TBS Final Report Summaries

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. Unless otherwise specified, all photos and illustrations were provided by the TSB. For the benefit of our readers, all the occurrence titles are hyperlinked to the full TSB report on the TSB Web site. —Ed.

TSB Final Report A10Q0213—Runway Excursion

On November 30, 2010, a U.S.-registered Boeing 737-823 departed Dallas/Fort Worth International Airport, U.S.A., on a scheduled flight to Montréal/Pierre Elliott Trudeau International Airport, Que. At 19:53 EST, after touching down on Runway 24R in light rain during the hours of darkness, the aircraft gradually veered left of the centreline. It departed the runway surface and stopped in the grass and mud, approximately 90 ft from the runway edge and 6 600 ft from the threshold. None of the 106 passengers, 6 crew members or 1 off-duty crew member were injured. Evacuation was not deemed necessary; all passengers and cabin crew deplaned via an air stair and were transported by bus to the terminal. Damage to the aircraft was minor. The TSB authorized the release of this report on September 19, 2013.


Boeing 737 off the runway

Findings as to causes and contributing factors

  1. Following a stabilized approach and normal landing, the aircraft deviated left of the runway centreline, likely as the result of a nose gear steering metering, low-slew rate jam.
  2. The delayed response to the uncommanded steering event by the pilot flying was not sufficient to counteract the movement toward the left, and the aircraft departed the runway surface.

Findings as to risk

  1. In the absence of information on uncommanded steering events due to nose gear steering rate jams, there is a risk that the cause of these events will continue to be unresolved and unmitigated, leading to a risk of runway excursions.
  2. The lack of flight data recorder information or other types of recording devices on the nose gear steering system may hinder the identification of safety deficiencies.

Other finding

  1. The flight operational quality assuranceFootnote 1 programs in place at many airlines already target certain events with a view to underlining safety concerns. With additional filters, it would be possible to flag steering events in order to help in verifying for rate-jam events.

Safety action taken

Operator

In April 2011, as part of its pilots’ recurrent training human factors class, the operator introduced a simulation and discussion of this Boeing 737 runway excursion. This training is given to company pilots to educate them on the possibility of a runway excursion due to a nose wheel steering problem on landing roll-out after a normal approach and landing.

Safety concern

Despite efforts in analyzing past nose gear steering, low-slew rate-jam events and carrying out post-event valve examinations, the cause of these uncommanded steering events remains uncertain. The safety review process completed by the manufacturer and based on a quantitative, cycle-based occurrence rate of 1 X 10-7, classified this event as an extremely remote probability and gave it an acceptable risk level, combined with a major severity level. An occurrence rate of 1 X 10-7 meets the Federal Aviation Regulations (FARs) certification requirements. Additionally, an acceptable level of risk does not require further tracking of the hazard in the Federal Aviation Administration (FAA) Hazard Tracking System. Consequently, other than flight data analysis and valve examination, the manufacturer has not taken further action following the 11 known nose gear steering, rate-jam events that have occurred over the past 21 years.

Rate of occurrence determines whether a manufacturer needs to take safety action. In order to determine the rate of occurrence, there is a need to capture as many events as possible. This capture allows identification of possible safety deficiencies and aids in the application of risk-mitigation strategies. Since no defences have been put in place to mitigate the risk of a runway excursion following a rate jam, damage to aircraft and injury to aircraft occupants remains a possibility.

The present low rate of known nose gear steering rate jams may be explained by the fact that, directional control difficulties on takeoff or landing would not often result in an excursion, damage or injury, and therefore would not be reported. The lack of reporting may also be due, in part, to the fact that operators, flight crew and maintenance personnel have not been made aware of the possibility of rate-jam events, nor have they been provided information on how to recognize, react or troubleshoot these events. The rate of occurrence would have to show a significant increase to validate corrective action, as safety action is based on FARs certification and on in-service fleet following requirements.

Despite technological advancements in recording devices, many Boeing aircraft do not record nose wheel steering system parameters. Boeing models affected include 707/720, 727, 737, 747 (some models), 757, 767 and 777.

The cause of these low-slew nose gear steering rate jams over the past 21 years remains uncertain. A lack of recognition and reporting prevents adequate data collection, analysis and implementation of risk-mitigation strategies if necessary.

The Board is concerned that, in the absence of information as to the cause of uncommanded steering events due to nose gear steering rate jams, there remains a risk for runway excursions to occur.

TSB Final Report A11C0047—Double Engine Power Loss and Forced Landing

On April 1, 2011, at 15:03 CST, a Construcciones Aeronauticas SA (CASA) C-212-CC40 departed from Saskatoon/Diefenbaker International Airport (CYXE), Sask., under VFR for a geophysical survey flight to the east of Saskatoon. On board were 2 pilots and a survey equipment operator. During the flight, an internal component in the right engine of the CASA C‑212 failed, causing the engine to lose power. The crew of three then completed the engine failure checklist, stowed the survey equipment and turned toward Saskatoon airport. Fourteen minutes later, with the aircraft just short of the airport, the left engine lost power. The aircraft impacted a concrete noise abatement wall as the crew executed a forced landing adjacent to a road. The survey equipment operator was fatally injured, the first officer was seriously injured and the captain suffered minor injuries. The aircraft was destroyed. The TSB authorized the release of this report on December 12, 2012.

