awesome sight, 747 venting fuel.
 

Cruising to the west of BN this afternoon, 0600UTC and passed (he passed me, actually) a 747 on descent into Bn with hugh contrails of fuel coming from the end of each wing. Gather it was a Japan Airlines flight in a hurry to spend some money.
Wonder what caused that decision which no doubt would not have been taken lightly.
BP

Far more likely to be just contrails from the wingtips rather than dumping fuel.
Anyway, the fuel dump pipes aren't in the tips, they're inboard a few metres.

Two questions:
How do you know it was a 747? The reason I ask is if it was close enough to identify, ATC would not let it 'dump fuel'!
How did you gather it was Japan Airlines?
Actioning the 'Fuel Jettison Checklist' is only done when the aircraft is above the Maximum Landing Weight and a landing is required as a matter of urgency. Under emergency conditions, the aircraft can be landed above Maximum Landing Weight.
No dramas in the news tonight!
Interesting none the less.

I thought you could only dump in dire emergency? Sounds like contrails to me.

correct me if im wrong but dont they also only dump fuel from one wing only?

The fuel dump valves on a 747 are from both wings, V1.

Unless the aircraft had an air turnback, or a divert (divart, in Nihongo) for an emergency, then it was more likely the dreaded "contrails", bp.

(Did you observe a cockpit window open, by any chance?? If you did, it MIGHT have been an emergency dump!! :E )

Fuel dumping is generally only done in cases of overweight landing - and then the aircraft is allocated a specific area - usually over water.

Occasionally, excess fuel - due to over-fuelling, expansion, or the transfer of fuel from one tank to another - may result in fuel being spilled overboard, without the knowledge of the crew.

On a jumbo, Fuel Jettison Non-Normal is normally carried out as Capt Fathom indicates but may also be carried out, if desired, as contained in several other checklists eg. Two-Engines Inoperative. Fuel Jettison is typically used shortly after takeoff when some form of problem (engine/ gear/ flap) makes further flight impractical. Can also be used at any time when the aircraft is above max landing weight and a prompt landing is required yet sufficient time is available or the severity of the problem does not require an immediate landing overweight.

Emergency - eg. uncontrolled fire, land overweight and ask questions later.

Vee1-rotate, 747 has two jettison valves, one on each wing. Jettison valves come off a common manifold pressurised by a total of six jettison pumps - two each in main tanks 2 and 3 and two in the centre wing tank. Jettison transfer valves also exist between main tanks 1 and 4 and their respective inboard mains (2 and 3) allowing fuel to be jettisoned from all four main tanks and the CWT simultaneously. Jettison rate with all six pumps on is about 2500 kg/min. CWT jettison pumps are also used as the normal supply pumps for fuel from the CWT to the fuel system.

747 fuel dump
 

I first saw the aircraft 12 O'clock high at about 40miles directly west of me with two large contrails. Thought it was a 777 or such like. As it got closer, and using a set of cockpit binos I saw that it was a 747 and thought it most unusual for such large contrails to be coming from the wing tips (and nothing from the engines) on descent to BN. Then heard transmission asking if the aircraft would be able to complete fuel dumping before reaching BN, and other transmissions vectoring traffic due inbound emergency. The aircraft was given vectors to continue fuel dumping via AMB. The crew had an American accent and I thought the callsign was Japan***.
Perhaps all an illusion!!! The truth is out there. Beam me back up Scotty!
BP

Yep.. me saw it too !!

I was near the ground - and i could see that it was a 747, it was low enough for me to see that. When i saw it, it was around 70nm West of BN and heading towards brisbane - and getting lower. I could not tell you if it was dumping fuel, however the trail that it left, streched for miles across the sky - i would have a guess at 10nm long trail it left !!! There were not any transmissions on my area freq...

Was certainly a sight that i had never seen before, as always - a camera was not close by...

Anyhow - thats my 2 cents worth.....:} :}

JAL aircraft but operated by JAZ (US Crews usually).

If you had been a day earlier and on the Eastern side of Brisbane you would have seen a QF 744 doing the same - BN-KLAX, jettison, then divert to SY.

6000FT or higher is the preferred level - and as said elsewhere, preferably over water.

Again I seriously doubt it was fuel dumping.
You know many hours in advance if you're going to land overweight from excess fuel, and in the 747 all you do to fix that is bump the speed up. I've spent about five hours at M 0.87 to burn off the excess because the Captain was a tad overcautious when ordering some before departure.
And even if you do arrive with a bit too much fuel all you do is get the flaps and gear out early to burn off some more.
It's not rocket science!

Well I believe you Bushy.

JAL do have flights ex brissy 18-wheeler.

If it was an even numbered flight (?) it was going home, especially in the arvo, and may have had some form of problem immediately following departure requiring a turnback.

I'm not saying that's not what happened, it's just not likely.
Anyone know the departure/arrival times of said aeroplane?

Have you considered the possibility that these were chemtrails?

We know, and They know that Oz is in an anxious state about the Ashes - could this be a mass spraying of tranquilliser?

UR,
perhaps we have already been sprayed... but most likely before the troops left for the old country to conquer, only to find their senses dulled to the point of a loss to england!!! :{

ps. it may make for an interesting series once they recover though... :cool:

JAL 747-300, Sydney to Osaka Flight 778.
Cabin had a burning smell so they landed in Brisbane. Was found to be a short circuit.
Link here.

Captain Can't,
Wash your mouth out with soap! Oh ye of little faith!

Well there you go, maybe a $100 part = a gazillion litres of JetA1 @ $1/litre dumped, landing fees, airframe and engine hours consumed, tech and FA costs, transit costs, environmental stuff.

And who says we aren't captive to the technology and we pay engineers too much?.:rolleyes: