Recently Released TSB Reports

ASL_Icons_Issue2_fmt4.jpeg

 

 

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 A08P0035—Loss of Visual Reference/Collision with Terrain

On February 7, 2008, at approximately 14:54 MST, a Bell 212’s main rotor blades struck the mountainside during an approach to a landing site to drop off skiers near Golden, B. C. The helicopter remained upright, but the main rotor separated from the helicopter and struck the fuselage. The pilot received fatal injuries and the ski guide seated in the front left seat received serious injuries. The guide and skiers seated in the rear of the helicopter were uninjured. The uninjured guide shut off the fuel valves and turned the battery switches off. There was no fire. The survivors were evacuated using local helicopter operators.

Map of helicopter fligh path

Helicopter flight path

Analysis

Examination of the helicopter did not reveal any defects that would have contributed to the accident. The helicopter was carrying three fewer passengers on the accident flight than on previous flights and had minimal though sufficient fuel, thus decreasing the helicopter’s gross weight. The density altitude was lower than the actual altitude and the prevailing wind was blowing strongly uphill. The combination of helicopter gross weight, density altitude, and wind would have increased the helicopter’s performance including its rate of climb on the accident flight.

The pilot was familiar with the ski resort and had flown to the drop-off site three times earlier in the day. Although the enroute flight path during the accident flight was similar to the paths flown on earlier flights, the approach to the drop-off site was flown at a lower altitude than on the previous flight, resulting in a flatter approach profile.

Visibility above the treeline varied. The accident flight destination was changed because a snow squall obscured visibility at the original drop-off site. The sky cover was overcast, a condition creating a uniform, diffused (flat) light that, particularly on monochromic and relatively featureless surfaces such as snow, provides no shadows or reflections that can be used as visual references. As well, blowing snow may have obscured ground features. The flags at the drop-off site, 600 ft ahead of the helicopter, were visible moments before the accident. However, it is not known if visibility towards the featureless, snow-covered mountainside adjacent to the helicopter was compromised by flat light and blowing snow. It is also not known why the approach on the accident flight was flown at a lower altitude than on the previous flight. It is possible that, due to poor visibility, the pilot was not aware of the helicopter’s proximity to the mountainside.

The helicopter’s forward and vertical speeds were very low when it contacted terrain, consistent with a normal landing. The helicopter did not slide forward after the skids contacted the snow; it remained upright and oriented in the direction it had been travelling. The low vertical and forward speeds at touchdown are consistent with the pilot intentionally landing the helicopter at the accident site. It is possible that, due to a lack of visual references and to blowing snow from the rotor downwash, the pilot was unaware that the helicopter was close enough for the rotor blades to strike the mountainside.

Wind direction had remained steadily uphill (approximately 90º to the flight path) for several hours prior to the accident, but wind and gust speeds had increased substantially. The upflowing air would have provided lift, allowing the helicopter to operate using less power than would have been required in still or downflowing air. It is possible that a decrease in the upflowing air caused a momentary decrease in lift and the helicopter descended into the mountainside before adequate additional power was applied. As well, if the helicopter’s airspeed had been allowed to decrease to below 20 kt, the resulting reduction of rotor efficiency may have caused the helicopter to descend into the mountainside.

The ski guide’s shutdown of the helicopter’s fuel and electrical system after the accident prevented injury to the passengers from leaking fuel and may also have prevented fire. The implementation of the heli-ski operator’s emergency response plan also reduced risk of further injury to the survivors.

Finding as to causes and contributing factors

  1. The helicopter’s main rotor blades contacted the mountainside during the landing in poor visibility for undetermined reasons. The main rotor separated and struck the fuselage.

Finding as to risk

  1. Further injury was reduced by the ski guide’s shutdown of the helicopter’s fuel and electrical systems and by implementing the heli-ski operator’s emergency response plan.

TSB Final Report A08C0237—Loss of Control and Collision with Terrain

On November 22, 2008, a  departed Runway 32 at God’s Lake Narrows, Man., for Thompson, Man., with two pilots, a flight nurse, and two patients on board. Shortly after takeoff, while in a climbing left turn, smoke and then fire emanated from the pedestal area in the cockpit. The crew continued the turn, intending to return to Runway 14 at God’s Lake Narrows. The aircraft contacted trees and came to rest in a wooded area about ½ NM northwest of the airport. The accident occurred at 21:40 CST. All five persons onboard evacuated the aircraft; two received minor injuries. At approximately 02:50, the accident site was located and the occupants were evacuated. The aircraft was destroyed by impact forces and a post-crash fire. The emergency locator transmitter (ELT) was consumed by the fire and whether or not it transmitted a signal is unknown.

