Figure 158: RNAV (GPS) RWY 11, Grand Junction (GJT)
FAA-CT-8080-3F · Instrument Rating supplement · asked on the Instrument Rating test
1 FAA question that refer to this figure
Question 1 · Instrument Rating
(Refer to FAA-CT-8080-3F, Figure 158.) With winds reported as from 330° at 4 knots, you are given instructions to taxi to runway 4 for departure and to expect takeoff after an airliner departs from runway 29. What effect would you expect from that airliner's vortices?
- A.The winds will push the vortices southeast of your takeoff path.
- B.The upwind vortex would tend to remain over the runway.
- C.The downwind vortex will rapidly dissipate.
Show answer and explanation
Correct: B. The upwind vortex would tend to remain over the runway.
Runway 29 at GJT is aligned about 297 degrees, so a wind from 330 at 4 knots gives a crosswind component of roughly 2 knots from the right. AIM 7-4-4 notes that a light cross-runway component of 1 to 5 knots can keep the upwind vortex over the runway for a while and hasten the drift of the downwind vortex, so the vortices are not simply blown clear and the downwind vortex does not dissipate because of the wind.
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