Utilizing airplanes for data collection to minimize aircraft overstepping runway limits
In the world of aviation, safety is paramount. One area that has seen significant advancements is the prevention of runway excursions, particularly during adverse weather conditions. A key player in this revolution is the Braking Action Computation Function (BACF) developed by Airbus and its subsidiary NAVBLUE.
Twenty-five percent of all runway excursions occur when rain, snow, or ice reduce an aircraft's deceleration capabilities during landing. To combat this, Airbus has equipped its aircraft with BACF, a tool designed to improve runway condition awareness. BACF allows the aircraft to measure braking efficiency during landing, providing pilots with empirically derived, real-time assessments of braking action.
BACF is another tool for preventing runway overruns in the future. It integrates onboard data to compute a braking action score or index that reflects the current friction and stopping capability on the runway. This insight helps pilots recognize deteriorated or variable surface conditions that may not be fully captured by external reports, thus increasing operational safety margin.
In the event of a runway with a slippery surface, such as a layer of snow covering it, BACF can be instrumental. It uses the aircraft as a sensor to measure and report braking action during landing, leading to more accurate landing distance computations. By accurately reflecting runway friction levels, BACF allows for more precise stopping distance calculations and reduces risks related to degraded braking environments.
Airbus has also enhanced its aircraft with the Runway Overrun Protection System (ROPS), which alerts the flight crew if a go-around is necessary or if they need to apply full deceleration means on the ground. The crew can share braking action information with air traffic controllers via radio, ensuring that all parties have the most up-to-date runway conditions.
The importance of timely deceleration when on the ground, including the use of manual braking and thrust reversers, has been emphasized. Reliable information from air traffic controllers and airport services is crucial for runway overrun prevention.
An incident on December 8, 2005, at Chicago-Midway, where an aircraft slid off the runway during a snowstorm and crashed into automobile traffic, underscores the importance of these systems. The investigation revealed that inaccurate wind information, a slippery runway, and insufficient use of brakes and thrust reversers caused the aircraft to overrun the runway at high speed.
In summary, BACF enhances runway condition situational awareness during landing by delivering real-time, data-driven braking action assessments, enabling adaptive braking management and safer runway rollout—especially critical in poor or changing conditions—thereby contributing to the prevention of runway overruns. BACF, ROPS, and effective communication between flight crews and air traffic controllers are all integral parts of a comprehensive approach to runway safety.
[1] Airbus (2021). Braking Action Computation Function (BACF). Retrieved from https://www.airbus.com/aircraft/operations/braking-action-computation-function.html [2] FAA (2019). Runway Safety. Retrieved from https://www.faa.gov/airports/runway_safety/media/Runway_Safety_Fact_Sheet.pdf
