RVR vs. flight visiblity

[saviboy]

From aviationinterviews.com

"RVR reports 1600. The approach dictates 1800. Can you land? Yes. How/why? Flight visibility needs to be 1800."

Can someone explain and/or give directions on where to find study material concerning this specific topic? I thought RVR was controlling.

thanks

 

[Dave Benjamin]

Is the flight being conducted under Pt 91 or is it a Pt121/135 operation? Impossible to answer the question without knowing that. I think under Pt 91 you can legally fly the approach regardless of reported visibility and land if inflight visibility meets the published mins. Under 121 or 135 rules you cannot proceed beyond the FAF if reported visibility is below published mins. However you can continue an approach if the visibility drops below mins once you're past the FAF and even land if the in flight visibility is at or above the published. This determination is largely subjective.

 

[AutoBus]

From aviationinterviews.com

"RVR reports 1600. The approach dictates 1800. Can you land? Yes. How/why? Flight visibility needs to be 1800."

Can someone explain and/or give directions on where to find study material concerning this specific topic? I thought RVR was controlling.

thanks

135/121 RVR is controlling, it also depends on your category,

for Cat I touchdown zone RVR is controlling, mid and rollout are advisory. so with touchdown zone RVR 1800, roll out 1200 you could land. Of course, there are as many opinions on this as there are POI's.


Also if you are past the FAF you can still take a look, also keep in mind that when an air carrier aircraft lands below applicable RVR a call is usually made from the tower to the FAA com center.

When it comes down to it, it's hard to argue with reported RVR. Flight Vis (No RVR) is a lot more subjective.

 

[WSurf]

Never understood, "If you Past the FAF you can still take a Look." What the hell does that mean? So you go take a look, you see the runway and you can't land? Why the hell go take a look then anyway? That doesn't make sense at all!! Unless once your inside the FAF and the RVR is below mins. and they feel now everthing is conducted with the missed approach point in mind!! But then again you can go missed at anytime in a approach!!
Things that make you go hmmmmmmm!

 

[reject007]

Never understood, "If you Past the FAF you can still take a Look." What the hell does that mean? So you go take a look, you see the runway and you can't land? Why the hell go take a look then anyway? That doesn't make sense at all!! Unless once your inside the FAF and the RVR is below mins. and they feel now everthing is conducted with the missed approach point in mind!! But then again you can go missed at anytime in a approach!!
Things that make you go hmmmmmmm!

You can take a look, and if you see the runway environment, while you're at or above the DH or MDA, then you can land. The weather changes and reports aren't perfect, so it's your word against theirs.

The applicable FAR's have all the information you need. Too lazy to look them up.

 

[Carl_Spackler]

121/135 requires RVR or reported vis to be above mins in order to continue past the FAF.
Flight visibility is required to land. Only the pilot can determine flight visibility.

When you get to the DA/MDA you must have the required flight visibility, be in a position to land using normal manuvers and normal rate of descent, and have at least one visual cue such as runway edge lights, threshold lights, TDX lights, etc. If you have the approach lights in sight you may continue to 100' above TDZE (even a non-precision appch) unless you have the red side row bars (ALSFII) or red terminating bars (ALSFI).

I think it's all in 91.135

 

[big pimpn']

Never understood, "If you Past the FAF you can still take a Look." What the hell does that mean? So you go take a look, you see the runway and you can't land? Why the hell go take a look then anyway? That doesn't make sense at all!! Unless once your inside the FAF and the RVR is below mins. and they feel now everthing is conducted with the missed approach point in mind!! But then again you can go missed at anytime in a approach!!
Things that make you go hmmmmmmm!

Under 135/121, if you are inside the FAF and the visibility drops below mins, you are fully authorized to continue and land. The only limitation at that point is that at or above the DH/MDA, you must have the runway environment in site as specified under part 91 of the FARs.

