Ask The Pilot

[harvyk]

I hope to organize a visit to the CASAs historical museum this year for AFF members at Essendon and give a more in depth talk about ATC from an Australian perspective, (I did a mini one at the ATC console on display in DRW during Ozfest), for anyone that might be interested, perhaps we could do a combined Pilot/ATC panel lunch with JB747 should he be available and another Mod giving his input from the private commercial aviation perspective ( Straitman ??).

Just say when (please not April...) I will be there...

 

[Mattg]

I know this probably sounds like a silly question, but what exactly does it mean to "dump fuel"?

 

[straitman]

I know this probably sounds like a silly question, but what exactly does it mean to "dump fuel"?

To dump fuel is exactly that.

To release some fuel into the atmosphere. Quite strictly controlled and no body really likes to do it due the cost. (except the F111s when they did a dump and burn for an airshow)

 

[meloz]

Back when I loved in wellington.

I once loved in Wellington, never did hear back from her.

Meloz

 

[jb747]

I know this probably sounds like a silly question, but what exactly does it mean to "dump fuel"?

Dumping fuel means that we just jettison it to the atmosphere.

In my 28 year airline career, I've done it once (50 tonnes). Even in the military, I only ever dumped a few tonnes.

Why..well because fuel has weight, and because it is flammable...

 

[jb747]

I once loved in Wellington, never did hear back from her.

Meloz

So did I, but I thought she was a pretty harsh ride.....

 

[Mattg]

Dumping fuel means that we just jettison it to the atmosphere.

In my 28 year airline career, I've done it once (50 tonnes). Even in the military, I only ever dumped a few tonnes.

Why..well because fuel has weight, and because it is flammable...

So the fuel just disintegrates in the air upon being released, does it?

 

[jb747]

So the fuel just disintegrates in the air upon being released, does it?

Basically. If you dump above 5000 ft, none will reach the ground.

It's not something that is done frivolously....there will almost always be some form of problem that forces you to land earlier, and so heavier, than planned.

 

[anat0l]

Basically. If you dump above 5000 ft, none will reach the ground.

It's not something that is done frivolously....there will almost always be some form of problem that forces you to land earlier, and so heavier, than planned.

I'm assuming that it doesn't "disintegrate" (i.e. it doesn't just disappear), but rather due to the velocity of the plane during a fuel dump, combined with the spray action, the fuel will diffuse easily within the air. Given the large fall distance compared to the area of dispersion, as the fuel disperses, the velocity of jet fuel particles decreases as it descends. Combine this with other environmental factors as it falls (e.g. winds, other possible obstructions, e.g. clouds, etc.), then it does seem very unlikely that any fuel would reach the ground.

You'd have to be dumping fuel at a much lower altitude to get any kind of noticeable effect of fuel hitting the ground.

It's almost like going to at least the 6th story of a building with a bottle of perfume, hitting the spray button repeatedly and seeing if any perfume reaches the ground.


Of course, it still remains that the fuel is being dumped in the air (though at very high altitudes one can argue just how much of an environmental effect it really will have). Either way, it's not a great course of action to take besides the cost of the wasted fuel.

 

[markis10]

Jet a1 breaks down into H20 and CO2 in the atmosphere as part of its evaporation process mostly, however a small proportion of the hydrocarbons do reach the ground in most cases.

http://www.iemr.org/pdfs/R_Contaminants/FuelDumpingv2_English.pdf

 

[jb747]

I can guarantee for you that if you do need to dump fuel, the environmental aspects of it are at the bottom of the priority list. Anyway, which is worse? An unburnt aerosol of fuel, or the waste products of burning it.

The only reason I dumped 50 tonnes was because I didn't have time to dump 60.....

 

[Mattg]

Basically. If you dump above 5000 ft, none will reach the ground.

It's not something that is done frivolously....there will almost always be some form of problem that forces you to land earlier, and so heavier, than planned.

