Story ID: 004
Accidents: December 2018
By: David Jack Kenny
Caption: AIN looks at recent business aviation accidents
Word Count: 1666
Preliminary Reports

Challenger Accident Followed Discrepant Airspeed Readings

Canadair CL-600-2B16 Challenger 604, March 11, 2018, near Shahr-e-Kurd, Iran – A preliminary report issued by Iran’s Aircraft Accident Investigation Board on September 30 identifies widening discrepancies between the left and right airspeed indicators as the first anomaly in a sequence that ended in the destruction of the aircraft less than nine minutes later. All three crew members and eight passengers on the Turkish-registered corporate jet were killed when it struck a mountainside at an altitude of about 7,500 feet. The airplane had departed from Dubain's Sharjah Airport in the United Arab Emirates an hour and a half earlier with an intended destination of Turkey’s Istanbul-Atatürk Airport.

Three and a half minutes after a sector handoff at Flight Level 360, the pilot requested and received clearance to climb to FL380. Reaching FL379, the pilot reported a malfunction and began descending to FL370 without waiting for a clearance. Airspeed as measured by radar decreased from 360 to 316 knots during the climb, then to 288 knots as the pilot reported a continued descent to FL340. Five and a half minutes after the initial climb request, the pilot reported being unable to maintain altitude at FL340. A garbled response to the controller’s request to state a requested flight level was the last transmission received from the aircraft, whose airspeed and altitude continued to decrease until it disappeared from radar three minutes later.

Investigators recovered the jet’s flight data and cockpit voice recorders, which revealed that its left- and right-side airspeed indicators began to diverge while it was still in level flight at FL360. This apparently went unnoticed until after the climb was initiated when the discrepancy reached 10 knots, triggering a warning chime. The left ASI initially showed increasing airspeed while the right indicated a continuing decrease; thrust was reduced to idle as the airplane climbed through FL370.

A series of stall warnings and stick shaker activations followed an initial overspeed warning (presumably triggered by the left-side airspeed readings). The flight crew never completed the Quick Reference Handbook’s procedures for resolving unreliable airspeed indications, and after disconnecting the autopilot, the captain ignored the first officer’s repeated admonitions to lower the nose, instead continuing to pull back on the control column until the airplane entered a deep stall that caused both engines to flame out. 

At the time of the accident, the airplane was operating in an area of unstable weather that included thunderstorms, moderate to severe turbulence, and icing conditions predicted to extend up to FL450.

Three Dead in Wanaka Helicopter Accident

Hughes 500, October 18, 2018, Otago, South Island, New Zealand – Two Department of Conservation employees and their pilot were killed when their aircraft crashed shortly after taking off from the Wanaka Airport. A post-crash fire consumed much of the wreckage. The Transportation Accident Investigation Commission has placed the site under a formal Evidence Protection Order.

Pilot Nick Wallis was the younger brother of Matthew Wallis, who was killed on a solo flight less than three months earlier when his Robinson R44 helicopter went down in Lake Wanaka.  Their father, Sir Tim Wallis, founded the popular Warbirds over Wanaka air show and survived 15 crashes of his own, including at least three in helicopters and two in World War II-vintage Supermarine Spitfires.

Coast Guard Suspends Search for Missing Turboprop

Piper PA-31T, October 25, 2018, 100 miles east-southeast of Charleston, South Carolina – Three days after the airplane was reported missing, the Coast Guard suspended its search for a missing Piper Cheyenne. The airplane is now presumed to have crashed into the Atlantic Ocean with no survivors. It was in level cruise flight at FL250 thirty-two minutes into a trip from Andrews, South Carolina, to Governors Harbour in the Bahamas when the pilot reported “an in-flight emergency” and attempted to divert to Charleston. Radar contact was lost just over a minute later.

Five people were on board the twin-engine turboprop, which was built in 1976 and owned by a flight club registered in Wilmington, Delaware. In addition to a Coast Guard HC-130 Hercules airplane and JH-60 Jayhawk helicopter, two Coast Guard cutters, a commercial freight carrier, and a Navy P-3 Orion airplane participated in the search.

Leicester City FC Owner Among Five Victims of Helicopter Crash

Agusta-Westland AW169, October 27, 2018, Leicester, United Kingdom – An hour after his Leicester City football club salvaged a 1-1 tie against West Ham United, team owner Vichai Srivaddhanaprabha, two members of his staff, and two professional pilots were killed when their helicopter spiraled out of control while taking off from the playing field. Srivaddhanaprabha, age 60, was reputed to be the fifth wealthiest person in his native Thailand and was acclaimed by Leicester City’s fans as perhaps the best club owner in England. Also killed were pilots Eric Swaffer and Izabela Roza Lechowicz and staff members Nusara Suknamai and Kaveporn Punpare.

