If you are a licensed guy with 737 approvals about 31/32k plus 20/25% max bonus at the end of the year dependant on the following:
1) your own personal performance as assessed by your supervisor
2) technical despatch reliability of fleet
3) number of tech delays over 4 hours
4) average number of deferred defects across fleet.
Overtime is also payed for extra days worked.
For information only; this years bonus is shortly to be announced and is expected to be around 90% of the max possible. For a top earner that equates to about 9k before Gordon Brown takes his cut.