Hi Superpilot, I take it what you have there is company guidance?
Is VNAV minima available?
- If yes you may fly down to VNAV minima provided that:
- The VNAV minima has been corrected for cold temperature (if below zero) thereby increasing
That much is certainly correct. Zero no doubt because that is the warmest temp in the ICAO correction table for a sea level airport. Although somewhere in the ICAO verbiage it says something suitably vague like 'if it is very much colder than ISA'.
- The actual temperature is not below the published minimum temperature
This one would seem to refer to 'uncompensated baro-VNAV'. According to the FAA AC 90-105A:
"Uncompensated baro-VNAV systems may not operate to the LNAV/VNAV DA when the actual temperature is below or above the temperature limitations. The temperature limitation will be shown as a note on the procedure. If the aircraft contains a temperature compensation capability, manufacturer instructions should be followed for use of the baro-VNAV function."
And according to the FAA AIM:
Aircraft using baro VNAV with temperature compensation or aircraft using an alternate means for vertical guidance (e.g., SBAS) may disregard the temperature restrictions.
- The approach must be flown with the autopilot on and fully managed
I assume that is a company or type specific thing.
- There is no requirement to increase altitude gates as terrain separation is guaranteed up to the minimum published temperature
I'm not sure what the definition of gate is there. Anyway, as far as altitudes, according to the FAA AIM:
The charted temperature limits are evaluated for the final approach segment only. Regardless of charted temperature limits or temperature compensation by the FMS, the pilot may need to manually compensate for cold temperature on minimum altitudes and the decision altitude.
ie if your airport is on the FAA 'Cold Temperature Restricted Airport' list, and it is cold enough, you
will correct the requisite segment altitudes. Meanwhile, according to Eurocontrol guidelines:
The flight crew is responsible for any necessary cold temperature corrections to all published minimum altitudes/heights including the altitudes/heights for the initial and intermediate segment(s); the DA/H; and subsequent missed approach altitudes/heights, except for APV/BARO-VNAV approach procedures. In accordance with ICAO Doc 8168, PANS-OPS, Volume I, Part II, Section 4, Chapter 1, § 1.4.1, the final approach path vertical path angle (VPA) is safeguarded against the effects of low temperature by the design of the procedure.
...which sounds a little like 'don't bother correcting your segment altitudes if doing a baro-VNAV procedure'. Whilst according to Transport Canada:
Regardless of whether the FMS provides temperature compensation of the vertical path or not, all altitudes on the approach, including DA, should still be temperature corrected.
The various references don't exactly dovetail. And I would not second guess company rules; there may be a good reason. But if the airport temp is cold enough for a correction then to my mind it makes sense to correct all segments like the Canadians say (and the FAA now also have a 'correct all segments option'). You would for an ILS so I don't see why you wouldn't for baro-VNAV. Discuss.
- A typical autopilot coupled approach will fly below the profile up to minima where it will be back on profile.
Would it be back on profile at minima or at TDZE? It strikes me that an uncompensated baro-VNAV would still be slightly below profile at minima.