WPR16FA086

The weight shift control aircraft encounter with a wake vortex from a preceding airplane, which resulted in a roll upset at an altitude too low for recovery. Contributing to the accident was the accident pilot's failure to recognize the potential for a wake vortex encounter.

The student pilot of the weight shift control (WSC) light sport aircraft, commonly referred to as a "trike," advised the air traffic control (ATC) tower that she was ready for departure and was instructed to hold short. A DeHavilland DHC-6 then landed, and, about 40 seconds later, the controller cleared the trike for departure on the same runway. When the trike was about 50 ft above ground level, it entered a steep right bank and descended to ground impact just north of the east-west runway. Postaccident examination of the airframe and engine did not reveal evidence of any pre-impact anomalies. Trajectory comparisons of the two aircraft, revealed that the trike likely encountered one of the wingtip vortices from the DHC-6, and the strength of that vortex, depending on the encounter geometry, likely far exceeded the roll authority of the trike. This resulted in an airborne loss of control at an altitude too low for recovery. Because the trike and the DHC-6 were of the same ATC weight category, no controller wake vortex advisory was required or issued, and all wake-separation decisions were the responsibility of the pilot. Despite the significant size and weight differences between the 10,500-pound DHC-6 and the 992-pound trike, the pilot opted to depart less than a minute after the DHC-6 landed. Review of the pilot's training syllabus indicated that wake vortices were part of the curriculum, but her actual knowledge and understanding of that subject could not be determined. Her training workbook appeared to be pristine and unused, and the instructor's signoffs appeared to all have been done in a single sitting, possibly even after the accident. This suggested the possibility that her training, academic knowledge, and study diligence left her inadequately prepared to appreciate and avoid the wake vortex hazard. Although the toxicology results indicated that the pilot had smoked cocaine, it was not possible to determine whether or not the pilot was experiencing any effects from smoking cocaine or from withdrawing from cocaine at the time of the accident. Based on the levels of diphenhydramine found, the pilot may have been impaired by its effects (somnolence, slowed psychomotor responses) at the time of the accident.

