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
‘Sink Rate’ Warning
Embraer 500 Phenom. Substantial damage. Two serious injuries.
The flight crew was conducting a charter flight with three passengers from San Jose, California, U.S., to Sedona, Arizona, the afternoon of May 25, 2011. The destination airport was at an elevation of 4,830 ft and was reporting visual meteorological conditions with surface winds from 250 degrees at 3 kt.
Nearing Sedona, the crew briefed for a visual approach to Runway 21, which was 5,132 ft (1,564 m) long and had a 1.9 percent downward gradient. The runway’s precision approach path indicator system was out of service. The crew planned to use an approach speed of 120 kt and a landing reference speed (VREF) of 99 kt, according to the report by the U.S. National Transportation Safety Board (NTSB).
Recorded weather data indicate that although the surface wind direction remained steady at 250 degrees, the velocity increased to 5 kt, with gusts to 14 kt, as the crew conducted the visual approach.
“The captain and the first officer reported that during final approach, it felt like the airplane was ‘pushed up’ as the wind shifted to a tailwind or updraft before landing near the runway number markings,” the report said.
A pilot-rated passenger later told investigators that he perceived the airplane was excessively high throughout the approach and that the bank angle during the turn from base to final was greater than 45 degrees.
The report said that the captain told the first officer that he was having difficulty judging the approach. However, when the airplane’s Enhanced Ground Proximity Warning System (EGPWS) generated a “sink rate, pull up” warning on final approach, the captain remarked, “Yeah, I gotcha.”
“Upon touchdown, the captain applied the brakes and thought that the initial braking was effective,” the report said. “However, he noticed that the airplane was not slowing down. The captain applied maximum braking, and the airplane began to veer to the right. He was able to correct back to the runway centerline, but the airplane subsequently exited the departure end of the runway and traveled down a steep embankment.”
The airplane struck a chain link fence and several trees before coming to a stop upright on a 40-degree slope. One passenger and the first officer were seriously injured; two other passengers and the captain escaped injury.
Investigators calculated that if the airplane had touched down at the planned VREF of 99 kt, the required landing distance would have been about 3,112 ft (949 m). However, recorded flight data indicated that airspeed was 124 kt just before the Phenom touched down. At that speed, the required landing distance was 5,624 ft (1,714 m) — or 492 ft (150 m) longer than the runway.
The NTSB concluded that the probable cause of the accident was “the pilots’ unstabilized approach and excessive airspeed during approach, which resulted in an insufficient landing distance to stop the airplane before overrunning the runway.”
Load Miscalculation
Boeing 737-800. No damage. No injuries.
While preparing for a flight with 150 passengers from Canberra, Australian Capital Territory, to Perth, Western Australia, on May 9, 2014, the flight crew received a load sheet showing the aircraft’s takeoff weight as 76,800 kg (169,313 lb). The calculated stabilizer trim setting was 5.5 units.
“Due to the relatively heavy weight of the aircraft, the elevation of Canberra Airport and the high terrain surrounding it, the ‘Flap 1’ setting was selected for takeoff,” said the report by the Australian Transport Safety Bureau. “As ‘Flap 5’ was the normal flap setting for takeoff, the company standard operating procedure when using Flap 1 was that the captain conducted the takeoff.”
The captain later told investigators that the 737 felt nose-heavy during rotation. “To rotate the aircraft and lift off from the runway, the captain found that significant back pressure was required on the control column,” the report said. He maintained steady back pressure on the control column to avoid over-rotation and a tail strike.
Data from the aircraft’s quick access recorder showed that airspeed exceeded the calculated takeoff safety speed (V2) by about 25 kt. “The aircraft climbed at a higher initial climb speed than normal, which resulted in a slightly reduced climb gradient, but the crew did not receive any terrain or other warnings,” the report said. “The crew did not experience any further issues during the flight.”
