Northwest Orient Airlines Flight 2501 was a DC-4 operating its daily transcontinental service between New York City and Seattle when it disappeared on the night of June 23, 1950.

The flight was carrying 55 passengers and three crew members; the loss of all 58 aboard made it the deadliest commercial airliner accident in America at the time.

Considerable light debris, upholstery, and human body fragments were found floating on the surface, but divers were unable to locate the plane's wreckage.

In his last report, Captain Lind requested permission to descend from 3,500 to 2,500 feet because of a severe electrical storm which was lashing the lake with high velocity winds.

Permission to descend was denied by the Civil Aeronautic Authority because there was much more traffic at the lower altitude.The missing airliner is the subject of an annual search by Michigan Shipwreck Research Associates (MSRA), a Michigan-based non-profit organization.

Valerie van Heest, MSRA co-director and author of the book Fatal Crossing, says human remains from the June 1950 crash into Lake Michigan washed ashore and were buried in a mass grave.

The site had long been unmarked, until cemetery sexton Mary Ann Frazier and her mother, Beverly Smith, working on a genealogy project, found it.