Saturday, August 1, 2009

Why do aircraft burn off fuel before climbing on long flights

Why do aircraft burn off fuel before climbing on long flights?
On my way back from Europe last week, we flew from Amsterdam to Minneapolis/St. Paul on a DC-10. The pilot described the flight path, saying we'd ascend to 10,000 feet (or so), burn off some fuel, climb to 26,000 feet (or so), burn off some more, and finally go to our cruising altitude of 36,000 feet. Why don't they just climb to 36,000 feet right away?
Air Travel - 5 Answers
Random Answers, Critics, Comments, Opinions :
1 :
I would assume it's a wait issue.
2 :
this in a course of action is very odd and would lead me to beleive that there was a problem that was not fully explained. i'm not a big fan of the dc-10's or a lot of their classes as well as some of the airbus transporters. i don't understand why the captain would even explain his/her actions to the passengers. or maybe your question just doesn't make that much sense.
3 :
Weight! You're not going to climb to cruising altitude with full tanks. It's a gradual ascent. DC-10 or A340 - makes no difference. You also don't land with full tanks because of weight. That's why pilots either dump fuel or circle to burn it off if their particular plane doesn't have a fuel dumping feature whenever they have to unexpectedly have to return to the airport. michinoku2001: The wings do not break off......You're correct about the blown tires though. Also, an overweight plane can also cause the breaks to overheat and catch fire.
4 :
The plane just can't climb very fast with all that weight onboard, so it gradually climbs as it burns fuel. If an aircraft like a DC-10 tried to land with a full fuel load the wings could actually break off and the tires blow out as it touched down, hence the fuel-dump in case of emergency.
5 :
This is definitely a weight issue. Although 10,000ft to level off does seem odd. Without looking at the departure and arrival procedures around EHAM, I'll have to assume you leveled off at 10,000 for a departure procedure for a short time. Also take for example a fully loaded MD-11 Cargo aircraft. We at Chicago Center talk to a Lufthansa Cargo aircraft that goes from Chicago O'Hare (ORD) to Frankfurt Am Main (EDDF) juist about every morning. Because of it's weight, it's initial altitude is usually only 29,000ft. (FL290). As it burns off fuel, it will request a higher altitude from atc as it is capable to climb due to it's lighter weight. It's final cruise altitude might be anywhere between FL370 to FL410. Other factors, like weather and atc preferential routing might, and usually does, play a factor. The same also applies to passenger aircraft as well. A Boeing 777 travelling from Europe to say, Dallas-Fort Worth, (DFW), might only climb to 32,000 (FL320) initially. But by the time you find youself getting into North America, you'll be anywhere from FL360-400. It's all about fuel economy.

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