•Inform ATS as soon as possible, preferably before the submission of the FP.

•Put ‘N’ in item 10 for the FP form.

•Comply with the published procedures for seeking exemption from the requirements for the mandatory carriage of a transponder.

•If required by the ATS authority, proceed directly to the nearest suitable aerodrome where the transponder can be repaired.

13.8 Code Selection. The preferred method of selecting/changing a code is to first set the option switch to standby (STBY) and then select the new code. On completion, reset the option switch to ON or ALT. Modern SSR installations have two controllers (designated A and B) with a switch that selects either the A controller or the B controller. In this case, the new code would be set on the controller not in use and the switch then set to that controller.

Airborne Collision Avoidance System (ACAS)

13.9 Background. The technical details of ACAS are covered in detail in 022 03 Warning and Recording. However, the response to the alerts generated by ACAS is a matter for consideration in Air Law. Basically, the system uses the redundant capacity of the SSR system to determine the proximity of another aircraft which is operating its SSR transponder. In areas where RVSM is applied, the use of ACAS is mandatory and operators are required to ensure compliance with the requirement.

13.10Use of ACAS. ACAS is to be used by pilots in the avoidance of potential collisions, the enhancement of situational awareness, and the active search for (and visual acquisition of) conflicting traffic. It must be understood by pilots that the use of and the exploitation of ACAS alerts and the procedures applicable, do not relieve the pilot of the basic responsibility for the safety of the aeroplane. In all cases, the pilot will be expected to exercise his/her best judgment and full authority in choosing the best course of action to be taken.

13.11Response to ACAS Alerts. ACAS generated alerts consist of Traffic Advisories (TAs) and Resolution Advisories (RAs). A TA is intended to alert the pilot to the possibility of an RA being generated. As such, pilots are not to manoeuvre the aircraft in response to a TA only. If an RA is generated, the pilot is to respond immediately unless in doing so the safety of the aeroplane would be jeopardized. In any case, stall warning, wind shear and GPWS alerts will have priority over ACAS. Pilots must be aware that visually acquired traffic may not be the cause of an RA and visual perception of an encounter may be misleading especially at night.

13.12Conflict. Should there be a conflict of Resolution Advisories between the aircraft, pilots must follow the RA and the equipment should offer a Reversal Advisory.

13.13ATC. As soon as would be permitted by the workload of the flight deck crew, ATC should be notified of the RA and the direction of any deviation from the current flight plan. Once the conflict is resolved, the aircraft should be promptly returned to the requirements of the current FP and again, ATC informed. Under some circumstance, it is possible that ATC issues instructions that are unknowingly contrary to ACAS RAs. It is vitally important that ATC is notified when an ATC instruction or clearance is not being followed because it conflicts with an ACAS RA.

13.14Disregarding RAs. RAs may be disregarded only when the pilot visually identifies the potentially conflicting traffic and decides no deviation from the current flight path is needed. Nevertheless ATC must be informed in these circumstances.

SSR and ACAS 13

Questions

Questions

1.When acknowledging mode/code setting instructions, pilots shall:

a.read back only the code to be set.

b.read back the mode and the code to be set.

c.use only the word ROGER.

d.use only the word WILCO.

2.The pilot of an aircraft losing two-way communications shall set the SSR transponder to Mode Alpha code:

a.7700

b.7600

c.2000

d.7500

3.When the SSR transponder appears to be unserviceable and repair is not possible before departure, then:

a.the aircraft would be permitted to depart to the nearest aerodrome where repair can be carried out.

b.the pilot must indicate the failure on the flight plan after which ATC will endeavour to provide for the flight to be continued.

c.the flight can only continue in the most direct manner.

d.the pilot will not be permitted to commence the flight.

4.What Mode A code shall be used to provide recognition of an aircraft emergency?

a.Code 7500

b.Code 7600

c.Code 7000

d.Code 7700

5.Which of the following correctly lists special purpose codes that are used in conjunction with SSR?

6.When an aircraft carries a serviceable transponder, the pilot is to operate the transponder:

a.only when the aircraft is flying within the airspace where SSR is used for ATC purposes.

b.only when the aircraft is flying in CAS.

c.only when direct by ATC.

d.at all times during flight regardless of whether or not the aircraft is within or outside airspace where SSR is used for ATC purposes.

13

Questions 13