Three South Carolina National Guard helicopter pilots walked away from a harrowing Dec. 3 emergency landing in which their UH-60 Black Hawk helicopter reportedly plummeted 6,000 feet in less than a minute after a main rotor failure.

The two pilots (the third pilot was a passenger) managed to land the helicopter in a field not far from a water treatment plant, a school and residences near I-77 just a couple miles southeast of Columbia, South Carolina, not far from Fort Jackson.

After a loud bang during the instrumentation flight, a vibration began and quickly escalated; it turned out that the motor had died.

The pilots assigned to Detachment 2, F Company, 1-171st General Support Aviation Battalion quickly responded with autorotation, said Lt. Col. Andrew Batten. That allows the blades to spin with their existing momentum from the then-failed motor, and conserve that momentum by angling them so air flows through them rather than directly against them.

They targeted a cornfield as a landing site, and maneuvered to streamline the descent, then maximize air resistance, caused by remaining momentum of the blades, against the fall by pitching upward at the end.

Batten, the state aviation officer for the Guard, said putting the aircraft down in the open landing space helped spare injury, collateral damage and more damage to the aircraft. So did the soft, saturated muddy ground at the time of the incident.

"The nature of the emergency required them to take emergency action steps," Batten told Army Times. "In certain emergencies they are required to respond without hesitation. The steps are kind of beaten into us in our training, from flight school to advanced training on particular aircraft."

Batten said "we anticipate it was a mechanical issue" that caused the malfunction.

After the landing, the Guard set to gathering evidence from the scene and preparing the Black Hawk for transport. The rotor blades — some shown in photos to be badly damaged — were taken off and transported separately. Gas was removed from the tank, some of it sampled as evidence.

Four days later a CH-47 Chinook helicopter sling-loaded the downed aircraft to McEntire Joint National Guard Base in Eastover, South Carolina.

An investigation into the cause of the malfunction is ongoing; because of that, Guard spokeswoman Maj. Cindi King said by policy the Guard could not name the three pilots or make them available for an interview. She said the investigation could take up to six months.

The frame's structural integrity was tested to ensure it could make the trip dangling from the Chinook without falling apart.

Eventually the helicopter was sling loaded under the Chinook, which was accompanied by a UH-72 Lakota flown in from the National Guard Army Aviation Support Facility in Greenville, South Carolina.

King said traffic on the highway backed up for miles as people who had seen the crash stopped to see what was going on.