Honeywell BENDIX KING KMH 880 System Installation Manual page 203

B
When checking the bottom antenna bearing accuracy, the relative altitude
difference between the simulated intruder and own aircraft altitude should
be -6,000 feet (or more). The test antenna should be below the mounting
plane of the bottom directional antenna.
Position the aircraft outside on a heading of north away from hangers and
other aircraft.
Static pressure to the aircraft using the static tester is not required unless
local conditions make it necessary.
Apply a radio altitude signal to the aircraft using the Radio Altimeter Test
Set or equivalent. Increase the radio altimeter to 1,000 feet or greater.
Disable the WOW logic to put the aircraft systems in the "AIRBORNE"
mode
Set up the TCAS Ramp Tester on headings listed in the following Figure.
On each heading in a CW direction initiate an intruder test scenario on the
TCAS Ramp Tester and measure the relative bearing to the intruder from
the traffic display.
Whenever testing the bottom directional antenna, set the landing gear logic
to "RETRACTED" (GEAR UP). Repeat the above steps for the bottom
antenna.
Rev 0, October/2000 10609I00.ZIPCDL
KMH 880/KTA 870
Page 4-33