CH12435 Sea King - Epilogue - Flight Safety Investigation Report

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Report / July 16, 2013 / Project number: CH12435-B-Cat

Location: 12 Wing Shearwater, Nova Scotia
Date: 2013-07-15
Status: Investigation Complete

FSIR - download PDF version, 508 kb

Epilogue

The crew planned a night trainer in the local Shearwater area and boarded the aircraft during a hot refuel with engines running and rotors turning. The aircraft had ground taxied to take off from Helipad 3 when it was recalled back to the inner ramp so that the aircraft captain could sign additional electronic aircraft records prior to the flight. After the aircraft came to a complete stop, the aircraft captain started removing his safety harness. The co-pilot then transferred control of the collective lever to the aircraft captain and, at the same time, was motioning to the marshaller. The aircraft then pitched forward rapidly.

As the aircraft’s tail rose, the aircraft rotated forward and pivoted on the extended main landing gear oleos before lifting off the ground. The main rotor disk then tilted rearward and impacted the tail pylon, causing it to separate from the fuselage. Once the aircraft fell back to the ground and started yawing right, it then rolled left as the left sponson collapsed and the main rotor blades struck the ground at the pilots’ 11 o’clock position. The aircraft yawed 120 degrees to the right before coming to rest on its left side, after which the crew conducted an emergency shutdown and egressed through the personnel door. There were no injuries or post-accident fire though flying debris damaged the surrounding hangars.

Post-accident maintenance inspections revealed no technical faults. The investigation focussed on flight control systems, aircrew actions and related human factors. The investigation explored the conditions creating incipient longitudinal pitchover, specifically the combination of a forward tip path plane, locked wheels, and collective movement. The transfer of control procedure was also investigated. The investigation concluded that CH12435 had an upload force set in the collective, causing the collective to rise easily, quickly and significantly if unguarded and/or jarred. The pilot employed a commonly accepted yet undocumented procedure for partial transfer of the collective control and released the collective without getting acknowledgement from the other pilot. Once the aircraft started to pitch forward, the pilots were unable to recognize and react in a timely manner to prevent the accident due to reduced visual cues.

Preventive measures include the establishment of Sea King maintenance procedures to set a neutral collective upload, clear direction on partial transfer of control, and measures to address the latent conditions that contributed to the accident.

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CANADIAN FORCES FLIGHT SAFETY INVESTIGATION REPORT (FSIR)
FINAL REPORT

FILE NUMBER: 1010-CH12435 (DFS 2-3-2)

FSOMS IDENTIFICATION NUMBER: 157254

DATE OF REPORT: 30 April 2015

OCCURRENCE CATEGORY: "A"

AIRCRAFT TYPE: CH124A Sea King

AIRCRAFT REGISTRATION NUMBER: CH12435

DATE OF OCCURRENCE: 15 July 2013

TIME OF OCCURRENCE (L): 2338 (L)

LOCATION: 12 Wing, Shearwater, Nova Scotia

OPERATOR: 423 (MH) Squadron, 12 Wing

This report was produced under authority of the Minister of National Defence (MND) pursuant to section 4.2 of the Aeronautics Act, and in accordance with A-GA-135-001/AA-001, Flight Safety for the Canadian Forces.

With the exception of Part 1, the contents of this report shall only be used for the sole purpose of accident prevention.  This report was released to the public under the authority of the Director of Flight Safety (DFS), National Defence Headquarters, pursuant to powers delegated to him by the Minister of National Defence as the Airworthiness Investigative Authority (AIA) of the Canadian Forces. 

SYNOPSIS

The crew planned a night trainer in the local Shearwater area and boarded the aircraft during a hot refuel with engines running and rotors turning.  The aircraft had ground taxied to take off from Helipad 3 when it was recalled back to the inner ramp so that the aircraft captain could sign additional electronic aircraft records prior to the flight.  After the aircraft came to a complete stop, the aircraft captain started removing his safety harness.  The co-pilot then transferred control of the collective lever to the aircraft captain and, at the same time, was motioning to the marshaller. The aircraft then pitched forward rapidly.

