Local Altimeter Setting?

chartbundle

chartbundle

Pattern Altitude
PoA Supporter
Joined
Sep 26, 2011
Messages
1,628
Location
State of Confusion
Display Name
Display name:
chartbundle
So, I figured I'd ask the collective wisdom of the Internet on this one. Since Google doesn't seem to be helping.

I was coming home today, back to KCVO and the local AWOS-3 is out of service and I'm not sure if the FBO acts as unicom, but they were closed anyway. I needed to fly an approach. 2 of them (ILS 17, RNAV 17) have a note saying "When local altimeter setting not received, procedure NA" 4 more(RNAV 35, VOR 17, VOR 35, VOR-A) have no such note.

I took these notes to mean I couldn't fly those approaches with the closest available altimeter, Eugene, because usually those say: "If local altimeter not received, use Eugene altimeter (and increase minimums X feet)" or similar. So I took the RNAV 35. Some time after I landed, a jet came in from the north,I wasn't listening on the radio, but I assume he probably didn't fly the VOR approach.

So, is "Local" at the field, is 23 miles "local"?
 
chartbundle said:
So, I figured I'd ask the collective wisdom of the Internet on this one. Since Google doesn't seem to be helping.

I was coming home today, back to KCVO and the local AWOS-3 is out of service and I'm not sure if the FBO acts as unicom, but they were closed anyway. I needed to fly an approach. 2 of them (ILS 17, RNAV 17) have a note saying "When local altimeter setting not received, procedure NA" 4 more(RNAV 35, VOR 17, VOR 35, VOR-A) have no such note.

I took these notes to mean I couldn't fly those approaches with the closest available altimeter, Eugene, because usually those say: "If local altimeter not received, use Eugene altimeter (and increase minimums X feet)" or similar. So I took the RNAV 35. Some time after I landed, a jet came in from the north,I wasn't listening on the radio, but I assume he probably didn't fly the VOR approach.

So, is "Local" at the field, is 23 miles "local"?
Click to expand...
That has no need to be on the ILS chart. It shouldn't be there. It goes without saying that the approach is not authorized without the the local altimeter setting for that airport, unless annotated otherwise. When the altimeter setting on which the approach is based is not available, the approach is not authorized. The RNAV approach is another matter. It's all in AIM 5-4-5 a. 4.
 
Last edited:
There's usually a way to get a somewhat local altimeter setting. Then how low was the weather? Maybe 50' hardly matters?

If one knows before departure just have a plan figured out.
 
BTW, if someone want a reference, one of them is AIM 5-4-5.a.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.
 
MauleSkinner said:
There's ALWAYS a way to do things illegally. ;)
Click to expand...

So what's the law on this matter? Would the setting of an altimeter on the ground showing the MSL altitude, obtained by radio from a pilot in that aircraft, violate any law if used while flying one of these IAPs?
 
roncachamp said:
So what's the law on this matter? Would the setting of an altimeter on the ground showing the MSL altitude, obtained by radio from a pilot in that aircraft, violate any law if used while flying one of these IAPs?
Click to expand...
Hmm. A case could be made for that. Somewhere its written that if you can't find an altimeter setting then set your altimeter to field elevation before departing. I guess if the guy on the airport has a plane that has a current IFR cert you could use that. I'd be a little reluctant to do it unless I knew the guy and trusted him.
 
It's interesting that the AIM says "from Air Traffic" unless specified otherwise. I don't recall if in previous approaches they'd give me the Eugene or Corvallis altimeter settings.

I suspect the lack of notes on the older procedures are from a time when the field didn't have an AWOS.

And this question is from a purely regulatory standpoint, the ceilings were almost high enough not to need an approach at all and there was no significant weather or terrain that would cause the Eugene and Corvallis altimeters to vary more than a tiny bit.
 
midlifeflyer said:
BTW, if someone want a reference, one of them is AIM 5-4-5.a.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.
Click to expand...
Yup. The note on the chart saying "when local altimeter setting not recieved, procedure not authorized" is redundant. It shouldn't be there. It kinda implies that if there are no notes about altimeter on a chart then you dont need one. "Dude, it doesn't say I need a local altimeter setting so I guess I don't need one." Yeah, thats kinda stretchin it. No ones going to do that.