Examination of the load sheet data showed that the calculated takeoff weight was 3,500 to 5,000 kg (7,716 to 11,023 lb) higher than the actual weight of the aircraft and that the stabilizer trim setting was 1 unit lower than it should have been.
Contributing to the miscalculation was an error in the assignment of the standard adult weight to 87 primary school children who were traveling together on the flight. The ages of the children had not been specified when the flight was booked, and all of the children subsequently had been assigned the standard adult weight (i.e., for those 12 years and older) of 87 kg (192 lb) during check-in.
An unspecified but apparently significant number of the children were younger than 12, however, and should have been assigned the standard weight for those aged 2 to 11 years of 32 kg (71 lb), the report said. Moreover, all 87 children (and the eight adults accompanying them) had been seated in the rear of the passenger cabin.
Door Departs in Flight
Canadair Challenger 600. Substantial damage. No injuries.
About three minutes after departing from Opa-Locka, Florida, U.S., for a positioning flight to Pompano Beach the afternoon of May 23, 2012, the flight crew heard a loud bang and realized that the main cabin door had separated from the airplane.
The pilot declared an emergency and diverted to Fort Lauderdale–Hollywood International Airport, which was about 4 nm (7 km) away. The pilot later told investigators that the noise in the cockpit was so loud that neither he nor the copilot could hear the radios. Nevertheless, the Challenger was landed without further incident.
Examination of the airplane showed that, after opening, the cabin door had struck and damaged the airplane’s fuselage before separating and falling onto a golf course. No one on the ground was hurt.
A ramp security video showed that the cabin door appeared to be closed but then opened momentarily and was closed again as the Challenger taxied from the ramp. “The copilot reported that he re-closed the door because it did not secure on the first attempt,” the NTSB report said. “He could not positively recall seeing the ‘Door Safe’ light illuminated after closing the door.”
Examination of the door revealed nothing that would have precluded normal operation. “An examination of the fuselage revealed a skin puncture that matched the location of the door pull-out handle and is consistent with the door being in the open position when the puncture occurred,” the report said.
The NTSB determined that the crew’s inadequate use of checklists was a contributing factor in the accident. Cockpit voice recorder data showed that “after the sound of the passenger door closing, neither crewmember mentioned the door warning lights,” the report said.
Turboprops
Nosewheel Steering Inoperative
ATR 72-212A. No damage. No injuries.
Inbound from Cork, Ireland, with 48 passengers and two flight attendants, the flight crew conducted an uneventful approach to Runway 23R at Manchester (England) Airport the night of May 15, 2014.
After touchdown, the copilot, the pilot flying, maintained directional control with the rudder, but as groundspeed decreased, the aircraft began veering left, despite use of the nosewheel steering system, said the report by the U.K. Air Accidents Investigation Branch (AAIB).
The commander took control, but she, too, found the nosewheel steering system ineffective in correcting the left turn. “The commander applied brakes and stopped the aircraft on the left side of the runway,” the report said.
Both pilots then noticed fault indications for two of the four multifunction computer (MFC) pushbuttons on the overhead panel. The report noted that the failure of the two MFC modules rendered the master warning, master caution and weight-on-wheels systems inoperative. The latter, in turn, rendered the nosewheel steering system inoperative.
“The pilots reset the MFC modules and all systems were restored, allowing them to taxi the aircraft to its stand without further incident,” the report said, noting that the aircraft manufacturer subsequently issued a service bulletin recommending installation of modified MFCs to preclude a dual failure.
Actuator Maintenance Faulted
Beech King Air 200. Substantial damage. No injuries.
The pilots were conducting a positioning flight from Blois, France, to Paris Le Bourget Airport the afternoon of May 10, 2012. When the landing gear was extended during an instrument landing system approach to Le Bourget’s Runway 27, they heard an unusual noise and saw that the red landing gear warning light was illuminated and the green down-and-locked light was off.
The airport traffic controller told the flight crew that the landing gear appeared to be extended. Nevertheless, the pilots conducted a go-around and retracted the gear.
