Dive summary:

• Investigators are trying to determine what caused a helicopter to hit the top of a tower crane being used to construct a luxury apartment building nearly 400 feet tall on the south shore of the River Thames in London on Jan. 16.
• The chopper knocked the boom of the crane into the streets below the Tower, One St. George Wharf, killing one person, and the aircraft crashed in a fireball on a side street off busy Vauxhall Street and killed the pilot.
• Contractors using Terex TC2800-1 mobile crane to bring down the tower crane found that much of it was undamaged, as was the building itself.

From the article:

"We had told pilots about [the crane], and it was lit during the night," says a [Civil Aviation Authority] spokesman. ...