Who flies the plane

When Things Go Wrong

Passengers aboard a British Airways flight from London to Hong Kong got a serious fright when an automated voice over the public address system said this: "This is an emergency announcement. We may shortly need to make an emergency landing on water."

There was no emergency though-the pilot had simply pushed the wrong button in the cockpit. Flight attendants immediately rushed through the aisles to assure panicked passengers that there was no Captain Sully-type situation at hand.

Our mystery pilot has had his own experiences with the computer having a mind of its own:

"Every once in a while there will be a situation where I have to take the plane off autopilot. It's not foolproof. For instance, there are a lot of holding patterns in the air space around New York. Let's say I'm headed due north and air traffic control wants us to make a turn east, but due to traffic they say to turn west and go all the way around to get there. I've had it where the autopilot will want to take the shortest way (in this case, east). If you're not paying attention the autopilot will automatically go the quickest way.

"Another time we were at 31,000 feet and the autopilot told the airplane to initiate a climb. I caught it within 200 feet or so and realized it was screwing up. I turned the autopilot off, and we had to descend below a certain altitude since we were no longer flying on autopilot."

Alamy

Aircraft are some of the most sophisticated machines in the world, with computers systems so advanced that the planes could seemingly fly themselves (Ryanair's always colorful CEO even suggested eliminating co-pilots). So just how much of what goes on during a commercial flight is automated by a computer?

Perhaps more than you think.

When Autopilot is in Use

"About 75 to 80 percent of a flight is done using the autopilot, in conjunction with the flight management system," says Kevin Hiatt, Executive Vice President of the Flight Safety Foundation in Alexandria, Virginia, and a former pilot for Delta Air Lines. The flight management system (FMS) automates many in-flight tasks, taking much of the workload off pilots.

"Autopilot keeps the heading and altitude steady," explains Hiatt, "Along with the autopilot, there are auto-throttles connected to the FMS. Certain performance numbers are put into the flight management computer, and by engaging all those at the same time, the airplane can descend, climb, and cruise more efficiently."

And while hand flying-pilot speak for when the airplane's controls are actually being manipulated by the pilot-still takes place during takeoffs and good-weather landings, it's the autopilot that's flying the plane for the bulk of the flights.

Airlines have their own rules as to when autopilot can switched on, but it's usually around an altitude of 1,000 feet. This is standard operating procedure on airlines across the board, whether pilots are flying a 777 or regional jet. That's definitely a good thing says Karen Kahn, a longtime captain with one of the major U.S. legacy carriers, since autopilot provides passengers with a smoother ride. "An airplane is much more touchy when it's not on autopilot," says Kahn, "It needs continual corrections." And you can feel the difference. "It's as if you were balancing on a ball and continually having to stay balanced as opposed to having something fixed to hold onto," she says.

Autopilot systems on commercial airlines have redundancies, with at least one, often two backup autopilots in case one fails. But there are critical moments when pilots must fly the airplane by hand.

"During the overwhelming majority of takeoffs, you have to hand fly the aircraft," explains Hiatt. Pilots engage autopilot at some point during the climb and, on a normal flight, only switch it off when it's time to land. If weather conditions are bad, with very limited visibility, a pilot can keep the autopilot on throughout the landing (keeping it on until after the brakes have been applied and the airplane is slowing to a stop).

"The pilot will use the auto flight system all the way through the descent phase up until approach, and then we say 'click it off,' which means we disengage autopilot," says Hiatt, "When you hear the landing gear come down, that's when the pilot generally starts to hand fly the aircraft."

And while problems with autopilot are rare, things do fail from time to time, according to Hiatt. "PA systems have problems, call buttons stick, computers can fail to a non-active mode," he says. And that, says Hiatt, is when those cornerstone "stick and rudder skills" come into play.

"A lot of people think that because they have Flight Simulator on their computer at home, there's nothing to flying," says Hiatt, "But you have to know what to do when the computer decides it doesn't want to go along."

What Pilots May Really Be Up To

In addition to providing a smoother ride for passengers by eliminating the need for constant manual corrections, Hiatt says autopilot makes flights safer, too.

"Pilots can multitask on other things related to the flight," he says, "They can also be more aware of the air traffic in the area, navigation and provide a much more economical and smoother flight."

Autopilot would also seem to free up a lot of time in the cockpit for pilots to, say, read a newspaper or watch a DVD on their laptop. And while nearly all airlines forbid such leisure activities in the cockpit (the only reading normally allowed in the cockpits is that of checklists and help manuals), one captain for a major U.S. airline-who prefers to remain anonymous-says the rules are regularly bent.

"Officially, we're not supposed to read [in the cockpit while flying]. But do I do it? Yeah," he says, "During a two hour flight, for about an hour and a half (when the plane is on autopilot) there's a whole lot of nothing going on. Hopefully I get along with the co-pilot and we have stuff to talk to about. But you run out of things to talk about. I'm in a hotel every night and they deliver a newspaper to my door, and if I'm sitting there on a two hour flight, I'm sorry, I know you're not supposed to, but I pull out the paper and read."

The anonymous pilot said he estimates about 50 percent of the pilots he flies with also pull out casual reading material to peruse once the autopilot has been switched on.

"And on a lot of airlines, their manuals are on laptops," he says, "On red-eyes from L.A. to New York in the middle of the night, I know those pilots are watching DVDs."

He does not feel, however, that such practices compromise safety.

"Airplanes are so automated now that if something goes wrong, all kinds of bells and whistles are going to go off," he says. "Quite honestly, nowadays, we're there if something goes wrong. And things do go wrong, so we'll pull out an appropriate checklist and troubleshoot."