* Most 50-seat planes being retired
* Fleet to shrink to 44 by end 2012 from 97 now
* No specifics on job cuts
ATLANTA, Sept 1 (Reuters) - Delta Air Lines Inc's (DAL.N) Comair regional subsidiary plans to cut jobs and reduce the size of its airplane fleet by more than half to lower costs, the carrier said on Wednesday.
In a memo to staff, Comair said it would retire most of its aging 50-seat jets in 2011 and 2012 and cut staff as the regional airline shrinks.
Comair, which has about 2,600 workers, did not comment on the number of planned job cuts but said the reductions would affect all departments.
"Our current cost structure -- which remains approximately 20 percent higher than our peers on a cost-per-block-hour basis -- does not enable us to be competitive in the current industry environment," Comair President John Bendoraitis said in a memo outlining the changes.
By the end of 2012, Comair expects to operate a total of 44 aircraft, down from 97 planes now, a spokeswoman said.
Delta sold its Mesaba and Compass regional units in July and had shopped around Comair [ID:nN01115223].