The torque sensor had accumulated approximately 6 470 hr since overhaul in 1997. The torque sensor assembly does not have a designated overhaul period and is normally overhauled with the engine. The laboratory analysis indicated that the case hardening of the gear tooth flanks and roots of two spur gears in the torque sensor gear train was below the manufacturer’s specification requirements and likely led to the wear of the loaded faces and flanks of the gear teeth. The combined wear of the two gears likely caused an abnormal vibration that produced excessive cyclic loading and eventual fatigue cracking in the tooth roots of the intermediate gear. The intermediate spur gear subsequently separated into several fragments and caused the loss of power transmission to the high-pressure, engine-driven fuel pump. The immediate result would have been fuel starvation of the engine, flameout and loss of power.


Failed gear on the torque sensor shaft

Left engine power loss

The left engine lost power due to fuel starvation. Investigators found debris in a fuel pump nozzle, which reduced the amount of fuel the pump delivered to the left collector tank. Fuel depletion in the left collector tank caused the engine to shut down while usable fuel remained in the left inboard tank. Additionally, the fuel cross-feed valve remained closed, which meant that the left engine was only receiving fuel from the left fuel tank, rather than from both tanks.


Debris found in fuel pump nozzle (ruler scale is cm)

Forced Landing

When the left engine lost power, the aircraft was approximately 3.4 NM from the threshold of Runway 27. The crew immediately determined that it was not possible to extend the glide to the airport.

The crew had limited altitude and time to prepare for and execute the forced landing. Although the multiple engine failure procedure specified that the flaps should be retracted, the crew elected to leave them set at 25%. Had the flaps been retracted, they would have needed to be re-extended a short time later to prepare for the forced landing, and any improvement in glide performance resulting from flap retraction would not have been sufficient for the aircraft to reach the runway or a better landing site than the one chosen.

The site that was chosen for the forced landing offered the most likelihood of success with the least risk to persons on the ground. The crew landed the aircraft under control while avoiding a busy highway to the left and residential buildings on the right. The concrete noise abatement wall ran parallel to the roadway and would initially have been difficult to see from the air. The crew received immediate assistance from bystanders and were aided by a quick response from Saskatoon emergency services personnel.

Findings as to causes and contributing factors

  1. The right engine lost power when the intermediate spur gear on the torque sensor shaft failed. This resulted in loss of drive to the high-pressure engine-driven pump, fuel starvation and immediate engine stoppage.
  2. The ability of the left-hand no. 2 ejector pump to deliver fuel to the collector tank was compromised by foreign object debris (FOD) in the ejector pump nozzle.
  3. When the fuel level in the left collector tank decreased, the left fuel level warning light likely illuminated but was not noticed by the crew.
  4. The pilots did not execute the fuel level warning checklist because they did not perceive the illumination of the FUEL LEVEL LEFT TANK warning light. Consequently, the fuel cross-feed valve remained closed and only fuel from the left wing was being supplied to the left engine.
  5. The left engine flamed out as a result of depletion of the collector tank and fuel starvation, and the crew had to make a forced landing resulting in an impact with a concrete noise abatement wall.

Findings as to risk

  1. Depending on the combination of fuel level and bank angle in single-engine uncoordinated flight, the ejector pump system may not have the delivery capacity, when the no. 1 ejector inlet is exposed, to prevent eventual depletion of the collector tank when the engine is operated at full power. Depletion of the collector tank will result in engine power loss.
  2. The master caution annunciator does not flash; this leads to a risk that the crew may not notice the illumination of an annunciator panel segment, in turn increasing the risk of them not taking action to correct the condition which activated the master caution.
  3. When cockpit voice and flight data recordings are not available to an investigation, this may preclude the identification and communication of safety deficiencies to advance transportation safety.
  4. Because the inlets of the ejector pumps are unscreened, there is a risk that FOD in the fuel tank may become lodged in an ejector nozzle and result in a decrease in the fuel delivery rate to the collector tank.

Other findings

  1. The crew’s decision not to recover or jettison the birds  immediately resulted in operation for an extended period with minimal climb performance.
  2. The composition and origin of the FOD, as well as how or when it had been introduced into the fuel tank, could not be determined.
  3. The SkyTrac system provided timely position information that would have assisted search and rescue personnel if position data had been required.
  4. Saskatoon police, firefighters and paramedics responded rapidly to the accident and provided effective assistance to the survivors.

Safety action taken

Operator

The operator grounded its remaining CASA C-212 aircraft immediately following the occurrence. Before recommencing operations on June 30, 2011, the company:

  • revised its CASA C-212 one engine inoperative emergency procedures to include supplying the operating engine with fuel from both the left and right tanks by opening the cross-feed valve; and
  • modified the aircraft with a remote-controlled cable cutter on the bird tow cables. This cutter permits the pilots to jettison the birds from the cockpit, eliminating the requirement for the survey equipment operator to leave his seat, and allows the pilots to quickly improve the climb performance of the aircraft in the event of a loss of engine power.

In October 2011, the aircraft was modified with the installation of a continuous ignition system for the engines.

The operator has also increased the frequency and expanded the scope of some maintenance inspections of the CASA C-212 fuel system, including cleaning of the ejector pump nozzles.

Transport Canada

On April 14, 2011, Transport Canada conducted an inspection of the company’s operational control and maintenance release processes exercised for the occurrence flight. The inspection determined that all processes reviewed met applicable regulatory requirements and were being followed as described in approved company manuals.

Honeywell Aerospace

Honeywell Aerospace has initiated a revision to the component maintenance manual for the torque sensor.

Airbus Military

Airbus Military has initiated a revision to the CASA C-212 Airplane Flight Manual procedure for engine failure in flight.

