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OAA Flight Performance & Planning. It's likely to be a bogus answer if you don't agree with it, it wouldn't be the first time...
On another note, I have stumbled upon a couple of questions involving the dumping of fuel to ensure level-off altitude isn't below obstacle clearance altitude during a drift down procedure. Is this common practice, as the only thing I have read about fuel dumping so far is regarding the procedure of doing so prior to landing to ensure not exceeding MSLM?
The OAA answer to question 3 is incorrect. Hopefully you should be able to see that is the case by applying common sense. If the aircraft gets heavier it won't climb so well. So if we are happy to be limited to a lower climb gradient we can be heavier.
I'm not an airline pilot, so I cannot comment on what is common practice. But if I knew that keeping any unnecessary fuel on board would cause me to hit the mountain tops, I would certanly dump any fuel that I didn't need.
I agree with you regarding question 3. It's just that as with the case of questions 1 & 2, it's easy to miss corrections, that's why it's seems like a better bet to run it by here, rather than just assume that I'm right and they're wrong.
The fuel dumping questions were:
If the level-off altitude is below the obstacle clearance altitude during a drift down procedure?
a. Fuel jettisoning should be started at the beginning of drift down. b. The recommended drift down speed should be disregarded and it should be flown at the stall speed plus 10 kt. c. Fuel jettisoning should be started when the obstacle clearance altitude clearance altitude is reached. d. The drift down should be flown with flaps in the approach configuration.
During a drift down following engine failure, what would be the correct procedure to follow?
a. Begin fuel jettison immediately, commensurate with having required reserves at destination. b. Do not commence fuel jettison until en-route obstacles have been cleared. c. Descend in the approach configuration. d. Disregard the flight manual and descend at Vs + 10 kts to the destination.
Correct answer for is a. for both questions. Looking at them in hindsight I realize that those are the only reasonable answers, it's just that when I came across them there had been no mention of fuel dumping in the previous chapters that I had read, other than for the purpose of ensuring MSLM, and I suppose that the intention after engine failure is to land as soon as possible, thus fuel dumping should be considered pertinent. However there is no mention in the question of what phase of flight is being referred to, and dumping of fuel doesn't seem to be advisory unless absolutely necessary. What had been brought to attention in the previous chapter however, was the use of drift down profile graphs, where one was to determine if the desired altitude, with regard to obstacle clearance, could be met with the current mass, and if not, (to my understanding) a second graph should be used to determine whether or not vertical clearance could be achieved using horisontal distance instead. Thus the reason for my inquery.
You are however absolutely right, Keith, it definately seems like a better idea, if need be, to dump some fuel rather than run in to a mountain top.
Just embarked on the Bristol GS study, any tips on helping me ease my pain?
Have read many of the posts in this forum and see a lot of people are struggling with the Gen Nav side of things, I've just purchased a book from Baz at Bristol GS 'Mathematics for Aviation', I sure hope that helps me understand the subject a lot better when I receive it
The tendency to call to mind common experiences or scenarios from the past and link them incorrectly to a perceived mental model is called:
a. Confirmation bias. b. Action slip. c. Environmental capture. d. Frequency bias.
Supposedly the right answer should be d. Is this correct? Couldn’t seem to find anything about frequency bias in reference to HP. I suppose that if one breaks it down, then it could be the right answer. However the definition of environmental capture seems quite fitting in the context…
Question: Which combination of answers of the following parameters give an increase or decrease of the take off ground run: 1 decreasing take off mass 2 increasing take off mass 3 increasing density 4 decreasing density 5 increasing flap setting 6 decreasing flap setting 7 increasing pressure altitude 8 decreasing pressure altitude
I think it would have to be B because it's the only one which lists conditions which all affect ground run in the same direction, as in, they all cause it to decrease. All the rest contain some conditions which cause and increase and some which cause a decrease.
a. No heading is specified so select one at random, 000 degrees for example.
b. Set the high-speed slide with the centre dot at 240 kts.
c. The question specifies a +45 wind component. This means a 45 kt tailwind component. This means that the ground speed is 240 TAS + 45 kts = 285 kts.
d. The question also specifies 150 left drift. So draw a cross where the 15 degrees left drift line crosses the 285 kt arc.
e. With 15 degrees left drift the track is 345 degrees. So the reverse track is 165 degrees.
f. Rotate window to align 165 degrees with true heading index.
g. The cross now indicates 19 degrees right drift. Align the 165 degrees track with 19 degrees right drift. The cross now indicates 15 degrees right drift. Align 165 degrees with 15 degrees right drift. The cross now indicates 16 degrees right drift. Align 165 degrees with 16 degrees right drift. Both the cross now indicates Move and the outer scale now indicate 16 degrees right drift, so the drift is balanced.
h. The cross is now on an arc 65 kts below the centre dot. The wind component was a headwind during the outward leg so it must be a tailwind during the return leg This means that the wind component is -65 kts.
There are quicker ways of doing the job (I saw one once here in PPRuNe but I can't remember what it was), but the above is the method described in the CRP 5 instruction sheet.
Last edited by keith williams; 29th Jun 2012 at 15:28.