Aviation Accident Summaries

Aviation Accident Summary WPR16FA029

Carlsbad, CA, USA

Aircraft #1

N711BE

AIRBUS HELICOPTERS AS350B3E

Analysis

The private pilot and the pilot-rated passenger departed for a flight in the pilot's newly purchased helicopter. The pilot practiced several landings in a field during the flight and then flew back to the departure airport, where the approach and hover taxi to the ramp were uneventful. The pilot made a landing attempt on a dolly but landed only partially on the dolly, which caused the helicopter to pitch nose up and strike the ground with its tail. The helicopter hit the dolly with such force that the dolly broke free from the chocks securing it and spun around. The helicopter climbed and spun upwards aggressively but stabilized after rotating 270° to the right. The pilot then landed the helicopter in an abnormal location that straddled the ramp and a taxiway. Ground crew personnel re-secured the dolly with chocks, and, after about 2 1/2 minutes, the pilot again attempted to land on the dolly, this time from the opposite direction. He made two unsuccessful attempts but was unable to maintain a stabilized approach each time. Although the pilot had the option to land on the ramp, he persisted in attempting to land on the dolly. On his third attempt, he again landed partially on the dolly, and the helicopter rocked back and forth striking the ground with its tailskid, before violently climbing and pitching nose down, while rolling right. The helicopter spun 180° to the left and pitched up steeply, and the tail rotor and vertical stabilizer struck the ground and separated. The helicopter hit the ground left side low, bounced, and rotated another 360° before landing hard on its belly. The main rotor blades continued to spin and the engine continued to operate; the helicopter spun on its belly at a rate of about one revolution per second for more than 5 minutes, while gradually sliding about 530 ft along the ramp. The tailboom and horizontal stabilizer then separated, and the helicopter violently rolled onto its side, shed its main rotor blades, and came to rest. Onboard video showed that the pilot became incapacitated during the final ground collision. The passenger remained conscious after the impact and reached for the throttle on the pilot's collective control shortly after the helicopter started to spin, but the throttle position remained unchanged. He then attempted to brace himself against the glare shield, but he eventually became incapacitated after about 2 minutes due to his injuries, the forces imposed by the spinning helicopter, or both. He did not make any attempt to reach up for the engine-start selector or the fuel shutoff lever. Postaccident examination did not reveal any anomalies with the helicopter's airframe or engine that would have precluded normal operation. In the weeks preceding the accident, the pilot had expressed concern to multiple flight instructors that he was having difficulty adjusting to the flight characteristics of the helicopter. In particular, he found dolly-landings challenging. Although the pilot had many years of experience flying a Bell 407 helicopter, there were two significant differences between the Bell 407 and the accident helicopter. First, their main rotor systems rotated in opposite directions; therefore, the foot pedal inputs required to counteract changes in torque during takeoff and landing were opposite. (The pilot's difficulty adapting to this difference was evidenced during most of the previous takeoffs captured by the onboard video when the helicopter yawed significantly after lifting off.) Second, the tips of the landing skids, which were used as a visual reference during landing, were forward of the pilot in the Bell 407 but just aft of the pilot in the accident helicopter. This change in visual reference would have been particularly significant during dolly landings, which require landing on a specific point directly below the pilot's field of view. The pilot had received about 11 hours of flight instruction in the helicopter, and, despite the fact that his instructors advised him not to fly without an instructor, he opted to fly with a passenger instead of an instructor on the accident flight. Although the passenger held a helicopter rating, he was not an instructor or professional helicopter pilot and had about 180 hours total in helicopters. Furthermore, it was likely that he had little or no experience in the accident helicopter make and model. The pilot's instructors reported a mobility problem with the pilot's left arm that affected his ability to reach overhead, but this problem likely did not contribute to the accident, because he had no need to reach overhead during landing. Postmortem toxicology testing identified amlodipine, valsartan, and rosuvastatin as well as diphenhydramine at 0.538 ug/ml and alprazolam at less than 0.05 mg/l in the pilot's blood. The pilot had heart disease and hypertension and used amlodipine, valsartan, and rosuvastatin for their treatment; however, these conditions and medications most likely did not contribute to the accident as they do not affect judgment or decision-making. Alprazolam is a significant central nervous system (CNS) depressant with the lower end of the therapeutic range at 0.0060 mg/l. The exact amount of alprazolam in the pilot could not be determined by testing and may have been very low. The therapeutic range for diphenhydramine is 0.0250 to 0.1120 ug/ml. However, diphenhydramine undergoes postmortem redistribution, and postmortem central blood levels may increase by about three times. When divided by three or four, the pilot's postmortem level suggests that he had therapeutic levels at the time of the crash. Compared to other antihistamines, diphenhydramine causes marked sedation and is also a CNS depressant. In addition, it may cause altered mood and impaired cognitive and psychomotor performance. The use of two CNS depressants simultaneously typically results in cognitive impairment which is magnified well beyond the simple addition of the effects, even when the amount of one of them may be low. Therefore, the pilot's decision-making, judgment, and psychomotor performance were most likely impaired by the combination of CNS depressants, diphenhydramine and alprazolam.