As the aircraft’s tail rose, the aircraft rotated forward and pivoted on the extended main landing gear oleos before lifting off the ground.  The main rotor disk then tilted rearward and impacted the tail pylon, causing it to separate from the fuselage.  Once the aircraft fell back to the ground and started yawing right, it then rolled left as the left sponson collapsed and the main rotor blades struck the ground at the pilots’ 11 o’clock position.  The aircraft yawed 120 degrees to the right before coming to rest on its left side, after which the crew conducted an emergency shutdown and egressed through the personnel door.  There were no injuries or post-accident fire though flying debris damaged the surrounding hangars.

Post-accident maintenance inspections revealed no technical faults.  The investigation focussed on flight control systems, aircrew actions and related human factors.  The investigation explored the conditions creating incipient longitudinal pitchover, specifically the combination of a forward tip path plane, locked wheels, and collective movement.  The transfer of control procedure was also investigated. The investigation concluded that CH12435 had an upload force set in the collective, causing the collective to rise easily, quickly and significantly if unguarded and/or jarred.  The pilot employed a commonly accepted yet undocumented procedure for partial transfer of the collective control and released the collective without getting acknowledgement from the other pilot.  Once the aircraft started to pitch forward, the pilots were unable to recognize and react in a timely manner to prevent the accident due to reduced visual cues.

Preventive measures include the establishment of Sea King maintenance procedures to set a neutral collective upload, clear direction on partial transfer of control, and measures to address the latent conditions that contributed to the accident.

TABLE OF CONTENTS

1. FACTUAL INFORMATION

2. ANALYSIS

3. CONCLUSIONS

4. PREVENTIVE MEASURES

Annex A - Abbreviations and Acronyms

Annex B - Fatigue and Crew Rest.

1.   FACTUAL INFORMATION

1.1. History of the Flight

1.1.1. The Sea King helicopter was crewed by 423 Maritime Helicopter (MH) Squadron (Sqn) personnel operating from 12 Wing, Shearwater, NS.  The crew consisted of an Aircraft Captain as the MH Captain (MHC) in the left seat, an Aircraft Captain as the MH Co-Pilot (MHCP) in the right seat, an Airborne Combat Systems Officer (ACSO) as the Tactical Coordinator (TACCO) and an Airborne Electronic Sensor Operator (AESOP) immediately behind the pilots’ seats.  All times are local.

1.1.2. On 15 Jul 13, the crew planned to fly a 1.5 hour night mission to complete pilot proficiency training.  At approximately 2325, they boarded the aircraft during a hot fuel/crew change and took on 800 pounds of fuel before taxiing to Helipad 3.  The crew was then advised by 423 (MH) Sqn Flight Dispatch Center to taxi back to Ramp 1 as an electronic acceptance signature was missing from the aircraft’s maintenance records.  The crew planned to keep the engines running and rotors turning while the MHC exited the aircraft to complete the appropriate authorizations.

1.1.3. When approaching Spot 1, the MHCP noticed three power carts in close proximity to the aircraft’s planned parking spot.  The crew elected to stop approximately 20 feet prior to the spot to ensure that sufficient space would be available to enable an easy taxi departure because Aircraft Maintenance Support Equipment (AMSE) equipment was positioned too close and forward of the spot.  The MHCP, who was at the controls, verbally initiated transfer of control of the collective to the MHC and attempted to signal to the marshaller his intention to remain at their current parking position.  During this time, the MHC began to un-strap in preparation for his exit.

1.1.4. After the MHCP set the parking brake, the crew felt the aircraft rapidly pitch forward and become airborne.  As the aircraft rotation increased, the MHC placed his hands on the flight controls, lowered the collective and applied full aft cyclic; this caused the main rotor blades to strike the tail pylon.  The aircraft fell to the ground, yawed to the right and rolled left as the tail pylon separated from the fuselage.  Shortly thereafter, the left sponson collapsed, causing the main rotor blades to strike the ground at the pilots’ 11 o’clock position.  The aircraft then continued to yaw 120 degrees to the right before coming to rest leaning on its left side (Figure 1).  The marshaller and the attending technician ran away from the aircraft as the accident sequence began and debris was thrown from the aircraft. 