TSB Final Report A11P0106—Aerodynamic Stall and Collision with Terrain

On July 5, 2011, at 15:00 PDT, a Cessna 152 with a flight instructor and a student pilot on board departed Boundary Bay, B.C., for a mountain training flight. At approximately 16:30, the aircraft collided with terrain at an elevation of 2 750 ft ASL, about 10 NM west of Harrison Lake, in daylight conditions. The ELT activated and was detected by the SARSAT system at 16:36. The Rescue Coordination Centre in Victoria, B.C., was alerted, and a search was commenced. The aircraft was destroyed by impact forces, and the occupants of the aircraft were fatally injured. There was no fire. The TSB authorized the release of this report on July 17, 2013.


Wreckage of Cessna 152

Analysis

The two occupants of the aircraft were fatally injured in the accident. There were no witnesses to the final moments of the flight, and there were no on-board recording devices to assist investigators. There was no indication that an aircraft system malfunction or the weather contributed to this occurrence. The aircraft impacted the ground in a steep, nose-down attitude, suggesting a stall and in-flight loss of control.

Wreckage and site analysis

The steep, nose-down attitude and low forward speed are consistent with a situation of loss of control in flight. Both these conditions are consistent with the aircraft having conducted a steep right turn and stalling from a height less than 200 ft above the ground. Had the aircraft stalled at a higher altitude, the dynamics of the crash and the wreckage pattern would have been different. It is not likely that the aircraft had yet entered a spin, as the engine was found to be at a high power setting (the first step in the spin recovery procedure is to immediately reduce engine power), and there was still forward movement when the aircraft struck the ground.

Mountain flying training

Mountain flying presents many complex and challenging situations. There is no requirement for pilots in Canada to undergo mountain flying training before flying in mountainous areas. As a result, pilots may receive no training or be left to study the available material by themselves. There is valuable information to be shared; however, without in-depth classroom instruction, a pilot might not gain adequate knowledge of the significant hazards of mountain flying and the recommended practices for avoiding them. In addition, advances in simulation make it possible for pilots to experience some of the challenges of mountain flying and gain the associated skills. Without proper training in mountain flying techniques, pilots and passengers are exposed to increased risk of collision with terrain when conducting mountain flying.

Canyon/tight turns

There is no one specific ideal canyon/tight turn that can be used on all aircraft types. Instead, a turn procedure should be developed for use with each type to ensure safety and minimize turn radius. It is important that emergency procedures, such as the canyon turn, be researched and tested on a particular aircraft type before being introduced into flight operations.

Possible accident conditions and actions

The accident occurred close to a route commonly used by the instructor for mountain flying training. It could not be determined why the aircraft entered this canyon; but, with insufficient performance to climb above the terrain at the highest point of the pass, it is likely that the pilots executed a turn in the canyon. Since the left-hand (east) side of the pass would have been exposed to the sun, it is more likely that they were flying on the left-hand side of the valley and attempted a right-hand turn. This attempt would have resulted in a turn toward a shadowed, steeply sloping surface. The lack of references associated with flying in the valley would have made it difficult for the pilots to visually determine their angle of bank relative to the horizon.


Estimated flight path with shadows at the time of the accident (Image: Google Earth)

It is not known why the aircraft was at such a low level before the crash. However, conducting a turn at a low altitude would have increased the risk level of the manoeuvre and was not in accordance with the flying school policy regarding minimum flight altitudes. If the instructor delayed the decision to initiate the turn-around, it would have further reduced safety margins. With the flaps in the up position, the stall speed would have been 7 kt higher than if the flaps had been fully down. In addition, it is possible that once the turn was initiated, the aircraft encountered a downdraft on the shadow side of the valley, which could have caused the aircraft to sink. If the pilots were not cross-checking their instruments, it is also possible that the loss of horizon and visual illusions caused by the surrounding terrain may have caused the pilots to inadvertently stall the aircraft while conducting the turn.

Although the throttle was found in a high power position, a reduction of power for even a few seconds during a critical manoeuvre would negatively affect aircraft performance. It is possible that the throttle was reapplied once the loss of performance was noted by the pilots. Any one of these factors, or a combination of them, could have caused the pilots to increase bank angle and increase angle of attack by pulling back on the control column, causing an aerodynamic stall. It is likely that the aircraft stalled aerodynamically while attempting a turn at an altitude from which the pilots could not recover before impact with terrain.

Finding as to causes and contributing factors

  1. It is likely that the aircraft stalled aerodynamically while attempting a turn at an altitude from which the pilots could not recover before impact with terrain.

Findings as to risk

  1. If weight and balance calculations are not documented, there is increased risk that aircraft will take off over the maximum approved gross weight.
  2. Without proper training in mountain flying techniques, pilots and passengers are exposed to increased risk of collision with terrain due to the complex nature of mountain flying.
  3. The reliance on an aircraft stall warning system that does not show progression toward an impending stall increases the risk of a pilot inadvertently entering a stall.
  4. If pilots are taught to fly with the stall warning activated during slow flight, there is increased risk that the aircraft may inadvertently stall during slow flight manoeuvring.
  5. If pilots are not taught how to recognize and recover from a high angle-of-bank stall, there is an increased risk of collision with terrain if one is encountered.
  6. If emergency procedures are not validated before implementation, there is increased risk that safety margins will be reduced due to unexpected performance degradation.
  7. If a flight school’s standards and procedures are not incorporated into company manuals, flight instructors may deviate from company-approved methods of instruction.
  8. Without flight tracking or some system of post-flight monitoring, there is a risk that management will not be aware of deviations from a school’s standards that expose a flight to hazards.
  9. If cockpit and data recordings are not available to an investigation, this unavailability may preclude the identification and communication of safety deficiencies to advance transportation safety.