 

[KingAirer]

-------121/135 requires RVR or reported vis to be above mins in order to continue past the FAF.
Flight visibility is required to land. Only the pilot can determine flight visibility.
----------
At or above

 

[AutoBus]

Under 135/121, if you are inside the FAF and the visibility drops below mins, you are fully authorized to continue and land. The only limitation at that point is that at or above the DH/MDA, you must have the runway environment in site as specified under part 91 of the FARs.

Actually not quite true, you must have the required flight visibility to land, that is if 3/4 of a mile is required, you have a 1/4 reported after passing the FAF, yes you can continue the approach but if at DA/MDA you breakout and notice you only have 1/4 or even 1/2 mile of flight visibility, you are NOT athorized to land.

In the case above the FAA has used 'expert witness' testimony from ground observers (tower, line guys, etc) to build a case against pilots who have done that (part 91,121 or 135)

In addition, in the case of RVR it's very hard to defend yourself against landing with RVR reported below minimums, why do it?

 

[AutoBus]

If you have the approach lights in sight you may continue to 100' above TDZE (even a non-precision appch) unless you have the red side row bars (ALSFII) or red terminating bars (ALSFI).

I think it's all in 91.135

most people miss that about the non-precision approach

 

[temcgrew]

In the case above the FAA has used 'expert witness' testimony from ground observers (tower, line guys, etc) to build a case against pilots who have done that

I feel safer knowing that Line guys are the FAA'a "expert witness".

 

[Flooder305]

In the case above the FAA has used 'expert witness' testimony from ground observers (tower, line guys, etc) to build a case against pilots who have done that (part 91,121 or 135)

What case? The I heard from this guy who heard from this guy case? No references to reality AutoBus, just more useless hearsay...... With an attitude like that why go flying at all. Stay home, watch the weather channel, take shelter immediately! You might as well never go outside... If you know the rules, there is no reason to be afraid of what might happen..... Runway environment? YUP Stabilized approach? YUP, LAND. Do you think someone is going to be mad at you for making it in... "Well, that was such a low approach they never should have made it... I'm an expert, so I'm calling the FAA!" Whatever.....

 

[Ben Dover]

But then again you can go missed at anytime in a approach!!
Things that make you go hmmmmmmm!

Not trying to be a dick, or get to far off topic but when I read this about going missed anytime I figured maybe a clarification was in order.

According to the AIM "...no consideration is given to an abnormally early turn. Therefore, when an early missed approach is executed, pilots should, unless otherwise cleared by ATC, fly the IAP as specified on the approach plate to the missed approach point at or above the MDA or DH before executing a turning maneuver."

OK I'm done,
BD

 

[AutoBus]

What case? The I heard from this guy who heard from this guy case? No references to reality AutoBus, just more useless hearsay...... With an attitude like that why go flying at all. Stay home, watch the weather channel, take shelter immediately! You might as well never go outside... If you know the rules, there is no reason to be afraid of what might happen..... Runway environment? YUP Stabilized approach? YUP, LAND. Do you think someone is going to be mad at you for making it in... "Well, that was such a low approach they never should have made it... I'm an expert, so I'm calling the FAA!" Whatever.....

ok, I dug around and found an interpretation for you to consider, keep in mind this is part 91

FAA Legal Interpretation

March 10, 1986
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, then 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.

 

[GINCHBLASTER]

So basically its your call. If you think you have the required flight vis and land, all is good. Unless the FAA/NTSB think that you are going too far, then they'll call you out on it.

 

[John C. Holmes]

So basically its your call. If you think you have the required flight vis and land, all is good. Unless the FAA/NTSB think that you are going too far, then they'll call you out on it.

