Visibility to land on Pt 121?

[Rally]

I was just at a interview and the tech guy asked me what we needed to descend below DH. I said approach lights or airport enviroment. Approach lights to 100 feet then airport enviroment or red bars. In addition at all times below DH you need to have your visibility. OR go missed. This question was posed after the visiblity had gone down after the FAF. He did'nt like that because he told me that no matter what you could could land even if you did'nt have your vis because you had runway enviroment. WTF? Needless to say I did'nt get the job because it stirred me up. The regs plainly state you need required vis for the IAP. Am I overlooking something or am I right for thinking these guy is a douch bag giving people interviews and giving them false information. Should'nt the examiner know the regs? jeez

 

[mmmdonut]

*sigh*


vis required to start the apch

vis not required to continue after the faf

da is lowest authorized alt

if you have at least one of the magic thingys listed in the FARs in sight at or above the DA, you may land.


its only complicated if you make it complicated

 

[Rally]

Oh really?

Upon reaching DH or at MDA, and at any time before the missed approach point, the pilot may continue the approach below DH or MDA if either the requirements of §91.175(l) of this chapter, or the following requirements are met:

(1) The aircraft is continuously in a position from which a descent to a landing on the intended runway can be made at a normal rate of descent using normal maneuvers, and where that descent rate will allow touchdown to occur within the touchdown zone of the runway of intended landing;

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

Whats that then?

 

[mmmdonut]

You had that all cut & pasted and ready to go....

RVR transmissometers don't measure flight vis - only your eyes do.

Maybe you turned the interviewers off in other ways.

 

[skeezer]

*sigh*


vis required to start the apch

vis not required to continue after the faf

da is lowest authorized alt

if you have at least one of the magic thingys listed in the FARs in sight at or above the DA, you may land.

You forgot flight visibility is required to land.

You don't need the reported vis from the FAF to DH, but you still need it to land.... Flight visibility that is.

I think most of the confusion results from two people thinking the same thing but not communicating it in the same way.


Skeezer

PS I just read your post and it looks like you are saying the same thing, just in a different way. See what I mean

 

[Rally]

This guy was adament that RVR even if RVR was 1000 and the chart said 1800 you could land as long as you had your runway enviroment. He told me to forget visbility and anways how are you going to tell what the vis is? I said "the decsion bars are 1000 feet from the runway" Thinking thats a good measure. (like a yard stick) I was just pretty to surprised to hear a pilot at a interview representing his company saying stuff that was blantently contradicting FARs. Hmm.

 

[mmmdonut]

Decision bars?

Do you mean aim point markings?

                                                          _
                                                _   
                                       _           The GP length is more than 1000'
                               _        
                        _
_______________________________________
                     |-------1000'----|

Looking down thru fog, you can often see the ground... looking out and down, you usually can't see the runway in front of you.

Flight vis is not measured.

 

[skeezer]

That guy was a douche then. Every company has one or two and sometimes they end up doing the interviews. We had a real big one at my company for a while and he finally got the boot. Usually those guys are nothing like the bulk of the pilot group at the company, just a freak who got placed in the wrong position.

Or, it could have been some grand scheme to test your CRM skills with a douche bag captain who wants to break the rules.

Peace!

Skeezer

 

[minitour]

Upon reaching DH or at MDA, and at any time before the missed approach point, the pilot may continue the approach below DH or MDA if either the requirements of §91.175(l) of this chapter, or the following requirements are met:

(1) The aircraft is continuously in a position from which a descent to a landing on the intended runway can be made at a normal rate of descent using normal maneuvers, and where that descent rate will allow touchdown to occur within the touchdown zone of the runway of intended landing;

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

Whats that then?

If you're willing to chance that because some operator told you it was okay, then good for you. If this is truly how this company operates, I don't think I'd want to work for them anyway. Some day I'm going to be PIC and if the feds are there some day and I don't go missed when the visibility is below minimums, its not going to be enough to say, "they told me it was okay."

Sounds like the guy was either on a power trip ("How much can I make him/her feel like I know more than he/she does") or didn't know what he was talking about. Either way, gotta move on. Good luck!

-mini

PS
Not in 121 ops, but I did stay at a Holiday Inn a week and a half ago...

 

[mmmdonut]

PS
Not in 121 ops, but I did stay at a Holiday Inn a week and a half ago...

Holiday Inn Express !!!

 

[BoeingBoy]

It really comes down to one question. Do you have the flight visibility required by the approach chart?

If the answer is yes you can land, if not, you must go around.

The FAA says that even though transmissometers measure vis down the runway (not flight vis--duh), if they are reporting less than mins and you have an incident (blown tire, veer off runway) they will absolutely violate you. The thinking is that flight vis at 1 foot above the runway = RVR. You get paid for flight time, go around and think about it...maybe your wake turbulence will clear the fog for the next pass.

