Cold Wx Correcting LPV Min's

[checkremarks]

Just wondering since LPV approaches are WAAS enabled and not Baro, do IFR pilots need to add cold wx corrections to LPV specific minimums?

[Rockie]

Yes you do. The lateral and vertical flight paths are based on 3 dimensional WAAS enhanced GPS positioning and are therefore accurate in space even if the approach were flown in a complete vacuum. But the FAF crossing altitude and DA are based on the barometric altimeter and will be subject to the same barometric errors as any other approach. You must remember though that the FAF crossing altitude may not be altered in any way unless it is done with a flight management system certified with the appropriate temp comp function. If not then just temp comp the DH. Think "ILS" except instead of fixed beams in space you have a fixed GPS/WAAS flight path in space.

Non- LPV approaches (LNAV/VNAV) use BARO-VNAV as the vertical reference, that's why there is a minimum temperature published in the remarks section of the plate. Below that temperature the vertical path will be so shallow as to compromise obstacle clearance and the approach may not be flown unless you use the same kind of FMS based temp comp. If you do have that then the minimum published temperature (TMIN) does not apply. DH still has to be temperature compensated.

LNAV approaches are essentially the same as any other non-precision approach and the FAF altitude should be temp comp'ed as well along with the MDA.

[oldncold]

Couple of weeks ago. Flew a uber equipped plane with lpv approach capability. On a approved lpv approach In -28c weather. It was vfr conditions. Min's were 2420. Ft. ( 275) agl. Cold wx correction is a soapbox point of mine. If you don't apply the correction in a non radar environment then. You could be a smoking hole in hard ifr if you refuse or dismiss. The correction apply the correction use the the cap gen to get it right and live your passengers expect nothing less