EDIT: The more I think about this maybe they are putting it on all charts now. There are still charts out there with no altimeter notes at all. They may be ones that havent been reviewed and updated. Maybe aterpster or johncollins will know.
 
Last edited:
luvflyin said:
Yup. The note on the chart saying "when local altimeter setting not recieved, procedure not authorized" is redundant. It shouldn't be there. It kinda implies that if there are no notes about altimeter on a chart then you dont need one. "Dude, it doesn't say I need a local altimeter setting so I guess I don't need one." Yeah, thats kinda stretchin it. No ones going to do that.

EDIT: The more I think about this maybe they are putting it on all charts now. There are still charts out there with no altimeter notes at all. They may be ones that havent been reviewed and updated. Maybe aterpster or johncollins will know.
Click to expand...
In the case of the approaches at KCVO, all of the approaches with the "NA" note have procedure amendment dates in November, 2016 (the date on the lower left); the three VOR-based ones have Amendment dates more than 13-22 years earlier. OTOH, all of them have Revision dates in 2017. That suggests a change to the way the source documents were written. My WAG is pretty much the same as yours: it's one of those things that came up in the Charting Forum as a way of avoiding the exact kind of confusion @chartbundle's post demonstrates. They seem to be doing that kind of thing a lot.
 
roncachamp said:
So what's the law on this matter? Would the setting of an altimeter on the ground showing the MSL altitude, obtained by radio from a pilot in that aircraft, violate any law if used while flying one of these IAPs?
Click to expand...


Yes, the reg says you must use a published procedure. A published procedure specifies the altimeter source(s). When the source is from an altimeter on the ground, there are two and the accuracy is certified.
 
roncachamp said:
So what's the law on this matter? Would the setting of an altimeter on the ground showing the MSL altitude, obtained by radio from a pilot in that aircraft, violate any law if used while flying one of these IAPs?
Click to expand...
AC91-14D was canceled a few months ago, but the method you suggest would not have been allowed. A two-altimeter average would have been under certain conditions, but only if they were less than .04" apart and the exact altitude of the altimeters was known.

As far as a regulatory reference, 91.175 says the approach has to be conducted in accordance with the Part 97 approach procedure.

Part 97 specifies that the approach procedure will be built according to 8260.something documentation, which tells them how to specify the altimeter setting sources. In the OP's case, they specified AWOS.
 
I realize we're not supposed to improvise, but say we are flying towards a higher pressure area, which we looked into before departure. On top of that, the ceiling & viz are a fair bit above minimums.

Just saying, I can think of much more risky endeavors when it comes to tooling around. I can also see a test answer in the mix too. O.K., so we checked the Notams, then just cancelled the flight.
 
You could always shoot the approach at Salem or Eugene and proceed VFR from there. :D
 
MauleSkinner said:
You could always shoot the approach at Salem or Eugene and proceed VFR from there. :D
Click to expand...
I'm being cranky: why do we shoot approaches using approach plates instead of flying approaches using approach charts?
 
MauleSkinner said:
AC91-14D was canceled a few months ago, but the method you suggest would not have been allowed. A two-altimeter average would have been under certain conditions, but only if they were less than .04" apart and the exact altitude of the altimeters was known.
Click to expand...

Advisory Circulars are not law.

As far as a regulatory reference, 91.175 says the approach has to be conducted in accordance with the Part 97 approach procedure.

Part 97 specifies that the approach procedure will be built according to 8260.something documentation, which tells them how to specify the altimeter setting sources. In the OP's case, they specified AWOS.
Click to expand...

There's no mention of altimeter settings in FAR 91.175 or Part 97. Order 8260.3C says nothing to pilots about the operation of aircraft.
 
roncachamp said:
Advisory Circulars are not law.
Click to expand...
Good thing I didn't say they were.

There's no mention of altimeter settings in FAR 91.175 or Part 97. Order 8260.3C says nothing to pilots about the operation of aircraft.
Click to expand...
True...just like Part 23/CAR3 says nothing to pilots about operation of the aircraft.
 
Last edited:
Isn't a proper setting from a station within 100 miles???

For some reason that sticks in My mind.

Now... approach charts caña de do stipulate minimums based on other station settings.
 
Kritchlow said:
Isn't a proper setting from a station within 100 miles???

For some reason that sticks in My mind.