Beechcraft A100 crashed in the woods

Findings as to causes and contributing factors

  1. An electrical short circuit in the cockpit pedestal area produced flames and smoke, which induced the crew to take emergency action.
  2. The detrimental effects of aging on the wires involved may have been a factor in this electrical arc event.
  3. The crew elected to return to the airport at low level in an environment with inadequate visual references. As a result, control of the aircraft was lost at an altitude from which a recovery was not possible.

Findings as to risk

  1. The actions specified in the standard operating procedures (SOP) do not include procedures for an electrical fire encountered at low altitude at night, which could lead to a loss of control

    .
  2. Visual inspection procedures in accordance with normal phase inspection requirements may be inadequate to detect defects progressing within wiring bundles, increasing the risk of electrical fires.

  3. In the event of an in-flight cockpit pedestal fire, the first officer does not have ready access to available fire extinguishers, reducing the likelihood of successfully fighting a fire of this nature.

  4. Sealed in plastic containers and stored behind each pilot seat, the oxygen masks and goggles are time consuming to access and cumbersome to apply and activate. This could increase the probability of injury or incapacitation through extended exposure to smoke or fumes, or could deter crews from using them, especially during periods of high cockpit workload.

Other finding

  1. A failure of the hot-mic recording function of the cockpit voice recorder (CVR) had gone undetected and information that would have been helpful to the investigation was not available.

TSB Final Report A08W0244—Controlled Flight Into Terrain

On December 13, 2008, a Dornier 228-202 was on a charter flight from Resolute Bay to Cambridge Bay, Nun., under instrument flight rules (IFR). While on final approach to Runway 31 True, the aircraft collided with the ground approximately 1.5 NM from the threshold at 01:43 MST. Of the 2 pilots and 12 passengers on board, 2 persons received serious injuries. The aircraft was substantially damaged. The ELT activated, and the crew notified the Cambridge Bay Airport radio operator of the accident via the aircraft radio. Local ground search efforts found the aircraft within 30 min and all occupants were removed from the site within 2 hr.

Analysis

Visual approach
From the time the flight left Resolute Bay until the occurrence, the visibility at Cambridge Bay deteriorated from 8 SM to as low as ¾ SM. The last observed visibility provided to the crew was variable from 1½ SM to 3 SM in snow and blowing snow and, as such, the weather was fluctuating below visual flight rules (VFR) limits. The crew would have been required to conduct an approach in accordance with IFR. By abandoning the full instrument approach and conducting an abbreviated visual approach, the flight reverted to VFR in reported weather conditions below VFR minimums. This reduced the protections against controlled flight into terrain afforded by adherence to published instrument procedures and associated company standard operating procedures (SOP).

Map of Radar plot of the occurrence aircraft.

Radar plot of the occurrence aircraft.
(The grey area represents land and the white area represents water.)

Monitoring of altitude
The crew members’ duties were not defined in their briefing for the approach. Except for minimum sector and LEXUP crossing altitudes, no other minimum descent altitudes, including the final approach descent profile or missed approach procedures, were discussed. Therefore, when the aircraft prematurely descended below the minimum altitude for the instrument approach, there was no trigger for the crew to terminate the approach. In low visibility at night over unlit terrain, it would have been difficult to visually judge height above the ground.

During the approach, the first officer’s attention was focused on re-programming the GPS and actioning the pre-landing checklist. The captain’s attention was directed outside the aircraft while flying with visual reference to the obscured lights of the town and the airport. Except for calling the 500-ft radar altimeter alert, there was no other monitoring or cross-checking of altitudes on the approach by either pilot. When the aircraft was at 500 ft AGL, it was about 120 ft lower than would have been required for a constant descent profile for the instrument approach.

GPS training
Although the pilots had been trained to use the KLN94 GPS, they were not trained in the use of the installed Garmin 430W GPS equipment. Therefore, during the accident flight, they were qualified to conduct IFR operations using only ground-based navigation aids as their primary source of navigation information. Their unfamiliarity with the GPS equipment and their difficulty in properly setting it up likely provided a distraction to the task of monitoring the proper lateral and vertical approach profiles. The full VOR/DME approach to Runway 31 True would have allowed the crew to make the approach using familiar equipment. This approach has the same minimum descent altitude and advisory visibility limits as the approach they were using.

