This is Xavier Chan Jun Yuan from Singapore. I am an aspiring student pilot and ever since I was introduced to your website through your book, I have found the information in both your book and website very interesting.
Also, you have been maintaining your website very well. I've seen other people asking you questions regarding aviation matters on your website and in your book.
Now I have two burning questions to ask you regarding the topic that you talked about on pages 178 and 179 of your book.
May I ask how does an aircraft dump its excess fuel in the event an emergency forces an unplanned landing?
May I also ask if the Airbus A330/A340 have this function and what other aircraft types have this function?
May you have a great day ahead and may your website soar to greater heights!
Dumping excess fuel on a plane is a very simple process. However there are certain considerations to be noted by the pilot. He must be mindful that he doesn’t dump the fuel lower than about 5000 feet from the ground or high terrain. Jettisoned fuel will normally be vaporized at this altitude and he should not carry out this process in a thunderstorm.
How much fuel to dump would depend on the current fuel on board. For example, if the fuel on board is 252 tons, he must ensure that he dumps 60 tons of fuel so that, for example if he flies an Airbus A340, the recommended maximum landing weight is 192 tons.
The plane is capable of dumping 1 ton (1000 kg) per minute or 60 tons per hour. So it would take about one hour to dump the excess fuel for a safe landing.
Fuel jettisoning (dumping) facility is available in most long range planes (eg. Boeing 777/747, Airbus A340/380) but optional on medium haul plane such as the Airbus A330.
In an emergency such as a fire where landing is the priority, the fuel dumping may be disregarded. The plane landing gears are still capable of absorbing the excess weight but they may require additional maintenance check.
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