Unformatted text preview: AIRCRAFT ACCIDENT REPORT PROJECT 1 Zonk Air Accident Report
1.0 Brief history of flight
On November 7, 2010, the accident aircraft, a Piper PA-31 with a registration number N517RL, arrived at Lake Tahoe Airport (KTVL) the day before. It was scheduled
to depart on Runway 18 at dusk from KTVL and return to Bob Hope Airport (KBUR) after
a short photo flight around the local area. On board were four passengers and one flight
crew with some photography equipment.
Weather reported at the KTVL to be 2 miles in lowering clouds and 900 feet
overcast and deteriorating. As the aircraft departs, the aircraft disappears into the mist
before re-appearing 5 miles away from Runway 18 with a steep left bank and trailing
smoke. The aircraft impacted a 100-foot communication tower and crashed about 6.1 miles
away from Runway 18. All passengers and the flight crew were fatally injured.
1.1 On-scene Actions
Specific investigative organization and procedures were completed and compliance
with the investigative procedures of the National Transportation Safety Board (NTSB). The
preparation phrase were conducted with executing initial coordination with relevant
parties, and preparing of data and equipment such as investigative equipment, personal
survival items, for diagramming and plotting, for witness interviewing, for collection of
evidence, photographic, report writing and administrative, technical data and personal
items, and carrying of the equipment. The initial action phrase were conducted after the
preparation phrase to establish a base of operations, arranging of security to protect the
wreckage as well, determine initial findings, conduct an organizational meeting, establish
safety rules, conduct initial walkthrough, take initial photographs, collect perishable
evidence, inventory the wreckage, begin a wreckage diagram and develop plans for
wreckage recovery, human remains, laboratory analysis and reconstruction. AIRCRAFT ACCIDENT REPORT PROJECT 2 1.2 On-scene Observations
According to the observations done on-scene, the mark of the first ground impact
was 400 feet away from the base of a 100 feet communication tower. By using some
mathematical formulas, the aircraft was calculated to impact the tower and traveled
downwards at an angle of approximately 75.9 degrees and 412.3 feet before impacting the
Vertical soot marks were observed on crushed portions of the fuselage and wing
roots. Slipstream soot marks can be found running along the side of the right engine
nacelle, aft towards the remains of the right horizontal stabilizer. However, no such soot
marks were found on the left horizontal stabilizer. Despite it, there were vertical soot trails
found on the damaged left engine nacelle, which was caused by the impact and burnt.
Even though the left propeller was intact, the tips were bent aft and blades
experienced little signs of trailing edge compression. The right propeller has span and
chord striations with a number of the classic “S” compressions on the trailing edges. In
addition, the blade tips were jagged and broken with missing pieces. Due to the fire and the
impact experienced, it is almost impossible to inspect other components.
After further inspections, the right engine was found to be providing some power
during impact while the left engine showed no evidence of any power being produced. In
addition, the fuel line support bracket in the left engine was appeared to have some
propagation cracks along the bolt-holes connecting to the firewall. With this observation, it
can be determined that the left wing broke off first.
The cockpit and cabin were destroyed to a point that it became unrecognizable.
Instruments were all destroyed but the throttle quadrant was only damaged. Despite being
damaged, it managed to show the levers, which are pushed forward into the cockpit panel.
Rescue crews were unsure if any devices and controls were disturbed during the rescue
stage, as they have to remove bodies and cut restraint systems. AIRCRAFT ACCIDENT REPORT PROJECT 3 The cargo was mostly burnt and scattered around the cockpit area and outside,
forward of the crash site. It was observed that there were no restraint systems around the
wreckage. According to the fuel attendant who helped the pilot with the cargo, he recalling
asking where were the straps or netting but the pilot told him that he will do it himself
later. Thus, there is a possibility that the pilot might have forgotten to tie down all the
1.3 Airport Information and Weather
According to the Federal Aviation Administration (FAA), KTVL is an operational
airport with no ATC tower. It is located 3 miles southwest of South Lake Tahoe, Canada,
and with an elevation of 6268.4 feet. KTVL has 2 runways, Runway 18/36. Runway 18 has
a 4-light PAPI on the left with a 3° visual glide path angle but Runway 36 does not have
any visual slope indicator. Runway 18/36 is 8541 feet long and 100 feet wide with an
excellent ASPH surface.
