Why can't this plane dump fuel?

General Questions
#1

This story recounts a pretty unpleasant ride for passengers on an A320 departing Las Vegas:

The plane took off and apparently lost hydraulics right away. Then it circled Las Vegas for five hours – lurching violently enough that people were vomiting – because it couldn’t dump fuel before an emergency landing and had to burn it off. The story says the A320 can’t dump fuel.

I thought dumping fuel was a typical feature on a passenger airliner, for exactly this reason. This turned out with just some nauseated passengers and a vomit-filled plane, but in that five hours the pilots might have lost control and crashed.

#2

If need be, an airliner can be landed successfully with “too much” fuel. The design of the aircraft precludes such landings without an analysis of the plane afterwards. The pilots get to make a judgement call. Fly the plane with screwy hydraulics (but there are multiple hydraulic systems to still allow the plane to fly safely), or land immediately and guarantee a multi-day grounding for the structural exam.

For the most part, there isn’t a need to dump fuel on a medium airliner. The quantities involved with the bigger iron (A330/340s, B747/777, etc) justify the added weight and complexity of a fuel dump system. The smaller stuff can just land if they really, really need to.

#3

Followup question – how is it better to circle a densely populated area for 5 hours rather than just pointing the plane straight and going to where they wanted to go in the first place?

#4

It something worse goes wrong during those five hours and if becomes less risky to emergency land the plane immediately than it is to maintain flight for the time required for the fuel to burn up, you are always close enough to an airport to do it.

#5

Lets see, 2 of 3 hydraulic systems out, yep I am keeping close to the place I took off from, in case I have to land now. I think they did the safest thing they could. They chose not to land heavy and kept close in case they had no choice.

CAPT

#6

Las Vegas isn’t exactly densely populated. It’s basically a shining beacon of debauchery in the midst of a vast, empty desert. A mile south of the airport there is no evidence of civilization at all.

So the pilots did what was sensible - they stayed close to the airport in case their situation deteriorated and they had to land right away. But as long as they had enough control to orbit, they could burn off fuel to make the emergency landing safer. They could still land heavy if they had too.

#7

But guys… you’re not answering my real question. Why does this particular airplane lack the ability to dump fuel? Am I wrong in thinking this is a standard feature in passenger planes?

Seems the desert around Vegas would be a fine place to dump fuel instead of circling for five hours.

#8

KCB615 answered it: because the fuel dump system adds complexity and weight to the aircraft, and isn’t considered strictly necessary for aircraft of that size.

Everything in engineering is a trade-off. And, who knows, maybe after this incident Airbus will take a look at their work and say, “hm, well, maybe we should have a fuel dump system after all…”

#9

According to Wiki, the A320 does not indeed have a fuel dump mechanism:

[

](http://en.wikipedia.org/wiki/Fuel_dumping)

But the OP is better off asking this question on Pprune.

#10

Is a “heavy” landing like this less safe than a normal landing? If not, it makes it sound like the pilots were more concerned with taking the plane out of commission (and costing their employer money) than they were with the comfort of the passengers, who from the sounds of the article were having a rough time of it.

#11

This surprises you?

The law requires that the safety of passengers be prioritized above making money, but there’s no law that says the comfort of the passengers should be given any such similar priority. If it did, we’d all have first-class seating, lavish in-flight meals and much shorter lines at the ticketing counter.

#12

Without knowing more details (and it’s a horribly written article) it’s hard to know exactly what factors the flight crew weighed in making their decision. Remember, though, that they’re on the plane along with everyone else. Even if you think they’d risk the passengers lives to save their employer a few bucks, do you think they’d risk their own?

I want to know why the plane was having such a rough ride. Were the faulty hydraulics moving the control surfaces somehow? Was there turbulent air and the pilots didn’t want to tax their remaining system to counteract it? Obviously they still had enough control to land.

#13

A heavy landing is unsafe if the runway isn’t long enough for you to land at that weight (heavier aircraft flies faster, lands faster, and needs more runway.) Also the nature of the problem could mean that some things aren’t working on the aircraft. For example a complete hydraulic failure would mean no flaps, no ground spoilers, no nose wheel steering, and only a limited number of brake applications. In the type I fly, a flap-less landing requires twice as much runway as a full flap landing.

The deal with flying is basically that you follow the rules as much as you can unless it is unsafe to, in which case you can do what you is necessary to ensure the safety of the flight and the passengers. Exceeding the maximum landing weight is breaking the rules and you only do it if it is unsafe to remain in the air. You don’t do it because Bill and Marge down the back are having a rough ride.

#14

That extra weight is also highly flammable in the event of a bad landing.

#15

Answered, yes you were wrong to think that was a standard feature in all airliners. This was already brought into public awareness about the A320 a few years ago when the LAX incident with the jammed nose landing gear happened, they had to stay circling over Long Beach until they burned some more fuel off.

The latter, likely. Lower-than-cruise level airspace around McCarran in a hot afternoon can be annoyingly bumpy on a completely normal flight. And let’s not forget that what to laypeople is shake rattle rock and roll, to aircrew is “a bit choppier than usual”.

The A320 is a FBW plane so I wonder if what would be done is for the control system to switch itself or be manually switched to a different mode when that sort of failure is detected… pilots, any facts on that?

#16

I’d be willing to bet the rough ride was due to turbulence. Edit: Turbulence is rough regardless of whether you are “counteracting it” or not and most passengers are only familiar with the odd bit of light chop you get at altitude and aren’t used to spending hours in the uncomfortable low level turbulence that they’ve normally climbed or descended through in a few minutes.

The aircraft had actually only lost one hydraulic system so still had two remaining. That shouldn’t have caused any control issues.

http://avherald.com/h?article=45165c68&opt=0

#17

That was the only reason I could think of why faulty hydraulics would lead to a rough ride, but not render the plane unflyable. Any reason to stay at the turbulent altitude; was the rough ride worth it in order to burn off the fuel faster?

#18

You burn fuel a lot faster at low level. It could be that there wasn’t any smooth air at a practical altitude.

#19

Still, at least the Daily Mail comment crowd are debating the really important part: was the newspaper wrong to use the word “careering” in the headline? (Answer: no :wink: )

#20

My eyes have learnt to become unfocussed whenever they detect the comments section of an online blog or news service ;).