Factual Information

HISTORY OF FLIGHTOn November 18, 2015, at 1623 Pacific standard time, an Airbus Helicopters AS350B3E, N711BE, departed controlled flight while landing on a dolly at Mc Clellan-Palomar Airport, Carlsbad, California. The private pilot and the pilot-rated passenger were fatally injured; the helicopter sustained substantial damage. The pilot, who was the owner, was operating the helicopter under the provisions of 14 Code of Federal Regulations Part 91. The local personal flight departed Carlsbad at 1412. Visual meteorological conditions prevailed, and no flight plan had been filed. The purpose of the flight was for the pilot to gain familiarity with the helicopter, which he had recently purchased. The entire accident sequence was captured on a series of airport security cameras and the mobile phone cameras of multiple witnesses. About 2 hours before the accident, the helicopter departed from its dolly on the east end of the Premier Jet fixed base operator (FBO) ramp, which was located midfield on the south side of runway 6/24. After departure, line crew moved the dolly to the west end of the ramp. Upon returning, the helicopter approached the airport from the northeast and was cleared to land on runway 24. It descended to midfield, turned left at taxiway A3, and approached the ramp in a low hover via the parallel taxiway A. The helicopter then began an approach to the dolly from the east, directly toward the sun. The helicopter landed short of, and partially on, the dolly with the center of its skids contacting the dolly's aft edge. The helicopter immediately rocked back, pitching nose up, and its tailskid struck the ground. The helicopter then began a series of fore and aft oscillations, and the dolly broke free from its front left chock, rotated to the right, and pivoted around its rear right wheel. The helicopter spun rapidly with the dolly for the first quarter of the turn and then quickly spiraled upward 270° to the right. The dolly came to rest to the north, having rotated 180°. The pilot repositioned the helicopter and landed it on the ground, straddling the ramp and taxiway A. Just before landing, the pilot was queried by the air traffic control tower controller and responded, "yeah, they didn't chock my cart, and I was like a skateboard out here," The tower controller then requested that the pilot switch to the ground control frequency. During the next 2 1/2 minutes, the line crew re-secured the dolly, installing chocks on three of the four wheels. The pilot then took off and climbed the helicopter to about 20 ft while it yawed to the left, and he repositioned it for an approach to the dolly now from the west. During the next 4 1/2 minutes, the pilot made three landing attempts, getting the helicopter to within about 5 ft vertically of the dolly on the first two attempts. After the first attempt, the pilot repositioned the helicopter by circling back around the dolly. After the second attempt, the pilot performed a hovering climb and backed the helicopter into position. A video of the third and final landing attempt was captured by a witness, who was located about 130 ft to the south. The witness was initially watching the helicopter from his airplane on the ramp, but he was concerned that the helicopter might crash, so he exited the airplane and positioned himself behind a car at the corner of the FBO's hangar. The video revealed that the helicopter hovered over the dolly for about 60 seconds and then landed short, teetering on the aft edge of the dolly (Image 1). The tailskid almost struck the ground, and the helicopter then rapidly pitched forward (Image 2) and then aft again. The tailskid then struck the ground (Image 3), and the helicopter pitched forward, rolled right (Images 4 and 5), and climbed out of view behind the hangar. Security cameras revealed that the helicopter then spun 180° to the left, and the nose pitched up to a 45° attitude. The tail rotor and vertical stabilizer assembly then struck the ground and separated, and the helicopter hit the ground left side low, bounced, and rotated another 360° before landing hard on its belly. Once on the ground, the main rotor blades continued to spin, while the helicopter started spinning on its belly, as the engine continued to operate (Image 6). The helicopter continued spinning at a rate of about one revolution per second for the next 5 minutes while incrementally sliding about 530 ft east along the ramp. The tailboom and horizontal stabilizer then separated, and the helicopter rolled onto its side, shedding the main rotor blades. The engine continued operating for another 30 seconds while the fire crew doused the helicopter. White smoke billowed from the engine's exhaust after the helicopter came to rest, but there was no fire. Image 1 - Helicopter Landing Short of the Dolly Image 2 - Helicopter Landing Short of the Dolly Image 3 - Helicopter Tail Striking the Ground Image 4 - Helicopter Rolling Right over the Dolly Image 5 - Helicopter Spinning 180 degrees, with Tail Striking the Ground Image 6 - Helicopter Spinning after Ground Collision PERSONNEL INFORMATIONThe pilot was seated in the front right seat, and the pilot-rated passenger was seated in the front left seat. Pilot The pilot held a private pilot certificate with ratings for airplane single-engine land and sea, multiengine land, instrument airplane, and rotorcraft-helicopter. He also held a type rating for the Cessna Citation Jet (CE-525S). The pilot held a third-class medical certificate issued on January 19, 2015, with the limitation that he must