Published June 12, 2009
As investigators search for clues to why Air France Flight 447 crashed, former pilots and aviation experts are debating whether the "fly-by-wire" technology in modern aircraft makes it difficult or impossible for a pilot to control a plane in distress.
The Airbus A330-200 that crashed into the Atlantic on May 31 — killing all 228 people aboard — relied on electronic rather than hydraulic or mechanical systems to control the aircraft.
It's akin to having a computer control your car, with the electronic brain doing the steering, hitting the gas and pumping the brakes as you tell it what to do.
Some pilots claim the old way was better. In an emergency, they say, passengers are better off having a skilled pilot working all the systems.
But planes built by Airbus, a European consortium based in Toulouse, France, give computers, not humans, the final authority on flight decisions.
Airbus' American rival, Boeing, also uses fly-by-wire systems on its newest planes, but their pilots have the ability to override the computers in an emergency.
As Airbus puts it, the "deflections of the flying control surfaces on the wing and tail are no longer driven directly by the pilots' controls, but by a computer which calculates exactly which control surfaces are needed to make the aircraft respond as the pilot wishes."
Because the computer "drives," Airbus says the system leads to "considerable reductions in the time and costs involved in training pilots and crew to operate" its planes.
Boeing uses fly-by-wire technology on its 777 jets and will also have it on its next-generation 787s, due out early next year.
Airbus uses it on its A320, A330 and A340 models, as well as the giant double-decker A380 jumbo jet, which began flying in late 2007.
Older commercial aircraft, including Boeing 747s, Lockheed Martin L-1011s and McDonnell Douglas DC-10s, use hydraulic controls.
Kevin Darcy, a licensed commercial pilot and former accident investigator for Boeing, said fly-by-wire and hydraulic systems both have inherent advantages.
"For instance, the Airbus system may prevent you from intentionally overloading the airplane," he told FOXNews.com. "The Boeing approach is to give you plenty of warning that you reached the limit, but if you insist on doing it, the airplane will let you do it."
In short, Boeing's design gives a "little bit more control to the pilot," Darcy said.
"But that's not to say that I endorse one over the other," he continued. "There's logic to both systems, and I can't say that one is better than the other."
Darcy, who now heads Safety Services International, an aviation consulting firm, said as systems fail on a fly-by-wire system, as they did on Flight 447, ultimate control shifts from pilot to computer.
"We don't really know what that means," Darcy said. "There was something going on that caused it to go into the lower modes and we don't know what that is. Without getting the flight data recorder, it's too difficult for anybody to get a clear understanding of what happened."
But some pilots have expressed concerns about the fly-by-wire system on industry blogs, some expressing fears that airplanes are becoming too automated.
Other former pilots contacted by FOXNews.com said that in an emergency, they'd rather not have to rely on a computer.
Jerry Sorlucco, a former US Airways captain who largely flew Boeing 767s, said although he's never flown an Airbus, he prefers not to rely on fly-by-wire technology.
"Given the preference, I'd prefer the Boeing concept, where the pilot retains more control and you're not putting stuff through funky computers," Sorlucco told FOXNews.com. "I don't like the idea of not being able to override systems that are built into the aircraft."
Sorlucco, who retired in 1997 after more than 37 years in aviation, acknowledged that Airbus manufactures a "wonderful product," adding that answers to the mystery of what downed Air France Flight 447 won't be known until its black boxes are located.
"It’s a hazardous environment no matter what kinds of systems you have, and there's any number of things that can put an airplane in trouble," he said. "But it's very important that they get the black box at the bottom of the ocean because there's a lot of Airbuses flying around."
John Cox, a former commercial airline pilot who has performed simulated flights on the Airbus A330, said he's heard plenty of feedback on the technology as head of Safety Operating Systems, a Washington, D.C.-based aviation consulting firm.
"You'll hear a lot of concern among professional pilots that the final authority may not rest with the pilots," Cox told FOXNews.com. "But that is under the normal system; there are alternative systems that have a degradation in the protections."
Investigators have analyzed 24 automatic messages that Flight 447 sent during its last minutes of flight.
The signals reportedly showed the plane's autopilot was not engaged, but it is unclear whether it was switched off by the pilots themselves or had stopped working due to conflicting airspeed readings.
Mary Anne Greczyn, an Airbus spokeswoman, said fly-by-wire technology was introduced by the company in 1988 with the A320 and has been used on every subsequent Airbus aircraft.
"The system, originally used in military aircraft many years before it was adopted for use in the commercial market, replaces the old-school mechanical flight control system of cables and pulleys, which are physically manipulated by a yoke," Greczyn said in a statement to FOXNews.com. "In FBW, an electronic signaling system sends the pilot's input via wires, to the actuators that move the control surfaces of the aircraft."
Among a fly-by-wire system's benefits are weight savings and flight envelope protection, or keeping the aircraft within safe operating parameters, Greczyn said.
In other words, the system is meant to cut down on human error by not letting a pilot maneuver the plane into extreme degrees of roll, pitch or yaw that would endanger the aircraft's structural integrity.
"The system maximizes safe control of the aircraft — for instance, in the case of the loss of reliable speed data, the autopilot turns off and gives control back to the pilot," Greczyn's statement continued.
Greczyn said fly-by-wire has no disadvantages and that no plans exist to issue "any sort" of alert the system.
Asked if a pilot can disengage the fly-by-wire system in the event of an emergency like the one experienced by Flight 447, Grecyzn replied, "It's akin to shutting off your ABS in your car as you are skidding on ice. You can do it, but you wouldn't want to."
Jim Proulx, a Boeing spokesman, declined to comment on the "philosophical difference" between the two designs, but he stressed that a pilot always has the final say in a Boeing aircraft.
"A Boeing pilot can always override any input in the airplane," he told FOXNews.com. "The pilot is the ultimate authority in the airplane."
The Airline Pilots Association — the world's largest pilot union, representing nearly 54,000 pilots — declined repeated requests for comment.
In 2000, Capt. Paul McCarthy, then the group's executive air safety chairman, told the Seattle Post-Intelligencer that its pilots had "strong opinions" on the issue.
"There are good arguments on both sides," McCarthy told the paper. "Both make legitimate points. And both sides are correct ... It's a good, healthy debate that will continue for the next five to 10 years until everyone is confident which way we should go."