MANILA, Philippines (AP) _ A hijacker armed with a pistol and a grenade robbed 290 people on a Philippines Airlines jet today before leaping from the plane with a homemade parachute, authorities said.

The Airbus 330 later landed at Manila's airport and the passengers were let off safely. Police began searching the area near the capital where the man was presumed to have landed, though it was not known if the hijacker survived.

The jetliner left Davao City, in the southern Philippines, for the 90-minute flight to Manila with 278 passengers and 12 crew aboard, PAL said.

The hijacker, wearing a blue ski mask and swimming goggles, told everyone to hide their faces in their laps and not to look at him, then he walked to the cockpit, passengers said in radio reports.

He ordered the pilot of Flight PR812 to return to Davao City, 600 miles from Manila, but the pilot said he did not have enough fuel, Manila airport general manager Antonio Gana said.

At one point, the hijacker fired a shot inside the cockpit, perhaps accidentally, said Emmanuel Generoso, one of the three pilots aboard.

``He was very tense,'' Generoso said. ``I don't think there's any political implications there. He had family problems, he needed the money, so that's what happened.''

The man was ``deranged'' and crying, Generoso said.

The plane was depressurized so that the hijacker could jump out while it circled 30 miles from Manila at 6,000 feet, PAL spokesman Rolando Estabillo said.

A strong gust of wind swept into the plane when the door was opened, a passenger said. The hijacker had difficulty getting out the door.

``I had to push him because he wanted to jump,'' a flight attendant said.

But asked whether the man could have survived his jump, Generoso, the pilot, said he doubted it, given the aircraft's speed and the turbulence in its wake.

The jet landed at the Manila airport 2 1/2 hours after taking off. It was not immediately clear if the hijacker had any accomplices aboard.

Passenger Ida Marie Bernasconi, a reporter for Manila's TV Channel 13, said the hijacker carried ropes and appeared to have prepared for his jump. He used the ropes to get out of the plane, she said, but did not describe how.

``Before he left, he collected all the money he could from the passengers,'' she said.

The hijacking recalled the case of the legendary D.B. Cooper, who took over a Northwest Orient Airlines flight on Nov. 24, 1971, demanding $200,000. After getting the money, he parachuted from the plane over Washington state. He hasn't been heard from since, although $5,880 of his loot was found by a boy playing on the banks of the Columbia River in 1980.

Security was heightened at all airports in the southern Philippines after the hijacking, Southern Command Lt. Gen. Deomedio Villanueva said. He said officials were investigating how the hijacker was able to board the plane.

The Davao airport has several security checks and passengers are frisked before they are allowed to board, Davao PAL manager Arturo Balaga said.

PAL said it was the first hijacking of one of its planes in 18 years. In 1982, a farmer armed with a grenade seized control of a PAL plane in Mactan, in the central Philippines, but he was eventually subdued with no injury to passengers.

The military is battling Muslim guerrillas fighting for a separate Islamic state in the impoverished southern Philippines. One band of rebels holds 21 Western and Asian hostages there.