NTSB Identification: CEN09FA099
14 CFR Part 91: General Aviation
Accident occurred Friday, December 19, 2008 in North Canton, OH
Probable Cause Approval Date: 01/28/2010
Aircraft: PIPER PA-32R, registration: N9299N
Injuries: 1 Fatal.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
The pilot obtained a weather briefing prior to the flight to Akron-Canton Regional Airport (CAK), Ohio, from College Park, Maryland. During the briefing, the pilot proposed a route of flight at an altitude of 6,000 feet. The briefer told the pilot that the freezing level at CAK at the time of the briefing was about 3,000 to 4,000 feet, but that the it may drop to the surface as the day progressed. The pilot indicated at the beginning of the 20-minute briefing that he was aware of the hazardous weather conditions and he expressed concern about them, but he decided to depart to CAK shortly after he received the briefing.
At the time of the accident, weather observations at CAK indicated broken clouds at 500 feet above ground level (agl), and overcast skies at 100 feet agl. Meteorological analysis showed a high likelihood of encountering supercooled large droplet (SLD) icing in the area. General aviation pilots operating into and out of CAK surrounding the time of the accident all reported icing conditions, with most of the icing occurring between 3,000 to 3,500 feet. The reports also indicated freezing rain. Three of the pilots reported a rapid accumulation of between 1 and 2 inches of ice within a 15-minute period prior to and after the accident. One pilot reported that he required a significant amount of engine power to maintain airspeed and had a hard landing due to ice accumulation on his airplane.
As the accident airplane approached CAK, the local air traffic controller (ATC) issued the pilot a vector to the instrument landing system (ILS) localizer course about two miles from the runway’s ILS outer marker. The controller advised the pilot to maintain 3,200 feet until established on the approach, and that the airplane was cleared for the approach. The pilot acknowledged and asked if there were any pilot reports of icing below 6,000 feet in the area. The controller responded that there were no reports of icing at that time, but asked the pilot to advise if he encountered any. The pilot did not report icing conditions.
The pilot made a gradual left turn to intercept the localizer, and then leveled out near the approach course heading. Although left of the localizer course, he began descending on the approach and stabilized the airplane at an airspeed of just over 100 knots. The controller told the pilot that he was left of the approach course centerline. The pilot acknowledged and reported that he was "correcting." Recorded radar track information showed that the pilot did not correct to the right, but continued to fly a course to the left of, and almost parallel to, the approach course centerline.
The controller then told the pilot that he was "well left" of the approach course. The airplane briefly turned right toward the approach course centerline, but seconds later, the airplane rolled into about a 30-degree left bank, and began turning away from the approach course centerline. While at 2,800 feet, the pilot requested clearance to perform a nonstandard 360-degree turn while about 2-1/2 miles northeast of the airport in order to reestablish the airplane on the approach course (the pilot had commenced the turn before hearing back from the controller). The controller responded that he was unable to approve the pilot's request.
The controller then instructed the pilot to climb and maintain 3,000 feet. The airplane's left bank gradually increased to about 40 degrees at that time. The controller asked the pilot for his present heading and the pilot responded "due north and climbing." The airplane began to climb while remaining in a 30 to 40-degree left bank. The controller instructed the pilot to climb without delay. Pitch increased above 20 degrees with the airplane still in a 30-degree left bank, and with airspeed significantly decreasing. Shortly thereafter, the airplane entered a spiral-like dive as the pilot declared an emergency. The controller advised the pilot to “…maintain altitude. The airport is two miles west of you," but the pilot did not respond and there was no further contact with the airplane. During these last radio transmissions, the airplane was in a continuous left turn with decreasing radius until it abruptly dropped off the radar.
A ground witness saw two bright lights coming almost nose first toward the ground with the engine “roaring.” The airplane impacted the ground in a nose-down and left-wing-low attitude. Postaccident examination of the airplane revealed no anomalies that would have precluded normal operation. An NTSB sound spectrum study of digital audio recording of ATC communications indicated normal engine operation.
Analysis of recorded radar data indicates that the airspeed, roll, and initiation of a climb brought the airplane close to an aerodynamic stall as it was maneuvering in a steep turn following the controller's instruction of "no delay" and the pilot's declaration of an emergency. The airplane subsequently stalled and rapidly descended to the ground. The characteristics of the descent are consistent with an abrupt stall during maneuvering that was likely aggravated by ice accumulation on the airplane.
Risk factors for spatial disorientation were present at the time of the accident, including dark night instrument meteorological conditions and maneuvering flight. The airplane's sequence of sustained turns was conducive to spatial disorientation, specifically a class of vestibular illusions known as somatogyral illusions. Furthermore, the pilot's report that he was headed "due north and climbing" as he placed the airplane into a turn of decreasing radius was inconsistent with his having an accurate awareness of the airplane's orientation.
The pilot reported a total flight time of 510 hours on his October 2007 FAA medical application, of which 50 hours were accumulated in the past 6 months. The pilot's total and recent instrument flight experience could not be determined. The pilot had a history of seasonal allergies, treated with prescription medication that was reported to the FAA. While an over-the-counter sedating antihistamine was found in the pilot's blood during postaccident toxicology testing, the investigation was unable to determine if the pilot was adversely affected by impairment.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot’s inappropriate control inputs as a result of spatial disorientation, which led to an aerodynamic stall and loss of control. Contributing to the accident were the pilot's decision to conduct flight into known icing conditions, ice accumulation that reduced the airplane's aerodynamic performance, and the pilot's failure to initially intercept and establish the airplane on the proper approach course. Full narrative available
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