| RogerF |
Posted - 20/07/2020 : 15:11:57
Hello.
I am a new user of LK8000 and I appreciate it.
I dare to make a suggestion concerning the Flight Level calculation based on the GPS altitude.
Currently, it takes into account the QNH defined in the basic settings.
However, it misses the correction for the temperature deviation with respect to the Standard (15°C at 1013mb pressure-altitude).
Such correction is required because the GPS provides a true altitude while airspace limits are rather referring to the altitude displayed by the altimeter (set on QNH or on 1013), without temperature correction.
A decent estimation of the correction is 0.4%/°C (to be applied to the altitude displayed by the altimeter).
For example, if the QNH is 1013 (FL = AMSL atitude) but the temperature is 15°C higher than standard:
- FL060 is reached when the GPS shows 6000 x (1 + 15° x 0.004) = 6360 ft.
- FL100 is reached when the GPS shows 10000 x (1 + 15° x 0.004) = 10600 ft.
As you see, this correction is as important as the QNH correction.
It affects non only the FL display, but also the information and warnings related to airspaces vertical limits.
To calculate the correction, the pilot should have the possibility to enter the temperature deviation (with respect to the standard atmosphere). |
