>So if that's the case then how is it possible to fly overtime,
>like the delta pilots are complaining about? They'd be illegal!
FAR limits 8 hrs/day; 30 hrs/week; 100 hrs/month; and 1000 hrs/year. 1000 hrs divided by 12 months = 75 hrs/month average. Most contracts are constructed to average close to that 75 hrs/month so the company doesn't run out of pilots who hit the 1000 hrs/year limit.
For example: AA's contract monthly max is 75 hrs. There is provision for company to "flex" to 78 hrs/month. There is provision for company to "reassign" pilots up to 5 hours over monthly maximum without pilot approval [happened to all MD90 pilots a bunch in the past 2 months]. There is provision for company to "offer" pilots overtime which requires prior approval from the pilot. It is this last provision (or something similar) that UA pilots were refusing during the summer and DL pilots are refusing now.
If an airline continues to reassign pilots beyond an average 75 hrs/month, it runs the risk of too many pilots reaching 1000 hrs/year limit prior to the end of the year. Hence the decision(s) to cancel some flights. Usually means the airline was undermanned for the basic contract terms (no pilots flying overtime).
Confused? Don't worry, so are we.