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7574EVER

Well-known member
Joined
Jul 5, 2004
Posts
288
Hey all. I'm doing some studying and have been through the AIM; but have had a hard time finding the answers to some things.

- What takes precedence when landing? RVR or visibility?

- What measures visibility?

- What's the difference between "Expect to cross at..." and "Cross at"?

- When can you AND can you not take off based on what the RVR is being reported?

I'm trying to brush up on my IFR stuff with questions off the gouges. Just trying to refresh my memory on all of this. Any help is appreciated.
 
Hey all. I'm doing some studying and have been through the AIM; but have had a hard time finding the answers to some things.

- What takes precedence when landing? RVR or visibility?



*flight* visibility.

91.175(c) Operation below DA/ DH or MDA. Except as provided in paragraph (l) of this section, where a DA/DH or MDA is applicable, no pilot may operate an aircraft, except a military aircraft of the United States, below the authorized MDA or continue an approach below the authorized DA/DH unless—

(1) (not germane)

(2) The flight visibility is not less than the visibility prescribed in the standard instrument approach being used; and


RVR is not particularly relevent to the question of whether or not you may legally land. *reported* visibility and RVR do determine whether you may or may not begin or continue an approach under 121 or 135. In operations under part 91 only, you may begin an approach regardless of reported vis or RVR.



- What measures visibility?

Which visibility? The visibility you need to land? That's flight visibility and the only way that can be measured is by the pilot looking out the window.


- What's the difference between "Expect to cross at..." and "Cross at"?


Anything from ATC which begins "expect..." is just that, a heads up as to what will be happening later. Depending on the partuiculars it may become relevant in a lost Comm situation. "Cross at...." is a clearence which you are expected to comply with.


- When can you AND can you not take off based on what the RVR is being reported?


In operations under part 91 only, You may take off without regard to reported visibility or RVR. The wisdom of such behavior is another question. Under Part 135 and 121 operations your Operations specifications will tell you in great detail what RVR you need to take off.
 

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