sentences:  The March 1, 1974, Allegheny system timetable lists flights operated by the airline with Convair 580 turboprops nonstop to Worcester and one-stop service to Boston.According to the April 15, 1975, Official Airline Guide (OAG), Allegheny and Delta were no longer serving Keene.This same OAG lists nonstop flights to New York LaGuardia Airport operated at this time by Air New England with Fairchild Hiller FH-227 turboprops.