Plane Crash

There was a story in the news today about a 7-year-old girl who survived a plane crash in rural Kentucky that killed her father, mother, 9-year-old sister, and 14-year-old cousin. Despite being dressed for Florida weather in shorts and t-shirt, after the crash she climbed out of the upside-down plane wreck and hiked 3/4 of a mile through a cold drizzle. She hiked through rugged, wooded terrain, across briars and brambles and creeks and fallen trees. She had no shoes and just one sock. She arrived at the home of a 71 year old man, who took her in and called 911. She was treated at a hospital for non-life-threatening injuries, and then released to a family member.

The airplane was a twin engine Piper PA-34 – what the aviation industry calls a “light twin.” The girl’s father was the plane’s pilot. He was a former commercial pilot and a flying instructor. He had been a pilot since the age of 16. According to the FAA, shortly before the crash he reported he was having engine trouble and was diverting to a nearby airport. The airplane crashed about 4 miles from the airport.

Some might be surprised that an engine failure on a twin-engine airplane could lead to a crash. Aren’t multi-engine aircraft supposed to be able to fly with one engine disabled?

Actually, that applies to commercial aircraft. Many light twins are not able to gain or hold altitude on one engine. You would expect an engine failure to reduce total thrust by 50%, but it’s always more. Thrust can be reduced by 80% or more. With a twin-engine plane, the best thing to do if an engine fails may be to make an emergency landing on the closest flat, open piece of ground and forget about trying to get to an airport. Thus the saying, “The advantage of a second engine is it gives you enough time to pick out where you want to crash.”

But there is more. With one engine dead, the pilot has to cope with asymmetrical thrust which wants to make the airplane yaw in the direction of the dead engine. Because of the way the airflow is disturbed by losing an engine, the rudder is less effective at controlling yaw. And the wing with the running engine has more lift than the other wing, and that disposes the airplane to rolling. The pilot gets into a pickle pretty fast, having to contend with a plane that is losing lift, yawing left or right, trying to roll, and with an engine that may be sputtering and creating drag on one wing. It’s not surprising that pilots have, while trying to kill the dying engine and feather its propeller, sometimes mistakenly shut down the remaining good engine instead of the failing engine.

I would say that an advantage of having one engine is that if an engine fails, you’re in a glider and you land. You don’t wrestle with the flight controls; you don’t have to decide between landing on a field or highway or trying to get to the nearest airport. This pilot who crashed in Kentucky thought he could get to a nearby airport; after all, one engine was, presumably, still running. By the time he realized the airplane was descending too fast to get to the airport, he was committed. There was more forest behind him than between him and the airport. At that point, he would have done what any pilot would have done: he would have flown his airplane to its very last microsecond.