Part 91 Instrument Approach Question

[pilothouston123]

asos indefinant ceiling, vis 1/8 wind calm


remote airport with full ILS. the only thing you will see is appraoch lights and runway lights at night. Pretty cool
I did it 20 times when I was flying my buddies to gamble.

 

[b350capt]

per the FAA:

...Enforcement action would only be taken in those cases in which the pilot could not resonably conclude flight visibility was at or above approach minimunms, but the pilot nevertheless proceeded to land.......

 

[A Squared]

per the FAA:

...Enforcement action would only be taken in those cases in which the pilot could not resonably conclude flight visibility was at or above approach minimunms, but the pilot nevertheless proceeded to land.......

Thanks, I thought I remembered reading those words in an interpretation, but didn't have a chance to sort through them to find the quote.

 

[gsrcrsx68]

Yeah you're correct. Take a look at the regulation. 91.175(b). it specifies that you may not descend below DH or MDA unless the flight visibility is greater than the minimum. Now go read the definition of "Flight Visibility" in Part 1. There is only one person that can determine the flight visibility, and that is the pilot. (Or I guess 2 persons in the case of a 2 pilot crew) It's impossible for an observer on the ground to determine how far you can see from the cockpit, and that is what flight visibility is.

Now, at this point in the discussion, your son-in-law may claim that RVR, if available, takes precedence over flight visibility (can you tell I've been through this argument before?) It does not. If he insists, ask him to show you where that is rated. He will not be able to.

I had this question as part of my practical. I was told better not land if RVR was below mins. Where would I look to support that? Well first I'd start with an approach would specify RVR, then I'd look 91.175(h)(1)...That specifies Ground visibility, not flight visibility be substituted for lack of rvr reported.

Then I'd go to ground visibility in part one and realise that I am not an accreddited observer or the U.S. National weather service or for that matter near the earths surface(although I guess that could be open for interpretation) and could not declare the visibility myself. I don't see anywhere I am allowed to convert RVR to flight visibility.

 

[minitour]

I don't see anywhere I am allowed to convert RVR to flight visibility.

You don't have to.

You don't need ground visibility to descend below MDA/DH and/or land. You just need flight visibility. All that 91.175(h) tells you is that, if RVR is specified in the approach, but it isn't reported (except for cat 2 and 3) as RVR for that runway, you should know that (for example) 3200 RVR = 5/8 Mile...ground visibility.

...assuming it's believable enough that the 3200RVR lets you in on an approach that you need 1 mile to land...

Good thread here...big thanks to the poster!

-mini

 

[A Squared]

I had this question as part of my practical. I was told better not land if RVR was below mins. Where would I look to support that? Well first I'd start with an approach would specify RVR, then I'd look 91.175(h)(1)...That specifies Ground visibility, not flight visibility be substituted for lack of rvr reported.

Then I'd go to ground visibility in part one and realise that I am not an accreddited observer or the U.S. National weather service or for that matter near the earths surface(although I guess that could be open for interpretation) and could not declare the visibility myself. I don't see anywhere I am allowed to convert RVR to flight visibility.

As Minitour pointed out, all 91.175(h) does is allow you to substitute Ground Vis for RVR if needed. It has nothing to do with whether you can descend below MDA/DA. that is governed by 91.175 (c) ...and that specifies flight visibility.

 

[gsrcrsx68]

You don't have to.

You don't need ground visibility to descend below MDA/DH and/or land.
-mini

Unless RVR is unavailable...then you need it To Land. True, 91.175 (c)(2) does allow you to operate under the DH, but operating under the DH does not mean you have met landing minimums...You can operate below the DH until 91.175(c)(1) is no longer possible.

The question morphed a bit from the original. The word "Land" got tossed in along the way. I still wont be landing if RVR is below landing minimums...Actually I wont even be flying then...

 

[paulsalem]

Unless RVR is unavailable...then you need it To Land. True, 91.175 (c)(2) does allow you to operate under the DH, but operating under the DH does not mean you have met landing minimums...You can operate below the DH until 91.175(c)(1) is no longer possible.

The question morphed a bit from the original. The word "Land" got tossed in along the way. I still wont be landing if RVR is below landing minimums...Actually I wont even be flying then...

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

RVR is NOT FLIGHT VISIBILITY

 

[gsrcrsx68]

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

RVR is NOT FLIGHT VISIBILITY

Nobody said RVR is Flight Visibilty. However you do find RVR under Visibility in the pilots glossary.

So are you saying you would be ok to land if a SIAP specified RVR and RVR was reported to be less than the minimum but you had the required flight visibility? I wouldn't do it.

Plus the allowed substitution for the landing minimums (where RVR is specified) is ground visibilty, not flight visibility.

The only thing I stated was I didn't believe you'd be ok to land...

 

[paulsalem]

Nobody said RVR is Flight Visibilty. However you do find RVR under Visibility in the pilots glossary.

So are you saying you would be ok to land if a SIAP specified RVR and RVR was reported to be less than the minimum but you had the required flight visibility? I wouldn't do it.

Plus the allowed substitution for the landing minimums is ground visibilty, not flight visibility.

The only thing I stated was I didn't believe you'd be ok to land...

By the letter of the law it would be legal.