Advisory Circulars

Commercial & Business Aviation


No. 0107R


Reporting Aircraft Defects and Unserviceabilities


This Air Carrier Advisory Circular (ACAC) is intended to provide guidance to air operators and pilots regarding the procedures for reporting aircraft defects and unserviceabilities.

This revision reflects a correction to the French translation.


Canadian Aviation Regulations (CARs), Part VI, General Operating and Flight Rules, Subpart 5 (CAR 605), and Commercial Air Services Standards 625.09 & 625.10.


Inspections have determined that pilots too often do not record aircraft defects and unserviceabilities in the aircrafts journey log as required by regulation. This likely, may be attributed, among other reasons, to the mistaken assumption that such entries in the journey log will always automatically ground the aircraft. The Canadian Aviation Regulations (CARs), implemented on October 10, 1996, outline in detail the requirements and procedures for reporting all aircraft defects and unserviceabilities. These regulations allow for the safe deferral of maintenance in certain cases.


CAR 605 states that the particulars of any defect in any part of an aircraft or its equipment shall be entered into the aircraft journey log as soon as practicable after the defect has been discovered but, at the latest, before the next flight. Any action subsequent to entering the defect in the journey log will normally depend upon whether the aircraft is subject to a Minimum Equipment List (MEL). For ease of reference and to assist operators and pilots to determine the appropriate action to be taken after a defect has been entered in the journey log, the appropriate regulations as well as certain provisions from the standards have been paraphrased for inclusion in this ACAC:

Aircraft with a Minimum Equipment List

Once a defect has been entered in the journey log of an aircraft with a MEL, the following procedures will apply:

  1. the aircraft will be operated in accordance with any conditions or limitations specified in the MEL; and
  2. a copy of the MEL will be carried on board the aircraft.

Aircraft without a Minimum Equipment List

Once a defect has been entered in the journey log of an aircraft without a MEL, the following procedures will apply:

  1. the pilot or operator will determine if the unserviceable equipment is required by the applicable airworthiness standards for day/night VFR or IFR flight, the aircraft manufacturer’s equipment list, the air operator certificate, an airworthiness directive or the CARs; and
  2. should the unserviceable equipment not be required for the intended flight, it shall be either removed from the aircraft or isolated/secured so it does not constitute a hazard to any other aircraft system or to any person on board the aircraft; the appropriate placards are to be then installed as required by the Aircraft Equipment and Maintenance Standards and an entry made in the journey log recording the action taken to remove, isolate or secure the unserviceable equipment.


Regulations require that a formal system be established to control aircraft defects. Such a system will ensure that the airworthiness effects of aircraft defects and unserviceabilities have been assessed and that there will be consistent application of the airworthiness standards.

The type of system used to control the deferral of repairs to defects and unserviceabilities will depend upon the type, size and complexity of the operator’s aircraft fleet. Although more complex operations will utilize a MEL, all operators must have an approved system, and this system must be detailed in the operator’s maintenance control manual (MCM). Compliance with the procedures outlined in the approved MCM is mandatory.

The final decision rests with the pilot-in-command to accept an aircraft for flight. A pilot can accept an aircraft with defects where the repair of these defects has been deferred in accordance with an approved system. However, a pilot who undertakes a flight in an aircraft that is not approved defect deferral system will be in contravention of the applicable CARs.


The ultimate responsibility for determining whether an aircraft may be operated with outstanding defects rests with the pilot-in-command. Accordingly, the CARs require that full details of all defects and unserviceabilities be recorded in the aircraft journey log. Only when such entries have been made in the journey log can the pilot-in-command be fully aware of the condition of the aircraft and make the correct decision concerning the intended flight.

A.J. LaFlamme
Commercial and Business Aviation

Commercial & Business Aviation Advisory Circulars (CBAAC) are intended to provide information and guidance regarding operational matters. A CBAAC may describe an acceptable, but not the only, means of demonstrating compliance with existing regulations. CBAACs in and of themselves do not change, create any additional, authorize changes in, or permit deviations from regulatory requirements.

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