have available glasses for near vision. No personal flight records were located for the pilot. At the time of his last medical application, he reported a total flight time of 25,000 hours, with 200 hours logged in the last 6 months. The pilot reported the same numbers on three other applications over the 5-year period preceding the accident, and 25,400 hours total time on his application dated January 18, 2011. His helicopter rating was issued in May 2001, at which time he reported on his rating application a total flight time of 14,000 hours in airplanes. The pilot had previously owned and flown a Cessna Citation business jet airplane and a Bell 407 helicopter. His 2001 helicopter checkride flight took place in a Bell 206B3. At the time of the accident, he was receiving recurrent training for the Citation, with the most recent flight 2 days before the accident. The pilot purchased the accident helicopter on October 29, 2015, and had flown demonstration and familiarization flights in it since September 20. According to the helicopter's flight logs, those flights totaled about 8.8 hours and were all conducted with a flight instructor present. The pilot then flew the helicopter with another instructor for an additional 2 hours on November 13. According to the two instructors who had flown with the pilot for the familiarization flights and the flight instructor who provided training in the Citation, the accident flight was the first time the pilot had flown in an AS350 without an instructor present. All had recommended that the pilot gain further instruction before flying without an instructor, and the pilot had concurred. The three instructors shared similar insights into the pilot's flying skills, reporting that, while he appeared to have extensive flying experience, he was anxious about the handling characteristics of the AS350 compared to the Bell 407, particularly during landing. The pilot said that he was having difficulty anticipating flight control forces because the helicopter controls felt "backwards" due to the opposing rotor direction of the AS350 compared to the Bell 407. Furthermore, he was having trouble landing on the dolly partly because the tips of the skids were just behind his seating location in the AS350, as opposed to the Bell 407, where he could see the skids just forward and below. Both helicopter instructors reported performing multiple dolly and simulated dolly landings with the pilot, stating that, although the pilot was not completely at ease, he was able to ultimately land on the dolly unaided. The pilot told the Citation instructor that, although he had practiced many landings in the helicopter, he still did not feel proficient and thought that the helicopter was very unstable close to the ground, especially when it was close to the dolly. One of the helicopter instructors reported that the pilot wanted to enable the helicopter's stability augmentation system (SAS) for landings because he had been told it would help his landings. The instructor stated that he wanted the pilot to be able to fly the helicopter proficiently without the use of the SAS. However, for demonstration purposes, they did two landings with the SAS enabled. During those attempts, the pilot appeared to be "fighting" against the SAS control inputs, with unsatisfactory results, and he did not understand how to use the SAS release button on the cyclic to override the SAS control inputs. Therefore, the pilot and instructor decided to turn the system off. Both helicopter instructors reported that the pilot appeared to have suffered an injury that restricted movement of his left arm. He could use his left arm to operate the flight controls and reach the lower sections of the flight panel, but he could not reach the upper controls, including the engine start selector panel, without the supportive aid of his right arm. One instructor stated that because of the injury, the pilot was unable to climb up onto the helicopter to perform preflight examinations of the rotor head. One helicopter instructor and the Citation instructor stated that the pilot's hands often shook and that it was particularly obvious when he held a pen, although once he grasped the flight controls the shaking stopped. Both helicopter instructors suggested that the pilot take formal factory-approved flight training, and one instructor stated that he had declined to provide any further instruction until the pilot had taken training at the Airbus Helicopters flight school. According to Airbus Helicopters, in early October, the pilot had signed up for a "B3 Pilot Transition Class" scheduled for November 2, but 2 days before the class he called to defer the training. No further communication from the pilot was received by Airbus Helicopters. The Citation instructor, who had known the pilot for 6 years, reported that the pilot was becoming concerned that age was starting to affect his reaction time when flying. The instructor had observed the pilot's degrading flight performance and had conversations with him about how maintaining proficiency through regular flying could help. He stated that the pilot was no longer fully proficient in the Citation, that his reaction times were becoming slower, and that he would often let the airplane get ahead of him. As such, the instructor recommended that the pilot always fly with him. He stated that the pilot mentioned that he was going to fly the helicopter for practice with a friend on the day of the accident. The pilot confided in all three instructors that, due to the difficulties he was having mastering