Q&A
What does 'acclimatized' mean, and why does it change my maximum FDP?
Acclimatized means your body clock is aligned with local time. If you're not, you read the FDP tables using the local time back in the zone you're still acclimatized to — which usually shortens the limit.
Turns on: CARs 700.28(5) , CARs 700.28(7) , CARs 700.01
Acclimatized is defined in CARs 700.01 as a flight crew member “whose biorhythm is aligned with local time” — in plain terms, you sleep at night and are awake during the day where you are now.
Why it matters
The 700.28 maximum-FDP tables are read using a start time that is the local time at the place you’re acclimatized to — not necessarily the wall clock where the flight duty period begins (AC 700-047 §§ 4.22–4.26).
- Acclimatized to where the FDP begins → start time is just local time.
- Not acclimatized → convert your report time to the local time back in the zone you’re still acclimatized to, and use that row.
Because your home-zone equivalent is often earlier in the day (and the early rows are the most restrictive), being unacclimatized usually shortens your maximum FDP.
When you count as acclimatized
An operator may assume you’re acclimatized to your home-base time zone unless previous duty has acclimatized you elsewhere. Only operating or positioning to a new zone — and then spending enough time there — changes it; a there-and-back trip the next day does not (AC 700-047 § 4.23).
After you leave the zone you’re acclimatized to, you become acclimatized to the new one once required rest has been given and you’ve spent 72 hours there (time-zone difference under 4 hours) or 96 hours (difference of 4 hours or more). Alternatively, your acclimatized time drifts 1 hour toward the new zone for every 24 hours you spend there (CARs 700.28(5); AC 700-047 §§ 4.24–4.26).
A note on other operations
The medevac rules (CARs 700.100 series) and 702 aerial-work rules don’t use acclimatization the way 703/704/705 do — check those subparts directly if that’s your operation.
See also: Maximum Flight Duty Period (700.28) · FDP calculator
Worked examples
Acclimatized to Calgary, reporting in Toronto
You're acclimatized to Mountain time. You report in Toronto (Eastern) at 07:00 local. Toronto is two zones east.
→ Use the 05:00–05:59 row (07:00 − 2 h), not 07:00–12:59.
AC 700-047 § 4.22
Acclimatized to Halifax, reporting in Vancouver
You're acclimatized to Atlantic time. You report in Vancouver (Pacific) at 07:00 local. Vancouver is four zones west.
→ Table start time is 11:00 (07:00 + 4 h) — still the 07:00–12:59 row.
AC 700-047 § 4.22
These examples are also run as automated checks against the FDP calculator.