Improving runway turnaround time and reducing runway excursion risk at landing
Following recent successful development testing, "Brake-To-Vacate" (BTV) and "Runway Overrun Warning and Prevention" (ROW/ROP) have both been approved and certified for the Airbus A380 by the European Aviation Safety Agency (EASA). BTV is an Airbus innovation in pilot aid to ease airport congestion and improve runway turnaround time, and ROW/ROP addresses runway excursion risk at landing. Both BTV and ROW/ROP are patented by Airbus.
1. Brake-to-Vacate (BTV) overview
BTV was designed by a transnational team in Toulouse, France and Filton, England. By harnessing the power of the A380's integral GPS and airport database based On-Board Airport Navigation System (OANS) combined with the Auto-Flight and Auto-Brake facilities, BTV gives pilots real-time visibility on realistic braking distances to reach their preferred exit. It also allows in-flight operational landing distance assessment during landing preparation. When the pilot chooses a runway exit point, the system indicates the estimated runway occupancy time and the minimum turnaround time. During the subsequent landing phase, and according to encountered runway conditions (i.e. 'wet' or 'dry'), the aircraft's deceleration is automatically regulated so it reaches the chosen exit at the correct speed. BTV benefits operators in the following additional ways: by lowering overall braking energy requirements and temperatures (thus reducing brake-wear); relieving maximum thrust-reverser usage on dry runways; respecting passengers' comfort (through regulated smooth deceleration); reducing noise, fuel consumption and CO2 emissions; enabling air traffic control to schedule up to 15 percent more aircraft departures; enabling airlines to maximise the number of aircraft rotations; and reducing the exposure time to a runway incursion risk (by minimising runway occupancy time).
2. Included function: Runway Overrun Warning (ROW) & Runway Overrun Prevention (ROP)
The complementary ROW/ROP system computes realistic operational landing distances and compares them to the available landing distance in real time, while accommodating factors including: aircraft velocity, position, altitude and weight; runway conditions; ambient temperature and wind; and runway elevation. The "ROW" forewarns the pilot, either, if the aircraft is approaching a runway which is deemed 'too short', or, if the remaining runway length becomes too short (e.g. if a 'late' touchdown point is predicted due to unstable approach conditions). In such cases following the ROW warning, the mandatory procedure for the pilot is to perform a 'go-around' for another approach attempt onto a runway with sufficient length. However, if another approach is not possible (for example in an emergency), the pilot may instead take an overriding decision to continue landing on the 'too short' runway. This is one example where the 'ROP' protection would automatically be activated to bring the aircraft to a stop in the shortest possible distance using full braking power, and with maximum reverse thrust if required. Note: the pilot has the authority to disengage ROP at any time.
BTV and ROW/ROP were first trialled on an A340-600 in 2004, and on the A380 in May 2008. The recent approval and certification by EASA paves the way for their introduction on the A380 with launch customers Air France and Lufthansa. BTV & ROW/ROP will also be a standard feature of the forthcoming A350 XWB aircraft.