The facility was scheduled to open in 1996 but a string of technical problems led to the date being repeatedly postponed.
Air traffic controllers have begun training to work at the high-tech new centre which will control many aircraft over the UK from next year.
The centre at Swanwick in Hampshire has been dogged by technical glitches and will open six years late.
The government is planning to privatise part of National Air Traffic Services (Nats), a move which is bitterly opposed by unions representing air traffic controllers.
Swanwick has been described by Nats as "the most advanced air traffic control centre in the world".
The £650m centre has been designed to take the strain off the existing centre at West Drayton near Heathrow.
Passenger delays
The huge growth in air traffic has lead to repeated complaints from controllers that they are overworked and last year a vital computer system broke down causing long delays for passengers.
The 135 new radar screens at Swanwick will be used to handle aircraft passing over Britain, rather than those preparing to land here.
Six hundred controllers will work in pairs, aided by new computer systems developed for the centre.
The facility was scheduled to open in 1996 but a string of technical problems led to the date being repeatedly postponed.
Managers now say everything is working and training started this week.
Even this phase of the project has been problematic however.
Hundreds of controllers have had to be taken off regular duties to undergo training and to minimise the impact on staffing levels, employees were asked to do up to 10 days overtime.
Members of the IPMS union refused. Their representatives said it would mean delays to the training programme.
But Nats says there will be enough staff, with or without the overtime deal.
Doubts over deadline
Opening the centre on time next January will be doubly difficult given the controversy surrounding the government's plans partly to sell off Nats.
The unions oppose the sale and independent advisors have reportedly warned the government that Serco, the bidder leading the race to take over air traffic control, does not have a satisfactory approach to managing safety.
Next week, the pilots' and air traffic controllers' unions will announce their support for another bidding consortium made up of airlines, which has promised not to make a profit out of the deal.
Ministers are hoping to announce the preferred bidder for the contract next month.
The government promised to put the sell-off on hold for three months after the Lords voted against the proposals.
Air traffic control is in for a bumpy ride over the next few years.