Now... approach charts caña de do stipulate minimums based on other station settings.
Click to expand...
100 miles is for enroute (and doesn't have much practical application these days). Yes, approach plates will sometimes give an alternate altimeter setting, along with the associated changes in target altitudes. But it's not proper to roll your own.
 
MauleSkinner said:
You could always shoot the approach at Salem or Eugene and proceed VFR from there. :D
Click to expand...
Pilot strafes airport at Salem damaging Instrument Landing system and is later arrested in Corvallis. Film on the 11 O'clock Eyewitness News.
 
Last edited:
midlifeflyer said:
In the case of the approaches at KCVO, all of the approaches with the "NA" note have procedure amendment dates in November, 2016 (the date on the lower left); the three VOR-based ones have Amendment dates more than 13-22 years earlier. OTOH, all of them have Revision dates in 2017. That suggests a change to the way the source documents were written. My WAG is pretty much the same as yours: it's one of those things that came up in the Charting Forum as a way of avoiding the exact kind of confusion @chartbundle's post demonstrates. They seem to be doing that kind of thing a lot.
Click to expand...
All the approaches at KOTH have Amendment dates of 25JUN15. None of them say anything about 'altimeter.' None of the subjects on the Charting Forums list of things they're working on mentions altimeter. Has anyone found any other approaches that say N/A without local altimeter?
 
Contact approach anyone?

A contact approach is an IFR Approach to an airport that does not require flying a specific procedure. Several conditions must be met for a contact approach:

- The pilot must request a contact approach.
- The controller cannot initiate a contact approach.
- The airport must have a published instrument approach.
- The pilot must remain clear of clouds, have at least one mile
flight visibility, and reasonably expect to continue to the destination
airport in those conditions.

The pilot assumes responsibility for obstruction clearance while conducting a contact approach.
 
mscard88 said:
Contact approach anyone?

A contact approach is an IFR Approach to an airport that does not require flying a specific procedure. Several conditions must be met for a contact approach:

- The pilot must request a contact approach.
- The controller cannot initiate a contact approach.
- The airport must have a published instrument approach.
- The pilot must remain clear of clouds, have at least one mile
flight visibility, and reasonably expect to continue to the destination
airport in those conditions.

The pilot assumes responsibility for obstruction clearance while conducting a contact approach.
Click to expand...
Yup. Request and get a Contact Approach and yer good to go. Ain't nuthin says you can't do it by say flying in from the north, dialing in 115.4 and moseying on down localizer. Oh, look we got us a glideslope to, this is gonna be easy. The hard part might be getting a controller who understands and will play along.
 
luvflyin said:
Yup. Request and get a Contact Approach and yer good to go. Ain't nuthin says you can't do it by say flying in from the north, dialing in 115.4 and moseying on down localizer. Oh, look we got us a glideslope to, this is gonna be easy. The hard part might be getting a controller who understands and will play along.
Click to expand...

Note that the "contact" in contact approach comes from contact flying, what we now call pilotage. Flying an ILS when cleared for a contact approach may not strictly violate any regulation but it's definitely inconsistent with the spirit of the procedure.
 
roncachamp said:
If the controller is unfamiliar with contact approaches, probably not. Many controllers are not familiar with them.
Click to expand...

That's surprising Ron. Don't think I ever cleared anyone for it but I was familiar with it. It's in the .65 and they should be familiar.
 
mscard88 said:
That's surprising Ron. Don't think I ever cleared anyone for it but I was familiar with it. It's in the .65 and they should be familiar.
Click to expand...
Yup. They should. Many of those who won't do it are familiar with it. In dense airspace with lotsa other airplanes around, a "Contact Approach gone 'wrong'" can be a controllers worst nightmare. Some just refuse. Some know when, where and how to do it.
 
roncachamp said:
Your statement implied the AC was binding, like a law.
Click to expand...
Maybe your understanding of English and common knowlege is a little weak. Even if anyone didn't know that an AC wasn't binding, surely they wouldn't believe that a CANCELED AC was binding.

If you want to argue that someone can sit on the ramp in their airplane and provide a usable altimeter setting, fine. If you want to try to pick nits that aren't there, don't waste your time. I'm done wasting mine.
 
Last edited:
You must log in or register to reply here.
Back
Top