Time based sequencing at Stockholm Arlanda airport

Sammanfattning: Present Air Traffic Control System is functioning well, but is not always optimal, neither from an operative nor an environmental perspective. Therefore a new concept within the system is under development. The proposed concept is designated as time based sequencing of aircraft. In time based sequencing connections, the aircraft are categorised depending on their navigation capability. On the one hand there are aircraft capable of navigating with a high precision and perform optimal descent profiles, denoted as Green Approach aircraft in the report. On the other hand there are all the other aircraft with less advanced navigation ability, denoted as non-precision aircraft in the report. Time based sequencing is about sequencing the arrival flow of aircraft in time. With the aid of CIES (a tool with the capability of sequencing the flow in time) the Air Traffic Control ( ATC) sequences the arriving traffic in terms of time. The Green approach aircraft are sequenced directly to the runways and are supposed to land with a precision of ±10 s, while the non-precision aircraft are sequenced to the so called entry points (basis for non-precision aircraft) so that a passage occurs above the entry points with a precision of ±30 s whereupon they perform an as far as possible optimal descent. Time based sequenced approaches are more environmental friendly than traditional procedures. With an optimal descent profile performed by a Green Approach aircraft, approximately 100 kg of jet fuel is saved. The intention of this thesis is to investigate which time deviations at the entry points for the arriving non-precision aircraft that can be accepted providing that aircraft are only ontrolled with speed adjustments (ordered by the ATC to the pilots) in order to avoid a transgression of the horizontal separation rules from entry point to landing. A simulation study is conducted with the intention of finding out which time deviations that can be accepted. On the basis of the results of the simulation study a solution is proposed. The position of the three shorter entry points should be moved further away from the runway to at least the same distance as the longest as it has the largest acceptable EAT deviation (enough for the approaching precision of ±30 s) on the highest rate (34) in order to achieve large acceptable EAT deviations for the other entry points. However, even if every entry point is on the same distance to runway as the uttermost, speed alternations are not sufficient to sustain the horizontal separation between aircraft. In case of higher rates than 34, the ATC would have to perform traditional procedures of managing arriving aircraft, i.e. leading the aircraft into S-curves. Hence, the proposal is to mix traditional approach procedures (allowing adar vectoring in order to guarantee separation) with time base sequenced approaches. If present positions of the entry points are kept, the result would be the same as above, except that the ATC would have to perform traditional procedures when the rate exceeds 28.