At that point in time, multiple witnesses and the ATC mentioned that the weather is
deteriorating with 2 miles in lowering clouds and 900 feet overcast according to the
weather report obtained by ATC. The density altitude is well within the operating limits of
the PA-31 as according to FAA, the PA-31 has a maximum operating altitude of 24,000
1.4 Flight Information and Mission
According to the employees of Zonk Air Charters, the flight is meant to be a sunset
photo flight within 20 miles of the airport. The passengers can choose to whether return
back to KTVL or continue to Burbank. The passengers are photographers as the cargo that
the fuel attendant load with the pilots were photography equipment.
According to an interview with Tahoe FBO Services employees, it was mentioned
that the fuel attendant asked the pilot about the flight and he recalled the pilot mentioning
wanting extra fuel in case the clients wants to return home to Burbank. Based on the AIRCRAFT ACCIDENT REPORT PROJECT 4 readings on the fuel truck and fuel record book, 1000 lbs of fuel were loaded onto the
aircraft. According to the flight documents in Zonk Air Charters, the four passengers had a
combined weight of 800 lbs while the pilot weighed 180 lbs. The four cargo trunks that
were loaded were estimated to be approximately 900 lbs. The center of gravity was aft and
outside the normal envelope datum when the cargo was loaded onto the aircraft.
According to the training and flight proficiency did by the owner who is a
designated Part 135 check airman, pilots are required to do their own pre-flight checks,
flight plans, obtaining weather, loading of passengers and conducting the mission. Thus,
there is a possibility that the pilot might have forgotten to file in any flight plan and obtain
weather reports. Thus, there was no VFR or IFP flight plan filed or weather report given to
the accident aircraft.
1.5 Aircraft Information
According to the FAA, the 1980 PA-31-310 (PA-31 Navajo) has a maximum weight
of 6500 lbs with two Lycoming IO-540 series reciprocating engines. When empty, the
aircraft weighs only 3900 lbs. The aircraft holds a valid FAA registration, airworthy
certificate and Form 337, which is for major repair and alternation. The total time on the
airframe was 15,000 hours+. Even though the engines had been rebuilt, both were still
within 10 hours of Time Before Overhaul (TBO) and the aircraft is within 2 hours of its
next 100-hour inspection.
According to the FAA, there was an Airworthiness Directive (AD) released on Nov
4, 2010, however, it does not apply to the engine mounted on the accident aircraft. Thus,
compliance with the AD is not required.
According to the maintenance records and personnel from another maintenance
company, a list of maintenance items for the aircraft was deferred. These items includes
repairing of loose cooling baffling on the right engine, tightening of friction controls on the
cockpit power quadrant, adding cargo nets and straps to the aircraft flight kit, adjusting AIRCRAFT ACCIDENT REPORT PROJECT 5 pilot’s seat springs, locking travel adjustment slide on the seat of the pilot, and inspecting
and replacing of the first aid kits. In addition, the logs are incomplete and some sign-offs
According to the report, the aircraft was seized by the DEA from a drug smuggler
ten years ago and the aircraft had been stored in a government’s hanger for two years
before auctioning off to various organizations before ending up in Zonk Air Charters. Most
of the original documents of the aircraft were lost during the shoot-out and a fire in the
1.6 Pilot Information
According to the company’s records, the pilot possessed a commercial multi-engine
instrument rating for a year. The pilot had a total of 300 flight hours, 50 of those hours in a
twin-engine aircraft and 15 hours out of the 50 hours were in the make and model of the
accident aircraft. The pilot had also clocked 5 hours of flight time in instrument
meteorological condition (IMC). Prior to joining Zonk Air Charters, the pilot flew a light
twin aircraft for a solar panel company in Arizona. In addition, the pilot completed his
multiengine training from an FBO, Super Pilot, in Arizona.
