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.
Jets
Deicing Not Available
Beech Premier 1A. Destroyed. Two fatalities, one serious injury.
The aircraft had been exposed to high humidity and to ambient temperatures at and slightly below freezing while parked outside all night at the Annemasse airport in eastern France. The resulting frost accumulation on the aircraft caused an aerodynamic stall from which the pilot was unable to recover during takeoff the morning of March 4, 2013, according to the Bureau d’Enquêtes et d’Analyses (BEA).
The aircraft was destroyed by the impact and subsequent fire. The pilot and a passenger occupying the right front seat were killed; a passenger seated in the rear of the cabin was seriously injured.
“The investigation showed that the pilot’s insufficient appreciation of the risks associated with ground-ice led him to take off with contamination of the critical airframe surfaces,” the BEA’s report said.
The pilot, 49, was employed by an aircraft charter and management company to fly the Premier, which is certified for single-pilot operation. He had logged 1,386 of his 7,050 flight hours in the light business jet.
The pilot apparently had intended to fly his passengers to Geneva, Switzerland, the previous evening, but a landing slot (reservation) was not available there. Nor were slots available at commercial airports in close proximity to Geneva. So, he positioned the aircraft to the Annemasse airport, which was uncontrolled and had no deicing facilities.
Whether the pilot detected the frost during his preflight inspection of the aircraft is unknown. The report said that the accumulation likely was thin and would have been difficult to detect without a tactile inspection. “In any case, he was not inclined to remove the layer of ice before undertaking the flight,” the report said, noting that the proper action would have been to delay the flight until the frost melted.
Those who witnessed the takeoff said that the aircraft entered a high nose-up pitch attitude after liftoff and climbed slowly while banking steeply left and right. Recorded data indicate that a stall warning sounded in the cockpit and the enhanced ground-proximity warning system (EGPWS) generated several “bank angle” warnings.
About 15 seconds after liftoff, the main landing gear struck the roof of a house to the right and about 500 m (1,641 ft) beyond the runway threshold. The aircraft then descended into a garden behind other houses. No one on the ground was hurt. The surviving passenger was thrown from the wreckage and rescued by passersby.
A data search conducted during the investigation revealed 45 other takeoff accidents between 1989 and 2012 involving aircraft with wings contaminated by frost or ice. More than two-thirds of the aircraft had not been deiced before takeoff, the report said.
Based on the findings of the investigation, the BEA issued several recommendations, including recurrent pilot training on the effects of airframe contamination, development of contamination-detection systems and installation of deicing facilities at all airports in France (ASW, 6/14).
Cascade of Systems Failures
Boeing 747-400. Substantial damage. No injuries.
Shortly after departing from London (England) Heathrow Airport with 340 passengers and 22 crewmembers for a flight to Malaysia the night of Aug. 17, 2012, the flight crew felt and saw indications of vibration of the no. 2 engine, followed by a loud bang and the message “ENG FAIL” on the engine indicating and crew alerting system (EICAS).
The crew shut down the no. 2 engine and received clearance from air traffic control (ATC) to hold at 19,000 ft above the North Sea to jettison fuel in preparation to return to Heathrow for a landing, said the report by the U.K. Air Accidents Investigation Branch (AAIB).
The crew decided to conduct an autoland approach to Heathrow’s Runway 09R. The aircraft was established on the localizer at 3,000 ft when the master warning system activated. The three autopilots disengaged, all the cockpit displays and lights flickered, and many failure messages appeared on the EICAS. The autothrottles then disengaged as the 747 intercepted the glideslope.
“The pilots decided that, with the runway in sight, the safest course of action was to continue the approach rather than manage the failures,” the report said, noting that the standby instruments continued to operate normally. “The commander continued the approach, manually flying the aircraft to a safe landing.”
