All flights designated with the prefix C are operated with Beech 99, Volpar Beech 18, Nord 262, DeHavilland Heron, and DeHavilland Twin Otter equipment, under the Allegheny trademark, "Allegheny Commuter" provided by independent corporations under agreements with Allegheny.Baltimore's airport is still listed as Friendship International Airport (BAL) in this timetable. It was probably a few months away from officially becoming Baltimore/Washington Airport which ultimately acquired the BWI code in 1982.
And, to distinguish between the two different types of jet equipment, Allegheny referred to its BAC1-11 as a Fanjet, and its DC-9s were Super Fanjets. The BAC1-11s joined the fleet as a result of the Mohawk Airlines acquisition in April, 1972.
Here is a the first installment of a two-part video from the late 60s that features Allegheny. Part two continues here.