Mode 3A fails at a high percentage in Transponder Monitor mode
This is the squawk code. In most systems it must be picked up from the transponder replies in
Transponder Monitor mode. The transponder replies only occur when the transponder is
interrogated by air traffic control radar. Make sure the Control Source is set to Transponder
Monitor in the echo app.
If everything else is good, follow the procedure to adjust the Transponder Threshold in the
advanced settings in the echo app.
Mode 3A only fails when squawk code is not 1200:
Mode 3A is about the squawk code transmitted by ADS-B. If there's no wired control link
between the echoUAT and transponder, or EFIS and transponder, then Transponder Monitor
mode must be used. Make sure the Control Source is set to Transponder Monitor in the echo
app.
Only NIC fails, or the GPS loses position sometimes:
NIC a category of GPS signal and position quality computed from received signals.
The minimum NIC for compliance is 8. Most Safe-Fly installations average around 9.
This is an issue with GPS reception. Check the GPS antenna connections and location.
The antenna should be facing straight up during level flight with a full view of the sky.
The antenna should not have any metal objects near it (except below the ground plane) or
anything else that may block, reflect, or interfere with signals. Small GPS antennas work best
with a 2+ inch diameter flat metal surface underneath them to act as a ground plane. 5+ inches
maximizes the ground plane effect. There should be at least an inch between the GPS antenna
and any other similar antenna. Try more separation. Large IFR GPS antennas need 9 inches
center-to-center and recommend 12 inches center-to-center.
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Safe-Fly 2020 GPS – Rev P GRT Avionics, Inc
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