Originally Posted by
Raptor71
First, is it necessary to correct the DA and platform altitude for cold temperatures as long as the OAT is above the minimum published temperature?
Besides, in your airline do you add 40/50ft to comply with the CDFA technique?
No, never correct DA and platform altitude when using LNAV/VNAV and LNAV/VNAV minimums. Yes, we add 50ft as it is an SOP for non-ILS approaches.
Originally Posted by
Raptor71
If we do not correct these altitudes, is it acceptable to fly a lower angle of descent? Does the procedure guarantees obstacle margin as long as the temperature is above the minimum published temperature? this margin decreasing when we are close to the mini published T.
Yes, it's the whole goal of the minimum temperature, it is checked in advance by the authorities, and the reason why you have to use VNAV to allow the lower minimums.
Originally Posted by
Raptor71
What happens if I decide to correct the altitudes (platform) and in consequence to fly the published angle of descent? Is that acceptable?
Why complicate life? Don't, it is not designed to do so. Don't try to re-invent the theory.
Originally Posted by
Raptor71
Finally, how does the system reacts if I put the temperature and QNH in the DESCENT FORECAST page?
Use correct temperature/QNH. Descent page will have an influence, however also note descent page is valid for the complete descent (TOD to RW/MA point). It is much more important to have the correct QNH on your altimeter.
Originally Posted by
Raptor71
I know that some FMC's will make some kind of corrections to keep optimum obstacle margin if temperature decreases close to the minimum temperature published for the procedure. Does it "update" the FAP ( making it closer to the runway)?
Fixes and distances are never updated/changed. Glidepaths are.