Altimeters
During the flights from Yellowknife, Cambridge Bay, and Resolute Bay, there was a difference in readings between the two altimeters installed in the aircraft. The pilots recognized this discrepancy and compensated by setting the first officer’s instrument to match the altitude reading on the captain’s altimeter. The crew did not determine that the captain’s altimeter was in error, although it would have been possible to determine which instrument was faulty by comparing altitude readings on the ground at known altitudes. Because altitude was not monitored in relation to aircraft position in the late stages of the approach at Cambridge Bay, it is unlikely that this error played a significant part in the occurrence. There was no company SOP to detect altimeter errors.

Photo of barometric pressure/pointer setting gears showing teeth damage

Barometric pressure/pointer setting gears.
The gear on the right had teeth damage.

An erratic altimeter barometric setting knob could be a symptom of internal gearing deterioration, which can result in loss of calibration. Because the only reference to this problem is found in the altimeter Component Maintenance Instruction Manual, which is not normally accessible to operator maintenance organizations, it is possible that an aircraft would be allowed to operate with a defective instrument with potential for calibration errors. Slippage of damaged gears could result in inaccurate readings.

Fatigue
The crew went to sleep early the night before the flight to Resolute Bay, but woke earlier than normal, likely reducing their sleep quality. Although the quality of the sleep obtained during the following day was likely less-than-optimal because it was obtained in the afternoon, it probably offset the effects of early rising and, to some extent, prepared the crew for the flight back to Yellowknife later that night. However, even a full 8 hr of rest would have been insufficient to shift the crew’s circadian rhythm and fully offset the performance decrements due to flying late at night when their bodies would have been approaching a circadian low. The perception that an 8-hr rest resets the flight/duty clock is consistent with the current regulations; however, when pilots attempt to fly later on the same day at a period of circadian low, there are likely to be performance decrements because the body’s internal clock cannot readily be reset. It is possible that fatigue could have reduced the crew’s level of cognitive and decision-making performance during the flight.

PAPI system
The PAPI systems at Cambridge Bay had not been inspected in accordance with the Airport Safety Program Manual. Although calibration of the equipment did not have a bearing on this occurrence, there was an increased risk of aircraft misalignment from the proper glide path, especially during night and reduced visibility conditions.

Findings as to causes and contributing factors

  1. An abbreviated visual approach was conducted at night in instrument meteorological conditions, which resulted in the flight crew’s inability to obtain sufficient visual reference to judge their height above the ground.

  2. The flight crew did not monitor pressure altimeter readings or reference the minimum altitude requirements in relation to aircraft position on the approach, resulting in controlled flight into terrain.

  3. The pilots had not received training and performance checks for the installed global positioning system (GPS) equipment, and were not fully competent in its use.

  4. The attempts at adjusting the settings likely distracted the pilots from maintaining the required track and ground clearance during the final approach.

Findings as to risk

  1. The precision approach path indicator systems (PAPI) at Cambridge Bay had not been inspected in accordance with the Airport Safety Program Manual. Although calibration of the equipment did not have a bearing on this occurrence, there was an increased risk of aircraft misalignment from the proper glide path, especially during night and reduced visibility conditions.

  2. The flight crew’s cross-check of barometric altimeter performance was not sufficient to detect which instrument was inaccurate. As a result, reference was made to a defective altimeter, which increased the risk of controlled flight into terrain.

  3. Operators’ maintenance organizations normally do not have access to the troubleshooting information contained in Component Maintenance Instruction Manuals for the Intercontinental Dynamics Corporation altimeters. Therefore, aircraft could be dispatched with damaged instruments with the potential for developing a loss of calibration during flight.

  4. The flight was conducted during a period in which the crew’s circadian rhythm cycle could result in cognitive and physical performance degradation unless recognized and managed.

Safety action

Operator
The company amended company policy and standard operating procedures as follows:

  • Approach briefings will be conducted before initiating descent and will cover the critical aspects of the approach.

