Experience, Training Make For Smooth River Landing
Just 2 minutes into a routine flight from New York's LaGuardia Airport to Charlotte, N.C., Capt. Chesley B. Sullenberger III had a difficult decision to make: Could he steer his 150-seat US Airways jetliner to New Jersey's small Teterboro Airport from just 1,600 feet above the Bronx? Or would he have to find another place to bring down the plane, which had lost both of its engines?
Opting instinctively for the river because he didn't think he could make the airfield, Sullenberger steered the plane over the Hudson River and set it down, wings perfectly balanced, slowly enough to not tear the aircraft apart.
While the cause of the accident is currently under investigation, some aviation experts say Sullenberger, who has been flying with the airline since 1980 and has more than 19,000 hours of flight time, executed "a textbook ditching." His extensive time as a commercial airline pilot, combined with his history as a military flier and a glider pilot, gave Sullenberger the skills he needed to bring the plane down safely.
"It appears that everybody did their job just as they're trained to do," says Frank Ayers, associate professor of aeronautical science and chairman of the Flight Training Department at Embry Riddle Aeronautical University in Daytona Beach, Fla. "The pilot did a beautiful job."
The Airbus A320 entered the water shortly after 3:30 p.m. All 155 passengers and crew on the flight survived.
Training For Emergencies
Airline pilots train for a wide range of emergencies, including engine failures, hydraulics and electrical systems failures and structural failures. In simulator practices, flight crews are presented with a problem or scenario and then asked what to do next, says Ayers, who is certified to fly the Boeing 757 and 767. "And even though there's no cabin crew in the back of the simulator, the pilots and first officers train to give commands to the crew," he says.
The range of emergencies for which pilots train is extensive, says John Ladd, a pilot who has flown with American Airlines for more than 17 years. American Airlines captains and first officers go through simulator training every nine months, practicing what Ladd calls "plain vanilla" emergencies like engine failures, wind shear, total hydraulic failure and two-engine loss at high altitude.
"They also give us emergencies that allow us to explore the flight envelope of the airplane," Ladd says, explaining that losing both engines on takeoff, airplane fires, structural problems and high-speed descents are still practiced, although not as regularly as other emergencies.
Early reports indicate that Flight 1549 lost both engines, leaving the airplane at a low altitude with little thrust.
"Typically, we don't practice double engine failure ditchings," Ladd says. "That's not a normal training thing. We talk about it, but we don't do it in a simulator. Engine failures? All the time. Double engine failures? Not so often."
Executing a water landing is especially tricky, and Richard Fanjoy, associate head of the Aviation Technology Department at Purdue University, says there's not much of a history of successful water landings for commercial airliners.
"All airplanes are made with some durability for impacts during hard landings, but the fact that this airliner was put down in such a way that it remained intact was a testament to both the airliner and the skill of the pilot," Fanjoy says.
'Landing' On The Water
So how exactly does a pilot land in the water?
"You want to land the airplane as slow as possible without stalling," says Embry Riddle's Ayers. "You also want to catch both engines in the water at the same time. Hit one wingtip first, and you'll cartwheel the plane." The A320 has one engine mounted below each wing.
Ladd says there is a checklist for "ditching" an airplane, but Sullenberger most likely didn't have time to go through it. "We have procedures for ditching, but it's the instinct that got him through it, as well as the training," he says.
The pilot most likely kept the landing gear retracted, but he also probably extended the wing slats and flaps. Slats extend the front, or leading edge of the wing, and flaps change the shape of the back, or trailing edge. Extending the slats and flaps changes the aerodynamics of the plane, generating more lift, but also more drag.
Engaging the flaps, which are used during takeoffs and landings, allowed Sullenberger to slow the plane down without letting it stall. Stalling is the point at which the wings stop generating lift, the force that keeps the plane in the air.
"The pilot had to make a trade-off between going too slow and stalling, and going too fast and crashing," Fanjoy says. "He maneuvered the airplane to maintain the best glide speed," referring to the range of speeds where the airplane is still maneuverable and hasn't stalled.
"If the whole airplane entered the water at once, it would be much harder to control," Ayers says.
Setting the tail of the plane into the water first is key, Ladd says. That lets the water slow the plane down. "The idea is to make the landing as soft as you can at as slow a speed as possible. If the nose is too low and going too fast, you risk flipping the plane tail-over-nose."
Floating Down The River
After setting down in the river, the airplane floated on the surface long enough to allow all of the passengers to safely exit. While large jets aren't specifically engineered to float, they do have features that can be employed in the case of a water landing.
Mary Anne Greczyn, communications manager at Airbus, says a "ditch switch" is standard equipment on all modern Airbus and Boeing aircraft. The switch, which is mounted on an overhead panel in the cockpit, can be pushed by the pilot to close off openings on the outside of the plane before it hits the water.
"The switch closes off the outflow valve and the avionics ventilation ports — anyplace air would go in or out," Greczyn says. Where air could go, so can water to flood the plane, so "it closes off openings below a theoretical float line."
Pilot Ladd says that while the ditch switch is useful, opening the main doors and emergency exits on the plane to let passengers out would negate any impact that closing the valves would have, once the plane is down.
Fuel and air in the wings also probably kept the plane afloat for as long as it was, Ladd says. Since fuel and air are less dense than the river water, the wings helped buoy the plane. And because the wings are located slightly forward of the center of the fuselage, the front of the plane was slightly propped up while the tail began to sink.
Military And Gliding Experience
The pilot of the US Airways flight, Sullenberger, also flew the F-4 for the Air Force from 1973 to 1980, and Ladd and Ayers, both military fliers themselves, say his military training no doubt helped him navigate Thursday's emergency.
And Sullenberger was also a glider pilot, which undoubtedly brought valuable skills to the crisis.
"Every glider landing he's ever made has been a power-off landing, and every power-off landing you make can't hurt, so that gave him a lot of training," Ayers says. "Everything he had done over his professional piloting career contributed to his success here."