An investigator with the National Transportation Safety Board says a western Iowa native who piloted an aircraft that crashed last Thursday may have violated federal safety recommendations for flying the plane under icing conditions.

The NTSB’s Steve Chealander says 47-year-old Marvin Renslow, a native of Shenandoah, reported "significant" ice on his wings and windshield just before the Continental turboprop pitched and rolled violently, then fell from the sky and pancaked onto a house, killing all 49 people onboard and one person on the ground.

Chealander says the NTSB’s preliminary investigation indicates the plane was on autopilot, which is against Renslow’s companies’ recommendations and is in violation of federal safety regulations. Chealander says pilots are required to fly their aircraft manually in severe icing situations, which Renslow was experiencing at an altitude of 2,300 feet, just before the plane crashed in Clarence, New York.

Families and friends of the crash victims gathered at a church in Clarence Sunday to mourn their losses while investigators combed through the wreckage, trying to retrieve the victims’ remains and gather more clues as to what caused the crash. Memorial services for Marvin Renslow will be held Friday evening, in Florida.