Section 9 Appendix
1
st
Ed Nov 2018
IDU-450 EFIS Software Version 8.0H (Rotorcraft)
9-5
Allowable Installed System Error #1 = 30’
Allowable Installed System Error #2 = 30’
3) Calculate altitude miscompare threshold based upon sum of above
allowable errors:
Altitude Miscompare Threshold = 160’
9.12. Airspeed Miscompare Threshold
Airspeed miscompare threshold is based upon allowable airspeed error.
There are two components to allowable airspeed error, instrument error
and installed system error. Allowable instrument error is based upon the
values of SAE AS8002A Table 3 as follows.
Table 9-3: Airspeed Error
Calibrated Airspeed
Allowed Error
50 knots
5 knots
80 knots
3 knots
100 knots
2 knots
120 knots
2 knots
150 knots
2 knots
200 knots
2 knots
Allowable installed system error is added on top of instrument. Error and
these values are derived from the regulations as follows.
Table 9-4: Airspeed Regulatory Reference
Regulation Allowed
Error
14 CFR §
27.1323
Starting from (0.8 x
V
CLIMB
): Greater of 5 knots or 3%.
Do not perform a comparison if either value is below (0.8
x
V
CLIMB
).
14 CFR §
29.1323
For climbing flight (VSI > 250 feet per minute):
Starting from (
V
TOS
– 10): 10 knots
Do not perform a comparison if either value is below
(
V
TOS
– 10)
For other flight regimes:
Starting from (0.8 x
V
TOS
): Greater of 5 knots or 3%.
Do not perform a comparison if either value is below (0.8
x
V
TOS
).
System uses
V
CLIMB
as a substitute for
V
TOS
.