Airbus this year will introduce a brake-to-vacate feature on its A380, aimed at making runway use safer and more efficient by reducing the number of overrun incidents.

The system is due to be certified by the European Aviation Safety Agency this month. Air France will be the first customer to use it when the airline takes delivery of its initial A380 this year. Plans call for the entire A380 fleet to be so equipped, though no time frame was given.

In late May, Airbus conducted a demonstration of the brake-to- vacate (BTV) system at Toulouse-LaBlagnac Airport using MSN001, the first A380. I was on board along with three other pilots and five journalists. Our flying experience ranged from seasoned (more than 30,000 hr. flight time) to nominal.

The Airbus-designed system allows the auto-flight computer to be programmed with a preset stopping distance. It permits pilots to select a specific runway exit and have the aircraft optimize the use of brakes and thrust reversers to enable that choice. Benefits include a reduction of up to 20% of wear and tear on brakes and the promise of less time spent on the runway, which frees up airport capacity, says Fabrice Villaume, Airbus’s project leader.

But the long-term primary benefit could be the enhanced safety factor. This is provided by two of the system’s capabilities: overrun warning (on final approach) and overrun protection (on touchdown).

These features should cut down on the occurrence of runway overruns, such as those experienced by an Air France A340 at Toronto Pearson International Airport in 2005 and a Southwest Airlines Boeing 737 at Chicago Midway Airport later the same year.

The overrun-warning function uses aircraft data and information about the runway, including whether it is wet or dry. When the system computes that the runway is too short when wet, an amber message appears in the primary flight display to alert the pilot. If it assess that the runway is too short when dry, the visual alert “RWY TOO SHORT” appears in red, accompanied by an audio warning. The goal is to alert pilots early to the possible need to go around.

The overrun protection feature kicks in once the aircraft is on the runway. It combines a set of audio and visual cues to help the pilot maximize braking. For instance, when the aircraft computer calculates the A380 will overrun the runway, maximum braking is applied and a warning is sounded to apply maximum reverse thrust, along with a red message in the primary flight display. Until stopping is assured, an audio callout advises to “Keep Max Reverse.”

After being briefed on the basic functions of the system, we proceeded to the aircraft for the 2.5-hr. sortie. Before flight, all takeoff speeds were entered and a rejected takeoff (RTO) set. On the A380, RTO is selected via a push button. The BTV feature has been added to the auto-brake panel, and would normally be selected during cruise, and no later than the approach, phase of flight.

The purple horizontal lines crossing Runway 32L at Toulouse indicate where the Airbus A380 will stop in dry or wet conditions. Credit: AIRBUS

For our demonstration, all landings were on the 3,500-meter (2.17-mi.) Runway 32L at Toulouse with a full stop and taxi back using exits S-10, S-8 and S-6 for landings with BTV.

The first landing was programmed for taxiway S-10 (500 meters of runway remaining) using idle reverse. Final approach was at 140 kt. indicated airspeed, with a ground speed of 131 kt. Nosegear touchdown was at 360 meters. BTV braking was applied and even though the pilot disconnected the feature a bit early, at 11 kt., the aircraft was positioned to turn off exactly at the predetermined spot.

I made the second takeoff and landing with the system programmed to vacate the runway at taxiway S-8 (1,200 meters remaining). Claude Lelaie, Airbus chief product safety officer, was in the right seat. I floated slightly just before touchdown, used maximum reverse as briefed and the aircraft slowed with BTV disconnecting at 10 kt. Final approach speed was 146 kt., with a ground speed of 136 kt. The A380 is a pleasure to fly and as reported three years ago when Aviation Week & Space Technology first flew the aircraft, it takes only minutes to acclimate to the side-stick controller (AW&ST Oct. 2, 2006, p. 48).

Later in the flight, we climbed to altitude for an advanced TCAS autopilot/flight director demonstration (see p. 37) and returned for the final landing on Runway 32L.

At this point, Armand Jacob was in the right seat. Jacob, a graduate of the U.S. test pilot program at Edwards AFB, Calif., is the senior test pilot for Airbus. I performed the final landing, where we set up for a maximum-braking demonstration of BTV. We simulated an emergency landing after takeoff (for instance in the case of fire). This would be the worst-case scenario. Runway length was set at just 1,650 meters, the location of exit S-6.

For the approach, Jacob added 15 kt. to our airspeed and instructed me to aim farther down the runway. As we approached, an aural and visual warning of “Runway Too Short” was triggered. Simulating an emergency, I landed and, at nosegear touchdown, aural/visual alerts sounded to use maximum reverse. At 70 kt., I reduced the thrust levers to idle to protect the engines. In an actual runway excursion, maximum brakes and reverse would be maintained until the aircraft is stopped.

Final approach was at 137 kt. indicated airspeed, with ground speed of 127 kt. Nosegear touchdown was at 845 meters along the simulated 1,650-meter runway. The system worked flawlessly and at 10 kt. BTV brakes released allowing an easy turnoff at taxiway S-6, which was the simulated runway end.

The brake-to-vacate system is intuitive. It updates information using predicted speed and wind up to the last 500 ft., after which it uses real speed and wind data. Landing parameters can easily be adjusted.

Before the briefing and flight demonstration I was skeptical of the need for, and effectiveness of, BTV. After the flight, I was convinced the feature will be a valuable tool for safer air carrier operations. Land-and-hold-short clearances, low-visibility approaches, increased runway capacity and decreased brake wear are just a few of its advantages.

There are several small but intriguing side benefits. For instance, the system can compute approximate brake heating and indicates to the flight crew projected turnaround time, thereby allowing pilots to select the optimum exit.

Airbus is still evolving the system and it will take a few iterations to have the BTV capability worked out to include all surface conditions and system failures, but that’s on the drawing board.

Although the system promises greater runway utilization, Lelaie concedes it will take some time to make air traffic control familiar with the feature and accept that the runway exit can be selected by the pilot in flight.

Airbus is working on expanding the feature beyond the A380. Work is to start this month to provide A320s with BTV capability. Given the widespread use of the narrowbody, installing the system on A320s would yield particularly significant savings in airport operations.

Because the A320 does not have the A380’s extensive electronic architecture, a more modest system will have to be used, however. An airline might have to choose the airports for which information is included in the database. For instance, a carrier like Air France might use the capability at Paris Charles de Gaulle, its hub, but not at all airports.

This quarter, Airbus wants to begin work to provide BTV functionality to A330s and A340s. The A350 should have some, but not all, of the capability in its baseline specification.

With Robert Wall in Toulouse.