Brief history of flight (Mission)
The fated aircraft owned by Zonk Air was a light twin turboprop departing from Tahoe Airport (KTVL). The aircraft carried four passengers and the pilot who were on a sunset photoshoot 20 miles from the airport. The flight was bound to return to KTVL after the shoot with an option to continue to Burbank, CA, owing to the extra fuel carried before takeoff. The cargo mainly contained suitcases labeled camera equipment, and some of them were piled up in the back seat without straps.
On-Scene actions (Scene Management Procedures)
All specific investigative organization and procedures were completed. As per FAA regulations, the accident site was controlled while all hazards were secured. The accident site was restricted to rescue and investigation personnel only. The size of the accident scene was estimated using the final stopping position of the wreckage, and the initial strikes pointed out by ground scars. Major components of the aircraft were located, their positions from the accident trail marked (including level of damage) and noting what was missing. Before wrapping up, numerous photographs of the accident site, the equipment, and the environment were taken before moving the wreckage. Furthermore, photographs of the positions of the gauges (such as throttle levels) and cockpit instruments were taken to aid the later stages of the investigation.
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On-Scene observations (What did you note and observe?)
The first impact point was a 100-foot communication tower. A ground scar with the red tip light was discovered 400 feet from the tower, this was the second impact point. The third impact point was 100 feet from the base of the communication tower, evidenced by a ground scar with the green tip light. The rest of the wreckage was 50 feet from the third impact scar. Initial and subsequent investigations revealed slipstream soot marks running along the right engine nacelle, towards what was left of the right horizontal stabilizer. The suit marks were absent on the left engine and horizontal stabilizer. These observations are consistent with witness accounts who stated that they noted smoke and fire (some of the witnesses) coming from the right engine nacelle.
Airport information and weather (Basic description and source)
Lake Tahoe Airport (KTVL) is an FAA certified airport. At takeoff, the ATC personnel of a possible downturn in the weather as there was marginal VFR. The local weather report (courtesy of the ATC) was two miles in lowering clouds and 900 feet overcast. Furthermore, the weather was determined to be deteriorating.
Flight information and mission (Who, what, where and why)
The fated flight carried four passengers and the pilot on a sunset photoshoot 20 miles from the airport. Though no flight plan was filed, the aircraft was bound to return to KTVL with the option to head to Burbank after the photo shoot. The accident happened five miles past the departure end of Runway 18 where the aircraft was reported to be descending in a steep left “rolling like” bank, trailing smoke. The aircraft had an empty weight of 3900 pounds and max gross weight of 6500 pounds. At takeoff, the aircraft was carrying 1000 pounds of fuel, 900 pounds of 4 cargo trunks, and five humans, all weighing a total of 980 pounds. In total, the aircraft took off with a weight of 6780 pounds, 280 pounds above its max gross weight.
Aircraft information (Type, history, performance, maintenance, etc.)
The fated aircraft, N517RL, was a 1980 PA-31-310 twin engine turbocharge “Navajo” with Lycoming IO-540 reciprocating engines (fully rebuilt). The aircraft had already logged 15000 + airframe hours. However, the aircraft and its engines were 2 hours of its next 100-hour inspection and 10 hours of time before overhaul (TBO), respectively. The owning company considered it “airworthy” and an airworthy certificated and Form 337. The aircraft’s original paperwork and maintenance logs had been lost in a shoot-out and subsequent fire at the former owner’s hangar. Three days prior to the fatal accident, an Airworthiness Directive (AD) had been issued for a cracking of fuel line support brackets. The AD recommended inspection and/or removal/replacement. Though the aircraft was scheduled to receive its 100-hour inspection, there was no indication that the operator or maintenance personnel complied with the AD.
Pilot information (certificates, hours, training, etc.)
