Transponder operation
ATC transponder instruction (TC AIM COM 8.1): operate as directed until further instructions or landing. Exceptions: emergency, communication failure, unlawful interference.
Ground/taxi cycle (TC AIM COM 8.1):
| Phase | Setting | When |
|---|---|---|
| Taxiing for takeoff | STANDBY | While taxiing |
| Before takeoff | ON (or NORMAL) | As late as practicable, normally on entering active runway |
| After landing | STANDBY or OFF | As soon as practicable, normally on exiting runway |
Which code to select:
- Select ATC-issued code before switching out of STANDBY.
| Code | Use | Cite |
|---|---|---|
1000 |
Select when ATC has issued no code | TC AIM COM 8.1 |
1200 |
Standard VFR, no ATS involvement | TC AIM COM 8.4 |
2000 |
IFR default in controlled or uncontrolled high-level airspace | TC AIM COM 8.2 |
Changing codes (TC AIM COM 8.1):
- Don't select STANDBY: target drops off the ATS display.
- If either of the first two digits to select is a
7, avoid7500,7600,7700: step through an intermediate code.1700to7100goes via1100, not7700. - Selecting one of these codes, even briefly, can trigger the ATS alarm.
Surveillance termination (TC AIM COM 8.2):
- "ATS surveillance terminated" alone is not an instruction to change to
2000; keep assigned discrete code until told otherwise.
MLAT aerodromes (TC AIM COM 8.1):
- Applies where CAP or CFS PRO section notes MLAT surface surveillance.
- Transponder transmits at all times on the manoeuvring area, overriding STANDBY-while-taxiing.
Trap: "Surveillance terminated" does not mean squawk 2000; keep assigned code until ATC changes it.
References
- TC AIM COM 8.1
- TC AIM COM 8.2