According to the witnesses, the pilot seems tired all the time and spend time
sleeping in the crew lounge before flights. The logbook of the pilot was never located and
the owner was unable to tell if he has experience in mountain flying and has completed his
1.7 Company Information and Operations
Zonk Air Charters is a certified to conduct operations under Part 135 and Part 91
and based in Oxnard, CA. The company operates three PA-31s and two Cessna 310s with
a group of six part-time pilots. The company had an owner and secretarial staff as well. All
maintenance was outsourced to various companies. Despite having no history of accidents,
the FAA cited Zonk Air Charters for having improper management of records in AIRCRAFT ACCIDENT REPORT PROJECT 6 accordance to CFR 135 operations. The owner, who is a designated Part 135 check airmen
conduct training and flight proficiency for the pilots.
Zonk Air Charters did not have any form of formal dispatching and flight
monitoring systems despite having an operations manual that states they are required to
have. In addition, there were no records indicating that the pilots received any form of
human factor training, a manual or procedures from the Safety Management System
According to the financial statement of Zonk Air Charters, the company is suffering
financially as it had difficulties in paying for fuel bills and maintenance inspections. In
addition, for two years, Zonk Air Charter had been up for sale.
1.8 Miscellaneous Information
According to the employee of Tahoe FBO Services, the pilot seems to be anxious
and rushing to execute the flight due to the fast-changing weather. Another employee
mentioned that the passengers jokingly told the pilot to hurry things up or they would leave
without him. However, there is a possibility that the pilot took it a wrong way.
Within Zonk Air Charter, the owner mentioned to pilots to always be safe when
making a decision to abort the flight but try to be creative. In addition, the owner told the
pilot to make the flight a good one for the passengers, as these are money making potential.
An employee of Zonk Air Charters mentioned that the other pilot who is supposed
to conduct this fly reported sick and this accident pilot took the flight. The accident pilot
had little time to get to the airport and take the flight with only a little rest.
1.9 Final Analysis
Without any proper form of documentation and safety cultures, the company was
unable to determine if the pilots had completed the check ride or required further training.
Due to the financial crisis of the company, certain maintenance processes were deferred. In
addition, despite the concerns about the fuel leaked raised by the pilot to the maintenance AIRCRAFT ACCIDENT REPORT PROJECT 7 personnel and the owner, both the owner and the maintenance personnel insisted that it was
normal due to the age of the aircraft.
Human factors training were not conducted for the pilots and staffs to allow them to
understand the nature of fatigue that can happen on a human body. In addition, the
company did not have a proper roster to have a scheduled and reserved pilot.
The probable cause of the accident was the failure of the right engine due to the cracks found on the fuel line support brackets causing a leaked in fuel. Ultimately causing
the engine to be on fire during flight. The contributing factors were the pilot’s fatigue, selfinduced stress, and the company’s lack of safety implementations and training. Due to the
little rest, the pilot received between the last flight and accident flight, affecting his
decision-making ability. In addition, due to the deteriorating weather and the importance of
the flight mentioned by the owner, the pilot rushes to take off to prevent any grounding of
flights. The lack of safety implementations and training causes the poor pilot allocation for
In order to prevent similar accidents, the following are the recommendations:
1) Zonk Air Charters should plan a duty roster for pilots containing the duty
pilot and reserved pilot for the mission. Rest time should be taken into
consideration when planning the roster.
2) Zonk Air Charters to conduct human factors training to allow staffs and
pilots to understand the importance of human factors and how can it affect
different factors such as decision-making.
3) Zonk Air Charters to maintain proper documentation procedures for both
pilots and maintenance of aircraft.
4) FAA to conduct regular audits on Zonk Air Charters to ensure that proper
documentation procedures are followed AIRCRAFT ACCIDENT REPORT PROJECT 8 5) FAA to conduct an inspection on the fuel line support brackets for
Lycoming IO-540 series engines and determine the cause.
6) FAA to release an AD to ensure that the support brackets are inspected and
in good condition to ensure a safe flight. ...
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