The engine and electrical system problems apparently were not directly related. Examination of the no. 2 engine, a Pratt & Whitney PW4056 that had accumulated 27,505 hours and 2,857 cycles since its last overhaul, revealed that spalling of the ceramic coating on the high-pressure turbine’s second-stage outer air seal had caused a portion of the seal to separate and strike a turbine blade. “Subsequent damage from the liberated blade resulted in imbalance of the high-speed rotor, leading to engine vibration,” the report said.
Investigators determined that the electrical system faults were triggered by a latent mechanical failure of a bus tie breaker. The failure occurred when all three autopilots were engaged for the autoland approach. The report said that the investigation prompted the aircraft manufacturer to develop procedures for detecting signs of impending failures of bus tie breakers.
Slam-Dunk Approach
Airbus A319. No damage. No injuries.
Based on the latest automatic terminal information system broadcast, the flight crew planned for an approach and landing on Runway 29 at the Tunis (Tunisia) Carthage airport the morning of March 24, 2012. The aircraft was inbound on a scheduled flight from Paris.
The descent from cruise altitude, Flight Level 350 (approximately 35,000 ft), was performed with a relatively low selected vertical speed of 1,000 fpm, said the BEA report. During the descent, an en route controller confirmed that Runway 29 was in use at Tunis.
However, as the A319 neared the 3-degree glide path for Runway 29, an approach controller told the crew that Runway 19 was active and requested that they conduct a direct approach to that runway. The crew acceded to the request and was cleared for the instrument landing system approach to Runway 19.
At the time, the aircraft was 33 nm (61 km) from the runway threshold and descending through 20,700 ft — about 10,000 ft above the 3-degree glide path to the runway — at 276 kt. The captain, the pilot flying, engaged the autoflight system’s “open descent” mode (which adjusts pitch attitude to maintain the selected airspeed), selected an airspeed of 300 kt and extended the air brakes, causing the descent rate to increase to 5,000 fpm.
The A319 was 13.5 nm (25 km) from the runway and descending through 10,000 ft when the captain disengaged the autopilot and called for extension of the landing gear. About 8 nm (15 km) from the runway, the aircraft was on the localizer but about 3,400 ft above the glideslope and descending at 4,400 fpm.
The aircraft subsequently was 1,000 ft above the glideslope, descending at 4,400 fpm and 240 kt, when the copilot told the controller that they were “a little above the path” and requested a 360-degree right turn, the report said. The controller told the copilot to repeat the request.
During this time, the aircraft had descended below the glideslope. The EGPWS generated “sink rate,” “pull up” and “too low, terrain” warnings. The A319 was about 398 ft above the ground when the captain initiated a go-around. The crew then flew a visual pattern and landed the aircraft without further incident.
BEA concluded that the unstabilized approach was caused by “the crew’s decision to undertake and continue an approach that required a glide path interception from above in conditions that did not offer a high chance of success.”
Turboprops
Elevator Separates on Takeoff
Piaggio P180. Substantial damage. No injuries.
The Avanti was 23 minutes behind schedule when it departed from Camarillo, California, U.S., early the morning of July 28, 2012, for a positioning flight to San Diego. The two passengers waiting for the airplane at San Diego were upset by the delay, said the report by the U.S. National Transportation Safety Board (NTSB).
After landing in San Diego, the captain performed only a partial preflight inspection of the airplane, and the first officer did not inspect it at all before they departed for a flight to Henderson, Nevada.
“The crew reported that they had a non-eventful departure and flight from San Diego, and that the captain noticed that more back-pressure on the flight controls was required for a normal landing upon arrival at Henderson,” the report said.
The pilots performed a post-flight inspection of the airplane and found that the left elevator was missing. Three days later, Camarillo Airport personnel found the elevator in the grass near the runway from which the Avanti had departed.
Examination of the airplane revealed that the self-locking nuts on the right elevator’s hinges were only finger-tight. Investigators found that both elevators had been removed and reinstalled during maintenance compliance with an airworthiness directive (AD) 54 days earlier.
