Human error frequently cause in PC-12 fatalities

In 12 previous accidents involving the Pilatus PC-12, the model of aircraft that crashed in Rockbridge County killing four people Sunday, pilot or human error was determined to be the cause nine times, according to National Transportation Safety Board records.

Four of those cases involved fatalities, and pilot or human error was the cause in each, according to NTSB records.

In one case, a technician walked under the plane’s still-spinning propeller while the aircraft was on the ground. Two cases were crashes caused by pilots failing to maintain airspeed, leading to stalls.

And in a fourth case, a pilot lost control of the aircraft after suffering from spatial disorientation “while turning in a cruise climb,” according to an NTSB accident report. That sent the airplane into “a tight descending spiral” and a fiery crash in Westphalia, Mo.

Finding answers to the mystery in Steeles Tavern, where a PC-12 piloted by Tampa, Fla., businessman Daniel Dorsch plunged into a McCormick Farm field, requires first that investigators pluck every single shattered piece of wreckage they can find.

The mission is to inventory the plane’s parts, not to reconstruct the aircraft as is the practice with airliners, according to NTSB spokesman Peter Knudson.

“They are collecting all pieces to ensure nothing separated during flight,’’ he said.

The collection of plane parts will extend beyond the crash scene only if parts are found missing.

Knudson said in the past, the NTSB has talked to other people living near a crash to see if they found missing plane parts.

The process is painstaking but necessary, retired Federal Aviation Administration flight inspector Graham Pitsenberger, of Staunton, said. Crash investigations do not stop when someone thinks a cause has been spotted.

“You have to keep on looking just when you think you know it all,’’ Pitsenberger said.

A determination on probable cause in the Rockbridge crash isn’t expected to come for months. Knudsen said a preliminary report on the accident is not likely until next week.

Since 2001, according to NTSB records, there have been 18 accidents involving the PC-12, considered among the industry’s finest and safest single-engine aircraft.

Determinations on probable cause still are pending in the last five cases, and a sixth happened in the Sea of Okhotsk and was handled by Russian authorities.

Eight cases have involved fatalities, including four cases since September that are still being investigated.

In the other cases, the crash in Missouri stands out because of the pilot’s struggle with the phenomenon known as spatial disorientation. Five to 10 percent of all general aviation accidents are blamed on spatial disorientation and 90 percent of those cases are fatal, according to the FAA.

The syndrome is described in Aircraft Owners and Pilots Association Air Safety Foundation literature as “any condition that deprives the pilot of natural, visual references to maintain orientation, such as clouds, fog, haze, darkness, terrain or sky backgrounds with indistinct contrast (such as arctic whiteout or clear, moonless skies over water).”

A pilot suffering from spatial disorientation has lost a visual reference of where the ground is, safety foundation President Bruce Landsberg said.

The cause can be clouds or sensory conflicts caused by sudden turns of the aircraft.

Landsberg said pilots who have spatial disorientation are taught to rely on the plane’s instruments to tell them where they are.

Just before Dorsch’s PC-12 crashed, he reported losing a panel, which could have meant an instrument panel. NTSB officials have not provided more specifics on that piece of the mystery.

Landsberg said on a plane as sophisticated as the PC-12, there are secondary instruments and even a turn coordinator which would allow the plane to remain in the air.

He said the turn coordinator will tell the pilot if the wings are level, which is most critical.

Landsberg said there are only about two fatal accidents a year in U.S. private aircraft involving a loss of instruments.

According to the NTSB, Dorsch, a veteran pilot of almost 30 years, sought a magnetic heading and was given a southwest course just before he reported the aircraft in descent. He had inquired with air traffic control about adverse weather, leading to the alteration in course. A steady rain fell throughout much of the area Sunday morning.

Landsberg said a PC-12 destined for Tampa would have had enough fuel to allow Dorsch to fly west of the weather. That’s what he was seeking to do when he reported trouble with the panel.

Killed along with Dorsch, 56, were his wife, Cyndie, 55; her dance instructor Stepan Matkovski; and Jenny Brown, a marketing director for Daniel Dorsch, according to relatives.

The four were returning to Tampa from a weekend trip to New York for a ballroom dance competition.

NTSB officials so far have declined to identify the victims.