FAR 91.144

vontresc

vontresc

En-Route
Joined
Aug 8, 2006
Messages
3,479
Location
Madison
Display Name
Display name:
vonSegelGoober
Ok, I forgot about FAR 91.144 until I came upon a question referencing it while studying for my Comm written.


Sec. 91.144 - Temporary restriction on flight operations during abnormally high barometric pressure conditions.
(a) Special flight restrictions. When any information indicates that barometric pressure on the route of flight currently exceeds or will exceed 31 inches of mercury, no person may operate an aircraft or initiate a flight contrary to the requirements established by the Administrator and published in a Notice to Airmen issued under this section. (b) Waivers. The Administrator is authorized to waive any restriction issued under paragraph (a) of this section to permit emergency supply, transport, or medical services to be delivered to isolated communities, where the operation can be conducted with an acceptable level of safety.

Why is the far there? Unfortunately I don't have access to an altimeter, but I'm pretty sure the adjustment only goes to 31". Can someone confirm this, or is there another good reason?

Thanks
 
I've talked about this with some of my friends. Although I don't think we ever checked an altimeter to make sure, we thought that was why the restriction was in place.

We thought it was worded wrong, rather word it as "When [blah blah blah] barometric pressure exceeds the limits of the altimeter installed in the aircraft", but I suppose that's because we're all engineers. :)
 
Ted, I'm not sure what you're saying...

Is excessive regulation caused by lawyers with no practical application or is it caused by engineers over-analyzing the problem?

:)
 
KennyFlys said:
Is excessive regulation caused by lawyers with no practical application or is it caused by engineers over-analyzing the problem?:)
Click to expand...

Kenny... that's harsh. :D Personally, I think most regulation is written by bureaucrats that are neither lawyers or engineers, but always wanted to be one.

Gary
 
Look at table 7-2-3 in the AIM. This was not invented by bureaucrats, it's there to save your butt.
 
I'd be more worried about flying with abnormally low pressures.

And Doc, if I am VFR, and am pretty good at estimating my AGL altitude when I am low and slow, how is it saving my butt? IFR I can see, but if the Hg is over 31.00" I'm not expecting much IMC.
 
A few years ago, Alaska had unusually low temperatures and altimeter settings that went below the Kollsman scale; there was no way for pilots to accurately set their barometers, and some operators whose op specs require a local altimeter setting for takeoff were grounded....but Part 91 guys were winging it. Thus the regulation. The conditions that brought it into being will probably come up every 50 years or so, but the FAA likes to have all of the bases covered.

Bob Gardner
 
EdFred said:
I'd be more worried about flying with abnormally low pressures.

And Doc, if I am VFR, and am pretty good at estimating my AGL altitude when I am low and slow, how is it saving my butt? IFR I can see, but if the Hg is over 31.00" I'm not expecting much IMC.
Click to expand...

I still see concern about assigned and expected altitudes in all classes of controlled airspace, even VFR.
 
alaskaflyer said:
I still see concern about assigned and expected altitudes in all classes of controlled airspace, even VFR.
Click to expand...

Perhaps you missed the low and slow part? I have a pretty good guess at whether I am around 1000 AGL or not. If I stay under 3000 AGL, and I'm not too worried about going the wrong direction for VFR cruise.

Pretty easy to do here in Michigan (estimate AGL) where we have a grid overlay on top of almost the entire lower peninsula. So again...how is it saving my butt?
 
EdFred said:
So again...how is it saving my butt?
Click to expand...

It's not saving YOUR butt if you are tooling around VFR, Low and Slow and not being controlled.

It CAN save the butt of someone tooling around on an IFR clearance, or in Class B or C airspace when controllers assign an altitude. THAT is what the regulation if for. If you are not working with a controller, no worries.
 
EdFred said:
Perhaps you missed the low and slow part? I have a pretty good guess at whether I am around 1000 AGL or not. If I stay under 3000 AGL, and I'm not too worried about going the wrong direction for VFR cruise.

Pretty easy to do here in Michigan (estimate AGL) where we have a grid overlay on top of almost the entire lower peninsula. So again...how is it saving my butt?
Click to expand...

I did miss the low and slow part. And I suspect that a NOTAM issued in those conditions would likely waive operations doing something similar - maybe.
 
It looks to me like what that means is a NOTAM would be issued which would cover any info regarding flying. I'd expect something like "VFR flight only, no instrument flight below flight levels" etc. Looks like it doesn't necessarily ban flight entirely. Similar to TFRs, there are ways to fly, just restricted ways.
 
alaskaflyer said:
And I suspect that a NOTAM issued in those conditions would likely waive operations doing something similar - maybe.
Click to expand...

Ted DuPuis said:
It looks to me like what that means is a NOTAM would be issued which would cover any info regarding flying. I'd expect something like "VFR flight only, no instrument flight below flight levels" etc. Looks like it doesn't necessarily ban flight entirely. Similar to TFRs, there are ways to fly, just restricted ways.
Click to expand...

Exactly.
 
Doesn't this have to do with using the setting 29.92 in the flight levels in cold air with extreme ambient pressure?
 
Steve said:
Doesn't this have to do with using the setting 29.92 in the flight levels in cold air with extreme ambient pressure?
Click to expand...

No. It has to do with setting the altimeter at one inch BELOW the given setting and compensating by 1,000 feet on the altimeter.

In the flight levels, they would just make one or more of the lower flight levels unusable. That is done on a regular basis.
 
Last edited:
Greg Bockelman said:
It's not saving YOUR butt if you are tooling around VFR, Low and Slow and not being controlled.

It CAN save the butt of someone tooling around on an IFR clearance, or in Class B or C airspace when controllers assign an altitude. THAT is what the regulation if for. If you are not working with a controller, no worries.
Click to expand...

Greg, I completely understand the under IFR part, but unless I read the reg wrong, or missed something reference outside 91.144, it says all operations, not just IFR.
 
EdFred said:
Greg, I completely understand the under IFR part, but unless I read the reg wrong, or missed something reference outside 91.144, it says all operations, not just IFR.
Click to expand...

I don't see where it says "all".

(a) Special flight restrictions. When any information indicates that barometric pressure on the route of flight currently exceeds or will exceed 31 inches of mercury, no person may operate an aircraft or initiate a flight contrary to the requirements established by the Administrator and published in a Notice to Airmen issued under this section.
Click to expand...

This says that one cannot operate contrary to the issued NOTAM. As long as the conditions of the NOTAM is met, go aviate.

(b) Waivers. The Administrator is authorized to waive any restriction issued under paragraph (a) of this section to permit emergency supply, transport, or medical services to be delivered to isolated communities, where the operation can be conducted with an acceptable level of safety.
Click to expand...

This just gives an out to any restrictions imposed by the NOTAM for those operations listed.
 
I was out flying the DC-3 when the Bar press was off the scale. I think it was 1988 the next day the FAA grounded everybody. Then they wrote the rule the next year. It didn't and won't save anyones butt. But it will cover the bureaucrat's butts.
 
Well, I suppose one day we'll find out just what happens - when the barometric pressure actually gets that high!
 
Ted DuPuis said:
Well, I suppose one day we'll find out just what happens - when the barometric pressure actually gets that high!
Click to expand...

You know how your engine is rated for 180hp? Bump it up a bit! :D
 
You must log in or register to reply here.
Back
Top