the AS350, he was most likely going to sell it and buy another Bell 407. All three instructors stated that they had never seen the pilot's logbooks and had, therefore, never made any entries. Pilot-Rated Passenger The pilot-rated passenger held a private pilot certificate with ratings for airplane single-engine land and rotorcraft-helicopter. His first rating was for rotorcraft-helicopter, and it was issued in December 2004 following a checkride in a Bell 206B3. He was issued his airplane single-engine land rating in December 2014, and, at that time, he reported on his rating application a total rotorcraft flight time of 179.6 hours, including 163 solo hours. He held a third-class medical certificate issued on May 29, 2014 with no limitations. No personal flight records for the pilot-rated passenger were located, and his currency or recent flight experience could not be determined. At the times of issuance of his two prior FAA medical examinations in 2008 and 2012, he reported total flight times of 185 and 200 hours respectively, with no flight time in the preceding 6 months on both occasions. AIRCRAFT INFORMATIONThe helicopter was manufactured in 2014 and equipped with a Turbomeca Arriel 2D engine. The helicopter had dual collective, cyclic, and foot pedal controls, with primary flight control intended from the right seat. The helicopter was maintained under a continuous airworthiness program and had accrued 35.2 hours of total time since new when the accident occurred. The last inspection took place 20.6 flight hours before the accident on August 15, 2015. The helicopter had undergone a series of twenty-three upgrades in May 2015, including the installation of an auxiliary side locker fuel tank, full length skid shoes, a radar altimeter, and a Genesys Aerosystems HeliSAS stability augmentation system and two-axis (pitch and roll) autopilot. The HeliSAS system provided attitude stabilization and force feedback to the cyclic control, via electro-mechanical servo actuators connected in parallel to the flight controls. The systems technical overview documentation stated: "The HeliSAS system is designed to be engaged at all times: "SAS" on before takeoff, and "SAS" off after landing. The "force feel" (force trim) feature enhances handling characteristics and mitigates inadvertent cyclic control inputs that could result in dangerous attitudes. The pilot may override the HeliSAS at any time with manual cyclic inputs. Only 3.5 lbs of pilot force in the pitch axis, and 3.0 lbs in the roll axis, at the cyclic control is required to override the system for pilot desired maneuvering when either the SAS or autopilot modes are engaged." The helicopter was serviced with the addition of 70 gallons of Jet A fuel on the morning of the accident. METEOROLOGICAL INFORMATIONAccording to the U.S. Naval Observatory's Astronomical Applications Department, the altitude of the sun when viewed from Carlsbad at 1620 would have been 4.3°, with an azimuth (E of N) of 243.7°. AIRPORT INFORMATIONThe helicopter was manufactured in 2014 and equipped with a Turbomeca Arriel 2D engine. The helicopter had dual collective, cyclic, and foot pedal controls, with primary flight control intended from the right seat. The helicopter was maintained under a continuous airworthiness program and had accrued 35.2 hours of total time since new when the accident occurred. The last inspection took place 20.6 flight hours before the accident on August 15, 2015. The helicopter had undergone a series of twenty-three upgrades in May 2015, including the installation of an auxiliary side locker fuel tank, full length skid shoes, a radar altimeter, and a Genesys Aerosystems HeliSAS stability augmentation system and two-axis (pitch and roll) autopilot. The HeliSAS system provided attitude stabilization and force feedback to the cyclic control, via electro-mechanical servo actuators connected in parallel to the flight controls. The systems technical overview documentation stated: "The HeliSAS system is designed to be engaged at all times: "SAS" on before takeoff, and "SAS" off after landing. The "force feel" (force trim) feature enhances handling characteristics and mitigates inadvertent cyclic control inputs that could result in dangerous attitudes. The pilot may override the HeliSAS at any time with manual cyclic inputs. Only 3.5 lbs of pilot force in the pitch axis, and 3.0 lbs in the roll axis, at the cyclic control is required to override the system for pilot desired maneuvering when either the SAS or autopilot modes are engaged." The helicopter was serviced with the addition of 70 gallons of Jet A fuel on the morning of the accident. WRECKAGE AND IMPACT INFORMATIONPostaccident examination of the helicopter did not reveal any anomalies with the airframe or engine that would have precluded normal operation. The throttle was found in the "FLIGHT" detent, and the left and right throttle controls could both be moved in concert with each other smoothly between the control detents. Dolly The pri

Probable Cause and Findings

The pilot's loss of control during landing on a dolly. Contributing to the accident were the pilot's decision to conduct the flight without an instructor despite multiple flight instructors' recommendations to the contrary, his failure to land on the ramp when he experienced difficulty landing on the dolly, and his impaired decision-making, judgment, and psychomotor performance, due to his use of a combination of two psychoactive drugs.

 

Source: NTSB Aviation Accident Database

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