Collision With a Drone

The following information provides an awareness of problems that might be avoided in the future. The information is based on final reports by official investigative authorities on aircraft accidents and incidents.

Occurred In Controlled Airspace

King Air A100. Minor damage. No injuries.

The flight crew was conducting a visual approach to Runway 24 at Quebec/Jean-Lesage International Airport the evening of Oct. 12, 2017, when they saw a drone in front of the King Air’s left wing. “The pilot had no time to take evasive action,” said the report by the Transportation Safety Board of Canada (TSB). “The impact was unavoidable.”

The collision occurred at 2,500 ft and about 7 nm (13 km) from the runway. The crew declared an emergency and landed the aircraft without further incident. The pilots and their six passengers were not injured. “The damage was limited to a dent at the point of impact on the left wing deicing boot, as well as scratches on the upper surface of the left wing,” the report said. “The damage was minor and had no effect on the airworthiness of the aircraft.”

The drone, which the King Air pilots described as being the size of a dinner plate, disintegrated on impact. Investigators found no debris from the drone and were unable to identify the operator.

The airport is in Class C controlled airspace, and the collision occurred inside the control zone. “All aircraft must obtain authorization from air traffic control (ATC) before entering this airspace,” the report said.

The drone was not detected by ATC radar. “A primary surveillance radar can detect an aircraft above a certain mass, even if it does not have a transponder,” the report said. “Generally speaking, drones cannot be detected by the primary surveillance radar because they are too small and made primarily of plastic.”

In Canada, a drone is categorized as a “model aircraft” if it is used for recreational purposes and as an “unmanned air vehicle (UAV)” if used for non-recreational purposes. The type of drone involved in the collision was not determined.

“It is easy for any consumer to purchase a drone without being informed of any regulations governing its use; retailers are under no obligation to inform consumers of the regulations in force,” the report said. “In this incident, there were no injuries and only minor damage to the aircraft. However, the use of drones near an aerodrome or within controlled airspace poses a serious risk to aviation safety.”

The report noted that the TSB received 30 reports from pilots who saw drones on their flight paths between 2014 and 2017; no collisions occurred. Moreover, in 2014, there were 41 known incidents in which operators of model aircraft and UAVs did not comply with Canadian regulations governing operation of the vehicles. The incident reports increased to 86 in 2015 and to 148 in 2016.

The TSB report said that, based on the incident reports, Transport Canada proposed regulatory amendments designed to reduce the potential risks that drones pose to airborne aircraft as well as to people and property on the ground.

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Jets

Nose-Heavy Takeoff

Boeing 737-800. No damage. No injuries.

While preparing for a charter flight from Malta to Manchester, England, the afternoon of Sept. 28, 2017, the flight crew set the 737’s stabilizer trim to 4.5 units, based on information provided by the load sheet. The handling agent who prepared the load sheet assumed an even distribution of the 136 passengers in the cabin. “The passengers’ actual seating positions were not passed to the handling agent,” said the report by the U.K. Air Accidents Investigation Branch. “Although not certain, the [flight] crew believed that all the passengers sat in their allocated seats.”

The load sheet indicated a mean aerodynamic chord (center of gravity) of 23 percent. However, not all the passengers occupied their allocated seats, and the actual distribution of the passengers was more forward than indicated by the load sheet. Investigators calculated an actual center of gravity of 17 percent. Thus, the aircraft was nose-heavy.

The takeoff was normal until the commander, the pilot flying (PF), attempted to rotate the 737 at the calculated rotation speed. “No rotation occurred with the normal pull effort,” the report said. “The PF continued to pull back, and then, with approximately 3/4 elevator deflection, the aircraft started a slow rotation [and] was airborne with approximately 300 m [984 ft] of runway remaining.”

“The [flight data recorder] data showed the aircraft was trimmed, once airborne, from the pre-takeoff setting of 4.5 units to approximately 7 units,” the report said. The crew then continued the flight and landed the 737 in Manchester without further incident.

False Stall Warnings

British Aerospace 146. No damage. No injuries.

A preflight inspection revealed damage to the left airflow sensor, which was replaced before the aircraft departed 30 minutes late from Malmö, Sweden, for a scheduled flight with 101 passengers to Bromma the morning of Sept. 29, 2016. “The takeoff was normal until liftoff, when the stick shaker was activated,” said the report by the Swedish Accident Investigation Authority. “By immediately checking the speed and attitude of the aircraft, along with the awareness that an airflow sensor was replaced before the flight, the flight crew could immediately identify the stall warnings as false.”