“It is likely that all four sets of attachment hardware for both elevators were not properly torqued during the AD maintenance,” the report said. “Additionally, 26 days before the event, a phase inspection was completed, during which the elevator should have been visually inspected and functionally checked. The airplane had flown 158.9 hours with loose elevator attachment hardware before the two sets of bolts on the left elevator had completely worked their way out of the hinges and the elevator departed the airplane.”
Moreover, the report said that the cockpit voice recording showed that the pilots had experienced unusual pitch control responses during all of the departures and landings the morning of the incident. “The flight crew could have identified the missing elevator during a preflight inspection at the intermediate airport, yet they decided to continue the flight despite the pitch control problems [they had] experienced.”
Rudder Jams on Approach
ATR 72-212A. Minor damage. No injuries.
The aircraft was en route with 27 passengers and four crewmembers from Tampere, Finland, to Helsinki the afternoon of Aug. 19, 2012. When the flight crew reduced airspeed below 185 kt during the approach to Runway 22L at Helsinki, they received a visual warning that the rudder travel limitation unit (TLU) had malfunctioned.
The aircraft was in visual meteorological conditions (VMC) and about 6 nm (11 km) from the runway when the warning occurred. The captain continued flying the approach while the first officer consulted the quick reference handbook (QRH).
“The flight crew did not have enough time to interpret the QRH’s instructions for a TLU fault [and] failed to switch on the TLU’s standby system,” said the English translation of the report by the Safety Investigation Authority of Finland.
The first officer was still reading the QRH when the aircraft descended below 500 ft. Although the airline required a go-around at this point because the approach technically was not stabilized, the captain decided to land the aircraft. He did not provide information about the situation to the cabin crew, and they prepared the cabin and passengers for a normal landing.
Investigators later found that the main TLU electric actuator had broken, preventing the TLU system from changing from the high-speed mode to the low-speed mode when airspeed was reduced for the approach. The fault limited rudder travel to about 4 degrees.
As a result, the captain did not have sufficient rudder authority to correct a right yaw induced by asymmetric thrust as he reduced power below flight idle shortly after touchdown. (The report noted that such asymmetries are normal in the ATR 72 and are usually corrected easily by rudder aerodynamic control.)
The captain applied wheel braking, but the aircraft veered off the right side of the runway. “The captain, using nose-wheel steering, managed to steer the aircraft back onto the runway,” the report said.
A belly-mounted avionics cooling fan, a landing gear fairing and a tire were damaged during the excursion. “The damage was not extensive because … the ground was sufficiently hard and level to support an aircraft of this weight class,” the report said. “The serious incident did not result in any injuries to persons or damage to runway equipment.”
The report concluded that the flight crew had “inadequate system awareness” and that the QRH did not provide clear instructions for using the TLU’s standby system. “The haste caused by the decision to continue the approach allowed too little time for the flight crew to sufficiently explore the difficult-to-read QRH.”
Piston Airplanes
Fatal Search for an Airport
Piper Apache. Destroyed. Three fatalities.
The pilot departed in VMC from Sullivan, Indiana, U.S., about 0135 local time on Aug. 8, 2011, to fly a passenger to Steubenville, Ohio, so that she could be with a relative who was to undergo surgery. The pilot knew that weather conditions at the destination were forecast to deteriorate, and although instrument-rated, he conducted the flight under visual flight rules with ATC flight-following services.
A controller provided radar vectors to the airport, but the pilot was unable to locate it due to fog. He told the controller that he would divert to Columbus, Ohio, about 100 nm (185 km) southwest but then decided to fly to an airport closer to Steubenville. When informed that the runway lights there were out of service, the pilot decided to try Millersburg, Ohio, about 58 nm (107 km) northwest.
“On the approach to the third airport, the pilot was initially unable to see it because fog was in the area and the airport beacon was out of service,” the NTSB report said. “Further, he was using the wrong frequency to activate the pilot-controlled runway lights.”
After receiving the correct frequency from ATC, the pilot reported that he had the runway in sight. A witness heard the Apache make three passes over the airport from different directions before it struck terrain at 0455.
“It is likely that the pilot was unable to see the airport and continued to fly in the vicinity [and] search for the runway, and [he] subsequently lost situational awareness and struck trees,” the report said.
