The father of one of three people whose small plane disappeared from radar said his son was planning to ask his girlfriend to marry him in the air.

Debris believed to be from the single-engine hybrid Cherokee was found in Lake Erie Sunday, about a mile from an oil slick, authorities said.

"We eventually were able to find quite a bit of debris that was floating -- all the aircraft parts, seats, cushions and, unfortunately, some clothing that probably came out of the airplane," said Capt. Kevin Caffery, of the Erie County Sheriff's Office.

Pilot James Regal, 22, of Butler, remains missing, along with his friend, Kevin Jesteadt, 24, of Prospect, and Lindsey Myers, 23.

Relatives said Jesteadt, a Slippery Rock Area High School graduate, planned to propose to Myers as they flew over Niagara Falls.

Jesteadt and Myers attend Edinboro University and have dated for about three years.