The Navy on Friday selected Lockheed Corp. to build 125 new submarine-hunting patrol planes, an award worth an estimated $4.5 billion.

A Navy spokesman said the new aircraft is a modified and more capable version of the P-3C Orion anti-submarine warfare patrol plane Lockheed has produced for the Navy for more than 20 years.The bid by Lockheed's Aeronautical Systems Co., Burbank, Calif., had been favored over those submitted by Boeing Co. and McDonnell Douglas Corp., which were modifications of civilian airliners.

Lockheed will continue production of the land-based P-3C until 1991, a Navy spokesman said. Production of the new aircraft, called the Long Range Air ASW Capable Aircraft, or LRAACA, will begin in 1994, the spokesman said.