| Date: | June 27, 2007 / year-entry #233 |
| Tags: | non-computer |
| Orig Link: | https://blogs.msdn.microsoft.com/oldnewthing/20070627-01/?p=26233 |
| Comments: | 24 |
| Summary: | A few weeks ago, I got a piece of email from a friend. Maintenance crew in cockpit. They just told the pilot that the airplane "double faulted." |
A few weeks ago, I got a piece of email from a friend.
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Comments (24)
Comments are closed. |
Maybe the plane was just playing tennis and lost the serve… maybe…
Maybe a "Faulted" is something the pilots were drinking, and they had a double….Or perhaps you misheard the maintenance guy and he offered the pilots a "double malted"…
That reminds me of a far-side joke. Pilot in cockpit says to co-pilot:
"Oh no! The fuel light is on! We’re going to crash and we’re all going to die!!!!
…
Whoops.. That’s just the intercom light."
I’m only really worried when the conversation involves the on-board computer repeatedly telling the pilot "sink rate, pull up." :P
Pilot: "Did the airplane compete in the gymnastics competition?"
Crew: "The airplane double vaulted."
or
Pilot: "Is the ceiling flat?"
Crew: "Nah, the airplane is double vaulted."
I was once on a flight out of Calgary. As we were backing out from the gate the plane stopped suddenly. After a few minutes we were pushed back into the gate and a tech in greasy overalls boards the plane and starts talking to the flight crew. The captain explained that one of their computers had crashed. The tech indicates that they should just reboot it and not worry about it. And off we went. Makes me think twice about upgrading to first class. I’d rather not have seen that.
On a related note…. this was the time I accidentally left my tools in my carry on bag. When I went though the x-ray machines, they guy motioned me over and told me I shouldn’t be carrying screwdrivers, wire cutters, etc. on board. I explained the mix up and they let me board. Ahh, the days before 9-11 were so innocent.
Also… don’t watch a Mayday marathon before flying.
On Jetblue they have live TV. I was watching 50 worst airline disasters while flying to Boston. great fun.
pilot to maint crew: "But we’re triple redundant, right?"
"Ok, it’s all good."
(In case someone reads this who doesn’t know what a double fault is.)
Double fault: Exception occurring when recovering from another exception. (Triple fault is exception when trying to handle a double fault.)
http://en.wikipedia.org/wiki/Double_fault
In 1999, in kinder, gentler days, I was in the cockpit of an Airbus A340 on a flight from Toronto to Vancouver (the pilot wanted to see my Garmin 195 Aviation GPS).
I asked if were true that the Airbus fly-by-wire system would sometimes do the equivalent of Control-Alt-Delete.
The answer was "all the time", i.e, not infrequently.
Perhaps that’s where the "double-faulted" comes from.
Many years ago, I was flying into Chicago’s O’Hare airport on United, which offered the ability to listen in on the Air Traffic Control chatter. I remember hearing something like the following:
ATC: United 1131 [my flight], descend to 2500 feet and report the runway.
Silence from the plane.
ATC: United 1131, repeat, descend to 2500 feet and report the runway.
United 1131: Descending to 2500 feet, still looking for the runway.
You’d be surprised at how low planes can get in IFR (bad weather) without being able to see the runway. At some airports, it’s literally a couple hundred feet above the ground.
Though "still looking for the runway" may sound disturbing, not being able to see the runway at 2500 feet altitude (assuming a roughly sea-level runway) is actually not at all remarkable. Vanilla Category 1 ILS (instrument landing system) approaches can have a decision height (DH) of 200 feet AGL (above ground level) assuming surrounding terrain and obstructions permit. I’ve flown plenty of approaches around Seattle with ~300-foot DHs in instrument training as a private pilot.
Anecdotally, it’s a truly amazing experience to go from being entirely surrounded by clouds and having no visibility whatsoever to suddenly dropping out of the bottom of the layer a few feet above your DH or MDA (minimum descent altitude, the rough equivalent for so-called non-precision approaches) to see the runway stretching out right in front of you.
Looking at it another way, if a plane is descending 1,000 feet per minute, 2,500 feet means you’re 2.5 minutes from the runway, which is a relatively long time.
And incidentally, Category IIIc ILS approaches (which require specific equipment on the aircraft and ground as well as specific crew training) actually have a zero DH. In other words, the pilots can land the plane — or more precisely, let the plane autoland itself — with zero visibility. (I’m playing a little fast and loose with the definition of "visbility"; technically instrument approaches have both a DH or MDA and a forward visibility requirement.)
Strangely, private pilots operating under Part 91 of the Federal Aviation Regulations can actually take off IFR in zero/zero visibility, not that I can imagine why anyone sane would do that.
Depends on the ILS in use. Most common will have a minimum decision altitude of 200 feet (the altitude at which you may not descent below unless you have the runway visually).
The most sophisticated ILS systems let you do a landing in zero visibility. But they require at least three autopilots to be functional and agreeing on the results (basically, the autopilots are doing the landing). Any disagreements and it’s instant overshoot procedure.
Anyhow, x86 lore – wasn’t it a trick to use the triple-fault to exit from protected mode back into real mode? (I can’t remember…)
"Double faulted" really means the plane’s dumb–it commits two faults per crew that enters the cockpit. Well, no, on second thought it means there was a tremor in the cockit due to two faults–aren’t quakes caused at times by faults? It’s everybody’s fault, really.
I was on a plane scheduled to fly from London Luton to Amsterdam, and the captain cam e on the intercom: ‘Welcome to flight ###. We will be departing for Paris in a few minutes’.
Everyone was looking puzzled, at eachother, and the captain came back on: ‘Uhm, it seems I won’t get to see the Eiffel tower today, we’re going to Amsterdam instead’.
Sighs of relief ensued :)
"Anecdotally, it’s a truly amazing experience to go from being entirely surrounded by clouds and having no visibility whatsoever to suddenly dropping out of the bottom of the layer a few feet above your DH or MDA (minimum descent altitude, the rough equivalent for so-called non-precision approaches) to see the runway stretching out right in front of you."
When I do this in Flight Simulator, I usually end up with the runway way to the left or right of me. :P In other words: precision ILS approaches, not my strong point. Especially in a small aircraft with strong crosswinds.
Playing Flight Simulator X online can also lead to some very interesting ATC conversations. A funny one I had recently, while flying around Gatwick (UK):
Aircraft A: "Tower, can you confirm my position. I don’t know where I am."
Tower: "Aircraft A, Gatwick Tower, I don’t have you on my scope."
Aircraft A: "Gatwick tower, I appear to be in Canada."
Me: "Just fly east for a bit…"
Got on to a local plane at Schipol Airport. We sit for a bit, then the pilot starts the engines. To the right, the blades go round jerkily for a bit, then the engine catches, and it runs. Left hand engine does the same routine, and just spits out smoke and coughs. After a few minutes trying, some greasmonkeys appear, lift covers off the engine, yank on a few things, tut, scratch heads, then get down. We then get off the plane, and have to get on another one.
Now, this plane just recently landed. So if the engine had started, we’d have been off, with an engine that was about to die. Nice thought.
@Hayden:
I had something similar happen to me once. I was in a small plane flying from Texarkana, Texas to Dallas when the cabin filled with a light haze of smoke, and something that looked like maple syrup was leaking out of the left engine.
I was sitting in the front row of passenger seats, so I got a good view.
The pilot was young, and she looked like she might be new. The first thing she did was pick up the intercom and announce "There’s no need to panic!" Then she opened up and read through a glossy manual for a few minutes. After that, she shut down the left engine. Thankfully, we returned to Texarkana without any more problems.
the "glossy manual" she used is a checklist. That she said "don’t panic" and used the checklist shows her professionalism.
One of double fault cases is when both the aileron and elevator are stuck at different deflections.
There was a story that the head of [insert large plane maker here] said he would only fly in 4 engined planes.
Why, he would be asked.
‘Because there are no 5 engined planes’.
I was on the tarmac in an Airbus when we taxied back to the terminal. Turns out one of the two computers had an error, and though there was a redundant computer, they wouldn’t start out with one already crashed.
Enter the tech, and they had to reboot the computer. Turns out the only way to reboot it was to cycle the power… for the entire jet. Which they did many times, each time the lights and air conditioning cutting out. Now I know why flying with only one would not be an option.
Better than hearing
Maintenance crew in cockpit. They just told the pilot that the airplane "blue screened."
Sorry, RC, I couldn’t resist.