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Question regarding fuel dumping
I just saw the NOVA program about how two fully loaded 747 jumbo jets
collided on a fog-blanketed runway on the island of Tenerife, claiming the lives of 583 people in 1977. The pilot of the KLM plane ordered his plane to be refueled, so he rolled down the runway with 55 tons of fuel for a flight to Las Palmas, which would take at most a half hour. The program said it was enough fuel to get the plane back to Amsterdam, let alone Las Palmas. It was obvious that the extra fuel fed the blaze that killed everyone on board and prevented the plane from making a slightly faster takeoff, which could have averted the disaster. My question is this: When should the pilot of a commercial jet dump his fuel in flight? He obviously wasn't going to do that and was going to land very heavy. Under what conditions is fuel dumping necessary? Thanks. AJ |
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Question regarding fuel dumping
"AJ" wrote in message
ups.com... My question is this: When should the pilot of a commercial jet dump his fuel in flight? He obviously wasn't going to do that and was going to land very heavy. Under what conditions is fuel dumping necessary? Economics are rather important in fuel management for large aircraft... On the one hand, carrying around that extra fuel when it is not necessary ends up burning more fuel... On the other hand, it's quite possible that one airport will have fuel at a price cheap enough that it is worthwhile to fuel up there instead the endpoint of the next leg of the flight... Assuming an aircraft has the capability to dump fuel (vs just fly around and burn it off), one reason that they might do it is in an emergency that had them landing at a greater weight than their maximum permissible landing weight... For large aircraft, it is not uncommon that they will have a max takeoff weight that is greater than their max landing weight... |
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Question regarding fuel dumping
AJ wrote:
Under what conditions is fuel dumping necessary? When the plane needs to land and the takeoff weight is somewhere over 100% of the landing weight. |
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Question regarding fuel dumping
Grumman-581 wrote: "AJ" wrote in message ups.com... My question is this: When should the pilot of a commercial jet dump his fuel in flight? He obviously wasn't going to do that and was going to land very heavy. Under what conditions is fuel dumping necessary? Economics are rather important in fuel management for large aircraft... On the one hand, carrying around that extra fuel when it is not necessary ends up burning more fuel... On the other hand, it's quite possible that one airport will have fuel at a price cheap enough that it is worthwhile to fuel up there instead the endpoint of the next leg of the flight Most airlines have matrix tables to compute the value of the cheaper fuel vs. the increased fuel burn required to carry extra fuel (its not free to carry extra fuel to 30,000 feet and then bring it back). However, in this case, economics had nothing to do with it. The captain was a training captain and did not fly the line very often. He was upset that he was going to be late because he had already diverted. His goal was to have a super fast turn around at his next (originally planned) destination and then get back home ASAP. Part of his motivation was probably to show the lowly line pilots how he was such a super pilot and was able to avoid delays better than them, part of it was that he didn't spend much time away from home and wanted to get home. That also explains why he originally started his take off roll w/o any clearance. Once the 1st officer mentioned it he stopped and got his route clearance but then started his take off role w/o tower clearance. He was in a mad hurry. Its also believed that because 99% of all his take off and landings were in the simulator that the danger of taking off w/o a clearance wasn't as intuitive to him. Trainingitis they called it. -Robert, CFII |
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Question regarding fuel dumping
Not all aircraft can dump fuel, they don't have the plumbing