Shortly after the aircraft entered instrument meteorological conditions 660 ft above the ground, the stick pusher (stall-recovery system) activated. The copilot, the PF, countered the control wheel deflection and used elevator trim to level the aircraft. The crew then consulted the emergency checklists and prevented further activation of the stall-warning and stall-recovery systems. They returned to Malmö and landed the aircraft without further incident.

Investigators found that the left airflow sensor, which comprises an electronic unit and an angle-of-attack vane, had been assembled incorrectly and provided angle-of-attack readings that were 45 to 50 degrees in error. The report said that, because of a “mix-up of test instructions,” the fault was not detected when the airflow sensor was installed before takeoff.

Engine Cowling Separates

Airbus A320-200. Substantial damage. No injuries.

The A320 was departing from Miami for a flight to Oranjestad, Aruba, the morning of Sept. 19, 2016, when a passenger told a flight attendant that the outboard fan cowling had separated from the right engine during takeoff. The flight attendant relayed the information to the flight crew.

“The flight crew leveled off at FL220 [Flight Level 220, approximately 22,000 ft] to assess the damage to the airplane,” said the report by the U.S. National Transportation Safety Board (NTSB). “The crew was not sure if the panel had detached completely or was not visible from inside the airplane. All systems appeared normal in the cockpit, but as a precaution, the crew elected to return to Miami, where the A320 was landed without further incident.”

None of the occupants was injured, but the cowling separation caused damage to the airplane’s right engine, engine pylon, right main landing gear and fuselage. Investigators found that a routine weekly maintenance check had been performed the night before the accident flight. “Part of the weekly check was to open the fan cowl doors to inspect the IDG [integrated drive generator,” the report said. The NTSB concluded that the outboard door likely was not latched properly after the IDG inspection was performed.

Passenger Falls From Airstairs

Cessna Citation 680. No damage. One serious injury.

After parking the Citation at Wilmington, Delaware, U.S., on Sept. 3, 2017, the captain exited the cockpit to open the cabin door. He told investigators that he found the lead passenger standing in front of the main cabin door, waiting to exit the aircraft.

The captain was able to reach around the passenger to open the door “but did not have room to exit the aircraft ahead of the passenger,” the NTSB report said. “As the passenger started down the airplane’s airstairs, her foot slipped. She landed on her knees, and she caught her balance by grabbing onto the hand rails. A subsequent medical examination revealed that the passenger had broken her ankle.”

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Turboprops

Nose Gear Jammed

Bombardier Q200. Substantial damage. No injuries.

The nose landing gear did not extend properly when the flight crew prepared to land at Washington Dulles International Airport the morning of Sept. 24, 2016. The crew retracted the main landing gear and climbed to 3,000 ft to troubleshoot the problem. “While at altitude, the flight crew attempted to lower the gear a second time, but the same result was indicated,” the NTSB report said. “They then performed the manual gear extension [procedure], but the nose gear still failed to extend.”

The crew conducted a low pass over the airport, and ground personnel confirmed that the main landing gear were extended but the nose gear was retracted and the gear doors were open. The crew declared an emergency and requested that airport emergency vehicles stand by for their landing.

“During the landing roll, the nose of the airplane contacted the runway surface,” the report said. “The captain shut down the engines after the airplane came to a stop and called for an evacuation.” None of the 21 passengers or three crewmembers was injured during the landing or evacuation.

The accident substantially damaged the Q200’s forward pressure vessel. Examination of the airplane disclosed that the frangible tow fuse had not been installed properly in the nose landing gear system during scheduled maintenance at Albany, New York, U.S., the night before the accident flight. The NTSB concluded that this prevented the nose gear from extending on approach to Dulles.

Wire Strike On Final

Cessna 441. Minor damage. No injuries.

The pilot was conducting a charter flight with nine passengers from Adelaide, Australia, to a dirt airstrip in Coorabie the morning of Sept. 5, 2016. He had not flown to the airstrip previously but had studied information provided by the operator showing that the airstrip was 900 m (2,953 ft) long and 25 m (82 ft) wide, and was on a slope that rose from about 30 ft at the threshold of Runway 32 to about 72 ft at the threshold of Runway 14.