  • In night conditions, a VFR briefing is acceptable only if the ceiling is above the applicable sector altitude and visibility greater than 5 statute miles (SM). If a night visual flight rules (VFR) approach is to be conducted, the aircraft cannot descend below the minimum safe altitude (MSA) until established on the final approach track. The briefing will be backed up with the appropriate navigation aids.

  • In instrument meteorological conditions (IMC), an IFR briefing must be completed.

  • If a published IFR approach exists, the IFR altitude and track limitations for that runway must be adhered to. In all cases, once established on final approach, descent from the MSA may only be made by:
  1. following the approach path indicator lights (if available);

  2. following a stabilized approach path until touchdown; and

  3. following the IFR approach limitations (if available).
  • Controlled flight into terrain (CFIT) and crew resource management (CRM) pilot training was enhanced and the frequency was increased from biennially (every two years) to annually.

Government of Nunavut
Airport Safety Management Manual
The weekly inspection procedure for precision approach path indicator system (PAPI)/abbreviated precision approach path indicator system (APAPI) systems at all Government of Nunavut airports has been implemented and emphasized with airport maintenance personnel. The inspections and reports filed with the regional managers are in conformance with Transport Canada publication TP 312, Aerodromes Standards and Recommended Practices, and the Government of Nunavut Airport Safety Program Manual. Procedures for record retention, including PAPI/APAPI inspections as well as all other required documentation, are being included in the Airport Safety Management Manual.

TSB Final Report A09A0036—Loss of Control—Collision with Terrain

On June 7, 2009, the pilot of a Britten-Norman Islander BN.2A-27 was tasked with a MEDEVAC flight to take a patient from Port Hope Simpson to St. Anthony, Nfld. The aircraft departed the company’s base of operations at Forteau, Nfld., at approximately 06:20 Newfoundland and Labrador daylight time. At approximately 06:50, he made radio contact with the airfield attendant at the Port Hope Simpson Airport, advising that he was 4 NM from the airport for landing. The weather in Port Hope Simpson was reported to be foggy. There were no further transmissions from the aircraft. Although the aircraft could not be seen, it could be heard west of the field. An application of power was heard, followed shortly thereafter by the sound of an impact. Once the fog cleared about 30 min later, smoke was visible in the hills approximately 4 NM to the west of the Port Hope Simpson Airport. A ground search team was dispatched from Port Hope Simpson and the wreckage was found at approximately 11:00. The sole occupant of the aircraft was fatally injured. The aircraft was destroyed by impact forces and a severe post-crash fire. There was no ELT signal.

Route Map of Britten-Norman Islander BN.2A-27 in

Route map

Analysis

The sole occupant of the aircraft was fatally injured in the accident. There were no witnesses to the final moments of the flight and there were no onboard recording devices to assist investigators. The aircraft impacted the ground in a near-vertical attitude, suggesting an in-flight loss of control. As a result, this analysis focuses on possible scenarios for why the aircraft departed controlled flight and collided with terrain.

Although the aircraft was extensively damaged, there did not appear to be any evidence suggesting a problem with the flight controls or engines. Also ruled out was the scenario of pilot incapacitation. The application of power less than two seconds before impact indicates that the pilot was still trying to fly the aircraft. The investigation also ruled out turbulence as a factor for loss of control because there were no significant conditions in the area that could cause turbulence.

Visibility and ceilings were reported to be quite low in the Port Hope Simpson area. Therefore, the pilot would have been faced with the decision to return to Forteau and wait for the weather to improve, find a routing under the weather following lower terrain, or climb up into the weather to conduct an instrument approach.

The following scenarios were considered:

  • If the pilot was attempting to return to Forteau, he was likely flying at a low altitude and a slower speed in order to maintain visual contact with the ground. The pilot may have inadvertently entered cloud and allowed his airspeed to decrease to the point of aerodynamic stall. Depending on the altitude of the aircraft at the point of stall, the pilot may not have been able to recover before the aircraft impacted the ground.

  • If the pilot was trying to fly below and around the weather and suddenly lost contact with the ground or was faced with rapidly rising terrain, he would have had to abruptly initiate evasive action. If trying to maximize the climb with a steep nose-high attitude he may have inadvertently allowed the speed to decrease to the point of aerodynamic stall. Alternatively, he may have tried to turn away from rising terrain/weather and in doing so increased the aerodynamic wing loading and the angle of attack to the point of aerodynamic stall. Depending on the altitude of the aircraft at the point of stall, the pilot may not have been able to recover before the aircraft impacted the ground.

