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3 Answers

GPS Approach.

Asked by: 4822 views Flight Instructor, Instrument Rating

As far as I know, LPV approaches or any other WAAS approaches are said to be not affected by the temperature, and whenever I fly LPV and load the box where I setup DA(H), the G1000 still provides temperature correction option.

So, does this mean that LPV will eventually get affected and will be allowed to descend lower to compensate for adversely low temp?

 

Connor.

3 Answers



  1. John D Collins on Oct 25, 2016

    Temperature compensation does not apply to the LPV final approach course vertical guidance. It could apply to other segments of the procedure where altitudes are MSL and the G1000 provides a VNAV capability to do the step downs. VNAV is based on MSL altitude.

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  2. Russ Roslewski on Oct 25, 2016

    While temperature does not affect the glideslope of an LPV, it certainly affects the barometric altimetry used to identify the start (glideslope intercept) and the end (DA) of the procedure. This fits under the fairly recent NOTAM entitled “Cold Temperature Restricted Airports”. An example is at Fort Wayne, IN, KSMD, where the NOTAM requires an adjustment on final below -27 C (the chart has a snowflake icon indicating -22 C – possible charting error).

    Does the G1000 compensate for temperature in this manner?

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  3. Best Answer


    John D Collins on Oct 26, 2016

    Russ,

    It is my understanding that the G1000 doesn’t use VNAV on the leg that intercepts the LPV GP. So on the standard RNAV T approach, the VNAV stops at the IF and is not provided on the IF to FAF leg. Unless the pilot commands a descent to the GP intercept altitude, the G1000 intercepts the GP on the IF segment and follows it down to the DA. There is a variation of the G1000 software that does support Baro VNAV on the approach segment, but I am unfamiliar with it.

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