Recently Released TSB Reports

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The following summaries are extracted from final reports issued by the Transportation Safety Board of Canada (TSB). They have been de-identified and include the TSB’s synopsis and selected findings. Some excerpts from the analysis section may be included, where needed, to better understand the findings. For the benefit of our readers, all the occurrence titles below are now hyperlinked to the full TSB report on the TSB Web site. —Ed.

TSB Final Report A08P0241—Aerodynamic Stall—Collision with Terrain

On August 3, 2008, at 07:08 Pacific Daylight Time (PDT), a Grumman G-21A Goose amphibian operating as a charter flight departed Port Hardy Airport, B.C., on a VFR flight to Chamiss Bay, B.C. At 08:49 and again at 09:08, the flight follower attempted to contact the tugboat meeting the aircraft at Chamiss Bay by radiotelephone but was unsuccessful. At 09:53, the flight follower reported the aircraft overdue to the joint rescue coordination centre (JRCC) in Victoria, B.C., and an aerial search was initiated. A search and rescue (SAR) aircraft located the wreckage on a hillside near Alice Lake, approximately 14 NM from its departure point. A post-crash fire had ignited. The emergency locator transmitter (ELT) had been destroyed in the crash and did not transmit. The accident happened at about 07:22. Of the seven occupants, the pilot and four passengers were fatally injured, one passenger suffered serious injuries, while another suffered minor injuries. The two survivors were evacuated from the accident site at approximately 16:10.

amphibian plane crashed in woods

Analysis

Nothing was found to indicate that there was any airframe or system malfunction before or during the flight.

The weather at Port Hardy was VFR, consistent with the forecast. Even though the ceiling was at 1 000 ft AGL, the visibility was very good at 20 SM. The pilot likely expected the clouds observed along the mountain ridge to the south and southwest of the airport to be patchy as per the graphic area forecast (GFA). Knowing that the weather at Chamiss Bay was sunny with good visibility, the pilot likely considered the clouds on the mountain tops as local phenomena, which he could negotiate to successfully cross the ridge. This assessment of the weather likely led the pilot to choose the direct route.

As the flight proceeded towards the higher terrain, the pilot likely discovered that the cloud coverage was more extensive than observed from the ground, with hilltops obscured. Considering that the pilot was not instrument rated and the aircraft was not certified for IFR flight, he would have rejected the idea of climbing into the clouds and proceeding under IFR. Instead, his options would have been to turn around (either return to Port Hardy or double-back to follow the low-level route along the coast), continue towards a pass that would allow him to cross the ridge into better weather, or try to fly above the clouds on the ridge and below the overcast ceiling. It is likely that he found the weather conditions at the pass to be unsuitable and instead elected to climb above the ridge and below the overcast ceiling. The climb began, gently at first, then more abruptly with what was probably full climb power. With clouds obscuring the ridge, the pilot would have recognized the risk of flight into terrain if he allowed the aircraft to penetrate the clouds. During the climb, the aircraft reached the stall angle and the left wing dropped. This caused the aircraft to lose considerable height. The pilot was able to recover from the stall in a nose-down attitude. Before he could raise the nose to the level position, the aircraft struck the tops of several trees, which slowed the aircraft before it fell to the ground.

The failure of the ELT to activate upon impact significantly increased the risk to survivors. In this case, the ELT was destroyed on impact, which hindered SAR efforts to locate the downed aircraft.

It is unknown whether the pilot attempted to contact flight following in the moments before the accident. The fact that the aircraft could not be reached did not alarm the company flight following because it was not unusual for aircraft to be out of radio range of the flight watch facility. It was also not unusual for pilots to land somewhere along their route to wait for weather to improve before continuing to destination. As a result, the company did not notify the Victoria JRCC until 09:53, about one hour after the aircraft’s expected arrival time back at Port Hardy. The lack of an effective means of tracking the flight progress led to delays in SAR action. These delays increased the risk to survivors.

Findings as to causes and contributing factors 

  1. While likely climbing to fly above a cloud-covered ridge and below the overcast ceiling, the aircraft stalled aerodynamically at a height from which full recovery could not be made before striking the trees.

  2. The aircraft broke apart upon impact, and electrical arcing from exposed wires in the presence of spilled fuel caused a fire that consumed most of the aircraft.

Findings as to risk 

  1. While the company’s established communications procedures and infrastructure met the regulatory requirements, they were not effective in ascertaining an aircraft’s position and flight progress, which delayed critical SAR action.

  2. The ELT was destroyed in the crash and failed to operate, making it difficult for SAR to find the aircraft. This prolonged the time the injured survivors had to wait for rescue and medical attention.

Safety action taken 

Operator
After conducting a risk assessment of its routes, the operator selected the latitude system, which provides an ELT-like function. This system has been installed on all company floatplanes.

The operator has recognized the need for a tailored pilot decision making (PDM) course for its subpart 703 VFR floatplane pilots. A flight training unit has been contracted to create a special PDM course for single-pilot float operations, and the company has worked closely with them to develop the course outline. The course is to consist of one day of classroom instruction and one of practical instruction in a simulator. Emphasis will be on cockpit resources for a single pilot, decision-making processes, physiological and psychological effects, GPS issues, and a review of relevant accidents.

The operator has instituted VFR line checks as part of its monitoring and quality control, which are similar to its subpart 704 and subpart 705 operations.

The operator reviewed its safety management system (SMS) manual and included revised risk assessment procedures. It also reviewed accident investigation procedures and contracted with outside consultants to conduct three days of accident investigation and risk assessment training for company management and supervisors.

