Instrument App. w/ INOP ASOS or AWOS

CoffeeIcePapers

CoffeeIcePapers

Well-Hung Member
I can't find anything in part 91 and don't recall reading anything about it. I was flying with a student we couldn't get the ASOS for some reason. It was not NOTAMed and we could pick up a nearby airport's ASOS, so I don't think it was our end.

ATC was able to give us current weather at an airport 40 miles away, which was significantly different than the weather we were in.

I decided I didn't really need to shoot the approach (it was just to get my student some actual and enroute training) and just requested the arrival back to the home airport. The approach plate for this airport didn't have alternate minimums if you have another airport's weather, either.

Is there anything in 91 prohibiting you from shooting an approach without the current weather? I don't think there is, and have been unable to find anything.
 
mojo6911 said:
Is there anything in 91 prohibiting you from shooting an approach without the current weather? I don't think there is, and have been unable to find anything.
Click to expand...
This is not from Part 91, but from the AIM, in regards to altimeter setting. My italics.

5-4-5. Instrument Approach Procedure Charts
4. Approach minimums are based on the local altimeter setting for that airport, unless annotated otherwise; e.g., Oklahoma City/Will Rogers World approaches are based on having a Will Rogers World altimeter setting. When a different altimeter source is required, or more than one source is authorized, it will be annotated on the approach chart; e.g., use Sidney altimeter setting, if not received, use Scottsbluff altimeter setting. Approach minimums may be raised when a nonlocal altimeter source is authorized. When more than one altimeter source is authorized, and the minima are different, they will be shown by separate lines in the approach minima box or a note; e.g., use Manhattan altimeter setting; when not available use Salina altimeter setting and increase all MDAs 40 feet. When the altimeter must be obtained from a source other than air traffic a note will indicate the source; e.g., Obtain local altimeter setting on CTAF. When the altimeter setting(s) on which the approach is based is not available, the approach is not authorized. Baro-VNAV must be flown using the local altimeter setting only. Where no local altimeter is available, the LNAV/VNAV line will still be published for use by WAAS receivers with a note that Baro-VNAV is not authorized. When a local and at least one other altimeter setting source is authorized and the local altimeter is not available Baro-VNAV is not authorized; however, the LNAV/VNAV minima can still be used by WAAS receivers using the alternate altimeter setting source.
 
ghogue said:
This is not from Part 91, but from the AIM, in regards to altimeter setting. My italics.

5-4-5. Instrument Approach Procedure Charts
4. Approach minimums are based on the local altimeter setting for that airport, unless annotated otherwise; e.g., Oklahoma City/Will Rogers World approaches are based on having a Will Rogers World altimeter setting. When a different altimeter source is required, or more than one source is authorized, it will be annotated on the approach chart; e.g., use Sidney altimeter setting, if not received, use Scottsbluff altimeter setting. Approach minimums may be raised when a nonlocal altimeter source is authorized. When more than one altimeter source is authorized, and the minima are different, they will be shown by separate lines in the approach minima box or a note; e.g., use Manhattan altimeter setting; when not available use Salina altimeter setting and increase all MDAs 40 feet. When the altimeter must be obtained from a source other than air traffic a note will indicate the source; e.g., Obtain local altimeter setting on CTAF. When the altimeter setting(s) on which the approach is based is not available, the approach is not authorized. Baro-VNAV must be flown using the local altimeter setting only. Where no local altimeter is available, the LNAV/VNAV line will still be published for use by WAAS receivers with a note that Baro-VNAV is not authorized. When a local and at least one other altimeter setting source is authorized and the local altimeter is not available Baro-VNAV is not authorized; however, the LNAV/VNAV minima can still be used by WAAS receivers using the alternate altimeter setting source.
Click to expand...


Thanks. I wonder where the regulatory requirement is listed for this.
 
Shoot it if it means that much to you.
I would care to, but that doesn't make it illegal.

Fiber yes
Cardboard, no.

And this is not my opinion because of the "AIM is not Regulatory" debate. I don't care much for that debate.
 
minitour said:
Pretty sure it's right there.

...wait...are you of the "The AIM isn't regulatory" crowd?

-mini
Click to expand...

I am of that crowd, however, I wouldn't willingly break something that it specifically says not to do, AIM or not. Like I said, I wasn't sure, and it didn't seem like a good idea, so I just came back. I was able to find the regs prohibiting this in 121 and 135, not 91.
 
mojo6911 said:
Thanks. I wonder where the regulatory requirement is listed for this.
Click to expand...

The instrument approach itself is regulatory and since the instrument approach is based on a particular altimeter setting stated in the approach, I don't see how it can be argued that the setting is optional.

Regardless, Federal agencies have a lot of latitude to interpret their own regulations and these interpretations are very often upheld by the courts, unless the interpretation is "arbitrary and capricious."
 
tgrayson said:
The instrument approach itself is regulatory and since the instrument approach is based on a particular altimeter setting stated in the approach, I don't see how it can be argued that the setting is optional.
Click to expand...

That is what I assumed, since other approaches specifically list other authorized altimeter settings you can use if the one at the airport is INOP.
 
I agree with skysnake, very informative thread. After glancing at the basics in the question, I automatically went to the whole altimeter within 100 nm reg. I almost totally forgot about the req. alt. settings and approved substitutes. (There's actually a few of those her in PHX)
 
What if the ASOS/AWOS is out but ATC somehow can give you the altimeter? Then you're legal I would assume.

/bit of a silly thought
 
You must log in or register to reply here.
Back
Top