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It was reported recently that the Swiss flight LX18 from Zurich to New York had detected an engine issue shortly after take-off and decided to land back in Zurich.

Apparently, the Airbus A330-343 cannot just dump the fuel and, fully tanked, was too heavy to land safely, so it had to fly for 5 hours in a loop just to burn the excess kerosene.

Would it have been too complicated to implement a fuel draining mechanism? What would have happened if they couldn't fly for 5 hours and had to emergency land right away? Wouldn't this inability to drop fuel be a safety hazard?

Pondlife
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Quora Feans
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    Closely related: Why doesn't the 737 have a fuel dump nozzle? – Tanner Swett Aug 20 '19 at 23:20
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    I would also guess that in densly populated Switzerland with its strict environmental protection rules such a thing as dropping fuel would be considered illegal and would result in a high penalty for the airline. – Christoph Aug 21 '19 at 15:20
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    @Christoph: they could drop it in Germany, couldn't they? Jokes by side, when you drop fuel it dissipates, it's not as if people on the ground were bathed in jet fuel all of a sudden. – Quora Feans Aug 21 '19 at 17:55
  • @Quora Feans: I'm no expert, just Swiss, but I think they can do it in the same way as I can drive somebody full speed to the next hospital if I have an ememgency (and I would), but still would loose my driving license in the process for several month and pay some thousands of Swiss francs for the court case and the penalty... – Christoph Aug 21 '19 at 18:30
  • Just FWIW, according to another thread on airliners.net, fuel dump seems optional definitely on A330-200 and maybe on A330-300. – Cpt Reynolds Aug 21 '19 at 21:47
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    I'm a bit surprised that neither of the answers actually address the title question being asked at this time: they both go on about why an overweight landing should be avoided, but not why the A330 doesn't have the ability to dump fuel like some competing airliners. – 0xdd Aug 22 '19 at 14:40
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    Somehow I'm not sure whether dumping it is better for the environment than burning it? –  Aug 23 '19 at 00:14
  • @Christoph: Maybe not: https://www.rts.ch/play/radio/on-en-parle/audio/la-question-minute-lexces-de-vitesse-est-il-autorise-en-cas-durgence-medicale?id=8046656. In France you can try to call the "état de nécessité" (122-7 du Code Pénal) – WoJ Aug 23 '19 at 10:01
  • Fuel dumping capability of twin-engine jets like the A330 is extra cost option that is fitted during aircraft construction. Not all airlines order the capability. Aircraft with more engines have more difficulty meeting FAR requirements (I don't recall which ones offhand) for climbing and landing near maximum structural takeoff weight, so are more often fitted with capability to dump fuel. – Peter Aug 23 '19 at 10:48

3 Answers3

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To supplement Jimmy's answer, if they had to land right away, they could have; it just would've resulted in an overweight landing being recorded, and which on most airliners triggers a special inspection of the landing gear and its attaching structure, and if nothing is permanently bent or cracked or broken, you are good to go.

An overweight landing in itself shouldn't result in damage unless the landing was hard, the overweight condition using up some of the structural safety margin, and if you know you are landing overweight you will take extra care to land smoothly.

Depending on the airplane, an overweight landing may apply a "penalty" so to speak, accelerating some inspection interval, or advancing a life limit on a structural component in the gear, or some other negative impact maintenance cost wise. So there may be a significant incentive to avoid it from a long term cost perspective even if it means wasting 5 hours of fuel going round and round in a hold.

In the case mentioned, the crew would have consulted with the airline's Maintenance Control organization on the private company radio frequency to discuss whether to land overweight or not, and if there wasn't an urgent need to land, the Capt would have agreed with Maint Control and burn off the fuel to avoid the overweight landing and its ramifications.