“Since the red landing gear indicator light was still illuminated, they applied the emergency landing gear extension procedure and found the same symptoms as during the initial approach,” said the report by the French Bureau d’Enquêtes et d’Analyses (BEA). “They carried out an approach to Runway 21 to take advantage of the headwind and in order not to block the main Runway 27 in the event of a problem.”
The nose landing gear collapsed during the landing roll, and the King Air came to a stop on the runway with damage to the forward fuselage and propellers. The pilots were not injured.
Examination of the landing gear system revealed stripped threads in the actuator sleeve that prevented movement of the actuator rod. Investigators found excessive clearance between the threaded sleeve and rod and determined that an unapproved grease had hardened inside the actuator.
The BEA concluded that “the serious incident was caused by improper maintenance of the actuator, leading to accelerated degradation of the threading on the piston rod sleeve.”
Continuing With a ‘Clunk’
Jetstream 4100. Substantial damage. No injuries.
The aircraft was being pushed back from the gate at Brussels (Belgium) National Airport the afternoon of May 28, 2012, when it came to an abrupt halt and the shear pin on the tow bar fractured.
The captain told investigators that neither he nor the copilot had applied the Jetstream’s brakes, and the tug driver had no idea why the aircraft had abruptly stopped, the AAIB report said. A ramp video revealed no sign of an external cause for the abrupt stop.
“The captain asked the ground agent to look to see if there were any signs of damage, and, when the agent said that he could see none, the captain decided to continue with the flight,” the report said.
The flight crew then conducted an uneventful flight to Southampton, England. “During the [subsequent] climb out of Southampton Airport, the crew experienced a ‘low, steady thumping’ below the cockpit after the landing gear was raised,” the report said.
After landing in Aberdeen, Scotland, the captain reported the anomaly, and a maintenance engineer found that the nosewheel was misaligned. The nosewheel was re-aligned and a five-day service check was completed that evening.
The Jetstream was operated on five sectors the next day. During four of the sectors, the crew heard or felt a clunk, which they described as similar to “metal stretching” beneath their feet and like “crushing a beer can,” the report said.
The captain reported the anomalies to the operator’s line maintenance control, but no defects were recorded on the aircraft’s technical log. Despite the captain’s report to maintenance control, the aircraft was not inspected before it departed from Southampton the next day, May 30, for a flight to Aberdeen.
“At approximately 5,000 feet during the climb, a clunking noise was heard by the crew,” the report said. “As with all the preceding sectors flown since the pushback at Brussels [two days earlier], there were no other indications or handling difficulties, and the aircraft continued and landed normally at Aberdeen.
“After landing, it was discovered that the aircraft had suffered damage to its forward keel and to the pressure bulkhead at the rear of the nose landing gear bay. … The aircraft was removed from service and moved to a hangar for a full inspection and evaluation.”
The report noted that the operator subsequently took action “to ensure that problems identified by crews or line engineers will be reported promptly so that appropriate corrective action can be taken.”
Piston Airplanes
Spatial Disorientation
Piper Seneca II. Destroyed. Three fatalities.
The pilot was conducting a volunteer medical transport flight, returning a patient and his spouse from a hospital in Bedford, Massachusetts, U.S., to their home in Rome, New York, the evening of May 24, 2013.
While en route, the pilot altered course several times to avoid areas of moderate to heavy precipitation called to his attention by air traffic controllers. Weather conditions at the destination airport, Griffiss International, included 10 mi (16 km) visibility in light rain, broken clouds at 2,300 ft and 2,800 feet, and an overcast at 3,700 ft.
Nearing Griffiss, the pilot navigated toward an initial approach fix for a global positioning system (GPS) approach. “The controller advised the pilot of areas of light to moderate precipitation along the airplane’s route and suggested a deviation to avoid the precipitation,” the NTSB report said. “However, the pilot elected to stay on course to [the initial approach fix].”
