The NTSB will release a preliminary report within 30 days, but it could be 18 to 24 months before the investigation concludes, he said.

Louisville officials are calling on people to report debris related to the deadly Nov. 4 UPS cargo plane crash that left a trail of destruction and thick black smoke stretching for miles.

The disaster also shut down the largest UPS package distribution hub and disrupted some flights in and out of the airport in Kentucky's largest city.