IFR minimums ?

[Ian_J]

Good question, Mark. I'll hunt around for the source. (It's correct though, visibility that is. )

But let me ask you something: For whom is a ceiling a minimum for an approach? (And not talking alternates or anything here - talking who needs a reported ceiling to legally shoot an approach?)

Yup. If you are in the clouds at MDA ... your visibility is going to be 0.

Not true at all. Plenty of us on here have done approaches where the "ceiling" was below the MDA or DH. However, if the cloud/fog isn't very thick, or if it is night time and the approach lights are turned up bright, you can see right through at MDA or DH and have the required flight visibility to at least descend 100 feet below.

When we're talking RVR values for visibility, you're already in a cloud.

 

[MidlifeFlyer]

135 guys take a look at this.
http://www.ntsb.gov/alj/O_n_O/docs/AVIATION/4002.PDF
Obvisously the dawg in this story screwed up and this is pretty old but it's funny how things can be viewed in the court of law.

Excellent!! You found the answer (although some would say the "court of law" is kind of an unnecessary complement to what goes on in administrative hearings).

For those without the patience to read it, it essentially says that, while the visibility on the IAP chart defines required minimum visibility, the MDA or DA does not define a minimum, but only the minimum descent altitude the pilot can go to before the visibility issue kicks in.IOW, the MDA is not a "weather condition" within the meaning of 135.225.

So, it appears the answer is indeed that visibility controls.

BTW, Mike, if you think that a case from 1993 is "pretty old" you must be "pretty young" And pretty smart to have turned this case up

 

[MidlifeFlyer]

Plenty of us on here have done approaches where the "ceiling" was below the MDA or DH. However, if the cloud/fog isn't very thick, or if it is night time and the approach lights are turned up bright, you can see right through at MDA or DH and have the required flight visibility to at least descend 100 feet below.

In addition, a ceiling can be broken, where you can reach MDA be above the ceiling an still meet the criteria to continue the approach.

That's why the NTSB's gymnastics in that case Mike found make sense.

 

[mikecweb]

Excellent!! You found the answer (although some would say the "court of law" is kind of an unnecessary complement to what goes on in administrative hearings).

For those without the patience to read it, it essentially says that, while the visibility on the IAP chart defines required minimum visibility, the MDA or DA does not define a minimum, but only the minimum descent altitude the pilot can go to before the visibility issue kicks in.IOW, the MDA is not a "weather condition" within the meaning of 135.225.

So, it appears the answer is indeed that visibility controls.

BTW, Mike, if you think that a case from 1993 is "pretty old" you must be "pretty young" And pretty smart to have turned this case up

Lets just say I was single digits when that report came out. I found it awhile back when researching random accidents involving 135 freight. I think it is very important for those who think regualtions are vague to help pilots out. Vague regulations and grey areas can bite you too.

Also include that the NTSB, which wrote this particular document, clearly disputes what both the FAA and judge seem to rule out of nowhere that ceilings are included in the "landing minimums". They called for the FAA to clarify their stance and to my understanding, correct me if I'm wrong, they haven't.

 

[MidlifeFlyer]

Also include that the NTSB, which wrote this particular document, clearly disputes what both the FAA and judge seem to rule out of nowhere that ceilings are included in the "landing minimums". They called for the FAA to clarify their stance and to my understanding, correct me if I'm wrong, they haven't.

Not as far as I know. I just did a quick search into the NTSB online database and this appears to be the only 135.225(a) case there.

I have a sense that part of the dressing down of the FAA is a little turf war going on. Notice how the NTSB treats the FAA's attempt to force it's ceiling interpretation:

==============================
While deference to the Administrator's validly adopted interpretations of the Federal Aviation Regulations is now explicitly required by statute, such deference cannot be readily accorded in the context of a hastily developed record that is sustained solely by argument of counsel. This is particularly so where the interpretation advanced is unsupported by citation of practice, precedent, or explicit documentation, and where it entails consequences not only for respondent, but for the aviation community generally
==============================

Unfortunately (for us), the NTSB ultimately loses this battle. You may have heard of the case - it's the one where a 121 captain mistakenly thought an ATC instruction was for him. He even read it back and was not corrected (he was stepped on). In the enforcement action, the FAA argues that the pilot was responsible for the failure to comply with the ATC instructions, and that the misunderstanding and failure of the readback to get it corrected did not excuse the violation. The NTSB thought this was ridiculous and overturned the FAA in language very similar to the language in the Krachun case you pointed to. If you're interested, check out http://ntsb.gov/alj/alj/O_n_O/docs/aviation/4670.PDF

This time, though, the FAA appealed to the US Court of Appeals, where, in a famous decision, FAA v. NTSB and Merrell,, 190 F.3d 571 (DC Cir 1999), the Court reversed the NTSB and upheld the FAA's interpretation:

==============================
The NTSB's refusal to defer to the FAA on this question of regulatory interpretation and air safety policy was error. The FAA is not required to promulgate interpretations through rulemaking or the issuance of policy guidances, but may instead do so through litigation before the NTSB. **** The fact that this mode of regulatory interpretation necessarily is advanced through the "litigation statements" of counsel does not relieve the NTSB of its statutory obligation to accord it due deference
==============================

 

[ppilot]

91.175(c) talks needing the required flight visibility in order to descend from the MDA or DA. But, that's not specific to 135 and, as mojo aptly put it , so ceiling is pretty irrelevant at that point (that's why I asked why it was a trick question).

OTOH, there are specific rules on when you can start or continue an approach based on reported minimums for 135 and 121 ops (135.225 and 121.651 for example) that don't apply to Part 91 ops (where you can start down even if 0/0 is being reported), which is what I thought was being discussed

Two different questions.

Okay, 135.225 (a)(2) says:

no pilot may begin an instrument approach procedure to an airport unless The latest weather report issued by that weather reporting facility indicates that weather conditions are at or above the authorized IFR landing minimums for that airport.


91.175(d) prescribes IFR landing minimums, and says

Landing. No pilot operating an aircraft, except a military aircraft of the United States, may land that aircraft when—
(2) For all other part 91 operations and parts 121, 125, 129, and 135 operations, the flight visibility is less than the visibility prescribed in the standard instrument approach procedure being used.


So it's all in the regulations, but unfortunately not spelled out nicely in one place.

 

[MidlifeFlyer]

So it's all in the regulations, but unfortunately not spelled out nicely in one place.

Yes but those two regulations talk abut two completely different things.

 

[ppilot]

Yes but those two regulations talk abut two completely different things.

No, no. 135.225 says that you can't start the approach if the weather is reported below landing minimums. 91.175 defines landing minimums; saying that landing minimums are flight visibility >= the visibility prescribed in the SIAP.