Airbus engineers are never satisfied, and customers of the European airframe builder should have only one response: thank goodness. While many point to the A380’s size as the achievement of which they are most proud–a maximum takeoff weight of roughly 1.2 million pounds and room for 525 passengers in typical long-haul configuration–the leviathan also incorporates radical new systems including brake-to-vacate (BTV), designed to reduce significantly the time an aircraft spends on the runway, overrun protection, and a new TCAS conflict resolution system, which the company believes will increase safety by a factor of two.
AIN reporter Robert Mark had a rare opportunity to fly the aircraft ahead of the Paris Air Show and here he shares insights into what its new technology actually delivers.
The cockpit of the A380 is massive by any measure, with some two-and-a-half feet of space between the two pilots once they’re seated. In addition to three jump seats, we had as many as seven people moving about behind us in flight after we switched off the seatbelt signs.
With several pilots planning to try their hand at the A380, the plan was to demonstrate the brake-to-vacate to each of us, then land and switch seats during the taxi back to Runway 32L at Toulouse. Takeoff weight was calculated as 846,575 pounds, considerably below the maximum of just over 1.2 million pounds.
The engines, started two at a time, are so far aft of the cabin that the gauges are the only indication of what is happening in the back. Even with the engines running, the noise level in the A380 cockpit was no more than in a regular automobile with the windows rolled up.
Taxiing the A380 is not nearly the challenge I had anticipated. The aircraft is equipped with two video cameras, one built into the leading edge of the vertical stabilizer and another under the belly a few feet behind the nose gear. Calling up each on the pilot’s multifunction display makes it easy to use the tiller to keep the nose gear on the centerline. With the outer main gear trunnions separated by just 46 feet–a footprint only slightly wider than that of a 747-400–the pilot will find it easy to nail the centerline.
V1 was calculated as 127 knots, VR 130 and V2 as 136, so any decision to abort would be problematic. In this configuration, however, the A380 would fly even if two engines quit on takeoff.
The Flight Plan
The day’s flight plan called for each demo pilot to take the left seat to view a demonstration of the updated TCAS, which was programmed with enough pseudo targets to fool the A380’s conflict system and trigger the automated response. The final landing of the day was planned as an all-out maximum braking effort to demonstrate what a pilot might experience should he ignore the computer’s call of “runway too short” and “land anyway,” or possibly during an emergency arrival.
Since that effort would produce maximum brake heating, there would be only a single demonstration, with all the guest pilots observing from the jump seats.
The strangest part of flying a very large aircraft is the loss of a degree of depth perception and a relation to speed. On takeoff, I brought the thrust levers up about one quarter, to be certain the four massive Rolls-Royce Trent 900 turbofans were stabilized for acceleration. But there was precious little sense of acceleration–some force pushed me back in the seat as I moved the levers to takeoff power, but not as much as I had expected, as I steered with the tiller to remain on the runway centerline.
Despite the diminished sensation of acceleration, the A380 reached V1 in what seemed like no more than 10 seconds and rotation speed shortly thereafter. Looking out through the expansive cockpit windows, it seemed we were too slow to fly, but rotate we did with a slight pull on the side stick to reach a 15-degree pitch angle. The A380 virtually leapt off the ground. At positive rate, I called for gear up and soon we were accelerating to 200 knots for the brief demonstration flight. I tried some 30- to 40-degree-bank turns before leveling off at 3,000 feet, and was amazed at how easy the three-quarter-million-pound-plus aircraft was to maneuver with simply a few movements of my left wrist.
Now level, I punched the autopilot on so I could pay close attention to the brake-to-vacate demonstration by senior vice president of safety Claude Lelaie.
Summoning the correct page on the multifunction display is easy thanks to the trackball that rests at a comfortable position beneath the pilot’s right hand. We selected S-8 at Toulouse–2,300 meters down–as our exit point for the first time around, which meant that if I was on the mark, we would have about 7,500 feet to stop the aircraft and turn off.
The key is to set autobrakes to auto and let the system figure out the rest. The pilot is expected to add maximum reverse and keep the aircraft on the centerline but do nothing else until 10 knots, at which speed the system will automatically disconnect.
Even with the autopilot off, the A380 was extremely light and easy to control down the ILS to touchdown. Once on the ground for the first landing, I pulled the reversers out and stayed on the pedals but off the brakes. The giant aircraft slowed until I disconnected the system about 10 feet from the S-8 intersection.
Runway Overrun Protection
Another test involved trying the runway overrun protection system by creating an artificially short runway in the flight management system. On short final, the technology calculated the touchdown zone and, based on our speed, concluded we’d never get it stopped. On short final at about 200 feet, it began yelling “runway too short” in a tone that was clear in its urgency. This would be the signal for a pilot to go around.
The final landing was a maximum-performance arrival targeting the closest intersection possible at Toulouse, S-6, approximately 5,413 feet from the start of the runway. Once the A380 was programmed, another pilot this time flew to short final, crossing the fence at ref speed. After touching down, he called for maximum reverse while the A380 worked the brakes. The first five seconds were exciting as the aircraft decelerated rapidly, and everyone in the cockpit applauded as we easily made S-6. Brake temperatures never exceeded 400 degrees C. On a low-visibility landing, it would have made for an impressive demonstration as well.
As a point of reference, the A380 uses reverse thrust on only the two inboard engines because of the aircraft’s vast wingspan. Engines one and four might well be so close to the outside edges of the runway, or even hanging outside the concrete area, that Airbus worried about FOD damage to those outer powerplants when in reverse.
During the TCAS demonstration, we climbed to FL100 in the Airbus practice area near Toulouse. With the aircraft fully coupled to the flight director and autopilot, TCAS traffic targets were generated by the A380 software significant enough to allow the aircraft to follow the commands. At the first sign of traffic, the system displayed a TCAS alert light to advise the crew that, should the target become a resolution advisory (RA), it would automatically move our airplane out of the way using the autopilot and autothrottles.
When the traffic became an RA, the power came up and the airplane smoothly entered a climb to match the TCAS command, much faster than a pilot would. But the most important element was how smoothly the autopilot/flight director combination made the aircraft climb, and how smoothly the A380 returned to its original altitude when clear of traffic. Another TCAS demo demanded the aircraft first descend and then almost immediately climb back to avoid another aircraft beneath us. The airplane certainly performed these maneuvers more smoothly than a human could have done.
Airbus firmly believes that maneuvering a big aircraft with pilot muscle power is no longer a good use of resources–especially since Airbus computers can take much of the mental gymnastics out of the equation, giving pilots more time for big-picture decisions. BTV is sure to be in the vanguard of efforts to increase runway capacity, with runway overrun protection evolving as a valuable corollary to the thinking process in Toulouse. The notion that the autopilot can resolve TCAS conflicts better than a hand-flying pilot is so simple that one wonders why it took this long to come to fruition.