Unexplained Overrun
Beech B60 Duke. Destroyed. Three fatalities.
One witness said that the engines sounded normal during the takeoff roll at Sedona, Arizona, U.S., the morning of July 26, 2012, but the airplane appeared to accelerate slowly. However, three other witnesses said that the engines “did not sound right” during the run-up and takeoff, said the NTSB report.
Density altitude was about 7,100 ft at the airport, which is at an elevation of 4,830 ft. The Duke was within weight and balance limits, and investigators calculated a takeoff roll of 2,805 ft (855 m) and an accelerate-stop distance of 4,900 ft (1,494 m).
“Directional control was maintained, and at midfield, the airplane had still not rotated,” the report said. “As the airplane continued down the 5,132-ft [1,564-m] runway, it did not appear to be accelerating, and about 100 yards [91 m] from the end of the runway, it appeared that it was not going to stop.”
The Duke overran the runway and traveled down a deep gully. The airplane was destroyed by the impact forces and a post-accident fire. The report said that examination of the airframe and engines revealed no signs of any malfunctions or failures that would have precluded normal operation of the airplane.
NTSB concluded that the probable causes of the accident were “the airplane’s failure to rotate and the pilot’s failure to reject the takeoff.”
Helicopters
Unmarked, Uncharted Wire
McDonnell Douglas 369E. Destroyed. Two serious injuries.
The pilot was flying the drug-enforcement observation helicopter about 500 ft above a valley floor near Jackson, Kentucky, U.S., the morning of July 29, 2013, when the main rotor head struck a utility wire.
“The pilot initiated an emergency descent, but he had limited control of the helicopter, and it collided with the valley floor,” the NTSB report said.
The wire was among four that had provided electrical power to a mine. “Because the mine had been closed for a long time, no one had reported the utility wire[s] to the Federal Aviation Administration for addition on the appropriate aeronautical chart,” the report said. Three of the wires had deteriorated and fallen.
Fire Traced to Instrument Panel
Eurocopter AS350B. Destroyed. No injuries.
The pilot was conducting a private, solo flight from Milton Keynes, England, to Manchester the evening of Aug. 3, 2013, when he detected an acrid odor and saw smoke and flames emanating from behind the lower left side of the instrument panel.
The pilot turned the master switch off, but smoke continued to fill the cockpit, affecting his breathing and vision. “In order to counter this, he opened the cabin door, and the smoke cleared enough for him to identify a suitable open field and carry out a successful landing,” said the AAIB report.
The pilot was able to exit the helicopter before it was destroyed by fire in the field near Fenny Drayton, Leicestershire.
“Owing to the extensive fire damage, it was not possible to establish what initiated the fire,” the report said. “However, given the description of the events by the pilot, it is most likely to have been related to the electrical system components or wiring behind the left side of the instrument panel.”
Distraction Triggers Control Loss
Robinson R44. Substantial damage. No injuries.
Shortly after departing from Tallahassee, Florida, U.S., at 0330 the morning of July 4, 2012, for a positioning flight, the pilot saw the clutch actuator warning light illuminate. “The pilot reached for the circuit breaker box under the passenger seat to pull the clutch circuit breaker and then felt ‘light in the seat,’” the NTSB report said.
The helicopter had entered a rapid descent. The pilot pulled the collective control, but the R44 continued to descend until it struck a lake. The pilot exited the helicopter and swam to shore.
Examination of the helicopter revealed nothing that would have precluded normal operation, and investigators were unable to determine why the clutch actuator light illuminated.
“It is likely that, while reaching down in an attempt to pull the clutch circuit breaker with a lack of outside visual references due to the night conditions and the helicopter’s location over a lake, the pilot made an inadvertent cyclic input that resulted in the helicopter’s nose-down attitude and subsequent descent,” the report said.
NTSB concluded that fatigue might have been a contributing factor. The pilot had driven for six hours and had flown about 3.5 hours before launching the positioning flight.