1.1.5. The crew conducted an emergency shutdown and egressed via the personnel door.  Several 12 Wing personnel then approached the aircraft to help the aircrew.  There was no post-accident fire.

1.2. Injury to Personnel

1.2.1.  Nil.

1.3. Damage to Aircraft

1.3.1. The aircraft sustained damage beyond economical repair (A category).  The fuselage showed skin buckling in multiple locations along the left side from the nose to the tail-wheel and deformation was evident on the right side, aft of the cargo door.  The main rotor blades suffered catastrophic damage as a result of impact with the radome, tail pylon, tail rotor driveshaft and the tarmac.  The underside of the aircraft suffered heavy damage along the left side as a result of the sponson collapsing.  The left vertical strut was fractured at the sponson support lug.   

1.3.2. The tail wheel assembly was compressed and bent aft with the locking pin and cable both sheared.  The tail pylon suffered two main rotor blade strikes that severed it from the fuselage and caused the tail rotor blades to contact the ground (Figure 2).

1.3.3. A post-accident visual inspection was carried out on the rotor and transmission with no attributing pre-existing conditions evident.  The engines and gearboxes were found secured to their respective mounting points.  They were subsequently visually inspected with no damage evident. 

1.3.4. Both main landing gear (MLG) were confirmed to be down and locked.  During the post-accident inspection, the utility hydraulic system was found to be depleted as a result of aircraft damage; however, the right MLG brakes were functioned from the cockpit with no anomalies evident.  The left MLG brakes were functioned off-aircraft at the wheel assembly, due to the sponson separation, with no anomalies detected.

Flight Control System

1.3.5. The flight control system was found to be intact from the cockpit to the main rotor with the exception of the yaw cables, which were severed when the tail pylon separated from the aircraft.  Rigging and flight control functional checks were carried out in accordance with the prescribed maintenance manual procedures with no major anomalies evident.  A slight upload of the collective was noted during the check but it was assessed to be within the technical manual’s prescribed limits.  Due to structural damage to the flight control closet, the lower rig pin bell crank failed to install freely and was taken into consideration during flight control assessment.  The cyclic position was noted to be marginally aft of center.

1.4. Collateral Damage

1.4.1. The aircraft rolled over on Ramp 1 just east of Spot 1.  The 150,000 m2 debris field was extensive, with items found as far away as 400 m, extending to hangar tops and adjacent taxiways.  There was significant damage to the 423 Sqn and 12 Aviation Maintenance Squadron (AMS) hangars, including components embedded in the hangar walls and doors, a few shattered windows, and a severed interior fire suppression system line.  Abrasions and some oil contamination were evident on the concrete ramp.  An environmental assessment determined that there were no environmental issues as a result of this accident.  

1.5. Personnel Information

1.5.1. All members of the 423 (MH) Sqn crew had valid aircrew categories and medicals.  The two MHCs needed to refresh their night currencies prior to flying with other MHCPs later that week.  A summary of the crew’s flying currency is found in Table 1.

 MHCMHCPTACCOAESOp
Total flying time (hours) 1066.4 1938.2 2223.1 2970.1
Hours on type 824.5 1450.3 1611.9 297.6
Hours last 30 days 8.0 3.1 10.5 8.6
Hours last 90 days 53.1 60.6 44.5 42.4
Night hours total 155.2 243.0 302.3 476.6
Night hours - last 30 days 0 0 0 0
Night hours - last 90 days 2.5 10.0 5.1 6.2
Duty time - last 24 hours 11 4 6.5 4
Duty time - last 48 hours 11 8 12.5 4

Table 1. Personnel Information

MHC

1.5.2. The MHC was a knowledgeable first tour pilot with over 800 hours on the Sea King.  He was a current MHC and MH Crew Commander (MHCC), and designated as MHCC for the mission.

1.5.3. The MHC’s crew day started at 1240.  He was scheduled for two flights, briefing first at 1315 for an 1800 take-off time, and then briefing again at 2230 for a 2345 take-off time.  He was seated in the left seat and was to monitor the MHCP, whose currency on several night evolutions had expired. Time-permitting, the MHC was going to refresh his own night currencies as well.  He had good quality sleep prior to the accident but had been awake approximately 14.5 hours at the time of the accident.  The accident occurred during the circadian rhythm trough (2230-0430) and at the time of his normal bedtime.

