Trying to shed the regional image implied by its name, Allegheny Airlines proposed yesterday to change its name to USAir.

"While the name Allegheny has a proud heritage and has served our company well since 1953, research has consistently and convincingly shown that a new name will enable our company to compete more effectively with the major airlines of this country," Edwin I. Colodny, Allegheny chairman and president, said yesterday.

The new name will reflect more accurately the changed and changing nature of the airline, Colodny told the Society of Airline Analysts in New York yesterday. As a result of airline deregualtion, the once northeastern carrier has recently expanded into Florida, Arizona, Texas and Alabama, and soon hopes to add new services to California, Colorado and Louisiana, he said.

The new longer-haul markets it is operating are already improving efficiency, Colodny said. He noted that the average passenger journey on Allegheny increased from 298 miles in February to 336 miles in March.

Shareholders are being asked to vote on the name change in a proxy statement to be mailed out today in preparation for the annual meeting May 10.

Colodny also said the company plans to phase out its fleet of 30 BAC 1-11 airplanes, the "least efficient" planes it is using, and replace most of them with DC-9s.

Besides the 30 British-made planes, Allegheny also flies 45 DC-9s and 11 727-100s and has on order two 727-200s and eight DC-9-30s, and options for 15 more of the two.

Colodny said the airline did not plan to make any immediate commitments for new technology aircraft-he named the Boeing 757s and 767s and the Airbus A300-but would concetrate instead on improving the economics of serving its existing markets. (Last year, Colodny had said he would buy two of the A300 wide-body jets, used exclusively in the United States so far by Eastern Airlines, if Allegheny got some California routes it now expects to get.)

"What I am portraying is a plan for controlled growth," Colodny said yesterday. "We do not intend to jeopardize the company's future by overexpansion and excessive debt commitments.

"Simply because the lid came off the cookie jar is not a reason to gorge and get a bellyache," he said.