When the Seneca then deviated from course, the controller queried the pilot, who said, “Yeah, I turned the wrong way here. I’m sorry. I thought I loaded the approach correctly, but I didn’t.”
The controller issued a heading to establish the airplane on course, and the pilot acknowledged. The Seneca then entered a descending left turn from 8,000 ft, and the controller was unable to hail the pilot. Before radar contact was lost, the airplane descended 3,700 ft in 36 seconds and accelerated to 240 kt.
Radar data and witness statements indicate that the Seneca broke up before striking terrain near Johnstown, New York. Investigators concluded that the pilot likely had become distracted in programming the GPS receiver while hand flying the airplane in low visibility and turbulence, which led to spatial disorientation and loss of control.
Inadequate Maintenance
Piper Chieftain. Substantial damage. No injuries.
A commercial pilot was receiving a flight competency check when the examiner simulated an engine failure on approach to Nelson (New Zealand) Airport on May 11, 2011. The pilot responded properly while continuing the approach, but the red “unsafe” light remained illuminated when he attempted to retract the landing gear.
The examiner discontinued the exercise, and the pilot cycled the landing gear twice, but the red light remained illuminated. “The pilot could see in the inspection mirror attached to the left engine cowl that the nose leg was turned about 45 degrees,” said the report by the New Zealand Transport Accident Investigation Commission (TAIC).
The pilots then held clear of the airport and consulted maintenance personnel by radio while attempting, unsuccessfully, to resolve the problem. Ultimately, they declared an emergency and returned to Nelson Airport for landing. The examiner shut down both engines before the pilot lowered the nose on touchdown. The propellers and the nose cone were substantially damaged during the landing, but the pilots were not hurt.
Investigators found that the nose landing gear had a history of defects, including failures to retract and extend. The TAIC concluded that “the nose landing gear jammed [during the check flight] as a result of wrong parts and incorrect maintenance over a number of years which allowed the landing gear to turn too far when full rudder was applied during the [simulated engine failure].”
Helicopters
Uncontrolled Rotation
Bell 206B. Substantial damage. Two fatalities, one serious injury.
The JetRanger had been chartered to track discarded caribou radio collars the morning of May 29, 2013. The pilot was maneuvering to land about 75 nm (139 km) north of Fort McMurray, Alberta, Canada, when the helicopter entered an uncommanded right rotation and descended into a wooded area. One passenger and the pilot were killed; the other passenger was seriously injured.
The Transportation Safety Board of Canada (TSB) ascribed the accident to loss of tail rotor effectiveness (LTE). “LTE is not related to an equipment or maintenance malfunction and may occur in all single-rotor helicopters at airspeeds less than 30 knots,” the TSB report said. “It is the result of the tail rotor not providing adequate thrust to maintain directional control.”
LTE typically occurs when a helicopter is operated at high power and low airspeed with a tail wind or a left crosswind, the report said. Recorded GPS data showed that the JetRanger was in a left turn with a groundspeed of 3 kt when it was exposed to a tail wind condition 19 ft above ground level.
Ineffective Dampers
Schweizer 296C-1. Substantial damage. No injuries.
A student helicopter pilot prepared to depart on a local solo flight from Chesterfield, Missouri, U.S., the afternoon of May 26, 2012. As he increased power for takeoff, the helicopter began to shake.
“He reduced engine power, but the oscillations became stronger and ultimately uncontrollable, resulting in substantial damage to the main and tail rotor blades, partial separation of the main rotor mast from the aft fuselage structure and partial separation of the tail boom from the fuselage,” the NTSB report said.
The report said that the Schweizer had encountered a phenomenon called ground resonance, “which develops when the rotor blades move out of phase with each other and cause the rotor disc to become unbalanced.”
Investigators determined that the ground resonance had been initiated by landing gear dampers that did not meet the manufacturer’s specifications. The aft dampers, which had been installed about a month before the accident, were overcharged. The forward dampers, which had not been replaced, were undercharged.