At airports like London Heathrow, transatlantic flights often have to go into holding patterns before they land. Airlines are anxious for flights to take off as soon as possible to get better spots in the holding pattern when they arrive, Planzer says. Even where holding patterns are not used, “bunching” of transatlantic flights as they arrive in terminal airspace also leads to headaches for controllers at congested airports.
Under the air bridge concept, departure planning and en route speeds would be calculated to achieve a precise, predetermined arrival time that would in theory require no holding pattern or flightpath extensions, and improve the spacing of approaching aircraft.
“We want to work flow management back upstream far enough so simple speed adjustments can help [transatlantic flights] merge efficiently with other traffic,” says Chip Meserole, Boeing's director for advanced air traffic management. Currently, “there is not enough predictability for aircraft to do much beyond getting [airborne] and getting in line.”
Enhanced arrival management capabilities that the FAA and NATS are introducing will also help extend flow-control horizons farther over the ocean.
The intention of the air bridge is to essentially achieve a basic level of 4-D trajectories, Meserole says. These are flight profiles that include precise timing as the fourth dimension, and are integral parts of future ATM blueprints in many countries.
While it would be more complicated to adjust speed on the North Atlantic track system or under procedural air traffic control, there is much that can be done to adjust the timing of entry into these transatlantic flows, Meserole says. But even on the North Atlantic track systems, the new initiatives by the ANSPs are making it easier to allow speed and altitude changes.
A core concept needed for the air bridge initiative is information-sharing among the three or four air navigation service providers involved in most transatlantic flights.
The aim should be to improve efficiency on the routes linking the top five airports on either side of the Atlantic, Planzer says. “Air traffic management between these city pairs should be homogenized, rather than transiting four different systems.”
Transatlantic information sharing is already occurring to some extent. For example, the FAA has begun providing traffic data to Eurocontrol's Central Flow Management Unit, says Meserole. He notes that the real benefit comes from not just sharing information, but in its effective application.