PBA Information PBA was based at HHR and was situated in a hangar on the southeast side of the airport. At the time of the accident, PBA owned and operated two aircraft, both of which were WSC aircraft. The hangar faced runway 25, served as the office for PBA personnel and customers, and housed at least one of PBA's two aircraft. According to the chief pilot, he was a founding member and co-owner of PBA when it began operations about 3 years before the accident. Shortly after the company began, he sold his share to another individual, whom the chief pilot described as a "silent partner." The silent partner and the other co-owner had been the owners ever since. Neither of the co-owners held any FAA pilot certificates. According to its website, PBA was "a Light Sport Aircraft training facility based in the scenic city of Los Angeles" that offered "introductory flight lessons as well as intermediate and advanced flight training" in their aircraft. The PBA website contained multiple references to the visual or experiential aspects of the flights, using phrases such as "breath taking views of scenic Southern California," "surreal moments," and "epic experience." The website's references to flight training included statements such as "Once in flight, you will have the opportunity to actually fly the aircraft " and "should you decide to continue your training." The "Yelp" website contained multiple reviews from persons who had made flights in the PBA WSC aircraft; those reviews were all consistent with aerial tour activities. PBA Aircraft Dispatch Sheets In response to an NTSB request for the aircraft's sign-out records, the chief pilot responded that he did not use any such sheets or system. When asked how PBA tracked flight time for billing purposes, the co-owner stated that the aircraft was equipped with a timer that would be started manually by the chief pilot or the flying pilot. The lack of a sign-out system precluded the determination of the time on the airplane at the time of the accident or a record of the aircraft usage/flight history. Altered Accident Pilot's Record The pilot's flight bag had been left in the PBA hangar for the flight; this was not an unusual procedure, since there was no stowage capability on the aircraft. The day after the accident, NTSB investigators visited the PBA hangar and examined the contents of the pilot's flight bag. The pilot's flight logbook was in her flight bag. A 3-ring binder that contained various pilot-related information and documents was maintained by PBA and provided to NTSB investigators for examination. One of the documents in that binder was the pilot's FAA student pilot certificate. That certificate had been photographed on the day of the accident (3/21/16) by Hawthorne Police Department personnel, and again by NTSB personnel on the following day (3/22/16). Comparisons of the photographs from the two different days revealed that the certificate had been altered in the period between when the two photographs were taken. The alteration was the addition of a hand-written solo cross-country flight endorsement dated 3/15/16 and signed by the PBA chief pilot. The chief pilot confirmed that he made the subject endorsement, but he did not provide any information as to why he altered the document after the accident. Pilot's Training Information and Records The Federal Aviation Regulations (FARs) specify the minimum requirements and standards for obtaining a pilot certificate with a WSC rating, and flight training organizations and instructors enable student pilots to meet these requirements via their curricula and training materials. According to information provided by the PBA chief pilot, the curriculum used for the pilot's training was contained in a "Training Syllabus & Work Book, Weight Shift Control Trike" (Paul Hamilton, 2014 edition). The chief pilot provided the original hardcopy of the pilot's training syllabus workbook to NTSB investigators. The workbook contained the overall lesson plan and was subdivided into individual numbered modules. Each module contained a "Ground Lesson" and a "Flight Lesson" printed on separate pages. Each lesson page had multiple checklist-style topic lists that were to be initialed by either the instructor or the student pilot. Each lesson page also had two dedicated, separate signoff lines, one each for the student pilot and the instructor. Review of the pilot's syllabus work book indicated that the "Flight Lesson" pages for the first twelve (of a total of fifteen) modules were fully initialed and signed as "completed" by the chief pilot. None of those pages was initialed or signed by the accident pilot. Only one of the "Ground Lesson" pages (that for Module 11) was initialed and signed by the chief pilot. As was the case for the "Flight Lesson" pages, none of the "Ground Lesson" pages were initialed or signed by the accident pilot. The syllabus workbook was observed to be in nearly pristine condition; all pages were consistently clean and new-appearing. None were stained or wrinkled, or exhibited any other indications of use. The syllabus workbook was spiral-bound, which precluded the easy removal or resequencing of pages. The pages were printed on both sides and numbered such that when the work book was opened, all the left-hand pages were even-numbered, and all the right-hand pages were odd-numbered. For all the modules, the "Flight Lesson" pages were on the even-numbered pages. For all the modules except one (Module 11), the "Ground Lesson" pages were on the odd-numbered pages. The Module 11 Ground Lesson was printed as an even-numbered page. The investigation identified two patterns with the pages that were initialed and signed by the chief pilot. The first pattern was that all the lesson pages that were initialed and signed by the chief pilot were even-numbered pages, irrespective of whether they were Flight or Ground lessons. None of the odd-numbered lesson pages, which were all Ground lessons, were initialed or signed by either the chief pilot or the student pilot. The second pattern was that all of the Chief Pilot's initials, signatures, and date entries appeared to be written with the same ink and pen tip. Student Pilot's Syllabus Wake Vortex Information Within the twelve instructor-initialed modules of the accident pilot's syllabus workbook, "wake vortex" avoidance was cited in two flight lessons and two ground lessons. The first citation was in the ground lesson for Module 4, and the last citation was in the ground lesson for Module 11. The chief pilot reported that his training of the accident pilot used the workbook guidance and references. The investigation was unable to determine what other training or study, if any, the pilot had obtained or conducted regarding wake turbulence. The HHR ATCT was operating at the time of the accident. The ATCT was a non-federal facility that was operated and staffed by the private contractor Serco. At the time of the accident, there were three controllers on duty in the ATCT. Those three individuals were performing the functions of ground control (GC), local control (LC), and controller-in-charge (CIC). All three controllers' statements indicated that each witnessed the airplane's right turn, descent, and impact. None of the three statements mentioned the presence or activity of any other aircraft. Serco-generated transcripts of the ATCT communications with the accident aircraft were provided to the investigation. Review of these transcripts indicated that they did not document any communications with, or any references to, any other aircraft. The investigation obtained and reviewed the archived radar tracking data for HHR for the period leading up to the accident. That data indicated that a DeHavilland DHC-6 conducted an approach to HHR runway 25 just before the accident. The radar coverage did not extend to ground level, but the DHC-6 did not re-appear, which was cons