Prevailing visibility is another thing altogether...the tower can frequently be calling less than 1/2 mile while your runway has better than 6000 vis.

Be conservative, if your runway's RVR is less than that required for the approach, go around early and make it easy on yourself. If you're out of gas and on fire it doesn't matter what the vis is...you're exercising PIC emergency authority....land.

 

[typhoonpilot]

This is an age old debate and I tend to agree with Rally and minitour here. The FARs are quite explicit when they say, " the flight visibility is not less than the visibility prescribed in the standard instrument approach being used ". One must be careful to listen to the question very clearly though. I would not try to land if the RVR was below minimums because they are telling you the condition on the runway. However, if the tower reported visibility was below the charted visibility minimums you could have a good argument to use flight visibility. Who knows how far away the tower is from the threshold and how different the wx conditions are ? In an interview you might want to look for ways to make it work and not be too rigid in your stance, but always have a bottom line that you will not cross for safety.

Another point slightly off topic on how to make it work is to ask the tower for the visibility or RVR again. It used to be some places would make it work for you. Arcata/Eureka was a prime example of that.

Typhoonpilot

 

[minitour]

Holiday Inn Express !!!

Nah...I sleep at the mainline locatioins...

 

[Singlecoil]

This does have the odor of a CRM question. He's giving you the scenario of a Captain insisting its OK to land and he wants to see how you'll react. He should be more up front with you that it is a hypothetical situation in my opinion. Personally I think going up against RVR is not wise. Anybody who has ever flow in blowing snow knows what I mean. You can see the runway just fine until you start your flare, then you can't see a bloody thing. Flight vis was 10 miles, but RVR was 1000 for a reason.

 

[A Squared]

Posted by mmmm donut:

>>>>"The GP length is more than 1000' "

Yeah, you're right, for 1000' horizontally the glidepath distance is longer. More specifically for a 3 degree glidepath the distance is 1001.37 feet. What was your point again? That the extra 18 inches is going to make the difference when your required RVR is 1800 ????

 

[mmmdonut]

Good math, but you measured from the wrong point.


TDZ to start of runway : 1000'

Rope extended from end of aimpoint markings to point in space along glide slope at DA (200') : way more than 1000'

I think you measured to TCH. (approx 50')

keep workin on it though.

 

[Andy Neill]

So if you saw the fixed distance markers (1000' down the runway) at a DH of 200 above touchdown, then the run to the asphalt would be 200/sin(3 degrees) = 3821' (3827' flight vis). If you had descended to 100 above touchdown before seeing the fixed distance markers then the run to the asphalt would be 1911' (1913' flight vis). I don't see what either one of those calculations has to do with the point at hand, however.

If I were wearing the 4 stripes, and I saw the required amount of visibility from my nose to the ashphalt, I would land regardless of what the RVR or prevailing visilbility was being reported. If I couldn't see that far down the runway, I wouldn't even if the RVR was reporting above mins.

 

[A Squared]

Good math, but you measured from the wrong point.


TDZ to start of runway : 1000'

Rope extended from end of aimpoint markings to point in space along glide slope at DA (200') : way more than 1000'

I think you measured to TCH. (approx 50')

keep workin on it though.

Ahhh, OK, I misunderstood you the first time around, I thought that you were trying to say that the flight visibility was more than the ground visibility because it was measured along the glidepath (sloping) rather than horiozontally.

 

[mmmdonut]

Ahhh, OK, I misunderstood you the first time around, I thought that you were trying to say that the flight visibility was more than the ground visibility because it was measured along the glidepath (sloping) rather than horiozontally.

Naw... skeezer was right.. this is just a commonly miscommunicated subject. I'm confused!!

 

[atldc9]

On another note, for Cat II or III ops, if you receive a report of required RVR being less then required for the approach at any point prior to touchdown, you must execute a missed approach. The old rule of once inside the FAF does not apply to CAT II and III ops.

 

[FlyChicaga]

This is all pretty simple, and it seems people are making it more difficult with Trigonometry. Did I even spell that right?

If you are outside the FAF on an instrument approach, and the visibility reported or RVR reported is below minimums, you must discontinue the approach.

If you are inside the FAF on an instrument approach, and the visibility reported is below minimums, then you can continue to DH. If, at DH, you have the approach lights in sight, you can continue down to 100 ft above the touchdown zone. At 100 ft, if you do not have the runway environment in sight (reference the FARs; the list of items to identify the runway) then you must go around. If you do have the runway environment in sight, you can land. That is because the flight visibility was enough to identify the runway and land.

Now, if RVR is being reported (touchdown) and goes below mins while inside the FAF, you must go-around. RVR is controlling.

So, to the original poster of this thread... let's say you are flying an approach with a 200 ft decision height, with required visibility 1/2 or 2400 RVR.

Inside the FAF, tower says "visibility now 1/4 mile." You can continue to DH of 200 ft. Now, at 200 ft, you see the MALSR approach lights. "Continuing."

