Pilot lands at president's air base

The helicopter landed at the home of Air Force One

A Swiss pilot has triggered a security scare after landing his helicopter at Andrews Air Force base in the US state of Maryland, home to the presidential plane Air Force One.

The pilot had apparently become lost trying to land at Indian Head airport, seven to 10 miles (11 to 16 kilometres) away.

Security personnel were on the scene immediately, said the 89th Airlift Wing, which manages the presidential fleet.

Bush was at Camp David when the helicopter landed

The incident came at a time of heightened alert at US military bases amid a continuing threat of attack by terrorists.

The Air Force said the helicopter came down at about 1700 local time (2200 GMT) on Saturday.

It said the FBI and Air Force Office of Special Investigations were examining what had happened.

The Air Force said the pilot, who had identification with him, remained at the base, with his helicopter, while an investigation was carried out.

President George W Bush was at the Camp David retreat in Maryland when the helicopter landed and was not expected to use the air base around that time.

Security alerts

Aviation authorities imposed flight restrictions over parts of Washington, New York and other cities in the wake of the 11 September 2001, attacks on the United States as a security measure.

There have been more alerts involving light aircraft since then.

In July, US military jets were scrambled after three small airplanes strayed into restricted airspace over the presidential Camp David retreat.

In June, the White House was briefly evacuated when a Cessna aircraft came within four miles (six kilometres) of the building.