"The wing's angle relative to its speed reaches a point where it no longer generates lift, and once it no longer generates lift, the 800,000 pound object is going to come down," Booth said.
Elena Garrett, of Jeffersonville, Ind., just across the Ohio River from Louisville, said ex-husband Timothy Garrett would have turned 52 on Saturday. They have two daughters together, ages 11 and 12.
"We're all devastated," Elena Garrett said about his death. "We were still best friends. He's the best father I've ever seen (and) ready to help anybody. He would give the shirt off his back for anybody."
Bill Hasler said his family learned Monday morning that his brother, Brad, was one of the crash victims.
"Brad was a wonderful father to two young children, a beloved husband to a wife who is expecting another child, a loving son, and the most loyal and supportive brother I could have ever asked for," Bill Hasler said in a statement. "His influence in the lives of all of us who loved him is immeasurable, and our grief is indescribable."
National Airlines was based until recently at Michigan's Willow Run Airport, west of Detroit. It carries cargo both commercially and for the military, Kaufman said. She said the company employs about 225 people.
Summan had worked 2½ years for National Air Cargo, said his wife, Rajnit Summan.
Rajnit Summan said she last spoke to her husband Sunday.
"I told him to be safe," she said.