TSB Final Report A08W0162—Controlled Flight Into Water

On August 9, 2008, the pilot and sole occupant of the Bell 206B helicopter was departing from its base on the west bank of the Yukon River at Carmacks, Y.T., at about 07:00 Pacific Daylight Time (PDT). After lifting off the pad into a low hover facing away from the river, the pilot pedal-turned through 180 degrees to the left and departed over the river on an easterly heading. Shortly thereafter, there was a loud impact and splash, and pieces of wreckage drifted down the river. A pilot and two aircraft maintenance engineers (AME), who were preparing a Bell 205 helicopter for flight from an adjacent pad, immediately started the aircraft, tracked the aft fuselage section that was floating down the river, and assisted in its recovery. The submerged forward fuselage section, engine, and transmission were not recovered until located by side-scan sonar on August 17, 2008. The pilot drowned.

piece of helicopter fuselage

Analysis

A normal helicopter departure requires the pilot to lower the nose of the aircraft slightly and to increase collective pitch to initiate forward flight and begin to climb. During the departure/climb phase of the flight, any problems, such as a loss of power, would be countered by raising the nose to initiate a flare to slow the helicopter for landing. In this occurrence, the pilot accelerated to about 40 knots through translation in a level or slightly nose-down attitude, flying in a straight line for about 14 seconds until impact. Engine and rotor sounds were normal, and wreckage examination did not reveal mechanical or control anomalies that would have prevented the helicopter from accelerating and climbing.

The pilot had lifted off facing away from the sun and then had turned to face directly into the sun as he began forward flight. A more common departure procedure in a single-engine helicopter would be to turn 90 degrees to the left or right, to accelerate and climb along the riverbank before turning out over the water. This would decrease the risk of having to ditch in the fast-flowing river in case of an engine or power train failure.

The sun was at a low angle above his horizon and the bright sunlight was compounded by its strong reflection off the water. The resulting glare on and through the windscreen would have obscured the pilot’s forward vision before his eyes could react to the sudden brightness, especially because he was not wearing sunglasses. The bright light would also have obscured the instrument panel in shadow, depriving the pilot of backup instrument information.

During this period, the helicopter would have been accelerating. Somatogravic illusion would likely have caused the pilot to sense that the aircraft was climbing at about an 8.5-degree angle when, in fact, the aircraft was descending slightly until impact.

Findings as to causes and contributing factors 

  1. The pilot’s forward vision was obscured by the bright sunlight and glare from the surface of the river.

  2. The pilot most likely lost visual reference with terrain and descended into the surface of the river.

  3. It is likely that the pilot did not realize that the helicopter was descending instead of climbing due to somatogravic illusion.

Finding as to risk

  1. Departing over water, instead of accelerating and climbing along the shoreline, increases the risk of losing visual references and the risk of ditching into water in the event of a power train failure.

TSB Final Report A08A0106—Loss of Control—Stall/Spin

On August 18, 2008, the amateur-built Denney Kitfox IV, a single-engine tail-wheel configured aircraft, had departed from a private airstrip on a local flight near the community of Huntington, N.S. The aircraft flew in the local area for approximately 15 minutes until a local resident heard the sound of impact at approximately 11:30 Atlantic Daylight Time (ADT). There were no eyewitnesses to the accident. Within minutes of the impact, the aircraft was found along the edge of the access road to the pilot’s residence. The pilot was critically injured and was transported to hospital. The aircraft came to rest directly along the extended centreline of Runway 20 of the private airstrip, about 275 ft beyond the departure end. The aircraft was destroyed and there was no fire.

aircraft impact orientation - nose down - on edge of runway

Aircraft impact orientation

Analysis

With no eyewitness accounts and without the pilot being able to recall any significant moments of the accident flight, investigators had to rely on an analysis of information from the accident site and the pilot’s experience/currency to determine the most likely cause of the accident.

The aircraft’s impact orientation indicates there was a departure from controlled flight, resulting from a stall/spin scenario. The stall/spin scenario was not a result of a structural failure in flight, no engine or control anomalies were noted during the wreckage examination, the weather was determined not to be a factor, and a stall/spin scenario would not have been deliberately initiated at such a low altitude. The most likely scenario leading to the accident would be the pilot’s lack of currency and inexperience on type, leading to a failure to detect the symptoms of an approaching stall and apply the appropriate corrections in a timely manner, resulting in an unintentional stall/spin situation. Once the aircraft had departed controlled flight, there was insufficient altitude to recover. Within seconds, the flight profile would have changed from horizontal to vertical with the aircraft contacting the ground shortly after.

The pilot was inexperienced on this aircraft type and was not very familiar with the symptoms that it would display prior to a stall. The pilot was inexperienced on tail-wheel aircraft handling and had not flown this aircraft from his airstrip prior to this flight. During the course of a practice touch-and-go, the pilot would have been preoccupied with controlling the aircraft directionally on the ground and initial climb out. It is possible that due to this distraction, the pilot’s unfamiliarity with the aircraft, and the lack of a stall warning device, the decreasing airspeed in the climb and the approaching stall symptoms may have been missed. With a low airspeed, a high angle of attack, and the engine at climb power, if a stall occurred, a right wing drop and associated spin is likely. Based on the location of the crash site, the proximity of the aircraft to the surrounding trees and power wires, an indication of right-hand rotation at impact, and the aircraft’s orientation make this scenario the most plausible.

