Application-based requirements for data linked winds aloft

The winds aloft are important for choosing flight trajectories and predicting arrivals or conflicts in airspace. Frequent samples of the winds aloft taken by aircraft can contribute to better weather forecasting, and they can also be used directly in flight applications. The applicability of wind measurements by in-trail aircraft for trajectory arrival forecasting was investigated. The results are used to recommend wind sampling parameters by aircraft and to assess the impact of wind report downlinks on Mode S data link loadings. It is pointed out that reports of winds and temperatures aloft are already operationally implemented and can be contributed by multiple data links to multiple air and ground users in the future. Even if only Mode S data link is relied upon, the downlink utilization should be tolerable. While constant report rates up to 10 minutes per aircraft may suffice as forecast inputs, real-time en route and terminal ATC applications require decreasing per-aircraft sampling periods with airspace utilization. It is concluded that this and data link constraints argue for the contract polling mode, putting responsibility on the applications themselves for defining sampling parameters of each aircraft