Someone who knows explain RVR.

[A Squared]

Its in the Ops Specs for the individual Airline.

Which Ops spec is it written into? Is this common? Can someone give me an example of the specific wording from their ops specs? I've never seen it, but then the only Ops Specs I've studied are the ones at my airline. Obviously, if it's written into a company's ops specs than it is controlling for that particular companies operations. However, I think that "RVR is controlling" as a general statement is still incorrect, It's not controlling if it's not written into the Ops Specs, (and it's not in mine) and it's not controlling for Part 91 operations.

 

[A Squared]

I think I've found the source of the myth.

I was thumbing thorough my Ops Specs. looking for something else, and I saw that in the Ops spec for takeoff minimums (CO56) it says that If RVR is measured for a runway, it is controlling for takeoff operations on that runway.

That's a long way from being controlling for landing. I think probably that folks have read this, and have not quite remembered that it was for takeoff visibility.

I also came across this legal interpretation which states specifically that RVR is controlling over flight visibility.

FAA Legal Interpretation:
March 10, 1986

Mr. Larry K. Johnson

Dear Mr. Johnson:
This is in response to your letter of February 6 requesting an interpretation of Federal Aviation Regulation (FAR) Part 91, Section 91.116.

Specifically, you request clarification of the term "flight visibility" in connection with the requirement in FAR 91.116(c) that an aircraft not be operated below a published decision height or minimum descent altitude if the flight visibility is less than the visibility prescribed in the standard instrument approach procedure being used. The question arises as to whether descent below the DH or MDA can be made when the runway visual range (RVR) is reported at less than the published minimum RVR for the approach but the flight visibility is greater than that minimum.

The flight visibility is controlling. If the flight visibility exceeds the published minimum for the approach, than the pilot may proceed as long as the other requirements of paragraph 91.116(c) are met regardless of the reported RVR. The National Transportation Safety Board (NTSB) has upheld this interpretation in several enforcement cases. However, the pilot's judgment of flight visibility is not necessarily conclusive if there is a question as to the actual flight visibility conditions at the time of the approach. Reported visibility and other evidence of record may be considered by the Federal Aviation Administration and the NTSB in determining the actual flight visibility.


Enforcement action would be taken only in those cases in which the pilot could not reasonably conclude that flight visibility was at or above approach minimums, but the pilot nevertheless proceeded to land or descent below DH or MDA.

Sincerely, David L. Bennett
Manager, Airspace and Air Traffic Law Branch
Regulations and Enforcement Division

Of course I suppose it could be written in some Ops specs, somewhere, but I'm skeptical. If that's the case, I'd be interested to see the wording from the Ops specs. Sampson?????

I

 

[NEDude]

There is a reason as to why approach lighting is configured the way it is. I am on the road right now, but somewhere I have a graphic which shows visual references on the ALS. For instance at 200' above TDZE, if you can see xxxx on the ALS, you have 2400' of flight visibility. It shows it for 100' above TDZE elevation as well. The chart comes from the FAA, and the criteria has been used successfully to defend pilots who have landed below RVR. When I get home I will try and find it and give more details. But the key is flight visibility is the controlling element for landing, not RVR. And if you can prove you have it, there shouldn't be an issue.