Flights landing at Heathrow airport have been unaffected by the switchover to a new control tower, National Air Traffic Services has said.
The new control tower is crucial for operations at Terminal 5
Passengers were warned on Friday they could face delays as air traffic controllers got used to the new system.
The switchover took place at 0200 BST and a spokeswoman said all operations were running normally.
The number of flights landing was reduced anticipating teething problems following the switchover.
The switchover to the £50m tower is central to the start of operations at Terminal 5, which begin in March 2008.
The 285ft (87m) tower replaces the 1955 existing tower which was designed by architect Sir Frederick Gibberd.