Jan 14

Cold Temperature Altitude Corrections concerning Lnav/Vnav,Lnav


Dear Petr,

Good evening and happy New Year to all, hopefully COVID Free!!!

I would like to discuss about cold temp.corrections especially shooting an RNP approach,par example if we operate within the uncompensated temp scale in a APV Lnav/Vnav App,do we have to correct DA in case below 0 Celcius but above uncompensated Temp limit for the particular Approach?

Operational Guidelines For PBN Approach DGAC

(7.5.4 Case of temperatures below minimum temperatures published on the approach chart

On the RNAV(GNSS) approach charts for which there is an APV BaroVNAV approach (presence of LNAV/VNAV minima), a minimum temperature use is published.

As a general rule, pilots should not use the FMS (Baro)VNAV function when the temperature is below the temperature limit published on the approach chart.

The associated non-precision approach (LNAV) can be performed but management of the vertical plane should use another flight technique (vertical speed (V/S) or flight path angle (FPA).

Pilots should then apply the cold temperature corrections necessary to comply with the different published minimum altitudes, i.e.:

- The altitude heights for the final segment (FAF, SDF, altitude/distance table);

- The MDA/H; and

- The V/S and/or FPA values.

1. If temperature variations cannot be compensated for by avionics system, APV BaroVNAV approach is not allowed when temperature transmitted to the crew is lower than limit temperature published on the approach chart.

2. If temperature variations can be compensated for by avionics system, APV Baro VNAV approach is allowed but pilots must then apply cold temperature corrections required to comply with DA/DH.


The short answer is yes. DA needs to be corrected regardless of the system when the temperature is 0 and below. On a BARO-VNAV APV (LNAV/VNAV minima) the descent profile will be covered until the temperature limit. But the LNAV/VNAV minima still need to be temperature corrected. It is the same as with ILS DA, you also need to correct the DA there.

I hope it helps,

- Petr

Petr hi,

thks for the reply,the same thought with your reply I had also,

but today after a conversation with my FOM,he guided me to check the

AMC2.CAT.OP.MPA.126 paragraph(d)(2)(i)(B) which says 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

Please check it,