Safety action taken

Flying school

Following the occurrence, the flying school implemented the following safety actions:

  • suspension of mountain flying instruction pending review and analysis using safety management system (SMS) principles;
  • the creation of a formal, regimented Mountain Flying Training Syllabus and training for all instructors that includes defined procedures for canyon turns, minimum altitudes, mandatory routing and standard operating procedures;
  • modifications to the mountain flying program, including ground school before flight, prescribed new routing, and the use of flight training devices to enhance pilot awareness of hazards;
  • mandatory written test on mountain flying awareness to ensure students have comprehension of the principles taught before flight;
  • mountain flying review seminars open to the public and aimed at past and current students who are interested in the latest information and the revised syllabus;
  • workshops held for instructors in effective leadership and risk management and focused on the identification of instructors taking control at appropriate points in different training scenarios, flight management under different training scenarios, and identification and appropriate management of student and air exercises based on experience and training;
  • change to sign-out sheet to require the pilot to insert the actual takeoff weight and takeoff arm, with initialing by both the student and the instructor required;
  • portable global positioning system (GPS) to be carried on all flights outside the Lower Mainland to allow for increased oversight by both senior management and instructional staff.

TSB Final Report A11Q0136—Engine Stoppage and Forced Landing on Water

On July 18, 2011, at approximately 14:48 EDT, a Cessna A185E floatplane left the La Tuque, Que., seaplane base for a 20-min sightseeing flight. The aircraft took off towards the north and climbed to an altitude of approximately 1 600 ft ASL. After approximately 12 min of flight time, the engine failed, and the propeller began spinning in the air. The pilot decided to proceed with an emergency ditching in the Bostonnais River. During the descent, the pilot attempted to restart the engine without success. The terrain surrounding the river forced the pilot to execute a sharp left turn. The aircraft stalled, nosedived and struck the surface of the water. The aircraft tumbled and came to rest inverted in the water. Local residents reacted quickly, contacting emergency services and offering assistance. Of the 5 passengers on board, the pilot and 3 passengers survived and 1 passenger died. The ELT was triggered on impact, but no transmission was received. The TSB authorized the release of this report on April 17, 2013.

Findings as to causes and contributing factors

  1. The pilot did not measure the quantity of fuel with the dipstick before departing on the accident flight. Relying only on an estimation of the remaining fuel in the tanks, the pilot could not predict the precise moment at which the left tank would run dry.
  2. The fuel quantity indicators on this type of aircraft were not reliable. As a result, the pilot could not be sure of the quantity of available fuel in the left tank during flight.
  3. The engine very likely lost power due to momentary fuel starvation in the left tank.
  4. Following the loss of power, the pilot did not activate the auxiliary electric fuel pump and was not able to restart the engine.
  5. The pilot very likely pulled back on the yolk, contributing to an aerodynamic stall which took place at an altitude that precluded recovery.
  6. The safety briefing provided by the pilot to the occupants was incomplete; the pilot did not point out the location of the safety features cards on board the aircraft and did not instruct the occupants on how to use the personal flotation device (PFD).

Findings as to risk

  1. When the passenger guides available at the seaplane base are not distributed to passengers before takeoff, there is a risk that passengers may not recognize or appreciate the importance of emergency procedures in the event of an accident.
  2. When safety instructions are provided during taxi with the engine running, there is a risk that noise or other distractions may prevent passengers from clearly understanding the information provided and being better prepared in case of emergency.
  3. When the pilot does not provide complete safety instructions to occupants, there is a risk that passengers will not be adequately prepared in the event of an emergency.
  4. When passengers egress an aircraft without their PFDs, their risk of drowning increases, particularly if they are injured.
  5. If safety instructions are presented to children while they are distracted, there is a risk that they will not be able to egress the aircraft on their own.
  6. When information is not presented to occupants regarding emergency egress and the use of a PFD in the event of an inverted and submerged aircraft, there is a risk that occupants will not be able to egress the aircraft.

Other findings

  1. The airplane was equipped with an ELT that activated on impact. However, no signal was received because the antenna was submerged.
  2. The rapid assistance provided by local residents likely increased the occupants’ chances of survival.

Safety action taken

Operator

New safety measures have been incorporated into the company’s operating procedures since May 2012, and the operations manual (COM) has been modified as well. The company showed its support for TSB Recommendation A11-06 by amending its COM to indicate that the wearing of PFDs is mandatory at all times for all occupants, including the pilot. The PFDs provided to pilots and passengers must be inflatable and must not inflate automatically when they come in contact with water. The manual stipulates that the pilot must always remind passengers to only inflate their PFDs once they have evacuated the aircraft.                     

In addition, the COM specifies that passenger safety briefings must now be given prior to engine start-up and include a demonstration of the use of PFDs in the event of accidental capsizing. What’s more, the emergency procedures and passenger briefing for an emergency landing include the instruction to unlock doors prior to impact.

The company’s training program now includes mandatory initial training, for all its pilots, on emergency egress procedures for floatplanes, with particular emphasis on underwater egress from capsized floatplanes. In addition, company pilots will be required to take rescue training.

In response to TSB Recommendation A11-05, Transport Canada issued a safety alert recommending aircraft design improvements facilitating egress. To allow rapid egress following a survivable collision with water, the operator has acquired a Supplemental Type Certificate (STC) needed for the purpose of adding jettisonable windows and moving the door handles on its DHC-2 Beaver aircraft, thereby demonstrating its support for TSB Recommendation A11-05.

TSB Final Report A11A0101—Stuck Elevator Control

On December 10, 2011, at 10:28 NST, a Hawker Beechcraft 1900D aircraft was conducting a scheduled passenger flight from Gander to Goose Bay, N.L., with 2 crew members and 13 passengers on board. After the crew began the takeoff roll on Runway 21, they noted that the control column was stuck in the full forward position. The takeoff was rejected, and the aircraft was taxied back to the terminal. The aircraft was not damaged, and there were no injuries.  The TSB authorized the release of this report on November 6, 2013.

