Jim, I haven't looked up the part 121 rules since I left the airlines, but
as I recall, the "duty time" is defined as flight time. No limit on how
long a crewmember can sit idling on the ground. Last I looked it was 8
hours a 24 hour day, 40 hours in a 7 day week, 100 hours in any 30 day
period ("month") and 1000 hours in a calendar year. Perhaps that has
changed.

We had three or four crews during the last week of December on almost any
flight. Fly one leg, run out of yearly time. Swap with another crew. Fly
one leg, run out of time ...

Jim



Every minute is costly, whether the plane is at cruise or
parked with the crew waiting.