LONDON, JULY 21 (TUESDAY) -- A Trans World Airlines jumbo jet carrying 380 passengers aborted a landing last Friday at London's Heathrow airport 600 feet from the runway, after the pilot was told his wheels were not down, a TWA official said yesterday.

An alarm system inside the Boeing 747 and an air controller alerted the pilot at about the same time as the plane came in to land after a flight from New York, TWA International Division Vice-President Charles Adams told reporters. The pilot aborted the landing, pulled his plane into a steep climb and came around to touch down safely.

"We are treating this as a very serious matter," Adams said. "This is the first time an incident like this has happened with TWA."

United Press International added the following:

TWA immediately suspended the pilot -- an American with 20 years flying experience -- the first officer and the flight engineer. They were flown back to New York for an investigation, a TWA spokesman said. They were not identified.

TWA Flight 701 was traveling at 160 mph and was between 45 seconds and 1 minute from landing when the controller issued his warning, officials said.

Aviation officials said under normal procedures, an airline crew runs through a "strict" prelanding check list and activates the undercarriage four minutes before landing, while at an altitude of 1,500 feet. The jetliner's cockpits are equipped with lights to inform the captain when his undercarriage is locked.

"There is a strict checklist on both landing and takeoff," said Adams. "But that is not to say the list was not properly adhered to. We will be listening to the debrief with great interest." He said the flight's voice box recorder would also be examined.