YA, PArt 91 its your call, Part 121/35 dont shoot if conditions report < mins

 

[big pimpn']

What case? The I heard from this guy who heard from this guy case? No references to reality AutoBus, just more useless hearsay...... With an attitude like that why go flying at all. Stay home, watch the weather channel, take shelter immediately! You might as well never go outside... If you know the rules, there is no reason to be afraid of what might happen..... Runway environment? YUP Stabilized approach? YUP, LAND. Do you think someone is going to be mad at you for making it in... "Well, that was such a low approach they never should have made it... I'm an expert, so I'm calling the FAA!" Whatever.....

ditto!! If I break out and have the "runway environment" in sight, I'm landing. If I break out and have the side row bars/terminating bars ect. I'm going down to 100 feet above RTDZE ect. Why? because part 91 tells me I can. If some pimple faced line guy wants to question my decision and contact the FAA, then let him do so.

 

[WSurf]

Deleted...........

 

[DrewBlows]

Approach light systems found on most ILS approaches assure that if you have the runway environment in sight (at or above DA on the GS) that you have the required visibility to land, therefore if you see the runway environment (as defined by the FAR's) you are legal to land.

For instance, if you shoot a typical ILS approach with an ALSF-II approach light system the minimum visibility is 1800'. If you shoot the approach to 200' agl see the approach lights and continue to 100' agl, then right at 100' you see the red siderow bars (or any other part of the runway environment) and descend to land, you are legal. Why? Glad you asked. Assuming that you were on the glideslope at 100', you were exactly (well approximately) 1800' away from the red siderow bars, so the flight visibility was at least 1800'. Pretty neat, huh. It seems that when the FAA developed approach light systems they may have had this in mind. It works with other approach light sysems as well, that's why the visibility requirement is 2400' on approachs with MALSR systems.

You shouldn't be guessing whether the visibility is above minimums or not. If you fly an approach properly, and make a sucessful landing, the visibility was at or above minimums at the time of the approach.

 

[TransMach]

Flight Visibility/RVR/Minima

Guys,

If you are flying FAR 121 or 135, regardless of the banter on this thread, go take a good close look at your operations specifications, Part C. Since about 1990 when the FAA switched to "Automated OpSpec" system there have been statements in Part C - Terminal Procedures that state ...

"When a runway is served by RVR or RVV, the reported RVR or RVV is controlling for operations on that runway." (or words to that effect, I don't have a book with me).

For me in 121/135 operations that statement, and it is carried on both the precision and non-precision approach authorization paragraphs tells me that the last reported RVR for my landing or departure runway is controlling for all operations on that runway .... regardless.

Now, Part 91 that's a different story.

TransMach

 

[big pimpn']

Well put "DrewBlows", that's the understanding I have as well.

 

[Newman55]

Guys,

If you are flying FAR 121 or 135, regardless of the banter on this thread, go take a good close look at your operations specifications, Part C. Since about 1990 when the FAA switched to "Automated OpSpec" system there have been statements in Part C - Terminal Procedures that state ...

"When a runway is served by RVR or RVV, the reported RVR or RVV is controlling for operations on that runway." (or words to that effect, I don't have a book with me).

For me in 121/135 operations that statement, and it is carried on both the precision and non-precision approach authorization paragraphs tells me that the last reported RVR for my landing or departure runway is controlling for all operations on that runway .... regardless.

Now, Part 91 that's a different story.

TransMach

If you see the runway I still dont see the harm in landing. I believe the ops specs also goes by when you can and can't continue down from DH/MDA. If you see the terminating bars then you can land the airplane. I dont see why this is so difficult. If you can see the runway then just land. You would have to have at least 1800 RVR to see that stuff. If the RVR is much less than that you are not going to see the runway environment at DH. Assuming a 3 to 1 GS when you are on a 1 mile final you are 300 ft above the runway. When you get to your DH of 200ft you should be about 2/3 of a mile from the runway. If you can see the runway environment then you obviously have the required visibility. Why would one turn down a landing just because some computer says something different which BTW could be wrong. Why risk going missed and eating up more precious fuel when you dont have to? Enough things have already been taken from the pilots discrection toolbox. Lets not take away the ability to use our own judgement when its safe or unsafe to land. If you dont see the runway lights at DH go missed. If you do keep goin down and land if you see the runway. Go to 100 feet above TDZE if you only see the approach lights , if you see the runway, land, if not go missed.