Bishop can best be described as a young man who had very few friends and was very much a loner

Tampa Police Chief Bennie Holder

Although a terror motive has been ruled out, Bishop was revealed to have been obsessed by the devastating suicide hijack attacks of 11 September and was carrying a suicide note "expressing sympathy" for Osama Bin Laden.

He "clearly stated he had acted alone without any help from anyone else," said Tampa Police Chief Bennie Holder.

Mr Holder said there was no evidence that Bishop was trying to harm anyone else.

He portrayed him as a loner, with few friends, and no apparent links to Bin Laden's al-Qaeda group.

Military air space

The ninth-grade student from Palm Harbor had turned up for a scheduled flying lesson at St Petersburg-Clearwater International Airport on Saturday afternoon.

Charles Bishop was killed instantly

"His flight instructor told him to go and prepare for the flight, but he just took off," an airport spokeswoman, Kate Hughes, told reporters.

Two US military F-15 fighter aircraft and a US Coast Guard helicopter were scrambled to intercept the Cessna 172R plane.

Concern was heightened when it flew into restricted airspace over the nearby MacDill Air Force Base - headquarters of the US Central Command in charge of the war in Afghanistan.

After a nine-minute flight, the plane flew into the 28th and 29th floors of the 42-storey Bank of America building, despite being intercepted by the helicopter.

"There was no doubt he died on impact," said Fire Department Captain Bill Wade.

As the crash happened on a Saturday, there were few people in the office building, and no casualities were reported there.

Only the area immediately around the crash site was damaged, and most of the building is expected to be open for business on Monday morning, although there are concerns about the risk of debris falling to the street below.

'Happy kid'

Although Bishop was a student pilot, he had been taking flying lessons since March and was not seen as a complete novice.

He had no record of any trouble with the police in the past.

"He was an honour student. He got straight As. He liked school. He was a happy kid," said Ross Stewart, one of his classmates.

Another classmate said that Bishop had read an essay out in class after 11 September attacks.

"It was real expressive about how he felt, how disappointed he was," said Derek Perryman.