The newly hired (one year) pilot possessed a commercial multi-engine instrument rating. The pilot had a total of 300 hours, 50 hours in twins with 15 hours in make and model of the mishap aircraft. The pilot had 5 hours of actual instrument meteorological condition (IMC) flight time. He had completed three flights with the principle company, Zonk Air, all day light, VFR sightseeing tours. Prior to working at Zonk Air, the pilot was employed in Arizona, flying a light twin, Part 91, for a solar panel company. Prior to that, the pilot received multi-engine flight training from a FBO, called “Super Pilot” based in Arizona, but it is no longer in business.
Company information and operations (Who, what where why)
The aircraft was operated by “Zonk Air Charters” that was based in Oxnard, CA. The company operates three of the mishap aircrafts (PA-31), and 2 1979 Cessna 310s. The company is certified for Part 135 and Part 91 operations, with six part-time pilots, the owner, and secretarial staff. The company outsources its maintenance to another operation on the field. The company had been cited by the FAA for failing to maintain proper records in accordance to CFR 135 operations. Zonk Air had been up for sale for two years, was delinquent in paying fuel bills and maintenance inspections, and was in the process of filing for Chapter 11, bankruptcy protection.
1.8 Final analysis (Your analysis for causes - prove and bring it all together here)
Overall, the accident was caused by negligence on the part of the pilot and Zonk Air. The mishap aircraft had a problem where there was a possible power loss and noted a few minor fuel droplets below the right engine on a preflight, but ground tests conducted by another line pilot could not duplicate the problem. The owner stated he was aware of the rough running engine and a few drops of fuel, but it was "just the nature of this aircraft.” This points to an intermittent problem with the aircraft that had remained uncorrected in the previous maintenance checks and overhauls. The AD issued three days prior was ignored as there was no documentation to indicate compliance. Lastly, the pilot took off with 280 pounds above the maximum gross weight. The ATC personnel reported that the aircraft’s ground run and initial climb to screen height took three quarters of the runway. Furthermore, witness reports indicated that the pilot put 900 pounds of luggage piled in the back seat, without distributing their weight or tying them down. This was later confirmed by the remains of the burnt wreckage.
From takeoff to the fateful accident, the aircraft lost all radio communications with the ATC. The pilot’s negligence also contributed to the accident as he forgot to properly perform his pre-flight check. The pilot was also tired (and had personal problems at home that drove him to work extra) and was in a hurry, according to witness reports. These are all recognized human factors that contribute to aircraft accidents ( Kharoufah et al., 2018; Kelly & Efthymiou, 2019 ). For instance, had the pilot had done his job, he would have noticed that the aircraft exceeded its gross weight and be cognizant of the lack of compliance with the previously issued AD.
1.9 Conclusion (The probable and contributing causes)
It is possible that the mishap aircraft went down in the following manner. First, mishap aircraft took off successfully and started it initial climb. However, the problematic engine failed and caught fire. The loss of power was minor as the pilot would have trimmed for the asymmetric thrust with radar deflections to compensate for the turning moment. The aircraft, therefore, would have turned around and landed (albeit a heavy landing) with one engine inoperable. Unfortunately, the unstrapped luggage in the backseat shifted to the left with the loss of engine power. As a result, the mishap aircraft shifted its center of gravity and lost its balance. The fact that it was above its max gross weight meant that it did not have power to sustain the climb and started to descend. There might have been a slight chance that the pilot would position the aircraft and glide to perform an emergency landing had he the climbed high enough to gain the required potential energy.
2.0 Recommendations (Realistic, doable suggestions)
Therefore, it is recommended that the company Zonk Air’s flight operations be suspended and its entire fleet inspected. Furthermore, it is recommended that the FAA issue an advisory circular (or emphasize its existing ones) that pertains to the human factors of flight, especially compliance with regulations any operator is certified for.
References
Kelly, D., & Efthymiou, M. (2019). An analysis of human factors in fifty controlled flight into terrain aviation accidents from 2007 to 2017. Journal of Safety Research , 69 , 155-165.
Kharoufah, H., Murray, J., Baxter, G., & Wild, G. (2018). A review of human factors causations in commercial air transport accidents and incidents: From to 2000–2016. Progress in Aerospace Sciences , 99 , 1-13.