Witness accounts suggest that the helicopter began a steep climb from the playing field, reaching an altitude of about 200 feet before yawing out of control and descending just beyond the stadium wall, where it crashed into a parking lot. While the aircraft’s rotation could be consistent with either a loss of tail rotor effectiveness or a mechanical problem in the tail-rotor drive system, the Aircraft Accident Investigation Branch stresses that its inquiry has only begun. The wreckage has been transported to the AAIB facility at Farnborough, where specialists succeeded in downloading data from its fire-damaged flight recorder.

Two weeks after the accident, thousands of Leicester residents joined in a “5,000-to-1” march to honor the victims. The event took its name from the pre-season odds against the team’s eventual 2016 Premier League championship. (See additional story on page ??)

Final Reports

Precise Cause of Maltese Crash Not Determined

Swearingen SA227 AT, October 24, 2016, Malta International Airport, Kirkop, Malta – In a final report issued October 24, French authorities concluded that a jam or malfunction of the airplane’s flight controls caused it to depart controlled flight during an attempted takeoff, but the extent of impact damage made it impossible to determine which of three possible failures was responsible. The twin-engine turboprop pitched up steeply immediately after liftoff, rolled off the right wing after entering a power-off stall, and crashed in a partially inverted nose-low attitude, killing all five on board. The entire sequence lasted just 10 seconds. Flight testing using a Pilatus PC-7 aerobatic trainer found that the accident trajectory was best approximated by holding aft stick throughout. 

The airplane was operated by the French defense ministry to conduct maritime surveillance, and the investigation was complicated by repeated modifications made to its airframe and flight controls since 1985. The technicians who returned it to service in 2011 after six years of inactivity did not have access to specific documentation of the 1985 modifications, which were carried out under the provisions of the International Traffic in Arms Regulations when the aircraft was initially prepared for security duties.

Spectral analysis and examination of the wreckage ruled out any loss of engine power. The BEA-É’s investigation eliminated multiple possible causes, but was unable to rule out three distinct scenarios. Breakage of the high-frequency radio antenna, a cable running over the aft fuselage to the vertical stabilizer, and its subsequent entanglement in the elevator was considered unlikely but not impossible. An inappropriate pilot response to a malfunction of the stall avoidance system could not be ruled out, particularly in light of evidence that the “SAS Fault” warning light was illuminated at impact. The explanation considered most likely was a jam or breakage of an elevator cable in the section of the fuselage that could not be reconstructed, a hypothesis that could neither be confirmed nor disproved.

Scheduling, Pilot Fatigue Contributed to Gear-Up Landing

Beech 200T, January 27, 2017, West Palm Beach, Florida – Despite statements from both the pilot and copilot asserting that all three gear position indicator lights were green on final approach, the NTSB concluded that the pilot neglected to extend the landing gear until just before touchdown, causing it to collapse under the airplane’s weight when it landed with the gear still in transit. Skid marks from all three tires ended at the airplane’s resting place on the right side of the runway. There was no evidence of any prior mechanical malfunction, but all three legs were found only partially extended.

Damage to the aircraft included strikes to both propellers and penetration of the pressure vessel by a propeller blade. The nose gear actuator was driven up into the gear well and penetrated the nose skin. In his written statement, the pilot acknowledged having woken up “several times” during just over six hours of sleep the night before, and having eaten nothing other than a banana at breakfast the day of the accident. The flight was his seventh of the day for a combined total of 5.2 hours.

Bird Strikes Bring Down HEMS Flight

Bell 407, November 19, 2017, Stuttgart, Arkansas – A collision with a flock of snow geese caused the loss of an EMS helicopter en route to pick up a patient. The pilot and both medical crew members were killed when the Air Methods helicopter hit the bank of a reservoir shortly before 7:00 p.m., two hours after sunset on a moonless night. In its finding of probable cause issued on November 5, the NTSB noted that “multiple bird remains, identified as snow geese, were located in the cockpit and embedded in the pilot's clothing and boot.” 

While the pilot appeared to have been using night vision goggles, the lack of moonlight or ground illumination at the scene made it unlikely he could have seen the birds in time to avoid the collision.  “…It could not be determined if the bird strikes jammed the pilot's controls and/or incapacitated the pilot.”