FAA Instrument Test question

[bigulua]

My question pertains to question 4360 of the FAA Instrument-Airplane Written Test. The question asks for time en route and provides limited information. One of the components missing from the flight plan (and necessary for calculations) is wind direction and speed. The flight plan specifies a crusing altitude of 11,000 ft. Winds aloft at different altitudes are also provided in the problem: 2422+11 at 9,000 ft and 2324+5 at 12,000 ft. There is also an 18 degree east variation, which is given. To me it would made sense to interpolate these values for the wind at 11,000 ft, which I figured at 215 degrees at 23 kt. However, when checking the answer to the problem in the Gleim's Study Guide, it instructs you to use the values for the wind at 12,000 ft, which is notes is "closest to the planned altitude of 11,000 ft). MY QUESTION IS: Why wouldn't you interpolate for the values at 11,000 ft in the name of being accurate as possible!? In previous FAA questions on both the Private and Instrument tests, I believe that you are always advised to be as accurate as possible when doing computations. Why then cut a corner is this problem? If anyone can shed some light on this, I would greatly appreciate it.

 

[A Squared]

well,

for those particular forecast values, the difference between interpolating vs using the 12,000' values would be aproximately 3 degrees and 2/3 of a knot. Not enough to make a real difference and I'd certainly just use the 12,000 value in real life as it is silly to assume that the winds forecast is accurate to within 3 degrees and 2/3 of a knot. However this is an FAA exam, which has only a passing relationship to reality, so for the purposes of doing the exam, I'd probably do each step as precisely as possible. The answers are pretty close together and too many approximations might be enough to make you chose another answer.

I know that on the ATP exam, there were flight planning questions involving a flight of 2 hours, in which the 3 possible answers were all within 4 minutes; maximum of 2 minutes between the answers. It was impossible to actually arrive at the "correct" answer using the traditional "whiz wheel" e6-b, it just couldn't be read to that precision. Anyway, point is, do all the calculations as precisely as possible on hte exam, you're only going to do a few of them in your career (hopefully) and use a common sense approach in real life.

Oh, and another thing, the advice you read in the Gleims guide or any test guide is not infallible. It may not be the best answer, and they may not give the same "correct" answer as the FAA. I've seen this on a flight engineer exam. Unfortunately I went with the book answer insetad of chosing the answer my brain was telling me was corect. I got that question wrong.