There is some controversy about how pilots should track “actual instrument time”, a somewhat vaguely defined term in Canadian regulations.

Actual instrument time is primarily required for licensing purposes to maintain IFR currency, which in Canada requires 6 hours of simulated or actual instrument time each six months. No currency – no can go IFR. Instrument time is also needed for certain higher level pilot licenses/ratings, in particular the ATPL (airline transport pilot license). Pilots on a professional (ATPL) track need to log hours like mad in order to compete with other wannabes. They sometimes adopt the most liberal conceivable interpretation to meet/exceed the minimum requirements and apparent experience. Since there is no physical record of the weather conditions surrounding a particular airplane on a particular flight, there may be little evidence available to contradict a habitual exaggerator.

As I understand it from all the various Transport Canada publications (CARs, AIP, study guides), “actual instrument time” is that time where, because of actual weather conditions, reference to instruments is necessary to maintain control of the airplane. As such, it is at most the “air time” – the amount of time the airplane spends in the air instead of just taxiing around on the ground. (By the way, it is the accumulation of this same air time that dictates maintenance schedules in Canada.) Time spent in bright blue air, far from clouds, would not count toward “actual instrument time”.

I have heard of other (mis)interpretations of the “actual instrument time” term. Some suggest that any time flown on an IFR flight plan counts, even in VFR weather conditions. Some suggest that flight (“engine-on”) rather than air (“flying”) time is limiting. Some suggest that any IFR flight that involved touching cloud even momentarily, counts in its entirety. I say “wishful thinking”. If you don’t need to constantly scan the the instruments to keep the plane upright, you’re not flying on instruments, and you can’t log instrument time. There is a small side question as to whether one may log instrument time during conditions that, even though technically VFR, still require instrument scanning. Such conditions include flying over a slanted weird cloud mass, during dark night, or with mist-blocked horizons. I believe it is legitimate to log such time, if instrument scanning was genuinely required.

For what it’s worth, the US FAR rules (61.51(g)(1)) define the same “instrument time” concept thusly:

A person may log instrument time only for that flight time when the person operates the aircraft solely by reference to instruments under actual or simulated instrument flight conditions.

I believe this definition meshes with mine up above. I wish Transport Canada would adopt it, and also cover the “side question” above about logging instrument time in putative VMC.

UPDATE: A local pilot acquaintance called Transport Canada, and they appear to agree with me, but frustratingly, didn’t point to a specific piece of regulative text to explain.