Analysis

Stuck elevator control

The occurrence aircraft had been parked outside, with its tail pointed into gusty winds; the operator’s personnel did not always install the control locks. The Airplane Flight Manual (AFM) indicates that gust locks should be installed after flight and removed before flight. Installing the control locks protects the flight controls from abnormal forces such as gusty winds. Without the control lock installed, gusty winds can cause the elevators to move up and down rapidly. This movement would cause the control column to slam back and forth. The rapid downward movement, in combination with the down-spring and bob-weight force, would result in the control column vertical portion flexing under the strain of the combined forces. In this occurrence, the damage noted on the bob weight was more severe than what was observed when the elevators were allowed to free-fall or from pushing the control column forward. Therefore, the damage to the occurrence aircraft’s bob weight resulted from the elevators being repeatedly slammed down when the aircraft was parked outside, without the control locks installed, in gusty wind conditions.

When the operator’s personnel examined the aircraft after the occurrence, they had to push the stop bolt to the left to align the damage on the bob weight with the stop bolt. Once the stop bolt was released, it would have exerted a sideways force on the bob weight. This force would tend to hold the bob weight in position. With the bob weight held beyond its normal range of travel, the vertical portion of the T-shaped column would have been flexed forward. The design of the elevator position sensor system is such that it will read, and the flight data recorder (FDR) will record, movement beyond the normal range of travel. At the start of the occurrence flight, the elevator position indication was 1.1° beyond normal. This position is indicative of the control column travelling beyond its normal range of travel. The control column was stuck forward because the bob weight became jammed on the stop bolt.

No elevator control check was carried out during the daily maintenance inspection (DI) or the after-start checks, which resulted in the stuck control condition going undetected. The flight crew’s first indication of the elevator controls being stuck was at about rotation speed.

Findings as to causes and contributing factors

  1. The aircraft was parked outside, without the control locks installed, in gusty wind conditions, causing damage to the bob weight from the elevators being repeatedly slammed down.
  2. The design of the stop-bolt bracket allowed the bob weight to travel beyond its normal operating range, resulting in the control column being stuck forward because the bob weight became jammed on the stop bolt.
  3. No elevator control check was carried out during the daily maintenance inspection, nor as required by the after-start checks, which resulted in the stuck elevator control condition going undetected.

Findings as to risk

  1. When manufacturers do not provide clear and concise information in their communications, operators may not fully understand and appreciate the safety issue and what can be done to mitigate the risk.
  2. When crews engage in non-essential communication while a sterile cockpit environment is required, there is an increased risk of distraction that may cause them to make unintentional errors.
  3. When operators do not carry out a complete pre-flight inspection in accordance with the manufacturer’s instructions, there is a risk that a critical item will get missed, which could jeopardize the safety of flight.
  4. When organizations don’t identify the underlying unsafe condition, then it is likely that the resulting mitigation may not be effective in preventing a recurrence of the event.
  5. When a manufacturer’s maintenance documents include cautions/warnings pertaining to actions that may cause damage to aircraft systems and the cautions/warnings are not included in the Airplane Flight Manual, there is a risk that flight crews will be unaware of these concerns and inadvertently cause damage to the aircraft system.
  6. When manufacturers’ communications contain concerns related to both flight operations and maintenance and the communications’ emphasis is maintenance-related, it is possible that operators will not recognize the need to distribute the communication to their flight operations department for consideration of the operational implications, possibly jeopardizing safety of flight.
  7. When organizations do not use modern safety management practices, there is an increased risk that hazards will not be identified and mitigated.
  8. When operators are not aware of the TSB’s reporting requirements and therefore do not advise the TSB of a reportable accident or incident, there is a risk that potentially valuable information will be lost.
  9. When flight crews do not take precautions to preserve cockpit voice recorder data and flight data recorder data following a reportable occurrence, there is a risk that potentially valuable information may be lost.

Other findings

  1. When flight data recorders capture only the minimum required parameters as defined by the Canadian Aviation Regulations, potentially valuable information will not be recorded.
  2. The bob weight from aircraft UE-345 did not meet the manufacturer’s specified values for antimony content or hardness.
  3. The operator’s Company Operations Manual did not include procedures for preserving the flight data recorder / cockpit voice recorder following an accident or incident.
  4. At the operator, Safety Communiqué #321 was not forwarded to flight operations or the chief pilot, although it was addressed to both.

Safety action taken

Operator

Immediately following the occurrence, the company released an instruction to all staff requiring the use of flight control locks at any time when there is not a crew member at the controls of the aircraft. This instruction was also included as an amendment to the company standard operating procedures.

The operator’s flight crew training now incorporates the control lock issue and loss of flight control as a simulated occurrence during all flight crew training.

After receipt of SB 27-4119, the company ordered the associated elevator bob-weight stop kits for its aircraft.

Federal Aviation Administration (FAA)

On December 23, 2011, the FAA issued Emergency Airworthiness Directive 2011-27-51, effective immediately upon receipt.

Hawker Beechcraft Corporation

In May 2012, Hawker Beechcraft Corporation issued Model Communiqué #104 to announce newly developed Airliner Maintenance Manual inspection procedures intended to identify and correct noted damage to the stop bolt, the stop-bolt bracket, the bob weight and other supporting structures. These procedures require an alignment check of the bob weight with the stop bolt to ensure that no part of the stop bolt protruded beyond the face of the bob weight, and a visual examination of the weight for evidence of scraping along the side and for evidence of damage to the stop bolt and stop-bolt bracket.