Nearing the airstrip, the pilot spoke with another company pilot who had just landed without incident on Runway 14. The other pilot recommended that he land on Runway 32, instead, due to the downslope of Runway 14.

Accordingly, the 441 pilot conducted a straight-in approach to Runway 32. During the approach, the aircraft suddenly decelerated from about 120 to 110 kt. “At the same time, there was a slight shudder of the right engine and a change in the sound of the propeller pitch,” said the report by the Australian Transport Safety Bureau. “The pilot checked the engine instruments and the annunciator panel, and there were no abnormal indications.”

The pilot conducted a go-around and subsequently landed the aircraft without further incident on Runway 32. “While back-tracking [on the runway], the pilot sighted a power pole on a hill beyond the Runway 32 threshold,” the report said. “After shutting the aircraft down, the pilot noticed damage to the right propeller blades and suspected that the aircraft had struck a power line. Witnesses on the ground confirmed that they had seen and heard the aircraft strike the power line.”

The report noted that the power line was 7.5 m (25 ft) above the ground and 370 m (1,214 ft) from the threshold of Runway 32, and was not required to be marked, according to Australian standards. The pilot said that he might not have struck the power line if he had conducted a steeper approach.

Investigators determined that an aircraft on a normal 3-degree glide path would clear the power line but that the 441 likely was on a 1-degree glide path when the wire strike occurred. The report cited Flight Safety Foundation guidance advising that an uphill runway slope can create an illusion of being too high on approach. “That illusion may induce the pilot to ‘correct’ the approach, resulting in a lower flight path, or may prevent the pilot from detecting when the aircraft is too low during the approach,” the report said.

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Piston Airplanes

Impaired By Poor Eyesight, Drug Use

Cessna T337G. Destroyed. One fatality.

Night visual meteorological conditions (VMC) prevailed as the pilot descended from 7,500 ft to land at Aurora Municipal Airport in Sugar Grove, Illinois, U.S., on Sept. 28, 2014. During a conversation with the airport traffic controller about nearby traffic, the pilot was asked to activate his transponder’s identification feature and was told that the Skymaster appeared to be descending through 1,800 ft (about 100 ft above pattern altitude) and that there were no other aircraft nearby.

“According to radar track and engine-monitoring data, the pilot did not attempt to slow the airplane’s descent [rate of 1,050 fpm before] colliding with trees located along a ridge at an elevation of about 645 ft,” the NTSB report said. “A post-accident examination of the airplane and flight instruments did not reveal any anomalies that would have precluded normal operation.”

Investigators found that the 80-year-old pilot’s eyesight was affected by cataracts and by glaucoma. “Although the pilot met the Federal Aviation Administration medical certification standard of 20/40 vision in daylight conditions, the glaucoma and cataracts likely impaired his night vision and, as such, impeded his ability to judge altitude using available visual cues in dark nighttime conditions,” the report said.

In addition, toxicological tests revealed that the pilot’s blood contained therapeutic levels of diphenhydramine, a sedating antihistamine. “Research has shown that the use of diphenhydramine can impair cognitive and psychomotor performance,” the report said. “The pilot’s failure to identify the airplane’s low altitude during cruise descent further supports that he was likely impaired by the use of diphenhydramine.”

Trim Failure Causes Control Loss

Cessna T310Q. Destroyed. One fatality.

The pilot was departing from Wichita, Kansas, U.S., the afternoon of Sept. 25, 2015, when witnesses saw the airplane suddenly pitch nose-down and descend rapidly to the ground about 2 nm (4 km) from the airport.

Examination of the wreckage revealed that the bolt, nut and cotter pin that secure the elevator trim tab pushrod to the trim tab actuator were missing. “The pushrod became jammed aft of the forward elevator spar, creating an abnormally large trim-tab-up (nose-down) condition,” the NTSB report said.

Measurements taken during tests of the elevator trim system in another 310 showed that “the airplane nose-down pitching moment at this increased deflection would create a forward force on the control yoke that a pilot would likely not be able to overcome,” the report said.

Based on the findings of the investigation, the manufacturer issued a service bulletin recommending replacement of the hardware securing the elevator trim pushrods in several 300- and 400-series Cessna twins. An airworthiness directive subsequently issued by the U.S. Federal Aviation Administration required compliance with the service bulletin.

Gear-Down Water Landing

Grumman G-44. Substantial damage. Two minor injuries.

