather than setting up best glide angle so they have inadvertently traded altitude for nothing. repeated attempts to restart in oxygen-richer air is tempting but also sacrifices horizontal glide distance.

Quote: Nareed

For one thing airplanes can glide. That is, they can convert altitude to speed at a known rate. They don't just simply fall down. But the other thing is aircraft carry an electric generator connected to a propeller about as large as that on a single-engine Cessna. It's stored in the fuselage, but pops out automatically if all other power fails. It's called a Ram Air Turbine.

Planes do fall at fairly well known rate, but you want precise details and their vertical speed indicator did not function without power. The total glide was over 80 miles.

The ram air turbine, is driven by the forward motion of the aircraft so it was less effective as the plane slowed for landing. The lack of hydraulic pressure prevented flap/slat extension which would have, under normal landing conditions, reduced the stall speed of the aircraft.

The pilot used a glider maneuver (forward slip) to increase drag and slow the plane.

Not human error, but another case of a B767 running out of fuel because three hijackers refused to believe the pilot. The pilot and first officer survived, because at the last minute the hijackers left the cockpit allowing them to control the crash somewhat.

The hijackers demanded the plane be flown to Australia.The captain tried to explain they had only taken on the fuel needed for the scheduled flight and thus could not even make a quarter of the journey, but the hijackers did not believe him. They had been reading the in-flight magazine stating that the maximum flying time of the airplane was 11 hours.

Instead of flying towards Australia, the captain followed the African coastline. The hijackers noticed that land was still visible and forced the pilot to steer east. Leul secretly headed for the Comoro Islands, which lie midway between Madagascar and the African mainland (abut 200 miles from mainland).

Quote: Pacomartin

Planes do fall at fairly well known rate, but you want precise details and their vertical speed indicator did not function without power. The total glide was over 80 miles.

That's why it was so important to get good data from the flight controllers.

It's a little-known fact modern civil aviation radar does not track planes like military radar. Instead when sweeped by radar, modern planes send a signal from their transponder, which contains some basic flight info like airspeed and altitude. When the engines went out, so did the transponder. The controllers had to rig up their system to track the plane's position and attitude, so they could relay data like rate of decent.

In 1996, an Aero Peru 757 took off with tape covering the plane's static ports. This left them with faulty speed and altitude data. the pilots did realize their data was wrong, so they asked the controller for radar data. the controller relayed the data relayed by the transponder, which naturally agreed with the flight instruments. Neither party knew, or noticed, that essentially the flight controller was giving them back the exact same bad data they already had. The plane crashed in the ocean.

Even with relatively "good data" a significant portion of it may be supplied by what BBB referred to as "ghosting". the Controller sees a blip and the associated data tag on the screen but its not from determined data its from expected but not received data that has been extrapolated to a new but unverified position.

What is an interesting point about this story is how often did people screw up the metric conversion and the fuel gages caught the error?

I think it is too much to believe that insufficient fuel was only transferred one time, and it happened to be the one flight that the gages didn't work. I bet nobody reported those instances so as not to get anyone in trouble. If they had reported the instance, perhaps more careful control over the paperwork could have been instituted.

that is why the faa often offers a moratorium on charges if you report voluntarily within ten days.

Its gives them all that "near miss" data .

Quote: Fleastiff

Its gives them all that "near miss" data .

Interesting. Trust your regulator.

We had an interesting case at work.
We were told to charge our plane tickets on our federal credit cards, and then itemizing them as an expense. We would include the receipt from the plane ticket as proof that we spent the money (just like a hotel receipt or a car rental receipt).

Then some regulators decided that it was better if the plane tickets paid by a government travel agency before the trip. One guy in the office would have the office secretary prepare his travel claims. The secretary filled out the claims like always, itemized the plane ticket and included the ticket receipt. But inadvertently the traveller was reimbursed for a plane ticket that was already paid for. But he never noticed since he didn't go through his own travel claims.

Well a major review was authorized for all travel procedures, and in the process they found these travel claims. There was no intent for fraud because the plane receipt was clearly in the return, it was just something that was a victim of a change in procedure. But instead of allowing the traveller to pay back the money unintentionally given out twice, they launched a congressional investigation and lambasted him on the floor of congress. He was ultimately suspended for a period of time without pay.The final kicker was the review recommended that employees charge their tickets on federal credit cards again (the original procedure) to prevent such accidents from happening.

Regulators claim to want to know about mistakes in procedure, but they really want blood. It makes them look good.

Quote: Pacomartin

What is an interesting point about this story is how often did people screw up the metric conversion and the fuel gages caught the error?

It depends how many planes at the time used metric measurements (there's a pleonasm for you). Since there were no other Air Canada planes running out of fuel on a regular basis. We can assume any such errors were caught and corrected somehow.

Keep in mind at that time many planes, even small ones like the DC-9 and 727, carried three cockpit crew: the two pilots and a flight engineer. the latter was tasked with keeping an eye on the fuel. But then, too, also at that time most planes would have used imperial units.