An airliner came within seconds of disaster when the flight crew failed to put the landing gear down in time.

Crew aboard a US Airways flight, carrying 197 passengers from Philadelphia to Gatwick, put landing gear in the correct position just two seconds before it hit the tarmac.

A report published this week by the Government's Air Accident Investigation Branch gives a detailed account of the incident on November 6, 2005.

It says the flight operator pulled the lever to deploy landing gear at 500ft when the pilot had given the command for it to be deployed at 1,000ft.

The usual practice for US Airways pilots is to deploy at 2,000ft as the gear takes time to drop and lock into position.

An air traffic controller spotted the mistake and told the crew to abort the landing and go around for another approach.

In a transcript of the conversation between flight crew and control tower, the controller said: "US Air Nine Eight. It looks like your gear's not down. If it's not down go around, say again, go around, maintain altitude three thousand."

The flight crew said: "We have three gear down and locked, three."

The controller said: "US Air Nine Eight, roger, then you're cleared to land."

The report says by choosing the landing gear to be deployed at 1,000ft the pilot had left no room to correct mistakes.

The flight operator pushed the lever down seconds before the conversation, so the landing gear light was switched on. An alarm from the on-board Ground Proximity Warning System (GPWS) sounded for 11 seconds, when the aircraft was descending from 229 to 90ft above the runway.

In an interview two weeks after the landing, the pilot said he had not noticed the alert because he was too busy.

The report says: "The controller became concerned when the crew said the gear was down but he could see it was not."

It says the crew should have aborted the landing when it became clear there was a problem and the GPWS alarm had been ineffective as it had either not been heard or acted on.

It says: "Although a safe landing was made, safety margins were compromised."

A US Airways spokeswoman said: "We take safety very seriously and would never do anything to jeopardise our passengers."