Subsequently, the third 200‑hr inspection and the 5 000‑hr inspection were revised and became mandatory.

In June 2013, Hawker Beechcraft Corporation issued Mandatory Service Bulletin SB 27-4119. This Service Bulletin introduces Kit 114-5060 (KIT − BOB WEIGHT STOP, ELEVATOR SYSTEM) for Model 1900-series airplanes and provides parts and instructions to install a second elevator bob-weight stop bolt.

TSB Final Report A12W0031—Loss of Control and Collision with Terrain

On March 30, 2012, a Bell 206B helicopter departed the Kananaskis/Nakoda base near Kananaskis, Alta., on a VFR day tour flight, with 1 pilot and 4 passengers on board. Approximately 13 min after departure, at about 10:10 MDT, the helicopter crashed in a steep, snow-covered avalanche corridor, in a cirque near Loder Peak, Alta. About 1 hr and 29 min later, the operator was advised by the Joint Rescue Coordination Centre in Trenton, Ont., that the helicopter’s 406 MHz ELT was transmitting. A company helicopter was dispatched to search the tour route and found the wreckage at approximately 12:06. All occupants were extracted from the site. The 4 passengers sustained minor injuries. The pilot succumbed to injuries approximately 5 hr after the accident, following removal from the accident site. There was no post-crash fire. The TSB authorized the release of this report on May 29, 2013.


Route of flight

Analysis

The investigation found nothing to indicate any airframe failure or system malfunction before or during the flight. The helicopter was being operated within its weight and centre-of-gravity limits at the time of the accident. As well, the weather at the time of the accident was suitable for VFR flight. Other than 2.6 hr of flight time obtained in February 2012 toward a Robinson R44 helicopter endorsement, there was no record of the pilot having flown for approximately 21 months when hired by the operator. At the time of hiring, the pilot had little or no mountain flying training or actual mountain flying experience.

Based on the pilot’s self-reports of having approximately 500 hr of helicopter flight experience in B.C. and no accidents, the company considered the pilot to have adequate knowledge, skill and experience to safely conduct mountain tour flights with minimal recurrent flight training and checkout. That the pilot had a previous accident, no prior mountain flying training and minimal mountain flight experience was not identified. As a result, the pilot received very little instruction from the operator in mountain flying techniques and a minimal evaluation of abilities in that environment. The pilot’s reluctance to fly in close proximity to rock outcrops during flight training heightened the company’s confidence in the pilot’s ability to safely conduct tour flights within the mountainous local area.

Before an earlier filming flight on which the pilot rode along, the pilot flew exclusively on the eastern side of Loder Peak over relatively gentle terrain. The pilot’s change of routing to the western side on subsequent flights and operation in very close proximity to the steep, rugged terrain were likely influenced by the positive experience on the filming flight. The change was also likely motivated by a desire to provide the tour passengers with a more thrilling experience. The change in the pilot’s routing was unknown to the company. Although this information was available through the Sky Connect system, the company did not have a program in place to monitor the flight profiles of inexperienced pilots. The company’s flight-following procedures did not identify that the helicopter had stopped transmitting its satellite tracking position and that the pilot had not reported landing at Brokenleg Lake. This lack of information delayed initiation of search-and-rescue (SAR) operations.

While flying below the western side of the mountain ridge and climbing toward a saddle leading to the eastern side of the ridge, the helicopter entered a shallow but very steep cirque. The company guideline stipulating that ridge crossing was to be carried out above 500 ft from any pass was not followed, increasing the risk of collision with terrain. In attempting to outclimb the terrain while presented with an illusion resulting from the lack of a true horizon and in very close proximity to the rugged rock faces, the pilot may have experienced difficulty in maintaining a constant pitch attitude. There may have been a tendency to raise the nose, when facing the mountain,  with substantial loss of airspeed and climb performance. The illusion may have been compounded by a tailwind, resulting in significant movement across the ground at a low airspeed and a visual illusion of higher than actual airspeed. The turbulence that was experienced indicates that the helicopter may have entered an area of down-flowing air, or the turbulence may have been the result of a loss of translational lift, either of which would have resulted in increased power demands.

It is likely that the pilot recognized the loss of climb performance and attempted to turn left, away from the mountain and into the drop-off area. However, the decision to make this turn was likely made too late to avoid a decrease in airspeed below translational lift speed. Severe damage to the main- and tail-rotor systems indicates the application of high power when the tail rotor blades struck the rock face. Rapid, multiple rotations to the right indicate a loss of tail rotor effectiveness, which could be explained with two scenarios:

  1. During an uncoordinated left turn in very close proximity to the rock face and at low airspeed, the tail rotor contacted the ground;  the rotor and its drive system were destroyed.
  2. The high-density altitude (7 600 ft) would have required further increase in anti-torque from the tail rotor. An unanticipated right yaw occurred when airspeed deteriorated below translational lift speed, and the pilot initiated a turn to the left. A turn with left pedal input would have placed the relative wind on the left side of the aircraft, where a combination of tail rotor vortex ring state (210° to 330° relative wind) and main rotor vortex interference (285° to 315° relative wind) would have reduced tail rotor effectiveness.

Both of these situations would have resulted in an uncontrolled rotation to the right and, unless the pilot made a substantial reduction in power, rapid rotation would have continued. In close proximity to the terrain, a significant power reduction would not have been possible without the helicopter impacting the steep mountainside at a high rate of descent. The rapid right rotation would have been accompanied by an uncontrolled descent. The helicopter was unable to hover out of ground effect, and rotation would have further reduced this capability.

