You bet!!
You can bid for annual vacation, in April, since the yearly vacation cycle starts in May. Pretty sure it has to do with the Mayan calendar, since we do lots of Central American flying....
Anyway, you can bid part, or all, of your allocated days (based on longevity). You put in two or three choices. Vacation start-stop dates are in 7-day blocks, because no pilot would want a vacation in other than one-week increments.
And they all start on the same day of the week (I think it is Monday).
You can also try holding back some week-long vacation days to use in "monthly bidding." In July, I can bid for vacation in September, as an example.
You put in your annual bids and monthlies, and the sytem processes it.
The awards come out, and you get nothing you asked for in the annual bid, then get assigned vacation each month by the company for the least usable and convenient time.
At least, that's my experience.
