"There are times when you have engine failure or instrument failure, most of the time it's pilot failure," said Max Krumpe, who has been flying since 1950.
Krumpe said it can take as many as 30 hours to get used to an airplane, even when a pilot has flown hundreds of hours in another type of airplane.
He said different instruments, aircraft weights, engine sizes and landing gear can make one plane handle differently than another, even though they may be roughly the same size and have the same number of engines.
"If you respect (the plane) it'll respect you. But accidents do happen," Krumpe said.
Flying an unfamiliar plane can lead to problems, Alphin said.
A Piper Saratoga like the one Kennedy was flying when he crashed has retractable landing gear. That reduces drag and makes it a faster plane than a trainer like a Cessna 182, the plane in which Kennedy had logged most of his training hours, he said.
Alphin said pilots call the Piper Saratoga PA32 II HP a "clean" airplane: a fast, responsive craft with little drag to slow it down.
"That plane will get away from you so fast it'll make your head spin," Alphin said.
Once a pilot is in trouble "you feel like you're swimming in glue," said Joe Hartt, chief pilot at Hagerstown Aircraft Services and a certified flight instructor.
All the knowledge a pilot has gained through hours of training must be called upon, he said.
Flying only by the guidance of instruments can be hazardous, Hartt said. Vertigo, a sense of dizziness, can result when pilots can't see where they are flying.
Vertigo can make a pilot feel as if the plane is making a hard turn, when that may not be the case. If the pilot reacts to the false impression, the results can be disastrous, he said.
A 15-minute experience more than two decades ago helped teach Hartt the dangers of flying without visibility.
He was taking a solo flight in a Cessna 172 to qualify for his private pilot's license when he flew into bad weather.
Heading toward London, Ky., in mountainous country, Hartt was skimming across the bottoms of increasingly heavy clouds at an altitude of about 3,000 feet.
He saw lightning in the distance, and decided to climb another 2,000 feet into the clouds to get above the mountain tops.
When rain started to pound the Cessna's windshield, he called for radio assistance.
"The operator started screaming, 'What are you doing in the clouds!' I guess he thought he wasn't going to hear from me again," Hartt said.
After Hartt landed, his instructors lectured him, made him watch movies about the dangers of flying in poor conditions and put him on probation.