But, during the long flight, the plane will of course use and burn off the fuel, shedding those pounds along the way. The manufacturers consider this in their design of an aircraft, so by the time a plane reaches its destination, it'll be light enough to land safely.
Sometimes, however, in an emergency situation, a plane might be forced to land earlier than expected. And that's when fuel dumping comes in. As we mentioned, the difference between maximum takeoff weight and maximum landing weight for a large commercial aircraft can be more than , pounds. But let's say that soon after takeoff a passenger on board has a medical emergency that requires an early landing, or the captain becomes aware of a maintenance problem that requires attention.
Neither of these situations are uncommon. The pilot will have a few options. He or she may choose to fly around in order to burn fuel. In this case, the pilot can drop the gear or flaps to help a plane burn fuel faster or "dirty up the airplane" [source: Getline]. However, this option is less than ideal for a medical emergency. Another solution is to eject fuel. This can be as easy as the flip of a switch in the cockpit. The system consists of pumps and valves designed to let fuel jettison from nozzles on the wings of the aircraft.
Such a system can eject thousands of pounds of fuel per minute, and it looks like a contrail when it's released [source: Scott ]. Not all planes are equipped with this sophisticated system, however. FAA spokesperson Alison Duquette says that narrow-body planes, like the Airbus A or the Boeing , aren't built with fuel dumping abilities. But larger, wide-body planes, like the Boeing and , which have added tanks, can dump fuel.
Thankfully, most of the fuel will evaporate before it even hits the ground. This is more likely on warmer days and when an aircraft is high up in the atmosphere -- ideally above 5, feet 1, meters. Because fuel jettison isn't very common and is done in emergency-type situations, Duquette says the FAA doesn't have hard-and-fast regulations about it, and air traffic controllers will help pilots in the process, keeping them separated from other aircraft.
The last option in an emergency is to simply land overweight. In fact, Boeing maintains that neither landing overweight nor fuel dumping has led to any accidents [source: Colella ]. Before takeoff, the flight planner calculates the amount of fuel needed to complete the trip. So that enough fuel gets burned off over the course of the flight and the plane's weight comes down and then it's safe to land. A pilot will choose to dump fuel only on very rare occasions.
Brickhouse: Unless you have a medical emergency on board, someone is dying, you don't really have time to fly around and burn fuel. So, in that case that's when you would dump fuel so that you can lose weight quickly. Narrator: If the pilot has a little more time or doesn't have the capacity to dump fuel like in a lot of smaller crafts, they might dirty up the plane, this means purposefully creating drag and flying around in circles in order to burn off the excess fuel.
But if a passenger is critical, like the woman from , they might not have time for that. Fuel jettisoning systems can dump thousands of pounds a second. Most can get a plane back down to its max landing weight in 15 minutes or less, and it's usually as easy as flipping a switch in the cockpit. Most systems are a series of pumps and valves that divert the fuel to the tips of the wings. The fuel streams behind the plane in what looks like contrails and yes, there is a fail-safe in place to stop the pilot from expelling all the fuel at once.
But it's not just a pilot's judgment that decides when and how fuel gets dumped. The Federal Aviation Administration has a handful of regulations in place: the plane has to be at least 2, feet above the highest obstacle along the route, at least five miles from any other aircraft and away from populated areas and bodies of water whenever possible. But aside from this page of FAA policy, that's about it when it comes to regulations.
Dumping fuel into the atmosphere isn't free of consequences, but the Environmental Protection Agency just isn't worried about it. It regards the practice as exceedingly rare and leans into the fact that airlines don't promote it because it's a waste of money.
Brickhouse: If we get to a point where we're seeing more aircraft with the capability to dump fuel and we're seeing more aircraft dumping fuel and maybe not from an emergency point of view, then maybe yes, that would be something that the EPA would need to look into. Back in January, a Delta en route to Shanghai from Los Angeles suffered an emergency after take-off and had to shut down one of the engines.
The plane then had to dump 15, gallons of fuel at the height of feet over a suburb of the coastal city. Unfortunately, it was over three schools, including one for small children. The fuel dump affected over 50 people, who claimed to see the plane pass overhead and then noticed a powerful smell of fuel. It was only after this point that they noticed their eyes burning, skin itching, and some breathing problems—fortunately, no other significant injuries.
Since then, there have been two lawsuits launched, and the FAA is still conducting its investigation. Watch this space. Journalist - Working in news media for over a decade with outlets including 9News and the Discovery Channel, Nick is an airline marketing specialist with a Masters level education.
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