  • The aircraft was equipped with a GPS; however, the company was not approved to conduct IFR approaches using the GPS. The company was certified for two-pilot IFR operations, but single-pilot IFR operations were not approved due to the lack of a functioning autopilot. The lack of a functioning autopilot imposes a high workload on a single pilot in IFR conditions (for example, tuning radios, programming navigation aids, reviewing approach plates, handling communications, and flying the aircraft). If the pilot decided to execute a GPS approach, it is possible that he inadvertently allowed the airspeed to decay towards the stalling speed while occupied with other flying-related tasks. Depending on the altitude of the aircraft at the point of stall, the pilot may not have been able to recover before the aircraft impacted the ground.

  • The investigation also considered the possibility of icing in cloud while conducting an IFR approach as an initiating factor to a stall. It is unlikely that the pilot would climb any higher than the MSA while reverting from VFR low level flight to an IFR approach. The possibility of icing in cloud was eliminated as the freezing level was above the MSA for the approach. The instrument approach scenario is unlikely, given that the minimum descent altitudes (MDA) for both runways would have precluded a visual descent and landing.

None of these scenarios could be validated; however, an aerodynamic stall is a common factor.

Map showing ocation of the crash site relative to the airstrip.

Location of the crash site relative to the airstrip

Finding as to causes and contributing factors

  1. The aircraft departed controlled flight, likely in an aerodynamic stall, and impacted terrain for undetermined reasons.

Other finding

  1. The lack of onboard recording devices prevented the investigation from determining the reasons why the aircraft departed controlled flight.

TSB Final Report A09P0210—In-Flight Breakup

On July 22, 2009, a Robinson R44 Astro helicopter took off from a heliport near Creston, B. C., at about 12:45 PDT with only the student pilot on board. The helicopter was on a daylight VFR flight in visual meteorological conditions in the local training area, practicing flight manoeuvres. At about 14:00, while flying over level marshland, the helicopter experienced an in-flight breakup. The helicopter struck the ground about 8.5 NM northwest of Creston, at an elevation of 2 100 ft ASL. The bulk of the fuselage fell into the Kootenay River, leaving a wreckage path of several hundred metres. The student pilot was fatally injured and the helicopter was destroyed by in-flight and ground impact forces. There was no fire. The ELT was functioning when found; however, no signal was detected because the unit was under water and it was designed to transmit a signal on 121.5 and 243 MHz, which are no longer monitored by the search and rescue satellite system.

Overhead view of accident flight path.

Accident flight path

Analysis

The lack of an onboard flight recorder hindered the accurate reconstruction of the flight.

Based on the proposed training agenda, the student pilot’s intentions, and the flight tracking unit data, it is most likely that the student pilot had been following the proposed training plan and was practicing steep turns in the area when the accident occurred.

Wreckage damage and distribution also indicate that the lead event was the main rotor flapping down into the tailboom severing the tail rotor driveshaft, tailboom, and tail rotor assembly in one unit. This damage and loss of airframe structure was catastrophic and immediately rendered the helicopter uncontrollable.

The cause of this excessive rotor flapping could not be identified, and this analysis explores the possible reasons and circumstances for this aerodynamic phenomenon.

Mast bumping
Main rotor blade impact marks on the tailboom are indications of extreme in-flight rotor flapping. Frequently, such rotor strikes signify low-to-moderate rotor RPM, and in this accident, the tailboom contact marks, the proximity of the separated components, and the rotor blade damage are all characteristic of a rotor strike being the initiating event of the in-flight breakup and resulting loss of control.

There are some situations where inappropriate pilot control inputs could influence excessive rotor flapping and mast bumping, which is a pre-condition for rotor-to-tailboom contact that often leads to in-flight breakup. For example, Robinson Helicopters warned pilots about the risk of low-g manoeuvres in the R44, stating that loss of control and mast bumping are often the result. In a similar fashion, rapid flight control deflection could lead to rotor instability and excessive rotor flapping angles.

Airframe examinations did not identify any mechanical condition that might have led to mast bumping. The other factor to consider, therefore, is pilot flight control inputs. Without flight data recorder information, the regime of flight and the student pilot’s actions are unknown. However, several assumptions can be made, namely:

  • no adverse mechanical condition existed;

  • the helicopter was functioning correctly; and

  • the student pilot was conducting steep turns.

