Navigate / EASA

AMC1 ACNS.D.AC.010 Transponder characteristics 

ED Decision 2013/031/R

(a)     Transponder capabilities.

(1)     To be approved, the Mode A/C only transponder should hold an EASA equipment authorisation in accordance with European Technical Standard Order ETSO-C74d, or an equivalent standard that is consistent with ICAO Annex 10 Volume IV, and which is acceptable to EASA.

(2)     The Mode A/C only transponder should be a class 2A / class 2B as defined in ETSO-C74d.

Note 1: ETSO-C74d Class 2 equipment meets EUROCAE Document 1/WG9 /71 June 1972 with amendment 1 and 2. Amendment 2 contains the requirements and tests to show that the transponder correctly replies to Mode A/C-only all call interrogations and to Mode A/C/S all-call interrogations used by Mode S radars.

Note 2: RTCA DO-144 does not include requirement to reply to Mode A/C/S All-Call and Mode A/C-Only All-Call interrogations and is, therefore, not sufficient to prove the compliance. RTCA DO-144A contains the requirements for the equipment to reply to Mode A/C/S All-Call and Mode A/C-Only All-Call interrogations.

(b)     Minimum reply rate

(1)     Mode A/C only transponders should be capable of continuously generating at least 500 replies per second for a 15-pulse coded reply.

(2)     Transponder installations used solely below 4 500 m (15 000 ft), or below a lesser altitude established by the appropriate authority or by regional air navigation agreement, and in aircraft with a maximum cruising true airspeed not exceeding 90 m/s (175 knots) should be capable of generating at least 1 000 15-pulse coded replies per second for a duration of 0,1 s.

         Note: The rate of 1 000 replies per second for a limited duration of 100ms is an acceptable deviation to ETSO-C74d.

(3)     Transponder installations operated above 4 500 m (15 000 ft) or in aircraft with a maximum cruising true airspeed in excess of 90 m/s (175 knots) should be capable of generating at least 1 200 15-pulse coded replies per second for a duration of 0,1 s.

         Note 1: A 15-pulse reply includes 2 framing pulses, 12 information pulses, and the SPI pulse.

         Note 2: The transponder should be capable of replying to this short-term burst rate, even though the transponder may not be capable of sustaining this rate.

         Note 3: The rate of 1 200 replies per second for a limited duration of 0,1 s is an acceptable deviation to ETSO-C74d.

(c)      Minimum output power level

The transponder power output capability should be verified as follows depending on the aircraft capability:

(1)     For aircraft that operate at altitudes exceeding 4 570 m (15 000 ft) or with maximum cruising speed exceeding 90 m/s (175 knots), the class of the transponder declared in the transponder DDP should be Class A.

(2)     For aircraft operating at or below 4 570m (15 000 ft) with a maximum cruising airspeed of 90 m/s (175 knots) or less, the class of the transponder declared in the transponder DDP should be Class A or Class B.