Altimeter over 31.00Hg?!

[Dilly]

So my understanding is a NOTAM will be published if the Baro pressure ever gets above 31.00, because the Altimeters are not able to accurately measure anything above that. My question is really what, why and how this is the case. Does this affect VFR flight with G1000?

 

[MauleSkinner]

The numbers in the kollsman window only go to 31.00. If you can’t set the altimeter, it won’t be accurate.

 

[RussR]

Does anybody know what the NOTAM will say in this event? How does it recommend you deal with the mechanical limitations of an altimeter?

 

[Bell206]

My question is really what, why and how this is the case.

Most mechanical altimeters only go to 31.00. However, there are altimeters in service that can adjust for readings above 31.00.

Does anybody know what the NOTAM will say in this event? How does it recommend you deal with the mechanical limitations of an altimeter?

I believe if you look in the FAA Order that controls NOTAMs there are examples of it in the Appendices. I think the guidance or procedure is in the AIM if I recall but not 100% sure.

 

[William Pete Hodges]

The AIM says set altimeter to 31.0 and fly normally. Inform ATC of your limitations an be aware that if the pressure is above 31, then the altitude reading will be less than nomal, and only VFR approaches in fair weather are approved.

 

[Rgbeard]

14 CFR 91.144(a) covers this