The onset of the stall would likely have been abrupt and without warning, leaving little time or altitude to effect a recovery. In this accident, if the aircraft was so equipped, a stall warning horn may have sounded early enough to give the pilot time to take action to avoid the stall.

The pilot survived his extensive injuries as a result of timely medical care because a local resident heard the impact and quickly located the accident site.

Findings as to causes and contributing factors 

  1. The pilot was inexperienced on the aircraft type and had not flown it in the previous ten months; he may have been unfamiliar with the symptoms of an impending aircraft stall and the proper corrective action.

  2. The aircraft was operating at the departure end of Runway 20 at low altitude when it stalled and entered an incipient spin from which there was insufficient height to recover before it collided with terrain.

Findings as to risk 

  1. In the absence of a stall warning device on amateur-built aircraft, pilots may not be able to detect an impending stall.

  2. With an emergency locator transmitter (ELT) switch in the OFF position during an aircraft accident, it is possible that a seriously injured pilot might succumb to injuries before help arrives.

TSB Final Report A09W0037—Risk of Collision

On March 6, 2009, a Bombardier CL-600-2D15 had been cleared to the Whitehorse International Airport, Y.T., for an approach. Whitehorse International Airport is located in a mountainous, non-radar environment and at the time of the occurrence a winter snow storm was moving through the area. An instrument landing system (ILS) approach to Runway 31L was hand-flown by the captain using the head-up guidance system (HGS). On initial contact, no current position report or estimate for the airport was given by the crew or requested by the tower. Whitehorse tower requested the aircraft to report 10 mi. final, and advised that sweeping was in progress. The crew acknowledged the request. The aircraft landed approximately nine minutes later, at 13:50 Pacific Standard Time (PST), after flying over two runway snow sweepers operating on the portion of the runway located before the displaced threshold for Runway 31L. A position report was not provided to Whitehorse tower at 10 mi. final and no landing clearance was issued. The weather report issued 10 minutes after landing reported the ceiling as vertical visibility 600 ft, visibility of 3/4 SM in light snow and drifting snow with a runway visual range (RVR) of 4 500 ft.

Artist’s impression of risk of collision event, as the CL-600 overflew the two snow sweepers on final approach
Artist’s impression of risk of collision event, as the CL-600
overflew the two snow sweepers on final approach

Findings as to causes and contributing factors 

  1. Communication transfers between the Edmonton area control centre (ACC) and Whitehorse tower did not take place in accordance with the Inter Unit Arrangement between the two facilities, resulting in a wide variation in aircraft position at the time of the communication transfer.

  2. The relieving tower controller did not establish the position of the CL-600 on initial contact. The relieving tower controller assumed that the CL-600 was 45 NM from the airport and this resulted in an inaccurate assessment of the flight time left prior to the aircraft’s arrival.

  3. Information that the CL-600 would have to hold was not communicated to the relieving tower controller during the position transfer briefing and the flight progress strip did not contain holding information, a fix reference or an airport ETA for the CL-600. This reduced the opportunity for the relieving tower controller to establish accurate initial situational awareness and allowed the 45 mile from airport assumption to persist.

  4. The mental models of the flight crew and the Whitehorse tower controller were not aligned; the flight crew believed the Whitehorse controller knew their location when tower communication was established and their current position was not requested.

  5. The first officer handled all aircraft-ATC communications following the decision to conduct an HGS approach, and several communication errors subsequently occurred. The pattern of communication errors was consistent with task saturation.

  6. Whitehorse tower’s instruction to call 10 mi. final became a prospective memory task with no relevant memory reminder cue for the first officer. As well, the significance of the instruction to report 10 mi. final as a cue for the relieving tower controller to remove the trucks from the runway and issue the landing clearance was not recognized by the flight crew; thus the call was missed.

  7. The relieving tower controller relied entirely on the instruction for the CL-600 to report 10 mi. final to establish situational awareness prior to the aircraft entering the Whitehorse control zone. When the crew did not comply with the instruction to report 10 mi. final, the relieving tower controller did not receive the necessary trigger to issue a landing clearance.

  8. The flight crew’s perception that the approach clearance meant there was no equipment on the runway demonstrated a misunderstanding of the difference between an approach clearance and a landing clearance relative to the status of the active runway.

  9. The flight crew’s perception was that there were no vehicles or obstructions in the touchdown zone. The captain, believing that the trucks were holding until the flight landed, elected to land without the flight receiving a landing clearance.

Findings as to risk 

  1. There were differences in how the relieving tower controller, compared to other Whitehorse tower controllers, routinely handled IFR arrivals which created the potential for situational ambiguity between controllers, especially during position transfers.

  2. A pilot flying’s (PF) attention resources may be fully occupied, due to moderate to high perceived workload, when hand-flying an approach using the HGS under instrument meteorological conditions (IMC), resulting in a significantly reduced capacity to monitor radio communications and provide support to the pilot not flying (PNF).

  3. To properly assess applicants for pilot positions, operators need access to information on experience and performance that is factual, objective, and (preferably) standardized. Transport Canada pilot records are not available to employers—this may lead to the appointment of pilots to positions for which they are unsuited, thereby compromising safety.

  4. The crew had no assurance that other maintenance vehicles were not on the runway beyond its field of view. Had there been another vehicle on the unseen portion of the runway, the decision to continue the landing would have exacerbated the risk of collision.

Other findings 

  1. The cockpit voice recorder (CVR) was not secured following the incident and the incident was not reported to the TSB by the quickest available means, which resulted in the loss of beneficial investigative evidence.

