Cold temperature correction questions

[fickle raft]

At what point do you actually have to start applying temperature correction? Of course this is dependent on the effect being simulated in the first place, but let's assume it is, as an option via Active Sky in MSFS and I believe in XP12 by default (can't recall). RNAV approach charts in the applicable parts of the world will of course will tell you what the minimum temperature is for uncompensated Baro-VNAV. In that case can I just avoid doing temperature correction on all waypoints before the FAF? What about for an ILS? For straight in RNAVs the waypoints can be quite similar to an ILS but there's usually not a note about temperature correction on an ILS chart (because, obviously, you don't need temperature correction on the glideslope). So that leads me to think you should always apply it below a certain temperature to all the pre-FAF waypoints, and to your minimums (but again, how does that work if you can do the RNAV with uncompensated Baro-VNAV?).

Also, from what I've seen, it is expressly forbidden to modify ANY altitude constraints due to the extremely high risk of fucking it up and suddenly flying an unauthorized procedure - does this mean I have no choice other than to fly it in say VNAV or FPA with just a mental temperature correction on the intercept altitude (e.g. labelled by hand on an approach chart but never entered anywhere in the FMS) and to also have to do altitude checks at every mile with the compensated value, plus entering corrected minimums for LNAV-only?

(I assume FLS and IAN apply automatic temperature correction to the descent path anyways but in the current software revision modelled by Fenix, FLS overrides FINAL APP rather than coexisting alongside it so I have it disabled)

[green crescent]

For us it was any altitude below MSA (when 0degrees or below) has to be temp corrected. Minima, MAA, platform alt

[fickle raft]

would you apply a temperature correction to the MSA itself too?

[green crescent]

Dont think we did that

As or RNP, no idea it was rare enough to fly an RNP (maybe once a week) let alone with temps below 0

[fickle raft]

that's fair, but here's an example that I did in the sim a few days ago - via ULBAR

this one does not have any altitude checks probably because it's RNP AR but the RNAV Z has it

for this approach the threshold is -18C. I guess if for example you're at -12C you can just apply corrections below the MSA all the way to the intercept point and that should be enough?

unless of course you've engaged FINAL APP from ULBAR on the RNAV Y (which is what happened with me) - in which case temperature correction would be forbidden aside from the minimums to my understanding