MicroStep-MIS MSB780X1D - Hqnh Set Altitude for QNH Corrected Pressure

MSB780(X) - User’s Guide
g is gravitational acceleration 9.81 m.s
−2
R is gas constant 287 J.kg
−1
K
−1
T
QF E
is temperature in K (see tqfe and tqfea commands)
or (if ICAO mode turned on)
QF E = p ·

1 +
β · (−h
QF E
)
T
QF E

−g
β·R
i
(10)
where
p is adjusted output pressure in
β is atmospheric temperature lapse rate -0.0065 K.m
−1
h
QF E
is height difference between barometer elevation and official aerodrome elevation in m
g is gravitational acceleration 9.80665 m.s
−2
R
i
is gas constant 287.05287 J.kg
−1
K
−1
T
QF E
is temperature in K (see tqfe and tqfea commands)
6.45 “hqnh” Set altitude for QNH corrected pressure
Using this command you can set hqnh, which is geometric (not geopotential) official aerodrome
elevation. The hqnh is a positive number in cases when the barometer is above see level.
hqnh<cr>
HQNH:<cr><lf>
Actual value 0.00 m<cr><lf>
Distance scale [ft, m]: m<cr>
Set altitude in m, ranges -30.00 .. 5000.00 : 100<cr>
New altitude is: 100.00m<cr><lf>
wait..OK<cr><lf>
Available altitude units are m (meters), ft (feet).
Table of valid altitude ranges for different units is in table 15.
The corrected QNH pressure is computed using formula 11 or 12 if ICAO mode is turned on.
QNH = QF E · exp


h
QNH
· g
R ·

T +
α·h
QNH
2



(11)
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