Transponder equipment requirements
Transponder answers radar, improving ATS detection of aircraft.
| Mode | Adds |
|---|---|
| A | Identity code only |
| C | Automatic pressure-altitude reporting: ATC sees altitude beside code, quickly locates potential conflicts (TC AIM COM 8.1) |
| S | Datalink |
| ADS-B Out | Broadcasts GPS position |
Required in transponder airspace: transponder and automatic pressure-altitude reporting equipment (CAR 605.35).
Transponder airspace (CAR 601.03):
- All Class A, B, and C airspace
- Any Class D or E designated as transponder airspace in the Designated Airspace Handbook
- All Class E from 10,000 ft ASL up to and including 12,500 ft ASL, within radar coverage (TC AIM COM 8.2)
Exempt (CAR 605.35(1)): balloon or glider only. Nothing else exempt by type, weight, or flight rules.
Transponder quits in flight:
| Case | Action | Ref |
|---|---|---|
| Under an approved MEL | Allowed | CAR 605.35(2)(a) |
| Otherwise | Continue to the next aerodrome of intended landing | CAR 605.35(2)(b) |
| After landing | Completing planned flight schedule or going to maintenance facility needs ATC authorization | TC AIM COM 8.1 |
No working transponder before departure (CAR 605.35(3), TC AIM COM 8.1):
- ATC may authorize entry into transponder airspace, provided an ATC unit serves that airspace.
- Request must reach the ATC unit before the aircraft enters the airspace, including taking off from an airport inside it.
- Approval requires aviation safety unaffected; may carry conditions.
Special aviation events (CAR 605.35(4)): no serviceable transponder needed in Class A to E airspace with ATC service.
Trap: Transponder not needed everywhere below 12,500 ft ASL: Class E band starts at 10,000 ft ASL and needs radar coverage; below that only A/B/C and designated airspace require it. No-transponder authorization must be arranged before entry, not once inside.
References
- CARs 605.35
- CARs 601.03
- TC AIM COM 8.1
- TC AIM COM 8.2