  2. Wide area multilateration and automatic dependent surveillance-broadcast (ADS-B) technology may be useful tools to enhance tower controller situational awareness of traffic and reduce the risk of collision between arriving aircraft and ground vehicles in non-radar environments.

Safety action taken 

NAV CANADA 
On May 15, 2009, as a result of this incident, NAV CANADA issued Whitehorse Control Tower Operations Letter 09-04. The letter stated that the following procedure will be in effect:

On initial contact and in addition to the usual information (e.g. aircraft identity, type and altitude) the following must also be obtained from pilots:

  • position report from VFR and IFR aircraft which might include a VFR reporting point, an IFR navigation aid or distance (DME or GPS) back from an IFR navigation aid and,
  • from IFR aircraft the pilot’s ETA for the airport.

Transport Canada 
Transport Canada has undertaken, through its National Operations Branch Oversight Plan, to monitor Whitehorse tower and other units within uncontrolled or non-radar environments, in order to identify possible systemic issues related to communication protocols and the adherence to those protocols by all air traffic controllers.

Operator 
The operator has taken the following safety actions:

  • Increased emphasis on HGS usage for the CRJ fleet. On November 1, 2009, the CRJ aircraft operating manual was modified to state that the captain shall utilize the HGS, when serviceable, for all phases of flight as both the PF and PNF.
  • On June 11, 2010, the new Section 7.3.6 of the Flight Operations Control Manual (New Hire-Line Pilot Employment Follow-Up Procedure) was published. This procedure describes the process to evaluate the performance of new pilots and validate the effectiveness of training.
  • Recurrent training on uncontrolled airport operations has been added as a pre-briefing item. The training will include procedures published in the Transport Canada Aeronautical Information Manual (TC AIM) and will also include reference to the forthcoming language in the company operations manual (COM) with respect to supplemental information that must be communicated to air traffic services (ATS).

TSB Final Report A09A0016—Main Gearbox Malfunction/Collision with Water

(* This is a major accident report and only the summary and findings as to causes and contributing factors are listed in the ASL. Readers are encouraged to read the complete report on the TSB Web site.)

On March 12, 2009, at 09:17 Newfoundland Daylight Time (NDT), a Sikorsky S-92A departed St. John’s International Airport, N.L., with 16 passengers and 2 flight crew, to the Hibernia oil production platform. At approximately 09:45, 13 minutes after levelling off at a flight-planned altitude of 9 000 ft above sea level (ASL), a main gearbox oil pressure warning light illuminated. The helicopter was about 54 NM from the St. John’s International Airport. The flight crew declared an emergency, began a descent, and diverted back towards St. John’s. The crew descended to, and levelled off at, 800 ft ASL on a heading of 293° Magnetic with an airspeed of 133 kt. At 09:55, approximately 35 NM from St. John’s, the crew reported that they were ditching. Less than 1 minute later, the helicopter struck the water in a slight right-bank, nose-high attitude, with low speed and a high rate of descent. The fuselage was severely compromised and sank quickly in 169 metres of water. One passenger survived with serious injuries and was rescued approximately 1 hour and 20 minutes after the accident. The other 17 occupants of the helicopter died of drowning. There were no signals detected from either the emergency locator transmitter (ELT) or the personal locator beacons (PLB) worn by the occupants of the helicopter.

Wreckage layout
Wreckage layout: A—Cockpit; B—Upper deck/engines; C—Sponson;
D—Tail rotor; E—Main rotor blades; F—Cabin area

Findings as to causes and contributing factors 

  1. Galling on a titanium attachment stud holding the filter bowl assembly to the main gearbox (MGB) prevented the correct preload from being applied during installation. This condition was exacerbated by the number of oil filter replacements and the re-use of the original nuts.

  2. Titanium alloy oil filter bowl mounting studs had been used successfully in previous Sikorsky helicopter designs; in the S-92A, however, the number of unexpected oil filter changes resulted in excessive galling.

  3. Reduced preload led to an increase of the cyclic load experienced by one of the titanium MGB oil filter bowl assembly attachment studs during operation of CHI91, and to fatigue cracking of the stud, which then developed in a second stud due to increased loading resulting from the initial stud failure. The two studs broke in cruise flight resulting in a sudden loss of oil in the MGB.

  4. Following the Australian occurrence, Sikorsky and the U.S. Federal Aviation Administration (FAA) relied on new maintenance procedures to mitigate the risk of failure of damaged mounting studs on the MGB filter bowl assembly and did not require their immediate replacement.

  5. The operator did not effectively implement the mandatory maintenance procedures in aircraft maintenance manual (AMM) revision 13 and, therefore, damaged studs on the filter bowl assembly were not detected or replaced.

  6. Ten minutes after the red MGB OIL PRES warning, the loss of lubricant caused a catastrophic failure of the tail take-off pinion, which resulted in the loss of drive to the tail rotor shafts.

  7. The S-92A rotorcraft flight manual (RFM) MGB oil system failure procedure was ambiguous and lacked clearly defined symptoms of either a massive loss of MGB oil or a single MGB oil pump failure. This ambiguity contributed to the flight crew’s misdiagnosis that a faulty oil pump or sensor was the source of the problem.

  8. The pilots misdiagnosed the emergency due to a lack of understanding of the MGB oil system and an over-reliance on prevalent expectations that a loss of oil would result in an increase in oil temperature. This led the pilots to incorrectly rely on MGB oil temperature as a secondary indication of an impending MGB failure.

