go below dh w/ papi in sight??? trick question

[Da Vinci]

this is a trick? interview question which i cannot find a definite answer to.

we all know the magic answer list of items to see before decent below dh...and vasi is on the list. however...is papi enough to go below also???

i can't find any clarification to this answer anywhere. some assume vasi and papi same...some say it's not on the list...i'm not going down.

help!

 

[Amish RakeFight]

I would say yes, you can descend below DH but remain on the PAPI.

PAPI = Precision Approach Path Indicator.

a DH is found on a precision approach.

 

[A Squared]

this is a trick? interview question which i cannot find a definite answer to.

we all know the magic answer list of items to see before decent below dh...and vasi is on the list. however...is papi enough to go below also???

i can't find any clarification to this answer anywhere. some assume vasi and papi same...some say it's not on the list...i'm not going down.

help!

Well, unfortunately, the official answer is no. There is a chief counsel interpretation that states this. I'll try to dig it up. On hte one hand, you think WTF? a PAPI is essentially the same as a VASI, it's gotta count, on thoer hand from a strict literal standpoint, the regulation states "VASI" and a PAPI is not a VASI

 

[Da Vinci]

this is a great example of what my pilot friends and other internet searches have found...two very good answers that contradict. i actually saw one website (a ifr refresher school) had the list as 'vasi/papi' which is not what is actually written inthe far/aim. i'm interested to see what other opinions are and what support there is for them (as in far/aim quotes)

 

[A Squared]

I found the legal interpretation I mentioned. I was wrong, it's not a Chief Counsel interpretation, but rather a Regional counsel
....so it only applies to RJ's:laugh:

No seriously, it is no less official, but it at least leaves open the possibility that it the interpretation could be overruled by the office of Chief Counsel.

Commentary: notice how the lawyer is distancing himself from the opinion by emphasizing that the opinion actually comes from flight standards, and that he has only agreed that the answer is: " consistent with general principles of legal interpretation".....which is the safe answer for a bureaucrat. he won't lose his job over that. The rule says VASI so it's only a VASI, not a PAPI. To say otherwise would be establishing policy that didn't completely agree with the letter of the regulation, and that's a risky move.

At any rate, where we are now is that hte only official guidance I know of on hte subject says that PAPI cannot be used in lieu of a VASI for descent below MDA/DH in accordance with 91.175(c)

U.S. Department
Of Transportation

Federal Aviation Administration
Northwest Mountain Region
Colorado, Idaho, Montana
Oregon, Utah, Washington
Wyoming


1601 Lind Avenue, SW
Renton, WA 98055-4099
Tel: (425) 227-2007
Fax: (425) 227-1007

Office of the Regional Counsel

May 30, 2006

Re: Request for Interpretation of 14 CFR Section 91.175(c)(3)(vi)

Dear Mr. Ison:

We are in receipt of your letter, dated May 8, 2006, addressed to the Regional Counsel. In it, you asked whether 14 CFR § 91.175(c)(3)(vi) is restricted specifically to the visual approach slope indicator, as mentioned, or whether it includes all visual guide slope indicators.

The Regional Counsel assigned the matter to me. I, in turn, referred your request to Flight Standards because I perceived your question to be more technical than legal in nature. David Miller, an operations regional specialist in the Flight Standards Regional Office, located here in Renton, was kind enough to review your letter and he responded as follows (paraphrased):

' A pilot may not substitute any other visual glide slope indicator, such as the precision approach path indicator (PAPI), for the visual approach slope indicator (VASI). This is because the rule is very specific about what visual reverences may be used by the pilot to descend below decision height (DH) or minimum descent altitude (MDA). The rule provides for ten specific visual reference options but does not incorporate language permitting substitutions.'

I will only add that I reviewed the regulation, and Mr. Miller's analysis is consistent with general principles of legal interpretation, specifically, that, absent some reason to do otherwise, language statutes and regulations are given their ordinary meaning. I concur with Mr. Miller's reading of the rule.

I hope this answers your inquiry satisfactorily. If you have any further questions on this issue, please feel free to contact me further at the number below, or you may contact Mr. Miller at (425 7-2263.


SRI
David F. Shayne FAA Attorney (425) 227-2165

 

[Da Vinci]

that's good enough for me. thank you to all who responded!

 

[Groucho]

Here is another one. You fly an approach to minimums and get the runway enviornment in sight. You utilize the VASI and maintain a proper approach profile based on the indications, ie red over white. The glide slope indicator goes up a dot and a half and the GPWS calls "Glide Slope, Glide Slope".

Which is correct?

 

[Rez O. Lewshun]

The interview question is designed to test your ability to answer the question, but also see how you deal with a sticky question......

 

[charter dog]

Here is another one. You fly an approach to minimums and get the runway enviornment in sight. You utilize the VASI and maintain a proper approach profile based on the indications, ie red over white. The glide slope indicator goes up a dot and a half and the GPWS calls "Glide Slope, Glide Slope".

Which is correct?

Once below DA with visual reference on a Cat 1 ILS, follow the PAPI/VASI guidance regardless of the electronic G/S indication since it is not necessarily reliable this close to the runway. Flipping the NAV frequencies off the LOC will shut up the F%&&#n' GPWS!

From AIM 1-1-9 (d)(2)

2. The glide slope transmitter is located between 750 feet and 1,250 feet from the approach end of the runway (down the runway) and offset 250 to 650 feet from the runway centerline. It transmits a glide path beam 1.4 degrees wide (vertically). The signal provides descent information for navigation down to the lowest authorized decision height (DH) specified in the approved ILS approach procedure. The glidepath may not be suitable for navigation below the lowest authorized DH and any reference to glidepath indications below that height must be supplemented by visual reference to the runway environment. Glidepaths with no published DH are usable to runway threshold.

Best,​

 

[Groucho]

Once below DA with visual reference on a Cat 1 ILS, follow the PAPI/VASI guidance regardless of the electronic G/S indication since it is not necessarily reliable this close to the runway. Flipping the NAV frequencies off the LOC will shut up the F%&&#n' GPWS!

From AIM 1-1-9 (d)(2)

Best,​

Dang, You guys are too smart.