Originally Posted by Sniper

No, you need CR1 (10 hours), not CR2 (11 hours), because you were scheduled to operate less than 8 hours in a 24 hour period in this case. While I don't know your schedule for day 2 (or day 0, if this is in the middle of a trip), I'm assuming that since you say you were scheduled for NR1 originally, that was legal, so that would trigger CR1 (10 hours).

Whitlow triggers comp rest over 15 hours of duty day (because @ 15:01 of duty you now have less than 9 hours of lookback rest in the preceding 24 hours, you therefore are automatically on reduced rest and need compensatory rest when you duty off).

The amount of rest required (reduced, normal, or compensatory) is totally unrelated to the length of your duty day - it is based on your scheduled flight time - not actual flight time.

Yes, this means that you can fly 9+ hours in a duty period, trigger the whitlow letter with an over 15 hour duty day, and still only require compensatory rest of 10 hours when you duty off. Because though you flew 9+ hours, you were scheduled to fly less than 8 hours, which is what determines the length of your rest period (<8 hours flying = 10 hours normal rest). Whitlow then puts you into compensatory rest based on your original required normal rest (you were required 9 hours, so compensatory is 10 hours).