Preliminary Reports
Air Tour Helicopter Crashes in Vietnam, Bell 505 JetRanger X, April 5, 2023,, Ha Long Bay, Vietnam
The aircraft crashed into the ocean shortly after takeoff on a planned 10-minute sightseeing flight over Ha Long Bay, killing the pilot and all four passengers.
Search-and-rescue efforts were mobilized shortly after contact was lost; two bodies and portions of the wreckage were located about two hours after the accident. Two more bodies and the majority of the wreckage, including the lightweight flight recorder, were recovered the following day. The flight’s operator, Vietnam Helicopters, suspended all air-tour operations in the immediate aftermath of the crash.
Ha Long Bay, a UNESCO world natural heritage site, is a popular tourist destination renowned for its dramatic geologic formations. Initial press reports stated that all four passengers were Vietnamese nationals; the pilot’s nationality was not initially reported.
Go-around Accident Ends Flight Review, Daher TBM 940, April 7, 2023, Ashland, Oregon
The pilot and the instructor conducting his flight review escaped unharmed after the single-engine turboprop failed to respond as expected during an attempted go-around, instead descending into trees and shrubs off the left side of the runway. Tree branches blocked the pilot’s door, so both evacuated the aircraft through the passenger airstair door as “a small fire” ignited. The fire eventually “engulf[ed] much of the airplane.”
According to the pilot, some two and a half hours into the flight review the instructor posed a scenario requiring a weather diversion to Ashland. The pilot determined that winds favored Runway 30, entered the traffic pattern, and extended the downwind leg while configuring the airplane to assure a stabilized approach. Final approach was uneventful, with the landing gear and full flaps extended, engine torque greater than 10 percent, and airspeed “between 80 to 95 knots.”
As they crossed the threshold, the instructor described “a simulated obstruction on the runway” and called for a go-around. The pilot increased power to 70 percent torque and attempted to level the airplane, which instead yawed left despite right rudder and continued to descend until impact. There was no stall warning or any indication of an impending loss of control. The 2,650-hour pilot reported about 1,400 hours in TBM 700-series airplanes, during which he’d executed “many” go-arounds both with and without instructor supervision.
Final Reports
Night Ditching Prompts Call for NVIS Reassessment, MBB/Kawasaki BK117-C1, April 22, 2019, Auckland Islands, New Zealand
The Transport Accident Investigation Commission (TAIC) called on New Zealand’s Civil Aviation Authority to reevaluate its pilot and flight crew training requirements for using night vision imaging systems (NVIS) after a medical evacuation helicopter descended into the ocean while attempting to land at a planned overnight camping site. The pilot, paramedic, and winch operator were all wearing immersion suits and were able to escape from the sinking aircraft with minor injuries and reach shore; another rescue helicopter found them the following day. The sunken wreckage was recovered about three weeks later.
The crew had planned to arrive at Enderby Island before dark and stay overnight before rendezvousing with a fishing vessel to extract a sick crew member. Unexpected delays in departure pushed their arrival time back past nightfall and they continued a visual approach to their planned landing site using night vision goggles (NVGs), which enabled them to identify the hills around Port Ross and “part of Enderby Island.”
Believing the landing area to be covered by cloud, the pilot attempted to descend below the cloud level in clear skies over the sea before following the coastline back to their landing zone. As they turned toward land, the paramedic pointed out cliffs directly ahead, but the pilot was unable to react quickly enough to prevent impact.
The TAIC defines NVIS as the suite of “elements…required to safely operate an aircraft using NVGs,” including radar altimeters and compatible cockpit lighting systems, crew competence and recurrent training checks, and procedural requirements. Its review concluded: “The [current] minimum requirements…do not equate to proficiency” and recommended more stringent requirement for recurrent training in NVIS operations and crew resource management.
Misplaced Pick-up Downs Skydive Supervan, Cessna 208B Supervan 900, June 25, 2021, Teuge International Airport, the Netherlands
A mechanic’s error in replacing the magnetic pick-up in the propeller governor that provided data to the engine’s exhaust gas temperature (EGT) gauge led to contact between the pick-up and the governor’s toothed gear, eventually leading to a total loss of engine power on initial climb. Seventeen parachutists were on board when the Supervan’s engine flamed out while climbing through 400 feet; one suffered minor injuries in the ensuing forced landing. The pilot was unhurt, but the airplane “sustained substantial damage to the fuselage, wings, landing gear, and propeller.”
