Unserviceable equipment: MEL and no-MEL deferral
Required equipment must meet airworthiness standards and be serviceable (and functioning where circumstances require) before takeoff (CAR 605.06). Only 605.08, 605.09, 605.10 give relief.
Markings and placards (605.05): no takeoff unless the markings and placards required by the airworthiness standards are affixed to the aircraft or component. No MEL or deferral relief is written into this rule.
Safety override and flight permit (605.08):
| Rule | Effect | Cite |
|---|---|---|
| Safety override | No takeoff with unserviceable or removed equipment if the pilot-in-command (PIC) believes aviation safety is affected. Beats 605.09, 605.10 and the flight permit | 605.08(1) |
| Flight permit | Takeoff legal despite 605.09 and 605.10 when flown under a flight permit issued for that purpose | 605.08(2) |
With approved MEL (605.09):
- MEL lists systems and equipment that may stay unserviceable for a limited period, sometimes with added operational procedures or restrictions (Standard 625.07(i)).
- Operate within MEL conditions and limitations. Carry a copy on board (605.09(1)).
- If MEL conflicts with an airworthiness directive (AD): AD prevails (605.09(2)).
- MEL mandatory for that operator, not transferable (Standard 625.07(iii)).
Without MEL (605.10):
| Equipment | Rule | Cite |
|---|---|---|
| Required by day/night VFR or IFR standards, manufacturer's equipment list, AOC/SFOC/FTU certificate, AD or CARs | Must be serviceable. No deferral | 605.10(1) |
| Other equipment | May fly if: isolated or secured when left installed; required placards installed; both actions entered in journey log | 605.10(2) |
Who decides (no MEL):
- PIC reviews journey log before flight and decides whether a defect affects airworthiness (Standard 625.10(iv)).
- Journey log records full details of all defects (625.10(ii)).
- AME advice (inspection and maintenance release): advisable, not required. Pilot decides finally (625.10(vi), (ix)).
- Accepting aircraft with defects deferred under approved system: good defence against unairworthy-aircraft charge. Flying it out of compliance with that system: itself an offence (625.10(ix)).
Trap: 605.10(1) equipment never deferrable like "other" equipment. MEL, log entry, AME signature, placard or flight permit never overrides the PIC's safety opinion.
References
- CAR 605.05
- CAR 605.06
- CAR 605.08
- CAR 605.09
- CAR 605.10
- Standard 625.07
- Standard 625.10