Airborne spacing in the terminal area: controlled experiments on mixed equipage, abnormal situations...

A series of small-scale controller experiments was conducted to investigate two aspects: (1) the handling of non-nominal situations when using airborne spacing in the terminal area; (2) the benefits of using the route structure defined for airborne spacing in the terminal area, with no airborne spacing equipped aircraft.

The non-nominal situations considered were: mixed equipage, holding patterns and typical unexpected events (go-around, emergency, radio failure, spacing instructions not correctly executed). Handling mixed equipage and holding patterns was found to be feasible. Recovering from the unexpected events was found less difficult than anticipated and was evaluated as being similar to recovery in today's operations.Using the route structure without airborne spacing, heading instructions were no longer used and aircraft remained on lateral navigation mode. Even under high traffic load, the inter-aircraft spacing on final was as accurate as today, while descent profiles were improved. The flow of traffic was more orderly with a contained and predefined dispersion of trajectories.The route structure is a prerequisite for airborne spacing, and its use (without airborne spacing) could be seen as a preliminary step to prepare the implementation of airborne spacing. It could also be seen as a transition towards the systematic use of area navigation, or as a sound foundation to support further developments (e.g. continuous descent, target time of arrival).

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Airborne spacing in the terminal area: controlled experiments on mixed equipage, abnormal situations...