I'm in the process of reading through the Garmin NXi manual for the G36 in preparation for the eventual NXi release (boy, those Working Title guys have their hands full with this one!).

I'm reading about setting minimum alerts and apparently I can set it to either barometric or temperature and I'm wondering how do I make that determination? What factors come into play in choosing which setting to use for minimums? Does it matter?

 

31 minutes ago, CLE_AA-5B_GrummanTiger said:

which setting to use for minimums?

Barometric , always. (Except for CAT II AND III operations, where you'd use RADIO altimeter indications)

15 minutes ago, polosim said:

 

Barometric , always. (Except for CAT II AND III operations, where you'd use RADIO altimeter indications)

Thanks...I only fly GA aircraft anyway. I did a little reading about temperature compensation and that should only be used when temps fall below 0 or outside of ISA deviation. Bit surprised the NXi includes that for the G36, but I guess they wanted to cover all the bases.

Temperature will change how barometric pressure change through altitude, when temperature is low, pressure will drop more at given true height change, so your altimeter will show you are higher than actually it is.

Not sure for GA, but our aliner have procedure to manually change the DA/MDA when temperature is low, for a normal airport near seal level , it only need to be done below 0C, for example, if airport OAT is -5C and DA is 200, the corrected DA would be 215ft and that's what we'll put in altimeter when in such condition. If there is terrain or temperature is really low, the other procidure altitude such as FAF/FAP altitude and Missed approach altitude also need to be corrected and inform the ATC

Not familiar with Garmin NXi, but I assume what you read on the manual means it will automaticlly correct it if you input information in it?

https://www.faa.gov/air_traffic/publications/atpubs/aip_html/part2_enr_section_1.8.html

 

 

7 hours ago, C2615 said:

Temperature will change how barometric pressure change through altitude, when temperature is low, pressure will drop more at given true height change, so your altimeter will show you are higher than actually it is.

Not sure for GA, but our aliner have procedure to manually change the DA/MDA when temperature is low, for a normal airport near seal level , it only need to be done below 0C, for example, if airport OAT is -5C and DA is 200, the corrected DA would be 215ft and that's what we'll put in altimeter when in such condition. If there is terrain or temperature is really low, the other procidure altitude such as FAF/FAP altitude and Missed approach altitude also need to be corrected and inform the ATC

Not familiar with Garmin NXi, but I assume what you read on the manual means it will automaticlly correct it if you input information in it?

That is correct, the NXi has a field for temperature compensation. From what I read in it, it looks like pilots can choose between that or barometric. My guess is that I'd be using barometric minimums the majority of the time. After all, not a lot of GA are rated for flying in below-freezing temps! (I think)

EDIT: I take it back, you *can* fly GA in winter-time, it's just a lot more precautions and waiting for a crystal clear day. Supposed to be pretty amazing, I guess! https://www.aopa.org/news-and-media/all-news/2018/november/flight-training-magazine/out-in-the-cold

Edited July 21, 20214 yr by CLE_AA-5B_GrummanTiger

5 hours ago, jcomm said:

https://www.faa.gov/air_traffic/publications/atpubs/aip_html/part2_enr_section_1.8.html

 

 

Thanks, that's a handy table! I'll have to remember this when I try out some winter bush flying in Alaska, lol!

33 minutes ago, CLE_AA-5B_GrummanTiger said:

Thanks, that's a handy table! I'll have to remember this when I try out some winter bush flying in Alaska, lol!

A.aska mountain flyers have that adagio: "mountain tops are higher in the Winter..."

1 hour ago, CLE_AA-5B_GrummanTiger said:

I take it back, you *can* fly GA in winter-time, it's just a lot more precautions and waiting for a crystal clear day.

No issue flying my trusty Piper in winter times. In fact, it is probably the smoothest conditions you can ask for since there is little thermal activity and the air is rather dense. Just don't let engine cool down during your stop over (bring a thick blanket and drape it over the hood), don't conduct engine run-up on slippery parts of the taxiway and respect perils of crosswind on wintery runways (reduce your personal limits).

And yes we too correct for cold  temps when choosing safe enroute altitudes.

8 minutes ago, SAS443 said:

No issue flying my trusty Piper in winter times. In fact, it is probably the smoothest conditions you can ask for since there is little thermal activity and the air is rather dense. Just don't let engine cool down during your stop over (bring a thick blanket and drape it over the hood), don't conduct engine run-up on slippery parts of the taxiway and respect perils of crosswind on wintery runways (reduce your personal limits).

And yes we too correct for cold  temps when choosing safe enroute altitudes.

Yeah, that's what I read in the AOPA article, that and the skies tend to be so clear and visibility that goes on forever.

Which Piper, may I ask?

13 minutes ago, CLE_AA-5B_GrummanTiger said:

Which Piper, may I ask?

The slow ones! (Archer, Warrior)