Appendix 1 to AMC 20-15 – ACAS II/Mode S Transponder Ground Testing
Precautions
ED Decision 2011/001/R
Transponder/ACAS II system testing is a known source of ‘nuisance’ ACAS II warnings. The following information provides guidance which should be followed to minimise this risk:
— When not required, ensure all transponders are selected to ‘OFF’ or ‘Standby’.
— Before starting any test, contact the local Air Navigation Service Provider (ANSP) or Air Traffic Service (ATS) and advise them of your intention to conduct transponder testing. Advise of your start time and test duration. Also inform them of the altitude(s) at which you will be testing, your intended Aircraft Identification (Flight Id) and your intended Mode A code.
— Set the Mode A code to 7776 (or other Mode A code agreed with Air Traffic Control Unit).
Note: The Mode A code 7776 is assigned as a test code by the ORCAM Users Group, specifically for the testing of transponders.
— Set the Aircraft Identification (Flight Id) with the first 8 characters of the company name. This is the name of the company conducting the tests.
— Where possible, perform the testing inside a hangar to take advantage of any shielding properties it may provide.
— As a precaution, where practicable, use antenna transmission covers whether or not testing is performed inside or outside.
— When testing the altitude (Mode C or S) parameter, radiate directly into the ramp test set via the prescribed attenuator.
— In between testing, i.e. to transition from one altitude to another, select the transponder to ‘standby’ mode.
— If testing transponder/ACAS II system parameters that do not require ‘altitude’, set altitude to – 1000 feet (minus 1000 feet) or greater than 60,000 feet. This will minimise the possibility of ACAS II warning to airfield and over flying aircraft.
— When testing is complete select the transponder(s) to ‘OFF’ or ‘Standby’.
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