Braiam
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John K
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    On a commercial flight, is such a cost consideration (safety issues aside) a legitimate justification to keep passengers delayed for 5 hours? – JBentley Aug 21 '19 at 12:24
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    Yes. Same reason Maintenance Control will advise a crew to divert an airplane to airport X even though pax might prefer Y, because the airline has facilities at X. – John K Aug 21 '19 at 12:49
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    I usually wonder, if they thought they were OK to fly in circles for 5 hours, why not fly towards your destination for the same 5 hours? They could even alter their route to always be within a reasonable distance of runway able to support them landing. – SnakeDoc Aug 21 '19 at 17:29
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    @SnakeDoc The route from Zurich to New York might not "always be within a reasonable distance of [a] runway" (where that distance is shorter than usual) and 5 hours into an altered route might have them landing on some ice patch in the North Atlantic where services and spare parts might be hard to find. – WBT Aug 21 '19 at 18:14
  • @WBT well ya, in that case sure, but what about trans-national, domestic, and continental flights? The US is large... but you often hear about something happening to the plane and it then circling for hours before landing at it's original location instead of just spending that time flying towards the destination. – SnakeDoc Aug 22 '19 at 19:15
  • It depends on the airline, and its financial situation as well. Some airlines will eat costs to get pax there no matter what, others that are on the edge of bankruptcy all the time will shave pennies any way they can. In the Regional industry in the US, once upon a time, operators would spend money upgrading airplanes with optional Service Bulletins if the improvement paid for itself within 5 years. By 2010, they wouldn't touch it unless the payback was 1 year, and some won't do an SB unless there is an AD attached to it. They simply didn't have the cash to spare. – John K Aug 22 '19 at 19:20
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    Flying "toward" (but not actually to) your destination may be worse for passengers. Returning to the origin may mean returning to the airline's hub (Zurich) in this case, where they have facilities, staff, and are best positioned to arrange alternate flights and/or a new aircraft and crew. Taking passengers to another location may strand them somewhere without these resources (or worse, somewhere in the arctic). That's completely worth it if there's an emergency need to land there, but returning to the origin, especially if it's the airline's hub, is ultimately more convenient for everyone. – Zach Lipton Aug 23 '19 at 02:10
  • An overweight landing will often also add more stress on the tires (not unheard of that a few will blow up in this situation) and the brakes (which may heat it up quite a bit due to the additional energy to dissipate, to the point of becoming red hot, being a fire risk, and requiring the presence of fire engines to cool them down right after landing). An overweight landing is definitely possible if there's no other choice, but it's better if it can be avoided. – jcaron Aug 23 '19 at 15:24
  • Have to agree with 0xdd this doesn't answer the question. The question is "Why doesn't the A330 have fuel dump capability?", not "what are the pros/cons of an overweight landing?". You've answered that question very well, it's just the wrong one. – FreeMan Aug 23 '19 at 19:46
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I think the characterization that it's "too heavy to land safely" is erroneous; the fuel burning is probably out of circumspection and to allow for a better safety margin. The runway length may also be beyond the landing field length and/or the brake energy limit of the heavy weight, so decreasing weight would add to the safety if immediate return to land is not absolutely needed.

14CFR 25.473 requires that landing gear and supporting structures withstand a landing load at maximum takeoff weight at a contact speed of 6 ft/s. This is definitely reduced from the 10 ft/s design load for maximum landing weight, but is still larger than the typical landing speed of 2-4 ft/s. As I understand it, this requirement applies whether or not the aircraft has fuel dumping capability. Therefore, the aircraft has the immediate return to land capability, at least from a structures perspective.

So where does maximum landing weight and fuel dumping come in? On top of the distinction above, it is primarily a climb performance limitation as per 14CFR 25.1001: if the aircraft does not have a fuel dumping system, it must meet the all-engine-operating and one-engine-inoperative climb in the approach climb configuration at maximum takeoff weight. Otherwise, credit can be taken for maximum landing weight. So the design decision of whether incorporating a fuel jettisoning system or not comes down to this.

JZYL
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    There may be some additional burdens, like EPA fines for dumping fuel in flight in the US. I don't recall reading anything in particular, but it seems like something one of several government agencies may have purview over. – jww Aug 23 '19 at 07:40
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Also consider the location. Assuming the a/c can do so, there would be no issue (apart from pollution) in dumping fuel over sea. But you want to spray jet-A all over Zurich? Plenty of ignition sources on the ground. Really not good.

D Brooks
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    Jet fuel vaporises long before reaching the surface, be it land or sea. :) –  Aug 21 '19 at 11:00
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    Also jet fuel is quite hard to ignite, except in controlled conditions. For example dropping a lighted cigarette into a bucket of Jet-A has exactly the same effect as dropping it into a bucket of water. – alephzero Aug 21 '19 at 11:31
  • Also, Zürich has 40km long lake right next to the city: Lake Zurich. – Bianfable Aug 21 '19 at 11:33
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    @bogl D Brooks was concerned about ignition sources, which, as ClobberXD and alephzero mentioned, isn't actually an issue. Nevertheless, fuel dumping is always done away from population centers, because the airline operators don't want to dump fuel on their customers. – HiddenWindshield Aug 21 '19 at 14:20
  • @bogl People typically inhabit land. The sea, not so much. – zymhan Aug 21 '19 at 14:50
  • And if you have a problem, how far away from any potential landing site should you go to dump fuel? – WGroleau Aug 21 '19 at 15:04
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    @alephzero there's perhaps an interesting question there: I've seen those youtube ATC videos where they get a plane out a ways from a city before dumping fuel and then vector traffic around the area for a while after. How close (in time, in distance) to the dump would another plane need to fly before it would actually be in danger? – mbrig Aug 21 '19 at 16:45
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    @mbrig Feel free to ask that question by hitting the Ask Question button. – PerlDuck Aug 21 '19 at 17:32
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    Jet fuel is basically diesel with some additives to improve fluid characteristics at low temperatures. Just like diesel, it can only be ignited at very high pressures and very high temperatures. – forest Aug 22 '19 at 00:41
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    @forest This video shows how Diesel can be ignited when sprayed onto nothing more than a lit candle. – PerlDuck Aug 22 '19 at 16:29
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    @PerlDuck: Indeed, if dumped jet fuel wasn't flammable, this airshow trick wouldn't be possible. But presumably that works only for a certain range of fuel-to-air ratios; by the time it reaches the ground from any reasonable altitude, I'd expect the fuel to have evaporated and dispersed enough that it cannot be ignited any more. – Ilmari Karonen Aug 22 '19 at 16:45