Possible in-flight breakup scenario
Given the above factors that eliminate mechanical cause, it is reasonable to propose that the student pilot inadvertently induced the conditions necessary to cause mast bumping. It is known that low-g manoeuvring in the Robinson R44 helicopter can lead to excessive rotor flapping and mast bumping, as can some rapid and large collective or cyclic movements. It is clear that several combinations of flight circumstances exist that could lead to mast bumping, but the most plausible in this case is the student pilot manoeuvring quickly during a steep turn. In concert with an aft CG condition (forward cyclic bias), the student pilot may have had reduced forward cyclic travel.

The area where the accident occurred is known for its concentration of large migratory birds, and on the day of the accident, many birds were seen in the marshlands and adjacent waterways. The student pilot was well-versed on the consequences of bird strikes and had recently studied bird-avoidance techniques. He was characterized as being particularly sensitive to the dangers of collision with birds.

It is conceivable that the student pilot encountered a bird during his steep-turn practice. During his attempt to avoid it, he may have applied control inputs that led to excessive main rotor flapping and mast bumping. Had he also lowered the collective, pushed the nose forward, or both, he would have been even more greatly exposed to the large aerodynamic forces that cause mast bumping. Such reactive manoeuvring is instinctive and often rapid, and in conjunction with the control inputs and in-flight attitudes often seen in steep-turn manoeuvres, is likely to cause rotor path plane upset and reduced clearance from the tailboom. Such flight conditions make mast bumping almost inevitable. In-flight mast bumping is frequently irrecoverable and catastrophic, with either the mast being severed or a blade strike to the fuselage. In either case, the result is invariably fatal.

Measuring tape over tailboom rotor blade strike.

Tailboom rotor blade strike

Flight training and experience for R22 and R44 helicopters in Canada
United States SFAR 73 prescribes minimum requirements for pilots of R22 and R44 helicopters, both as the pilot-in-command, the student pilot, or the flight instructor. This regulation imposes specific training and experience criteria on United States licence holders because certain aerodynamic and design features of the helicopter cause specific flight characteristics that require particular pilot awareness and responsiveness. Following implementation of this SFAR in the United States, the in-flight breakup accident rate has fallen remarkably, suggesting that the provisions of the SFAR improve flight safety.

Relying solely upon the general awareness in the helicopter community of the operating vulnerabilities of the R22 and R44 helicopters, identified in SFAR 73, is inadequate in reducing the risk of in-flight upset (resulting from low-g manoeuvring or mast bumping for example) associated with these helicopters. While Canadian licensing requirements are more prescriptive, it can be reasonably argued that Canadian R22 and R44 pilots are at risk of inadvertent in-flight upset in the absence of the exposure to, and instruction about, the issues raised by the United States SFAR.

Findings as to causes and contributing factors

  1. During flight, an undetermined flight manoeuvre caused the main rotor blades to strike the tailboom.

  2. The blades severed the tailboom and tail rotor assembly, resulting in an in-flight breakup rendering the helicopter uncontrollable.

Findings as to risk

  1. Low-level flight operations in areas known for migratory bird traffic increase the exposure to the hazards of bird strike and require the highest level of attention and caution.

  2. In the absence of the exposure to, and the instruction about, the issues raised by United States Special Federal Aviation Regulation 73, some Canadian R22 and R44 pilots are at risk of inadvertent in-flight upset from low-g manoeuvring or mast bumping.

TSB Final Report A10O0018—In-Flight Separation and Impact with Terrain

On January 23, 2010, an amateur-built Vans RV-7A was part of a formation of three aircraft that departed Lindsay, Ont., on a VFR flight to Smiths Falls, Ont. En route, one of the three aircraft diverted to Bancroft, Ont. The two remaining aircraft continued with the RV-7A in tandem. The lead conducted a series of aerobatic manoeuvres, which the RV-7A was to film. While manoeuvring, the lead lost contact with the RV-7A. The lead conducted a visual search, but could not find the RV-7A. The JRCC was alerted and a search was conducted. The aircraft was located in a wooded area. It was destroyed on impact and the pilot, the sole occupant, was fatally injured. The accident occurred at approximately 13:45 EST. The ELT functioned, but its range was reduced significantly, as its antenna was sheared on impact.

Vans RV-7A aircraft crashed.

