The Taiwanese pilot who defected to mainland China three weeks ago threatened his copilot with an ax and handcuffed him to gain control of the plane, the copilot said today.

At a press conference on their return here, copilot Tung Kung-shin and flight mechanic Chiu Ming-chih told of how an "emotional" pilot Wang Xijue used force to divert their Boeing 747 cargo plane to Guangzhou in southern China.

This was the first time the two crew members have given their version of what started out on May 3 as a routine cargo flight between Bangkok and Hong Kong. The two had declined to give any interviews during their stay in Guangzhou.

Flight mechanic Chiu said that when he went to the plane's bathroom Wang made his first move. He returned from the bathroom to find the copilot in handcuffs.

Chiu said that he tried to struggle with Wang but the pilot struck him and sent him crashing to the floor of the plane. He showed reporters a knee injury.

The flight mechanic said he got on his knees and tried to reason with Wang, appealing to the close relationship the pilot and crew had developed over a decade and a half of flying together. He said Wang made it clear that he had been planning his defection for some time.

Copilot Tung said that to subdue him, Wang had jerked a chain around his neck and held an ax above his head. He then handcuffed the copilot to a bar above his head.

The copilot quoted Wang as saying, "I'm sorry, big brother, but I'm going to take the plane to Guangzhou."

The two China Airlines crew members returned to Taiwan today aboard the same cargo jet that had taken them as unwilling passengers to China. Their release and that of the plane was agreed on in unprecedented negotiations, conducted in Hong Kong May 17 to 20 by airline representatives from China and Taiwan.

Dressed in their China Airlines uniforms after a brief stopover in Hong Kong, the two crew members appeared to be in good condition. They did not shed any new light on why Wang Xijue defected to the mainland, but Chiu said he doubted Wang's statement about being eager to rejoin his father in China. He noted that Wang had shown no emotion when he met his father for the first time after being separated from him for many years.

Tung said that Chinese officials offered to arrange a meeting for him with his mother, who is still on the mainland, but that he refused.

In a press conference in Peking two weeks ago, Wang had criticized Taiwan, saying the island suffered from corruption, crime, traffic problems and a repressive secret police. But China Airlines officials have been telling reporters in Taiwan that the pilot had problems with a nagging wife. The couple was constantly arguing over money and other matters, the officials said.