The pilot told investigators that he neglected to retract the amphibious airplane’s landing gear after departing from a hard-surfaced runway to fly to a lake about 3 nm (6 km) away in Lakeport, California, U.S., the afternoon of Sept. 17, 2016. “The pilot reported that he did not use a checklist during the flight,” the NTSB report said.

The Widgeon flipped over when the extended landing gear struck the surface of the lake. The pilot and passenger sustained minor injuries, and the airplane’s fuselage and vertical stabilizer were substantially damaged.

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Helicopters

Fuel Pumps Unported

Bell 206B. Substantial damage. One fatality, one serious injury, one minor injury.

The crew was engaged in a pine beetle survey flight over mountainous terrain near Fox Creek, Alberta, Canada, the afternoon of Sept. 5, 2016. The pilot had conducted a similar flight the previous day and, according to company procedure, had pulled the circuit breaker for the rotor low-rpm warning system to silence the system after checking it before shutdown. He likely did not reset the circuit breaker before the accident flight, the TSB report said.

After flying for 2 hours and 20 minutes, the JetRanger was landed on a gravel bar for a 20-minute rest stop, during which the pilot remained at the controls with the engine running. The pilot mentioned to one of the surveyors that 30 gal (114 L) of fuel remained, allowing for about one more hour of flight before returning to Fox Creek Airport to refuel. “From the surveyor’s perspective, the fuel quantity gauge appeared to indicate approximately 24 gal [91 L],” the report said.

About 12 minutes after resuming the survey flight, the pilot was conducting a descending left turn about 160 ft above the ground when the engine flamed out. “The engine-out and rotor-low-rpm warning horns did not activate, and no warning lights illuminated on the annunciator panel,” the report said. “Within 2 to 3 seconds, the aircraft descended and struck the trees.”

The survey crewmember sitting in the front seat was killed, the survey crewmember in a back seat sustained minor injuries, and the pilot was seriously injured. The report said that the pilot was wearing a helmet, which likely saved his life.

Examination of the helicopter revealed no mechanical anomalies that could have caused the power loss. Investigators found the engine-relight switch in the “OFF” position but could not determine whether the switch was not armed by the pilot or was moved during impact. The relight system is designed to prevent a flameout by activating the engine ignition system if high-pressure rotor speed decreases below 96 percent.

The fuel tanks were ruptured on impact, but calculations indicated that the helicopter had 12 to 21 gal (45 to 79 L) of fuel when it crashed. The TSB concluded that one or both of the fuel boost pumps likely had unported during the turn, causing an interruption of fuel flow to the engine.

“The Bell 206B helicopter’s fuel system can be susceptible to unporting when operating with less than 20 gal [76 L] and acceleration forces are present,” the report said. “These forces can be due to turbulence or pilot flight control inputs.” The report noted that the company “did not have a policy in place for helicopters to land with a specified minimum quantity of fuel to ensure appropriate safety margins to prevent the unporting of boost pumps.”

Check Pilot Disengaged Hydraulics

Eurocopter AS350. Substantial damage. Two minor injuries.

The pilot was receiving an annual standardization check ride in Fullerton, California, U.S., the morning of Sept. 27, 2017. He was flying the downwind leg of the traffic pattern when the check pilot moved the hydraulic system cutoff switch to the “OFF” position. The pilot lowered the helicopter’s nose and flew a shallow approach to the runway. The helicopter was about 3 ft above the runway when the check pilot said, “Keep the speed up.”

“The evaluated pilot responded by lowering the nose; however, an uncontrollable rapid left yaw ensued,” the NTSB report said. “The check pilot took control and attempted to keep the helicopter over the runway, but the nose pitched down and the main rotor blades struck the ground.” The helicopter then settled upright on the runway.

Investigators concluded that the pilot had allowed airspeed to decrease below the minimum of 40 kt recommended by the AS350 flight manual for a loss of hydraulic pressure. The report noted that the manual also contains the following caution: “Do not attempt to carry out hover flight or any low-speed maneuver without hydraulic pressure assistance. The intensity and direction of the control feedback forces will change rapidly. This will result in excessive pilot workload, poor aircraft control and possible loss of control.”

The pilot was killed when the float-equipped Beaver struck terrain shortly after taking off in VMC from Willow Seaplane Base for a charter flight. According to witnesses, the pilot had made two takeoff attempts before the accident occurred.