Thanks JB I've always wondered about that. Thanks also to anat0l for the perfume analogy. The whole thing pretty much makes sense to me now.

 

[Awesom Andy]

I can guarantee for you that if you do need to dump fuel, the environmental aspects of it are at the bottom of the priority list. Anyway, which is worse? An unburnt aerosol of fuel, or the waste products of burning it.

The only reason I dumped 50 tonnes was because I didn't have time to dump 60.....

Whichever it goes, I would think that some fuel particles in the air is better for the environment than a bunch of burnt scrap metal left over from an unusable aircraft...

 

[Must...Fly!]

Bit of a left-field one jb747

Any idea if QF30/QF72 will feature on National Geographic on Air Crash Investigation? (Not implying any crashes took place here obviously!)

Personally I prefer reading the reports but there are some benefits eg the interviews.

NB: I intentionally did not mention QF32 since the final report has not been released yet.

 

[jb747]

Any idea if QF30/QF72 will feature on National Geographic on Air Crash Investigation? (Not implying any crashes took place here obviously!)

Personally I prefer reading the reports but there are some benefits eg the interviews.

NB: I intentionally did not mention QF32 since the final report has not been released yet.

QF72 has already had a mention on the show, as it was used to lead in a report about pilot error vs aircraft systems error....though even the little they did show was less than accurate. QF30...don't think so. I doubt that either event is good TV. Firstly, they won't have access to any voice data (it exists for the 72, but was overwritten in the 30), and secondly, because both events were over within about 5 minutes...the rest was just tidying up. Neither of the crews are all that interested in mainstream media publicity...especially for something that happened over 3 years ago.

The 32? Well, that probably fits the producer's wish list much better. It was long drawn out, involved a flash new aircraft, and the crew are less averse to the media.

 

[Flying Fox]

The only reason I dumped 50 tonnes was because I didn't have time to dump 60.....

Following on from this, the tubes that the fuel is dumped through look quite small and 1 ton of fuel sounds like a heck of a lot to me. So how many minutes does it take to dump 1 ton of fuel?

 

[jb747]

Following on from this, the tubes that the fuel is dumped through look quite small and 1 ton of fuel sounds like a heck of a lot to me. So how many minutes does it take to dump 1 ton of fuel?

About 30 seconds.

 

[obrienja]

I recall attempting to ignore an ad for a 60 Minutes with the tagline something like "Minutes from Disaster" that I saw last weekend which seemed to be talking about QF32. I'm sure that the good people of Ch9 thoroughly researched the story though and presented all the facts in a balanced way.

 

[harvyk]

I recall attempting to ignore an ad for a 60 Minutes with the tagline something like "Minutes from Disaster" that I saw last weekend which seemed to be talking about QF32. I'm sure that the good people of Ch9 thoroughly researched the story though and presented all the facts in a balanced way.

Of course ch 9 have never tried to cash in on sensationalism, what will be amazing footage is the live cross to the ch 9 helicopter which happened to be next to QF32 as the engines all exploded (all 4 of them) and the plane did a nose dive where the pilots managed to pull the plane up only meters from the ground. (you can feel the respect I have for journalism in this country)

 

[LiamR]

I recall attempting to ignore an ad for a 60 Minutes with the tagline something like "Minutes from Disaster" that I saw last weekend which seemed to be talking about QF32. I'm sure that the good people of Ch9 thoroughly researched the story though and presented all the facts in a balanced way.

Of course ch 9 have never tried to cash in on sensationalism, what will be amazing footage is the live cross to the ch 9 helicopter which happened to be next to QF32 as the engines all exploded (all 4 of them) and the plane did a nose dive where the pilots managed to pull the plane up only meters from the ground. (you can feel the respect I have for journalism in this country)

I think this was the video you are talking about? 60 Minutes: Captain Fantastic on MSN Video

It did a rerun on 60 Minutes a few nights ago.