SRAP, IGS increases runway capacity and reduces noise - CAT

SRAP, IGS increases runway capacity and reduces noise

EUROCONTROL and Lufthansa Aviation Training (LAT) have used full motion flight simulators to evaluate the feasibility of “Secondary Runway Aiming Point (SRAP)” and “Increased Glide Slope (IGS)”, concepts focused on capacity and environmental benefits.

SRAP permits ‘light wake’ category aircraft to fly a final approach above the approach profile of heavier aircraft flying to the primary runway threshold; this enables them to avoid the wake vortex of the larger aircraft, and should result in an increase in runway throughput of up to 5%.

Crucially, the noise contour of the aircraft on approach to the SRAP moves towards the airport, reducing noise. The approach to the SRAP could be a normal “3-degree” slope or an increased glide slope to maximise benefits.

The two concepts being evaluated are part of EUROCONTROL’s contribution to the SESAR solution “Enhanced arrival procedures”, which focuses on mitigating noise and adapting wake avoidance procedures. Both have been successfully trialed in multiple real-time simulations.

The solution has been developed within SESAR 2020 project PJ02 “Increased runway and airport throughput”, which seeks to tackle capacity challenges at major airports.


EUROCONTROL is leading the project, working with partners to develop operational solutions and advanced air traffic control (ATC) tools.

To evaluate the feasibility from a pilot point of view, flight simulations were run in a professional Level D (highest degree of realism) 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 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 (12 crews consisting of 2 pilots each).