Prior to the flight, high and erratic EGT readings with the engine off prompted replacement of the pick-up. The mechanic followed the first four steps of the maintenance procedure but did not notice steps five through eight, which were therefore not carried out.
These included a system voltage check to confirm correct installation. A post-accident teardown found that the pick-up had been threaded into the governor assembly in the gap between two teeth of the rotating gear; the resulting contact fractured both the pick-up and the gear teeth, producing metal debris that restricted free movement of the ball head assembly and displaced the metering valve aft.
This in turn allowed the oil to drain from the propeller dome. As the propeller moved toward the feathered position, decreasing the rpm of the single-shaft engine, compressor discharge (P3) pressure in turn decreased, leading the fuel control unit to reduce fuel flow and initiating a feedback process resulting in engine stoppage.
The Dutch Safety Board’s report notes that the propeller governors of Honeywell TPE331 engines fitted with hydromechanical fuel controls, including that on the accident airplane, use 15-tooth gears. The gaps between teeth are wide enough to allow incorrectly installed magnetic pick-ups to penetrate the space between them, subjecting both components to the sort of impact damage that precipitated this accident. Those equipped with electronic fuel controls use gears with 29 teeth that do not provide enough clearance for the pick-ups to intrude between teeth.
Lack of Recent Experience Faulted in Fatal Stall, Beech E90, Nov. 15, 2021, Boyne City, Michigan
Modifications to the aircraft, including installation of five-bladed propellers that increased its deceleration rate, and the eight-month lag since the corporate jet pilot’s previous flight in the accident aircraft were cited as contributing to its apparent stall on final approach. The pilot and the only passenger, reportedly a student pilot interested in pursuing a professional flying career, were killed when the King Air crashed on final approach in heavy sleet.
Additional workload associated with exercising the airplane’s de-icing systems and the aerodynamic effects of the sleet itself were also cited as possible contributing factors.
The accident occurred on a Part 91 business flight from the Oakland County International Airport in Pontiac, Michigan, to Boyne City. ADS-B track data showed that on the final segment of the RNAV approach to Runway 27, the King Air’s groundspeed slowed from 129 to 88 knots in the course of one minute.
The last ADS-B fix came 3.2 nm from the threshold at an altitude of 600 feet and 88 knots groundspeed; the impact point was 600 feet further along the final approach course. An Airmet for moderate icing was in effect, and witness reports suggest that bands of heavy sleet were passing through the area. The airplane flight manual called for a minimum airspeed of 140 knots in icing conditions.
The 1974-model turboprop “had been modified numerous times” and was the original testbed for development of a supplemental type certificate (STC) for installation of Honeywell TPE331-10 engines and five-bladed McCauley propellers. At the time of the accident, it was one of only two with this STC installed.
The owner of the second modified airplane told investigators that moving the propeller controls to their high-rpm position caused rapid deceleration on final approach, prompting him not to do so until short final, and another jet pilot who had flown the accident aircraft recalled being surprised when it quickly slowed from 135 to 100 knots during level-off.
The 61-year-old, 13,000-hour airline transport pilot usually flew a Challenger 604 jet. While he had about 700 hours in E90 airplanes, his most recent flight in the accident airplane was during recurrent training on March 22, 2021.
Excessive Taxi Speed Leads to Runway Excursion, Swearingen SA226-AT Merlin IV, Feb. 26, 2022, San Andres Island-Gustavo Rojas Pinilla Airport, Colombia
Taxi speed well in excess of the manufacturer’s published limit was blamed for the loss of steering control that resulted in the twin-engine turboprop departing the left side of the runway. The crew was on an air ambulance flight to Medellín with one patient and two medical crew members on board and was cleared to back-taxi to the approach end of Runway 06.
About 200 meters (660 feet) into the taxi, the right engine increased power and the aircraft accelerated to 36 knots and began veering left. The crew’s efforts to counter the excursion were unsuccessful, and it drifted off the runway into the grass before they attempted to use the brakes. Braking proved ineffective due to poor traction on the grass, and the airplane continued until its nose struck the concrete wall bordering the airport, sustaining damage to the nose and left forward area of the fuselage. The airplane’s flight manual cites a maximum authorized taxi speed of just 10 knots.