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  • JorgeMartinsLusofona
    started a topic Q2539

    Q2539

    Dubious question, I mean... B or C?

    Question: An aircraft is approaching under visual flight rules an airfield whose runway is parallel to the coast. When downwind over the sea, the airfield is on the right. What wind effect should be anticipated on final approach and landing during a sunny afternoon?
    A. Headwind
    B. Crosswind from the left
    C. Crosswind from the right (Correct answer)
    D. Tailwind


    Info states:
    This is a sea breeze scenario.
    If the coast and runway are aligned East/West a right hand circuit would mean runway 27 in use, sea to the North and land to the South.
    At touch down the northerly sea breeze would be from the right.
    _____________________________________________

    Let?s get this straight:
    Imagine a runway parallel to coast, direction North/South, so the sea is on your left and the airport on your right. The question says that when you?re on downwind over the sea the runway is on your right.

    Here?s the dubious part: Either you intend to land on rwy 18 and on final approach the wind is coming from your right (sea breeze), or you intend to land on rwy 36 and when on final approach the wind is coming from your left (sea breeze).
    Both approaches can be flown on downwind over the sea, either left downwind or right, depending on runway.

    So, why exactly is the ?crosswind from the right? the correct answer? It depends on the runway, and I understand that the question is from the question bank, not yours. So it?s not your fault, of course.

    Regards

  • mikaylatjie
    replied
    Hey Jorge,

    I used a different method and got C as an answer.
    If you draw the aircraft next to a runway in the right downwind position, with the ocean on the left and the land/runway on the right--your aircraft will be on right downwind and the wind (sea breeze) will be coming from the left of the aircraft.

    However, the question asks for the wind on final approach:
    Once the aircraft turns onto final approach, the wind will be from the aircraft's right hand side (crosswind) because the aircraft has turned 180 degrees onto finals.
    Therefore answer C: "crosswind from the right" is correct.

    If the question had asked for the wind on the downwind leg, then answer B: "crosswind from the left" would've been correct.
    Last edited by mikaylatjie; 27-04-2019, 17:58.

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  • JorgeMartinsLusofona
    replied
    Re: Q2539

    Hey Yuri,

    After a few Picasso drawings I got it!

    I was completely missing the fact that the airport has to be always at your right, when you?re on downwind. Therefore you can only fly one downwind, in this case following my previous example, you can only fly the right downwind for runway 18. Because if you try to fly the left downwind for rwy 36 in order to be over the sea, you eventually end up with airport on your left, and that?s incorrect.

    And of course, the compass orientation of the runway is irrelevant!

    Now, on final approach we will expect, as Dick said, a crosswind from the right and a considerable tail wind component.

    Thank you Dick and Yuri.

    Regards,
    Jorge Martins

    Leave a comment:


  • Yuri
    replied
    Re: Q2539

    Hi Jorge,
    (I assume it's Jorge)

    Hopefully I can be some sort of help to you, and try to explain how to figure out this question.

    You started of correct with the info scenario, only I got confused when you stated that it meant that now runway 27 is in use!

    Well you can also use 09, and the crosswind will still be from your right!.

    How? simply place the A/C at the position as in the question stated and it works.

    Imagine an square Island and place your A/C overhead the sea and keep your land to the right, meaning now you have 4 position situations, N, E, S and West! in all of them you have your A/C downwind over the sea and you have your parallel runway to your right.

    You placed your A/C on the N side of the Island, which is okay, and you use runway 27 (East/West), therefore you can also still use 09 (West /East) if of course you position your A/C at the S part of the Island.

    Hope this clarifies now your situation in which you called it dubious! you simply placed your A/C position on the western side of the Island traveling South! you will now have the landmass on your left! if you would place it on the Eastern side it would work! still using runway 36 and your crosswind from the right.

    Remember the question did not state how the runway direction is running! It just stated parallel to the coast line, A/C downwind over the sea and airfield to your right.

    Hope this helps?

    Happy landings Yuri.

    Leave a comment:


  • Dick W
    replied
    Re: Q2539

    Interesting Question!

    The low level element of a sea breeze starts blowing inland at 90deg to the coast but s the sped increases it will follow normal geostrophic rules and turn right, in the Northern Hemisphere, and I suppose that the "sunny afternoon" clue implies that this efect has started.

    This means there is now a significant head/tail component that should decide your direction of landing. In the NH this would imply landing with the sea on your left. This could come from a left hand circuit, downwind over the sea, or a right hand circuit, downwind over land. The compass orientation of the coastline/runway doesn't matter.

    So I think that the aircraft in question has deliberately chosen the wrong runway and is going to land with a croswind from the right and a significant tailwind component - provided we are talking N Hemi.

    But these are my suggestions. The question should really be referrd back to ATPL Online for validation

    Dick

    On thinking more about this question it occurs to me that the examiner may be ignoring the daytime development of the sea breeze and only considers a sea breze straight across the beach. If so, N Hemi, downwind leg over the sea for a left hand circuit means wind from left on finals and for a right hand circuit finals wind from the right
    Last edited by Dick W; 22-12-2010, 18:31. Reason: Second thoughts

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