  9. By the time the helicopter crew had established that MGB oil pressure of less than 5 psi warranted a “land immediately” condition, the captain had dismissed ditching in the absence of other compelling indications such as unusual noises or vibrations.

  10. The captain’s decision to carry out pilot flying (PF) duties, as well as several pilot not flying (PNF) duties, resulted in excessive workload levels that delayed checklist completion and prevented the captain from recognizing critical cues available to him.

  11. The pilots had been taught during initial and recurrent S-92A simulator training that a gearbox failure would be gradual and always preceded by noise and vibration. This likely contributed to the captain’s decision to continue towards St. John’s International Airport.

  12. Rather than continuing with the descent and ditching as per the RFM, the helicopter was levelled off at 800 ft ASL, using a higher power setting and airspeed than required. This likely accelerated the loss of drive to the tail rotor and significantly reduced the probability of a successful, controlled ditching.

  13. The captain’s fixation on reaching shore, combined with the first officer’s non-assertiveness, prevented concerns about the helicopter’s flight profile from being incorporated into the captain’s decision-making process. The lack of recent, modern, crew resource management (CRM) training likely contributed to the communication and decision-making breakdowns which led to the selection of an unsafe flight profile.

  14. The throttles were shut off prior to lowering the collective, in response to the loss of tail rotor thrust. This caused significant main rotor RPM droop.

  15. The pilots experienced difficulties controlling the helicopter following the engine shut-down, placing the helicopter in a downwind autorotative descent with main rotor RPM and airspeed well below prescribed RFM limits. This led to an excessive rate of descent from which the pilots could not recover prior to impact.

  16. The severity of the impact likely rendered some passengers unconscious. The other occupants seated in the helicopter likely remained conscious for a short period of time, but became incapacitated due to the impact and cold water shock, and lost their breath hold ability before they could escape the rapidly sinking helicopter.

TSB Final Report A09P0187—Wake Turbulence Encounter—Collision with Terrain

On July 9, 2009, a Piper PA-31-350 Chieftain aircraft was operating under VFR on the final leg of a multi-leg cargo flight from Vancouver to Nanaimo and Victoria, B.C., with a return to Vancouver. The weather was visual meteorological conditions (VMC) and the last 9 minutes of the flight took place during official darkness. The flight was third for landing and turned onto the final approach course 1.5 NM behind and 700 ft below the flight path of a heavier Airbus A321, approaching Runway 26R at the Vancouver International Airport. At 22:08, Pacific Daylight Time (PDT), the target for the Chieftain disappeared from tower radar. The aircraft impacted the ground in an industrial area of Richmond, B.C., 3 NM short of the runway. There was a post-impact explosion and fire. The two crew members on board were fatally injured. There was property damage, but no injuries on the ground. The onboard emergency locator transmitter (ELT) was destroyed in the accident and no signal was detected.

Aircraft traffic pattern at 22:04:42

Aircraft traffic pattern at 22:04:42

 
Diagram and map of air traffic at 22:06:09

At 22:06:09, the Chieftain intercepts the localizer 1.5 NM
behind the Airbus, approximately 2.6
NM from the crash site.

Findings as to causes and contributing factors 

  1. The Piper Chieftain turned onto the final approach course within the wake turbulence area behind and below the heavier aircraft and encountered its wake, resulting in an upset and loss of control at an altitude that precluded recovery.

  2. The proximity of the faster trailing traffic limited the space available for the Chieftain to join the final approach course, requiring the Chieftain not to lag too far behind the preceding aircraft.

Findings as to risk 

  1. The current wake turbulence separation standards may be inadequate. As air traffic volume continues to grow, there is a risk that wake turbulence encounters will increase.

  2. Visual separation may not be an adequate defence to ensure that appropriate spacing for wake turbulence can be established or maintained, particularly in darkness.

  3. Neither the pilots nor the operator were required by regulation to account for employee duty time acquired at other non-aviation related places of employment. As a result, there was increased risk that pilots were operating while fatigued.

  4. Not maintaining engine accessories in accordance with manufacturers’ recommendations can lead to failure of systems critical to safety.

Other finding 

  1. The Piper Chieftain was not equipped with any type of cockpit recording devices, nor was it required to be. As a result, the level of collaboration and decision-making discussion between the two pilots remains unknown.

Safety action taken 

Operator
On July 24, 2009, the operator held a wake turbulence refresher session for all of its pilots.

Transportation Safety Board of Canada (TSB)
On January 12, 2011, the TSB issued Aviation Safety Advisory A09P0187-D3-A1, entitled Wake Turbulence Encounters During Visual Operations in Darkness, to NAV CANADA and copied to Transport Canada. The advisory suggested that NAV CANADA may wish to address ways to reduce the possibilities of hazardous encounters with wake turbulence within radar service areas during VMC in darkness.

The TSB also issued Aviation Safety Advisory A09P0187-D2-A1, entitled Pilot Fatigue, to Transport Canada. The advisory suggested that Transport Canada may wish to consider ways to ensure that all operators and flight crew take into account non-carrier time commitments for the purpose of flight crew fatigue management.

On March 31, 2011, Transport Canada responded and advised that in the summer of 2010, the Canadian Aviation Regulatory Advisory Council (CARAC) established the Flight Crew Fatigue Management Working Group. The Working Group has a mandate to review the Canadian Aviation Regulations (CARs) flight and duty time limitation and rest period requirements, as well as make recommendations for change where it is felt necessary.