installed. Those that do cannot dump all the fuel. Dumping done at altitude when possible and the fuel evaporates before it gets to the ground. § 25.1001 Fuel jettisoning system. (a) A fuel jettisoning system must be installed on each airplane unless it is shown that the airplane meets the climb requirements of §§25.119 and 25.121(d) at maximum takeoff weight, less the actual or computed weight of fuel necessary for a 15-minute flight comprised of a takeoff, go-around, and landing at the airport of departure with the airplane configuration, speed, power, and thrust the same as that used in meeting the applicable takeoff, approach, and landing climb performance requirements of this part. (b) If a fuel jettisoning system is required it must be capable of jettisoning enough fuel within 15 minutes, starting with the weight given in paragraph (a) of this section, to enable the airplane to meet the climb requirements of §§25.119 and 25.121(d), assuming that the fuel is jettisoned under the conditions, except weight, found least favorable during the flight tests prescribed in paragraph (c) of this section. (c) Fuel jettisoning must be demonstrated beginning at maximum takeoff weight with flaps and landing gear up and in- (1) A power-off glide at 1.3 VSR1; (2) A climb at the one-engine inoperative best rate-of-climb speed, with the critical engine inoperative and the remaining engines at maximum continuous power; and (3) Level flight at 1.3 V SR1; if the results of the tests in the conditions specified in paragraphs (c)(1) and (2) of this section show that this condition could be critical. (d) During the flight tests prescribed in paragraph (c) of this section, it must be shown that- (1) The fuel jettisoning system and its operation are free from fire hazard; (2) The fuel discharges clear of any part of the airplane; (3) Fuel or fumes do not enter any parts of the airplane; and (4) The jettisoning operation does not adversely affect the controllability of the airplane. (e) For reciprocating engine powered airplanes, means must be provided to prevent jettisoning the fuel in the tanks used for takeoff and landing below the level allowing 45 minutes flight at 75 percent maximum continuous power. However, if there is an auxiliary control independent of the main jettisoning control, the system may be designed to jettison the remaining fuel by means of the auxiliary jettisoning control. (f) For turbine engine powered airplanes, means must be provided to prevent jettisoning the fuel in the tanks used for takeoff and landing below the level allowing climb from sea level to 10,000 feet and thereafter allowing 45 minutes cruise at a speed for maximum range. However, if there is an auxiliary control independent of the main jettisoning control, the system may be designed to jettison the remaining fuel by means of the auxiliary jettisoning control. (g) The fuel jettisoning valve must be designed to allow flight personnel to close the valve during any part of the jettisoning operation. (h) Unless it is shown that using any means (including flaps, slots, and slats) for changing the airflow across or around the wings does not adversely affect fuel jettisoning, there must be a placard, adjacent to the jettisoning control, to warn flight crewmembers against jettisoning fuel while the means that change the airflow are being used. (i) The fuel jettisoning system must be designed so that any reasonably probable single malfunction in the system will not result in a hazardous condition due to unsymmetrical jettisoning of, or inability to jettison, fuel. [Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25-18, 33 FR 12226, Aug. 30, 1968; Amdt. 25-57, 49 FR 6848, Feb. 23, 1984; Amdt. 25-108, 67 FR 70827, Nov. 26, 2002] "Robert M. Gary" wrote in message ups.com... | | Grumman-581 wrote: | "AJ" wrote in message | ups.com... | My question is this: When should the pilot of a commercial jet dump his | fuel in flight? He obviously wasn't going to do that and was going | to land very heavy. Under what conditions is fuel dumping necessary? | | Economics are rather important in fuel management for large aircraft... On | the one hand, carrying around that extra fuel when it is not necessary ends | up burning more fuel... On the other hand, it's quite possible that one | airport will have fuel at a price cheap enough that it is worthwhile to fuel | up there instead the endpoint of the next leg of the flight | | | Most airlines have matrix tables to compute the value of the cheaper | fuel vs. the increased fuel burn required to carry extra fuel (its not | free to carry extra fuel to 30,000 feet and then bring it back). | However, in this case, economics had nothing to do with it. The captain | was a training captain and did not fly the line very often. He was | upset that he was going to be late because he had already diverted. His | goal was to have a super fast turn around at his next (originally | planned) destination and then get back home ASAP. Part of his | motivation was probably to show the lowly line pilots how he was such a | super pilot and was able to avoid delays better than them, part of it | was that he didn't spend much time away from home and wanted to get | home. That also explains why he originally started his take off roll | w/o any clearance. Once the 1st officer mentioned it he stopped and got | his route clearance but then started his take off role w/o tower | clearance. He was in a mad hurry. Its also believed that because 99% of | all his take off and landings were in the simulator that the danger of | taking off w/o a clearance wasn't as intuitive to him. Trainingitis | they called it. | | -Robert, CFII | |
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