GAITHSERSBURG, MD — Ice accumulation on the wings caused the 2014 plane crash that killed six people, including a woman and her two children who were killed after a piece of the plane struck their home, according to a National Transportation Safety Board report released Tuesday.

The pilot failed to turn on crucial de-icing equipment, according to the NTSB, leading to the ice accumulation and eventual stalling of the Embraer EMB-500 Phenom jet. The plane crashed in suburban Gaithersburg on Dec. 8, 2014, damaging three homes. Marie Gemmell and her sons, Cole and Devin died after a wing of the plane hit their home and caused a fire.

"Pilots must rely on checklists and procedures because relying only on memory can have deadly results,'' said NTSB Chairman Christopher A. Hart. "The pilot's failure to turn on the de-icing system in an icing situation proved to be disastrous." According to the report, the pilot had been warned about conditions on the ground when approaching Montgomery County Airpark. The airplane crashed less than a mile from the runway.