MINNEAPOLIS, JULY 31 -- One of three former Northwest Airlines pilots accused of flying while intoxicated does not get drunk easily because he is an alcoholic, his lawyer said today at his trial.

"A person who consumes alcohol builds up a tolerance to alcohol. Your body resists the effects of alcohol," attorney Peter Wold said, referring to his client, Capt. Norman "Lyle" Prouse.

Prouse is not "a skid row drunk" and had no trouble flying a Boeing 727 from Fargo, N.D., to Minneapolis March 8, despite evidence that he consumed at least 17 1/2 rum and Diet Cokes the night before, Wold said in his opening argument.

Prouse, of Conyers, Ga.; 1st Officer Robert Kirchner, of Highland Ranch, Colo.; and flight engineer Joseph Balzer, of Antioch, Tenn., are charged with operating the aircraft while under the influence of alcohol. The federal felony carries a maximum penalty of 15 years in prison and a $250,000 fine.

Prouse had been drinking for 35 years and entered a treatment program after his arrest, Wold said.

Assistant U.S. Attorney Elizabeth de la Vega said in her opening statement that while the pilots "may not have been staggering drunk," results of blood-alcohol tests will show their skills were seriously impaired.

All three pilots had blood-alcohol contents exceeding .04 percent, the Federal Aviation Administration's limit for flying, according to test results admitted as evidence.

Defense attorneys said Tuesday that the flight went flawlessly. "The issue is not what his condition was the night before or what his alcohol content was the next day," Wold said. "The government must show their abilities were impaired."