Video 

A video camera had been mounted behind and slightly over the starboard passenger seat of the RV-7A. It was positioned facing forward, looking out through the windscreen. The entire occurrence flight was recorded. The video showed that after takeoff, the RV-7A had maintained a formation position behind the other two aircraft.

Shortly after, the first aircraft left the formation and the RV-7A moved to a tighter right echelon formation position with the lead. Near Wolfe Lake, the lead began a series of manoeuvres. The RV-7A chased the lead through the manoeuvres and, at times, the lead could be seen within view of the recording video camera. During this type of manoeuvre, the pursuing aircraft must turn at a higher rate or g in order to maintain the lead within the field of view of the video camera.

During a pull-out from a rapid descent, there was a sudden onset of an airframe vibration (shuddering around the longitudinal axis), which was followed by a yawing motion, a roll and ground impact.

Video still image of the lead aircraft manoeuvring.

Video still image of the lead aircraft manoeuvring

Wreckage examination
The aircraft struck terrain at approximately 80° nose down, flipped over and came to rest upside down. The aircraft was destroyed from impact forces and there was no post-impact fire. Damage to the aircraft was consistent with severe impact forces. The vertical stabilizer and top half of the rudder were missing from the aircraft and could not be located at the wreckage site. After an extensive ground search, the vertical stabilizer and rudder were found approximately 0.6 NM southeast of the main wreckage site. The vertical stabilizer was intact. A portion of the rudder was attached to the vertical stabilizer. Numerous parts of the rudder, including the right aluminum skin and rudder trailing edge wedge, had separated from the main rudder structure and were located within 100 m of the vertical stabilizer. The rudder counterweight could not be found. The vertical stabilizer had completely separated from the fuselage. The fractures in the vertical spars occurred just above where the spars fastened to the fuselage. The fracture surfaces were consistent with failure by overstress.

Re-assembled tail section during investigation.

Picture of re-assembled tail section during the investigation. 
Pictures of the failed rudder are included in the TSB Final Report

Findings as to causes and contributing factors

  1. After painting, the rudder was not likely balanced, nor the aircraft reweighed. As a result, the rudder was susceptible to flutter at a lower speed than designed and the aircraft was over the maximum aerobatic gross weight during the manoeuvres.

  2. During the manoeuvring sequence, the speed of the aircraft reached 234 kt, exceeding the 124 kt manoeuvring speed and the 200 kt never exceed speed (Vne).

  3. The aircraft encountered either flutter or overstress of some rudder components. Subsequently, the vertical stabilizer and parts of the rudder separated from the empennage during flight. Consequently, the aircraft became uncontrollable resulting in the impact with terrain.

Finding as to risk

  1. Performing aerobatic manoeuvres below the minimum altitude required by the Canadian Aviation Regulations (CARs) introduces unnecessary risk.

TSB Final Report A10Q0111—Controlled Flight into Terrain at Cruising Altitude

On July 16, 2010, a float-equipped de Havilland Beaver DHC-2 Mk.I was flying under visual flight rules from Lac des Quatre to Lac Margane, Que., with one pilot and five passengers on board. A few minutes after takeoff, the pilot reported intentions of making a precautionary landing due to adverse weather conditions. At approximately 11:17 EST, the aircraft hit a mountain, 12 NM west-south-west of the southern part of Lac Péribonka. The aircraft was destroyed and partly consumed by the fire that broke out after the impact. The pilot and three passengers were killed; one passenger sustained serious injuries and one passenger sustained minor injuries. No ELT signal was received.

 Crashed Havilland Beaver DHC-2 Mk.I

Analysis 

The aircraft hit the side of a mountain at approximately 100 ft from the peak during level flight, in adverse weather conditions. The TSB analysis focuses on the decision to carry out this VFR flight in bad weather, and on the survival of the occupants.

At the time of the takeoff from Lac Margane to go pick up the passengers, the weather conditions met the VFR weather minima. Given the lack of weather observations in the area, it is customary to take off and then assess the conditions while airborne. Given the numerous lakes in the area, it is easy to make a precautionary landing should the weather conditions make it necessary to discontinue the flight.

The air mass was humid, the winds were calm and a band of precipitation had hit the region in the early morning. When the cold front moved in, the wind shifted from the south to the southwest, but the air mass remained humid. An air flow from the southwest in the Chute-des-Passes area is considered to be flowing upwards. This type of circulation, combined with very humid air, promotes persistent low ceilings.

