DENVER (AP) — Investigators say a small plane that crashed in the Colorado mountains, killing both people aboard, was preparing to land but didn’t make voice contact with the airport tower.

A preliminary report from National Transportation Safety Board released this week doesn’t list the cause of the Dec. 15 crash.

READ MORE: Colorado Water Suppliers Seeing 'Traditional Patterns' Change Each Year

The twin-engine Beech B-60 went down about 5 miles north of Edwards, killing 67-year-old Barton Harris of Brownwood, Texas and 73-year-old Jerry Hoggatt of Pelham, Ala.

READ MORE: 'This Is Offering Them Shelter For The Night': City Of Northglenn Converts Old Rec Center Into Winter Housing For Homeless

The NTSB says a controller at the Denver Air Route Traffic Control Center had cleared the plane to land at the Eagle County airport, but the pilot didn’t contact the airport tower.

The plane was registered to Bighawk Corp. of Brownwood, Texas.

MORE NEWS: VIDEO: Colorado Bobcat Hunts For Next Meal

(Copyright 2010 by The Associated Press. All Rights Reserved.)