When correcting DA or MDA for cold temperature I understand it is on the PFD, not on the FMC, that it is not allowed according to the manuals.
We use tables (or these days the EFB for more accurate numbers) and add to step-down and FAF altitudes in the FMC.
My understanding, and the procedure at a major UK operator with a large fleet of uncompensated B737s, is that you would fly the approach to LNAV/VNAV minima without any corrections provided the temperature was within the charted limit.
1. Our company applies cold temp corrections on baro-VNAV, as of recently, to all altitudes below temp corrected MSA. That includes, step-down altitudes, FAF, DA - despite what the FCOM Supp. Proc. says and the reference to AMC.CAT.OP.MPA.
It is my understanding that you can fly it within the temperature limit stated on the chart, BUT the DA or MDA should be corrected because it is not taken in account when constructing the path, in fact you can use different minima depending on the onboard equipment and certification, the path flown will be the same whatever minima you use, and will be flatter if cold or steeper if warm, but the minima should be temperature corrected.
Do you correct DA for an ILS if it is -20C?, I take that the answer is a yes, same should be done for other type of approaches.
Holy
what is going on up there?!?!?!?!
When adjusted, they came in high and hot???? oh well, they landed....That seems okay?
Adjust in PFD, FMC or well, somewhere?
Where EXACTLY do you think the NA above and NA below temperatures come from? The DA/MDA NOT accounted for in the design???
Some adjust, some dont, some do it here, some do it there, some just think about it....no problems with the flightpath, obstacle clearances, missed approach, TCH, or min airspace separation????
Correct the MSA??? dont correct the MSA... What 1000 feet doesnt matter in the airspace? min sep????
This thread has been very enlightening on the basics of baro-vnav....damn.
finally.....phew....it is just this simple...
As stated by someone else before, AMC2 CAT.OP.MPA.126 is quite clear about this:
For RNP APCH operations to LNAV/VNAV minima using Baro VNAV:- when the temperature is within promulgated limits, the flight crew should not make compensation to the altitude at the FAF and DA/H;
How about, correct the MSA after you get permission from ATC or they tell you to? Again, min sep in the airspace.
Again, procedures are designed with NA below at at 2.75 degree GPA (2.50 ICAO) and 3.5 GP NA above.
NO correction to the DA/MDA....