At 100 ft above TDZE, you see the HIRLs and centerline lights. You can land. You met the requirements to descend below DH, and met the requirements to land safely.

Change: Inside the FAF, tower says "touchdown RVR 1600, midfield 2400, rollout 2000." Can you land? No, you must go-around now, because RVR is controlling.


Hope this helps. If I am wrong on any of this, someone please feel free to correct me. But this is the way it has been explained to me many, many, many times.

 

[A Squared]

Now, if RVR is being reported (touchdown) and goes below mins while inside the FAF, you must go-around. RVR is controlling.

and:

Change: Inside the FAF, tower says "touchdown RVR 1600, midfield 2400, rollout 2000." Can you land? No, you must go-around now, because RVR is controlling..

Nope. this is a myth. An oft repeated myth, but a myth, nonetheless. RVR is not accorded any special status over and above reported ground visibility by the regulations. Yeah, RVR is more elaborately measured than visibility, and it's probably more reliable and accurate than reported ground visibility. But, like ground vis, RVR is NOT flight vis and flight vis is what counts.

Flight visibility is controlling. Period 91.175 and 121.651 both specify "flight visibility" If it *says* flight visibility, it *means* flight visibility. The FAA has made thier position on the issue clear. Read the legal interpretation below.

Note, though, that the FAA isn't going to unconditionally accept your determination of flight visibility. If you landed with 400 RVR and claimed that you had adequate flight vis, you might be subject to enforcement by a very skeptical FAA.






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

 

[FlyChicaga]

Hmm, interesting. I stand corrected. This is contrary to what is being taught in many training programs.

 

[A Squared]

This is contrary to what is being taught in many training programs.

Yeah, no doubt. That's what I meant by oft repeated myth. I'd heard it quite a bit too, and was about 75% convinced it was true, until I saw the legal interpretation.

 

[GCD]

In 1999, a Boeing 727 crew was violated for landing when the reported RVR was less than needed for their operation.


I posed this question to a good friend of mine who is an FAA Ops Inspector. He said that Inspectors argued this question all day at his FSDO. In the end they all agreed. If 1800 RVR is needed, but 1600 RVR was reported, then they would go with the PIC's judgement. However, if the reported RVR was less, say 1000 RVR, and something brought it to their attention, questions would be asked.

 

[Booster]

Are the FAR's Muddy!

91.175 Takeoff and landing under IFR.

(a) Instrument approaches to civil airports.

Unless otherwise authorized by the Administrator, when an instrument letdown to a civil airport is necessary, each person operating an aircraft, except a military aircraft of the United States, shall use a standard instrument approach procedure prescribed for the airport in part 97 of this chapter.

(b) Authorized DH or MDA. For the purpose of this section, when the approach procedure being used provides for and requires the use of a DH or MDA, the authorized DH or MDA is the highest of the following:

(1) The DH or MDA prescribed by the approach procedure.

(2) The DH or MDA prescribed for the pilot in command.

(3) The DH or MDA for which the aircraft is equipped.

(c) Operation below DH or MDA. Where a DH or MDA is applicable, no pilot may operate an aircraft, except a military aircraft of the United States, at any airport below the authorized MDA or continue an approach below the authorized DH unless -

(1) The aircraft is continuously in a position from which a descent to a landing on the intended runway can be made at a normal rate of descent using normal maneuvers, and for operations conducted under part 121 or part 135 unless that descent rate will allow touchdown to occur within the touchdown zone of the runway of intended landing;

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

125.381 Takeoff and landing weather minimums: IFR.

(b) Except as provided in paragraph (c) of this section, no pilot may execute an instrument approach procedure if the latest reported visibility is less than the landing minimums specified in the certificate holder's operations specifications.

Pilot/Controller Glossary

Landing Minimums - The minimum visibility prescribed for landing a civil aircraft while using an instrument approach procedure. The minimum applies with other limitations set forth in FAR Part 91 with respect to the Minimum Descent Altitude (MDA) or Decision Height (DH) prescribed in the instrument approach procedures as follows:

a.Straight-in landing minimums. A statement of MDA and visibility, or DH and visibility, required for a straight-in landing on a specified runway

Dictionary of Aero Terms

landing minimums, IFR (aircraft operation). The minimum visibility prescribed for landing a civil aircraft while using an instrument approach procedure. The minimums apply with other limitations set forth in 14 CFR Part 91 with respect to the minimum descent altitude (MDA) or decision height (DH) prescribed in the instrument approach procedures.

121.567 Instrument approach procedures and IFR landing minimums.
No person may make an instrument approach at an airport except in accordance with IFR weather minimums and instrument approach procedures set forth in the certificate holder's operations specifications.


My company allows us to begin an instrument approach if the VIS is at or better than the required published vis for that approach. We may continue the approach if VIS is reported as below the min required if we have already passed the FAF.