The response indicated that the Working Group has begun to discuss prescriptive requirements and that the matter raised in this Advisory has already been discussed extensively and will be considered further in their deliberations.

TSB Final Report A09Q0190—Collision with Cable

On November 12, 2009, a privately owned and operated Robinson R44 II Raven helicopter took off for a VFR flight from a work site at Baie-Trinité, to Baie-Comeau, Que. At 12:49 Eastern Standard Time (EST), the helicopter struck a ground wire atop a power line crossing the Franquelin River and crashed on the river bank below. The pilot sustained fatal injuries and the two passengers on board were seriously injured. A pedestrian discovered the wreckage at approximately 14:10 and advised the authorities.

cable marking on control tubes
Cable marking on control tubes

Analysis

Low flying increases the risk of collision with wires or other obstacles. The direction of flight into the sun would have caused glare on the windscreen and would have most likely decreased the pilot’s forward visibility and ability to see the wires. Also, the wires were unmarked, rendering them more difficult to detect. A thorough scan for obstacles in front and in periphery of the aircraft might have helped to detect the towers of Line 1615 situated atop the cliffs on either side of the river. Although the pilot saw the wires immediately prior to colliding with them and attempted evasive action, a collision with the first of the two ground wires ensued.

While the aircraft was equipped with a GPS capable of providing the pilot with obstacle and terrain warnings when flying at low altitude, only the terrain display feature was functional in the area the flight took place. In addition, it could not be determined if the pilot was aware of those features and associated limitations when used in Canada. The GPS is an aid to navigation and should not replace the use of authorized navigation charts.

Cables and wires may be unmarked if they are not considered to be an aeronautical or marine hazard. The towers atop the cliffs on either side of the river and the ground wire lines and main power lines were not deemed a hazard. While the location where Line 1615 crosses the Franquelin River is not close to an aerodrome, it is situated on the VFR GPS route from Baie-Comeau to Sept-Îles. Without careful flight planning, flights conducted at low level are at increased risk of collision with unmarked hazards such as wires or other obstacles.

The 406 MHz emergency locator transmitters (ELT) are relatively new to the aviation industry. The helicopter’s ELT installation included a programmable dongle, information which did not appear on the aircraft equipment list. The owner completed the required registering of the ELT unit but had not done a periodic self-test as recommended by the ELT manufacturer. The maintenance facility had confirmed the ELT unit tested serviceable but did not know the dongle was programmable and therefore had not programmed it or had it programmed to match the owner and aircraft information. No self-test or transmission test had been completed since the owner acquiring the aircraft. The fact that the programmed dongle information supersedes the ELT-programmed information was not widely known. The ELT manufacturer recommends a self-test once a month to verify the integrity of the installation; however, there are no regulatory requirements to conduct this self-test. A signal received by the COSPAS-SARSAT Canadian Mission Control Centre (CMCC) in the test mode would not necessarily initiate search and rescue in the same manner as that of a signal received in the normal mode.

The 406 and 121.5 MHz signals were significantly attenuated due to the severed antenna cable. The failure of the Q8 amplifier resulted in an additional attenuation of the 406 MHz signal. Activation of this type of ELT, even for test purposes, without a proper load such as an antenna, can result in damage to its circuitry, rendering the device unserviceable.

An improperly programmed dongle may result in the transmission of incorrect information, thereby delaying search and rescue.

Aerial view of accident site

Aerial view of accident site

Findings as to causes and contributing factors 

  1. The helicopter was flown at low altitude, increasing its exposure to a collision with obstacles.

  2. The sun’s glare likely degraded the pilot’s ability to detect the unmarked power lines and ground wires in time to avoid a collision.

  3. The helicopter struck the ground wire likely rendering the helicopter partially uncontrollable and it crashed in the river below.

Findings as to risk 

  1. Given the difficulty in seeing unmarked wires, pilots must plan their flight path appropriately before operating at low levels, especially in valleys.

  2. A dongle that has not been properly programmed may result in the transmission of incorrect information, thereby delaying search and rescue. An ELT self-test would confirm a programming fault.

  3. The ELT antenna cable became severed during the impact sequence, increasing the risk of the signal not being detected.

Other finding

  1. Turning an ELT ON or conducting a self-test without installing a load (antenna) may overload the transmission amplifier rendering the unit unserviceable.

  2. The GPS terrain display feature was operational in the area the flight took place; however, the obstacle warning feature was not. The GPS is an aid to navigation and should not replace the use of authorized navigation charts.

Safety action taken 
On July 12, 2010, the TSB sent an aviation safety information letter to Transport Canada on the 406 MHz ELT programmable dongle issue. It highlighted the importance of informing aircraft operators, owners, maintainers and avionics facilities of the purpose of the programmable dongle. A comprehensive article regarding the ELT programmable dongle was published in Issue 3/2011 of the Aviation Safety Letter.

TSB Final Report A10P0244—Collision with Terrain

On July 31, 2010, at 20:02 Pacific Daylight Time (PDT), a Convair 580 departed Kamloops to fight a wildfire near Lytton, B.C. The bombing run required crossing the edge of a ravine in the side of the Fraser River canyon before descending on the fire located in the ravine. About 22 minutes after departure, the aircraft approached the ravine and struck trees. An unanticipated retardant drop occurred coincident with the tree strikes. Seconds later, the aircraft entered a left-hand spin and collided with terrain. A post-impact explosion and fire consumed much of the wreckage. A signal was not received from the on-board emergency locator transmitter; nor was it recovered. Both crew members were fatally injured.

aircraft crashed in forest

Analysis—Operational Factors

In the absence of concrete data from recorders, the investigation looked at two possible operational factors:

  • The flight inadvertently entered a low energy condition approaching the ravine in an attempt to recover altitude.
  • A visual illusion affected the crew’s ability to recognize and assess the aircraft’s proximity to the rising terrain resulting in this being a controlled flight into terrain (CFIT) accident.

It was established that the aircraft descended more than 400 ft early in the circuit and was flying in a slow climb toward the edge of the ravine. A slow climb, rising terrain and the lack of a good horizon reference, are criteria that could contribute to the development of a low energy condition. Regardless of engine power, the low energy condition may not have allowed the aircraft sufficient time to pull up and establish an adequate climb, even with the benefit of the partial retardant drop. Airspeed and angle of attack (AOA) indicators should have provided visual indications of low energy conditions and impending stall awareness. But there was no audible or visual alert that would have drawn the crew’s attention to these indicators.

If the airspeed was low and an overshoot was commanded, the flaps would have to be retracted to 15°. This would result in a reduction in the initial rate of climb. The aircraft was interpreted as going into a descent when observed by the bird dog crew. However, the bird dog crew did not know that the Convair was climbing. Without a horizon reference, a reduction of the climb angle could appear to the bird dog crew as a change from level flight to a descent. Maximum power and 12° of flap, as found, would be consistent with an attempted go-around. While retracting flaps for a go-around, inadvertently holding the flap selector switch for one additional second would result in 2° or 3° more flap retraction than the target setting of 15°. There is no performance data in the aircraft operating manual (AOM) to determine a potential rate of climb.

Map of estimated flight path

Estimated flight path

However, this should not be an issue because the plan to climb out following the first intended drop and accelerate from 120 knots to 140 knots in the 20° flap configuration, with 7/8 of the load remaining on board, is indicative of the airplane capability at an appropriate airspeed.

Furthermore, a visual illusion may have affected the crew’s ability to recognize, or accurately assess, the aircraft’s flight path relative to the elevation of the rising terrain which, unbeknownst to the crew, put the aircraft too low before the edge of the ravine.

The local terrain was mountainous and precluded a good horizon reference. The flight occurred during the last hour of daylight in growing shadows and some smoke, which are factors that affect visibility. The action to continue the bombing run rather than take the exit route and circle for another attempt or to jettison the retardant load to improve the climb performance suggests the crew did not recognize the imminent danger ahead of them and may have neglected the altimeter, believing it was reasonable to continue and assess their progress visually. The criteria (a slow climb, rising terrain, lack of a good horizon reference) conducive to a low energy condition can also be conducive to a visual illusion producing a false sense of height, as observed during the TSB investigation flight.

Given the last-second response to avoid a collision with terrain at the edge of the ravine, and the partial retardant load drop, it is likely the crew was under the influence of a visual illusion. The aircraft’s proximity to terrain came as a surprise to the crew and as a result, affected the crew’s decisions and actions leading up to the event.

The bird dog pilot, however, had the benefit of flying consecutively lower circuits in the development of the bombing run to the target fire, and lighting conditions may have been slightly different. This opportunity may have reduced the likelihood of a height- or depth-perception illusion, and illusions were not discussed in any briefings to the Convair crew.

Findings as to causes and contributing factors 

  1. It could not be determined to what extent the initial collision with trees caused damage to the aircraft which may have affected its controllability.

  2. Visual illusion may have precluded recognition, or an accurate assessment, of the flight path profile in sufficient time to avoid the trees on rising terrain.

  3. Visual illusion may have contributed to the development of a low energy condition which impaired the aircraft performance when overshoot action was initiated.

  4. The aircraft entered an aerodynamic stall and spin from which recovery was not possible at such a low altitude.

Findings as to risk 

  1. Visual illusions give false impressions or misconceptions of actual conditions. Unrecognized and uncorrected spatial disorientation, caused by illusions, carries a high risk of incident or accident.

  2. Flight operations outside the approved weight and balance envelope increase the risk of unanticipated aircraft behaviour.

  3. The recommended maintenance check of the emergency drop (E–drop) system may not be performed and there is no requirement for flight crews to test the E–drop system, thereby increasing the risk that an unserviceable system will go undetected.

  4. The location of the E–drop selector requires crews to divert significant time and attention to identify and confirm the correct switch before operating it. This increases the risk of collision with terrain while attention is distracted.

Safety action taken 

Operator
Since the accident, the operator has taken further action to mitigate the risks of recurrence.

  1. The glare shield over the flight instrument panel in the Convair 580 has been modified to improve both pilots’ view of the top row of flight instruments, which include the airspeed indicators and the AOA indicator.

  2. A project has been initiated to change the E-drop selector from a guarded toggle switch to a large push-button type switch and relocate it to the middle of the glare shield, in full view and within reach of both pilots.

  3. A project is underway to modify the existing load release button on the left-hand control wheel to include a safety function which will jettison the entire retardant load if the button is depressed five times within three seconds.

  4. The operator’s pilot training program is being amended to incorporate more emphasis on emergency drop procedures.

  5. The operator is developing a stall–g–speed (SgS)[1] system for air tanker operations. This system will be initially installed on the Lockheed L–188 Electra air tanker.

decorative line above footnotes

[1] SgS defines a safety flight envelope for “low speed warning”, “vertical acceleration (g) warning” and “overspeed warning”. This system will provide flight crews with trend information relating airspeed, angle–of–attack, and “g” load information in a visual display with audio warnings and a stick–shaker function.

 

TSB Final Report A10O0240—Loss of Control and Collision with Terrain

On November 18, 2010, at approximately 18:19 Eastern Standard Time (EST), a Beechcraft F33A aircraft departed Toronto/Buttonville Municipal Airport for Kingston Airport, Ont., on a night VFR flight with an instructor and two commercially qualified students on board. Weather en route began to deteriorate and the aircraft was headed back to Toronto/Buttonville Municipal Airport. The aircraft was observed on radar to be westbound in level flight before it turned north and began to climb. The aircraft then turned abruptly to the left and descended; radar contact was lost. The aircraft was subsequently located in a ploughed level field approximately 10 NM east of the Toronto/Buttonville Municipal Airport. It was destroyed on ground impact and the three occupants were fatally injured. There was no fire and the emergency locator transmitter (ELT) did not activate. The accident occurred at approximately 18:44 EST during the hours of darkness.

Map showing location of accident site and weather conditions

Location of accident site and weather conditions

Analysis

The analysis will focus on the environmental conditions at the location of the occurrence, and provide a plausible scenario for the deviation in the flight path that led to the loss of directional control and rapid descent with no recovery prior to ground impact.

Deteriorating weather conditions encountered en route prompted the flight crew to cancel the planned flight to Kingston and return to Toronto/Buttonville. Radar data and recorded voice communications indicate that the return flight was normal until the climbing right turn. During that turn, airspeed was allowed to decrease suggesting that engine power was not increased to maintain a safe airspeed. The aircraft rolled into a steep left turn with a high rate of descent. The flight manoeuvre that was observed on radar and further supported by engineering estimations indicates a left wing stall followed by an abrupt left wing drop. The abruptness of the wing stall could have been exacerbated by any airframe icing which may have accumulated on the wings.

Weather information from other aircraft in the vicinity and from ground observations indicated that local weather conditions which included rain, snow, and freezing rain, were quite different from the conditions at either Oshawa airport or Toronto/Buttonville municipal airport. Encountering these weather conditions unexpectedly may have influenced the crew’s decision to intentionally deviate to the north to find better weather. Outside visual reference may have also been hampered by these weather conditions and by darkness.

Although it is impossible to ascertain who was controlling the aircraft at the time, it is logical to assume that the student was at the controls while the instructor was requesting the approach clearance. When the aircraft stalled, the instructor would have been attempting to recover control. The rapidity of the stall, the airspeed during the descent and the lack of available altitude prevented a full recovery before the aircraft struck the ground. This would have been compounded by limited visual reference due to the weather conditions and the lack of flight instruments on the right side of the instrument panel.

There were approximately eight seconds between the loss of control and when the aircraft struck the ground assuming a constant rate of descent of 9 600 ft/min. Ground impact marks show that, although the aircraft was nose down, it was in a near wings-level attitude, suggesting that the recovery had been initiated but altitude and excessive descent speed precluded full recovery.

Findings as to causes and contributing factors 

  1. After encountering adverse weather conditions, a climbing right turn was initiated. During the climbing turn, engine power was likely not increased and the airspeed decayed. The angle of attack on the left wing was allowed to increase until it stalled and dropped unexpectedly.

  2. The location of the flight instruments made it more difficult for the instructor in the right seat to see and react to them and control of the aircraft was not regained before the aircraft struck the ground in a non-survivable impact.

Safety action taken 

Flying school 
The flying school has instituted the following changes to its training program to enhance flight safety:

  • Group weather briefing—This is attended by all instructors and students who will be flying on that particular shift. By doing this, it is ensured that everyone has looked at the weather prior to their flight. The only exception is if a student is going on a Transport Canada flight test where the student will be graded by an examiner for checking weather.
  • Recurrent upset training for instructors—All instructors to go through upset training in flight training devices to assist them in any given circumstances where they need to take control of an aircraft and recover from an unusual attitude. This training is done with certain flight instruments failed.
  • Night flying ground briefing for instructors—A recurrent training session regarding night flying.
  • Weather briefing for instructors—A recurrent training session regarding weather hazards with a focus on icing.
  • Briefing on spatial disorientation for instructors—A recurrent training session reviewing different types of illusions and preventative measures.
  • Expanded indoctrination training for new instructors—New instructors to have an expanded indoctrination checklist they complete when they start teaching at the college.
  • The school’s aviation training program is broken up into different phases. An expanded training program is being developed for instructors who start training in a new phase of the program based on their past experience.
  • Standby attitude indicators to be installed in aircraft—The plan is for standby attitude indicators to be installed in all aircraft that require them. This is in the event there is a failure of the primary attitude indicator; the standby attitude indicator can be used to aid in flying the aircraft.

The school has instituted the limits shown below for single-engine at-night operations:

  • All night flying is to be conducted in VFR weather only.
  • Instrument or IFR training may be conducted at night in visual meteorological conditions (VMC) only.
  • VFR flight plans are to be filed at night outside of the circuit (no IFR filing even in VMC).
  • Reported and forecast visibility shall not be less than 6 SM. Authorized ceiling remains as per its Operations Manual Section 2.6.
  • There shall be no visible or forecast precipitation in the area of operation when flying in temperatures of 5°C or colder (at operating altitude).
  • No observers are permitted on board training flights at night, i.e., one student and one instructor only. Combined lessons where more than one student participates will be restricted to daytime flying.
  • Any exceptions to this policy will be at the sole discretion of the certificated flight instructor (CFI) or delegate on a case-by-case basis. 
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