The Air Force publicly introduced its secret stealth fighter aircraft Thursday at a Pentagon news conference that was abruptly canceled last month due to its potential impact on Tuesday's elections.

"The reason for making the announcement of this program was that we needed to be able to fly the aircraft to go fully operational and do daytime flying," Pentagon spokesman Dan Howard said.Until now, the Air Force has never even acknowledged the existence of the stealth fighter, called the F-117A, even though there have been numereous published news accounts of the plane.

To keep the program secret, the plane has only been flown at night. Daytime flying will use the full capability of the plane and lower costs, said Air Force spokesman Capt. Matthew Durham.

No costs or figures on the size and weight of the plane are being made public yet, Durham said. The F-117A will be listed for the first time in the 1990 budget that will be sent to Congress in January, he said.

The aircraft is made of non-metallic materials, which do not reflect radio beams and make it virtually invisible to enemy radar.

Howard said the single-seat, two-engine fighter has been operational since 1983 and was first flown in 1981.