By David Jensen
WITCHITA, Kan., 17 Dec. 2009. When a fly-by-wire Bonanza F33C made three landings without pilot input in Wichita, Kan., it proved that an autoland system developed for unmanned air vehicles (UAVs) could be adapted to manned aircraft. Significant as that achievement was, it did not end testing of the system, developed by Rockwell Collins in Cedar Rapids, Iowa. The avionics designer and Hawker Beechcraft are working collaboratively on the autoland system's advancement and exploring the way to its certification.
The two companies currently are reviewing data resulting from flight tests in which the Athena 411 automatic landing system controlled the Bonanza through an interface with the airplane's experimental fly-by-wire flight control system. The Rockwell Collins Athena 411 integrates a flight control system and inertial navigation system into a single, compact package.
The system contains a full suite of sensors and flight control algorithms, including an autolanding system. The tests on the Bonanza allowed the test team to assess the Athena 411's performance as an autopilot and as an emergency autolanding system when installed on a manned general aviation (GA) aircraft. Although no additional landings using the autoland system have been conducted since August, flight control research of the Athena 411-equipped Bonanza continues, according to Tom Hilpert, Hawker Beechcraft's director of product development and research.
A production emergency autolanding system will require interfaces with the airplane's landing gear, flap and braking systems, says Hilpert. During the Athena 411's three controlled landings, the Bonanza crew operated these systems in the landing sequence at predetermined points. "Now we want to interconnect the additional systems," he adds.
In another area of development, Hawker Beechcraft and Rockwell Collins are focusing on the smoothness of transition between commanded maneuvers during autopilot operations. "With a UAV, you can make abrupt maneuvers," Hilpert explains. "But a GA implementation requires that the autopilot inputs be smoother and more acceptable to a plane's occupants."
The two companies continue tests of the Athena 411 in manned, experimental aircraft, believing the technology can eventually become mature enough for use in civil and military aircraft. Hilpert points out that the autoland capability requires no significant investment in aircraft already equipped with an autopilot and integrated avionics. It is a matter of "enhancing" the aircraft systems' capabilities.
Where the expense emerges is in the autoland system's certification. There are no guidelines or precedent leading to the approval of a system or procedure that allows the pilot not to be in control of the aircraft, even though it would augment safety.
Nevertheless, Hawker Beechcraft broached the subject of autoland certification with FAA officials at this year's AirVenture/Oshkosh air show. "They recognize that current rules don't apply [to the technology]," says Hilpert, no doubt foreseeing a lengthy certification process.
However, an automatic landing system – sometimes called a "digital parachute" – could improve safety. For instance, one could imagine the Learjet 35, with professional golfer Payne Stewart onboard, landing safely instead of crashing on Oct. 25, 1999 into South Dakota grassland after cabin pressure was lost.
Of course, the pilot or someone else on board has to activate the system. With the system tested on the Bonanza, activation involves the push of a button. At that point, the flight management system – knowing the aircraft's position thanks to the GPS and inertial navigation – delves into its database in search of the nearest airport with a runway long enough to accommodate the aircraft. At the same time, the transponder codes are automatically changed to an emergency setting. With input from the navigation systems and attitude and heading reference system (AHRS), the autopilot then guides the airplane safely to a runway.