The minimal mountain flying experience that the pilot received during training and during the pilot competency check (PCC) would not have provided adequate preparation for the challenging situations presented in that environment. In addition, the mentoring provided by riding along with other low-time pilots with limited experience could have instilled the wrong perceptions on proper mountain flying procedures and techniques. These perceptions could have influenced the pilot’s decision-making, leading the pilot to place the aircraft in a hazardous situation while not recognizing the hazard. Extraction from the situation was delayed until safe options were not available.


Wreckage site

Findings as to causes and contributing factors

  1. The pilot conducted the tour flight using a route in very close proximity to mountainous terrain, in conditions in which environmental factors resulted in reduced performance margins.
  2. The visual illusion associated with the lack of a true horizon, combined with the illusion of higher-than-actual airspeed, may have resulted in pilot-initiated flight control inputs that further reduced helicopter performance.
  3. The pilot attempted to cross a mountain ridge at an altitude that did not provide safe terrain clearance, and the pilot did not use the available drop-off zone early enough, which increased the risk of collision with the terrain.
  4. The helicopter either sustained a tail rotor strike on terrain or, more likely, entered a condition of aerodynamic loss of tail rotor effectiveness, resulting in an uncontrolled rotation, loss of control and collision with terrain.
  5. The pilot had minimal mountain flying training and experience. As a result, it is likely that the pilot was unable to recognize the hazards associated with flying in mountainous terrain.
  6. The pilot was not wearing a helmet, which contributed to the level of injury.
  7. The company’s flight-following procedures did not identify that the aircraft had stopped transmitting its satellite tracking position, and that the pilot had not reported landing at Brokenleg Lake. This lack of information delayed initiation of SAR operations.

Findings as to risk

  1. By not using lightweight flight recording systems, small aircraft commercial operators are less able to effectively monitor flight operations through an internal flight data monitoring program, which precludes proactive identification and correction of safety deficiencies by an operator to reduce accident risk.
  2. If adequate surveillance is not maintained by Transport Canada, there is an increased risk that operator safety deficiencies will not be identified.
  3. The ELT did not activate at impact, and signal detection was delayed due to terrain and satellite geometry. Until improvements in ELT detection times arise from inauguration of the developmental MEOSAR SARSAT system, protracted SAR times can place victims of air accidents at risk for delayed response.

Safety action taken

Operator

As a result of this accident, the operator took the following measures to reduce operational risks:

  • All company pilots are now required to wear helmets while flying.
  • Permission is now obtained from company pilots at time of hire to inquire into their accident history.
  • The company pilot training syllabus has been enhanced to emphasize certain aspects of mountain flight training.
  • Internal company indoctrination training forms have been improved.
  • A quality assurance program has been put in place to validate that all company pilot training has been completed.

TSB Final Report A12P0136—Collision with Terrain

On August 13, 2012, a privately operated Piper PA-30 Twin Comanche departed Penticton Airport (CYYF), B.C., at 14:32 PDT on a VFR flight plan during daylight hours, to Boundary Bay (CZBB), B.C., with 1 pilot and 3 passengers on board. The aircraft flew northbound over Okanagan Lake for approximately 20 NM, before turning west into a valley; this was about 14 NM further than planned, due to a lower than expected rate of climb. At 14:54, an overflying airliner received an ELT signal, which the airliner pilot relayed to the area control centre (ACC). The ACC relayed it to the Joint Rescue Coordination Centre (JRCC). The aircraft wreckage was located about 2½ hr later, in a wooded area near the Brenda Mines site, approximately 18 NM west of Kelowna, B.C. There was no fire. All 4 occupants were critically injured; one occupant died at the site, and a second died in hospital two days later. The TSB investigation found that a number of factors contributed to the accident including a reduced rate of climb. The reduced rate of climb was attributed to atmospheric conditions, the aircraft being over its gross takeoff weight, reduced power in the right engine and the decision not to use available turbochargers. The TSB authorized the release of this report on September 19, 2013.

Analysis

Aircraft performance

The increased density altitude, from 3 300 ft at takeoff to over 7 000 ft at the accident site, resulted in reduced engine power and aerodynamic performance. In particular, the pilot’s decision not to use turbocharger boost resulted in the engines performing like normally aspirated engines, with continuously decreasing engine performance as the aircraft climbed.

The pilot did not calculate weight and balance for the accident flight or the previous leg. This was, in part, likely because the information necessary to do so was not readily available to the pilot, in the journey log or elsewhere in the aircraft. On the leg before the accident flight, the aircraft departed Boundary Bay with full fuel (about 6 hr in duration), which was substantially more than was necessary to conduct the intended 2 flight legs (about 2.6 hr in total duration). On the accident leg, once the additional passengers and their baggage came on board in Penticton, the aircraft was about 150 lb over its maximum gross weight. There were no steps taken to reduce aircraft weight, and this higher weight contributed to reduced climb performance.

The partially obstructed fuel nozzle prevented the right engine from producing as much power as the left engine. The exact amount of power reduction could not be determined, but the aircraft’s climb performance on the day of the accident was far lower than the figures stated in the pilot’s operating handbook. The fuel flow indicator showed that the right engine’s fuel flow was higher than the left engine’s, when in fact it was lower. As a result of that incorrect indication and the normal rpm and manifold pressure indications, it is likely that the pilot did not recognize the problem or its consequence.

The high density altitude conditions, high aircraft weight, non-use of available turbochargers and reduced power of the right engine all contributed to a reduced rate of climb.