Consequently, although light drizzle conditions prevailed in the area, it was not raining at the time of the accident. A substantial mass of clouds covered the flight area. At the time of departure from Lac des Quatre, the base of the cloud layer was at a height of less than 250 ft above the surface of the lake, and the visibility was such that the end of the lake could be seen.

The prolonged flying times between Lac Margane and Lac Grenier, and between Lac Grenier and Lac des Quatre, indicate that considerable detours had to be made before the flight arrived at its destination. It is therefore likely that the adverse weather conditions forced the pilot to follow the valleys and possibly to divert a few times. Moreover, the scope of these extended flight times suggests that it is quite likely that the weather conditions were below the thresholds prescribed by the Canadian Aviation Regulations (CAR).

Once the aircraft had arrived at Lac des Quatre, no pressures of an operational nature were forcing the pilot to expedite the return to the base on Lac Margane, since the pilot’s next flight was scheduled for 16:00. Consequently, it is reasonable to believe that the pilot was convinced of being able to return to the base in the existing weather conditions, since the pilot had just flown over the area.

Although the ceiling and the visibility forcasted in the GFA were, respectively, 800 ft AGL and 2 mi., the ceiling was below 300 ft since the base of the clouds covered the peak of the mountains located on the shore of Lac des Quatre, whose elevation is approximately 250 ft above the surface of the lake. Consequently, the weather conditions at the time of the takeoff from Lac des Quatre were below the minimum prescribed by the CARs for VFR flights.

The pilot had over 10 years of experience in the area, on this type of seaplane. The decision to take off in weather conditions below the minimum prescribed by the CARs was probably influenced by confidence the pilot had gained from successful past flights in similar conditions and from the fact that the pilot had just flown over the area. Since there is no direct communication between the operations manager and the pilot, the decision to take off from Lac des Quatre rested primarily on the pilot’s judgment.

The pilot could not validate his decision to take off with another pilot or a colleague. The pilot made the decision on his own, based on the situation, his subjective evaluation of the risks, his knowledge and his experience. Some experienced pilots are not always concerned about flying close to rising terrain in limited visibility conditions. They do not feel that the safety margin is reduced to the point of reaching the real limit where a CFIT accident will occur.

In this case, the important decision, as far as safety was concerned, was whether to take off or not. It is possible that a question from a passenger as to the legality or the necessity of taking off in such conditions might have encouraged the pilot to delay the departure, since the weather conditions would have improved in the next few hours. After takeoff, the pilot was confronted with conditions that were no longer suitable for VFR flight.

 Overhead view of Flight trajectory and position of wreck on the side of the mountain.

Flight trajectory and position of the wreck on the side of the mountain

The pilot decided to make a precautionary landing and notified the passengers as well as the base at Lac Sébastien that the aircraft would land.

The GPS warning alerts of ground proximity at less than 100 ft are of limited usefulness when the entire flight is carried out at low altitude, because such alerts are frequent. Consequently, during a low-altitude flight, the pilot does not have time to analyze the numerous alerts and decide, in a timely fashion, whether a manoeuvre to avoid collision needs to be performed.

Findings as to causes and contributing factors

  1. The pilot took off in weather conditions that were below the minimum for visual flight rules (VFR), and continued the flight in those conditions.


  2. After a late decision to carry out a precautionary landing, the pilot wound up in instrument meteorological conditions (IMC). Consequently, the visual references were reduced to the point of leading the aircraft to controlled flight into terrain (CFIT).


  3. The passenger at the rear of the aircraft was not seated on a seat compliant with aeronautical standards. The passenger was ejected from the plane at the moment of impact, which diminished his chances of survival.

Findings as to risk

  1. The lack of training on pilot decision-making (PDM) for air taxi operators exposes pilots and passengers to increased risk when flying in adverse weather conditions.


  2. In view of the absence of an ELT signal and the operator’s delay in calling, search efforts were initiated more than 3½ hours after the accident. That additional time lag can influence the seriousness of injuries and the survival of the occupants.

TC AIM—New Features

A new feature has been added to the “Explanation of Changes” section of the Transport Canada Aeronautical Information Manual (TC AIM). Instead of having to click on each link to print pages individually, you will now be able to open a separate PDF file and print all of the new pages at once. Another new feature of the upcoming TC AIM will be the introduction of full-colour images (e.g. graphics and charts).

Date modified: