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View Full Version : Pacific Diversion...why?


BlankBox
20th Dec 2005, 15:14
Saw all the good flight questions posed here ...so here's one of my own.
about 2 years ago this time we were flying YQR - KUL with 4 connecting
flights and short connecting times. The main leg was YVR - HKG via Air
Canada on an Airbus 344. I began watching this flight thru the
"Flightview" tool to kind of get a feel for what we might see on "our"
trip. Well, one day....that flight ....running about 1 1/2 - 2 hours late
suddenly divirted to an airport in Japan. Was on the ground for 41
minutes then completed the leg. I have often wondered since whether
this might have been a fuel related problem. e.g. Since it was so late
already ....was the jetstream that day so bad that the airliner
couldn't complete without "topping" up....or any other possibilities?

Thanx!

Globaliser
20th Dec 2005, 19:17
That's one possibility, although it seems to me that it would be odd if the diversion was in fact "sudden". (Caveat: Only SLF speaking here, but I would expect that a fuel diversion would be planned from some way out as the need ought not to take anyone by surprise even if it had arisen during the flight.)

Another possible reason for a sudden diversion followed by a short ground stop would be a medical emergency on board, someone who would be better off if offloaded at a diversion airport than carried a few more hours to the scheduled destination.

Carnage Matey!
20th Dec 2005, 19:32
Sounds like fuel shortage to me. Sometimes the winds are worse than forecast, sometimes you don't get the flight level you need, all of these can lead to a shortfall of fuel at destination. Another possibilty if you rwere travelling at this time of year is that the fuel got so cold that it approached the freezing point, which means you have to descend to a warmer air mass or fly faster to make the friction warm the fuel. As before, these will both lead to increased fuel burn.

Vacant Towers
21st Dec 2005, 02:43
Carnage Matey!, can you tell me the freezing point of jet fuel ?

And as well, can you tell me why the engine oil passes through heat exchangers in the fuel tanks.

Is it
A: to cool the oil
B: to warm the fuel
or
C: both the above.

I would also love to know which aircraft flight manual indicates to "descend to a warmer air mass or fly faster to make the friction warm the fuel."

VT

TopBunk
21st Dec 2005, 03:57
VT

I would also love to know which aircraft flight manual indicates to "descend to a warmer air mass or fly faster to make the friction warm the fuel."
B747-400 for a start. In BA our manual says '...fuel temp will cool at a rate of 3degC/hr to TAT-3degC. If necessary fueltemp can be increased by descent or climb into warmer air mass, deviating to warmer air mass or increasing Mach No. An increase of M0.01 will result in an increases TAT of between 0.5-0.7deg C.

Vacant Towers
21st Dec 2005, 04:12
I know I had seen it somewhere, but couldn't remember where (never 'on' the 744 tho). The joys of retirement:ok:

VT

BlankBox
21st Dec 2005, 14:27
...interesting! I'd assumed, beacause he was running so late that an abnormal headwind might have been the cause...now can see other possibilities
thanx!