Likely accident scenario

Although the pilot observed that the aircraft’s rate of climb after takeoff from Penticton was lower than anticipated and was aware that climbing to an altitude of 5 000 ft before turning west toward high terrain was recommended, the pilot turned west at a lower altitude. The pilot continued flying up the valley toward an area of higher terrain in an aircraft that had reduced performance.

The pilot decided to conduct the flight despite being aware that visibility to the west (the flight planned route) was reduced by smoke. Reduced visibility was almost certainly encountered in the vicinity of Brenda Mines.



Map showing the probable route up the lake to the accident site (dashed/double-dotted line), the published VFR route to the west of the lake (dashed line) and the low ground route connecting the two (dotted line)

Neither survivor recalled the final moments of the flight. There were no other witnesses to the crash, and there were no on-board recording devices. The last time the aircraft was seen by a witness, about 2 NM from the accident site, it was climbing slowly and was nearly at the same altitude as the accident site. It is not known why the pilot chose the accident flight path instead of a path slightly to its left that would have kept it over lower, unobstructed ground, but it is likely that visibility was reduced so that the pilot was unaware of the safer route.

The small number of trees that were damaged, the short length of the impact swath and the relative intactness of the wreckage indicate that the aircraft was travelling at slow speed at the time of impact. Damage to the trees and to the wings’ leading edges indicates that the aircraft was descending in a 45° right wing-low bank when it struck the trees. If the aircraft had been descending in this attitude for more than a few seconds, it is likely that the speed at impact would have been higher. It is therefore likely that the aircraft was flying at a relatively low altitude in lowered visibility over the trees just before impact. The low altitude above terrain would not have allowed sufficient room to manoeuvre, and the aircraft descended into the trees.

Pilot decision-making

The pilot had earned a commercial pilot’s licence and several endorsements, but had relatively little experience. As well, although the accident aircraft was fairly sophisticated—twin engine, turbocharged, with retractable gear and an autopilot—it was privately owned and operated, which meant that the pilot did not have the organizational support that a student or a pilot flying for a commercial operator would have. This support includes resources such as co-workers’ experience, co-pilot or instructor’s assistance, managerial supervision, recurrent training and company maintenance programs.

It is likely that the pilot had previously experienced each of the factors that contributed to the aircraft’s low rate of climb—high density altitude, high aircraft gross weight and degraded engine power—but it is unlikely that the pilot had dealt with all of them at the same time before the accident flight. As stated in the Transport Canada publication Pilot Decision Making (TP 13897), flying is a continuous process of decision-making. The process begins before the flight, when the pilot makes a plan that will result in a safe flight, and it continues throughout the flight, as the pilot monitors the results to determine whether the plan is working as anticipated. If it is not, the pilot needs to be able to revise the plan as necessary, often quickly. If the pilot does not recognize a situation that necessitates a change of plan or does not have an alternative plan, risk increases.

Findings as to causes and contributing factors

  1. The high density altitude conditions, high aircraft weight, non-use of available turbochargers and reduced power of the right engine all contributed to a reduced rate of climb.
  2. The pilot continued toward an area of higher terrain, and the aircraft was unable to climb rapidly enough to provide adequate terrain clearance.
  3. The aircraft collided with terrain, likely while in an area of reduced visibility.

Findings as to risk

  1. There is an increased risk of injury to occupants if the aircraft is not equipped with shoulder harnesses.
  2. If maintenance activities are not properly documented, an opportunity to correctly diagnose and rectify defects is lost.

Safety action taken

Transport Canada and NAV CANADA

NAV CANADA has issued a Canada Flight Supplement amendment for the Penticton, Oliver and Osoyoos Airports in the Okanagan Valley. The following warning has been added to the caution sections of these airports:

“Due to high terrain, it is recommended pilots proceeding E or W under VFR, maintain an alt of 5,000 feet (ASL) min before leaving the Okanagan Valley.”

The 25th edition of the NAV CANADA Vancouver VFR navigation chart (VNC), effective August 22, 2013, includes the new VFR route, as suggested by Transport Canada, between Princeton, Brenda Mines and Highway 97C to Okanagan Lake. An associated caution reads as follows:

−CAUTION−

VFR ROUTE VALLEY FLOOR HAS STEEP GRADIENT TO 4500 FEET ASL WITHIN 10NM OF OKANAGAN LAKE

Penticton Airport

The following sign was installed at Penticton Airport, advising pilots to climb to 5 000 ft before turning west or east when departing the Okanagan Valley.

Notice to Pilots. Due to high terrain surrounding this airport, it is recommended that pilots proceeding east or west under CFR, attain an altitude of 5,000 feet (ASL) minimum before leaving the Okanagan Valley. Airport Elevation is 1,129 feet (ASL)
Modified sign at Penticton Airport

 

When you push the weather and get into trouble, remember who put you there.

New Advisory Circular: Prevention and Recovery from Aeroplane Stalls

Transport Canada recently issued Advisory Circular (AC) No. 700-031, titled “Prevention and Recovery from Aeroplane Stalls”. The purpose of this document is to provide guidance to operators, pilots, flight crews and Transport Canada personnel for the prevention and recovery from stall events. It provides best practices and guidance for training, testing, and checking within existing regulations, to ensure correct and consistent responses to unexpected stall warnings and stick pusher activations. The AC emphasizes reducing the angle of attack (AOA) as the most important response to a stall event. This AC also provides guidance for operators and training providers on the development of stall and stick pusher event training. For complete details, please consult the AC 700-031 linked above.

Footnotes

Footnotes:

Footnote 1

Flight operational quality assurance (FOQA) is the term used in the U.S.A; flight data monitoring (FDM) is the term used in Canada.

Return to footnote 1 referrer

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