Tweaking runway landing position offers capacity dividend

Capacity at major airports could be boosted by five per cent by allowing smaller aircraft to land further down the runway.

Wake vortex restrictions at major airports cause a significant reduction in capacity but allowing a single aisle aircraft to approach the runway at a higher profile than that of a heavier aircraft in front of it – thus avoiding its turbulence – could be a way air traffic controllers could extract the maximum capacity from the tarmac available.

Eurocontrol and Lufthansa Aviation Training (LAT) say they used full motion flight simulators to evaluate the feasibility of both this so-called Secondary Runway Aiming Point (SRAP)  in addition to Increased Glide Slope (IGS) concepts to help boost capacity and reduce environmental impact.

SRAP essentially allows ‘light wake’ category aircraft to fly a final approach above the approach profile of heavier aircraft flying to the primary runway threshold, helping to avoid the wake vortex of the larger aircraft and resulting in an increase in runway throughput of up to 5 per cent.

Crucially, the partners point out, the noise contour of the aircraft on approach to the SRAP also moves towards the airport, reducing noise. The approach glide slope to the SRAP could be a normal 3-degree slope or an increased glide slope (IGS) which would maximise benefits.

The simulations form part of SESAR efforts to enhance arrival procedures which focus on mitigating noise and adapting wake avoidance procedures and this latest solution has been developed within a SESAR project to increase runway and airport throughput at major airports.

To evaluate the feasibility from a pilot point of view, flight simulations were run in a professional Level D full-motion Airbus A319 flight crew training simulator operated by Lufthansa Aviation Training. The visual system designed and implemented in the simulator to replicate runway markings, runway lights, approach lights and PAPI for both the primary and the Secondary Runway Aiming Points were, as far as possible, compliant with ICAO Annex 14 provisions.

The Secondary Runway Aiming Point (SRAP) itself was located 1,100 m after the primary runway threshold.
A standard ILS with a 3-degree glide slope was implemented serving the primary runway aiming point. For the SRAP, a GLS (ILS-like) approach with a 3-degree glide slope and an RNP approach with a 3.5 degree glide path to simulate an Increased Glide Slope (IGS) operation were flown. The simulated airport was Munich.
Two variants of the concept were tested with pilots:
• approaches with all lights illuminated, i.e. threshold lights and approach lights of both primary and secondary aiming points remained switched on
• approaches with threshold and approach lights illuminated for only one aiming point, serving the first aircraft in the approach sequence. Once this aircraft had landed, the threshold and approach lights for the aiming point of the next aircraft in the approach sequence were switched on.
A total of 12 simulator sessions were conducted with A319 type-rated pilots with 12 crews consisting of two pilots each.