Many people in the area claim to have witnessed fuel dumping. However, this is actually extremely rare. Fuel dumping would only occur if there were something seriously wrong with the flight. It’s main purpose is to drop weight in case of emergency. Think about this: if the plane was within spec on takeoff, why would it need to be lighter on landing? Planes probably don’t dump fuel without a very good reason.
Fuel dumping has occurred over Des Moines (one spectacular case that old-timers still talk about was in 1997 on a property south of the Post Office), but it is very rare and most planes today (supposedly) do not even have the ability to do it.
So if you have sighted something that looks like fuel dumping, please contact us. We definitely want to hear about it. Please include the exact time, location where you viewed it and airline. Also, you definitely -should- report it to the Port Of Seattle: 206-787-5393.
But before you reach for the phone: A lot of cases that look like dumping are actually a combination of the jet exhaust and water vapor.
Haven’t you ever wondered why Jet exhaust looks so clear when gas and diesel engine from car and truck exhaust is so ‘smokey’? First of all, jet fuel is basically kerosene, which burns clearer than gasoline. But it is also claimed that there are also number of additives in commercial jet fuel that make it burn clear (these are seriously toxic heavy metals, by the way.) But under the right atmospheric conditions those additives don’t work as intended and you get to see the ‘real’ exhaust, which you might easily mis-identify as ‘fuel dumping’.