MHCP

1.5.4. The MHCP was an experienced third tour pilot with over 1400 hours on the Sea King.  He was a current MHC, MHCC and a Readiness Pilot assigned to the Sqn Training and Readiness Office (STRO).

1.5.5. The MHCP’s crew day started at 2000.  He was seated in the right seat and was going to rectify all his 1 Canadian Air Division (1 CAD) and 12 Wing currency deficiencies as time allowed.  He had good quality sleep prior to the accident but had been awake approximately 15 hours at the time of the accident.  He attempted to sleep during the day but had difficulty.  The accident occurred during the circadian rhythm trough (2230-0430) and at the time of his normal bedtime.

TACCO

1.5.6. The TACCO was an experienced third tour ACSO with over 1300 hours on the Sea King.  The TACCO was a current MHCC and a Readiness ACSO assigned to the STRO.  At the time of the accident, the TACCO was standing at the upper personnel door, preparing for the MHC’s disembarkation.

AESOP

1.5.7. The AESOP was a multi-tour AESOP new to the Sea King community and had approximately 300 hours on type and over 2900 hours total.  The AESOP was current for the evolutions planned for the accident flight.  At the time of the accident, the AESOP was seated in his seat at the side-facing console.

1.6.  Aircraft Information

1.6.1. CH12435 is an A model Mark III, anti-submarine warfare configured Sea King helicopter based at 12 Wing, Shearwater.  It was declared serviceable prior to the accident.

Maintenance Records

1.6.2. A review of CH12435 maintenance records, both the hard copy and the electronic copy in the Automated Data for Aerospace Maintenance (ADAM), found no overdue inspections, out-of-sequence inspections, time-expired components, overhauls, modifications or special inspections.  The current airframe hours were 12956.5 hrs.  The next supplementary inspection due was #23, in 12.1 hrs, and the next major inspection due was Periodic #3, in 62.6 hrs.  The aircraft centre of gravity was within the specified tolerances.

Collective Upload

1.6.3. The two cockpit collective levers are coupled to each other and operate simultaneously to change the collective pitch of the main rotor blades.  Typically, the Sea King collective levers are adjusted using the collective open loop to allow for a slight upload, meaning that left unchecked by the pilot, the collective will slowly rise on its own.  The open loop [1] is adjusted by manipulating the tension in a spring, thus increasing or decreasing the amount of upload.  The pilots (right seat) collective is equipped with a collective pitch friction lock that can be rotated to increase friction and prevent the collective from creeping up or down while in flight.  As per the Canadian Forces Technical Order (CFTO) C-12-124-AA0/MF-000 6-2-18, the collective should remain in position with a maximum effort of approximately ¼ pound applied at the grip.

1.6.4. Aircraft CH12435 was connected to a hydraulic test stand several days after the accident.  An independent partial functional check was carried out in accordance with the Aircraft Operating Instruction (AOI) by a qualified Maintenance Test Pilot as a follow-on to all flight control functional checks.  The collective movement was easily initiated by bumping the collective when it was down, or by holding it down then releasing it and letting the spring motion start its travel up.  The force to counteract this upload was assessed to be within the ¼ pound tolerance.  The Instrument Panel Video Monitoring System (IPVMS) video recorded a rapid rise in collective from full down to full up, which took two seconds. 

1.7. Meteorological Information

1.7.1. Local time is 4 hours behind Coordinated Universal Time (UTC), referred to as Zulu (Z) time.

1.7.2. The night sky was clear with light winds from the west and visibility of 15 statute miles.  The temperature was 26° Celsius (C), dew point 18° C, altimeter setting 30.01" mercury and density altitude was 1637 feet above sea level.  The following 12 Wing METAR and TAF were observed at 0240Z 16 Jul 13, the approximate time of the accident:

METAR CYAW 160240Z 29006KT 15SM SKC 26/17 A3001 RMK DA1637FT SLP161 SKY00

TAF CYAW 160130Z 1602/1608 VRB03KT P6SM FEW250 RMK NXT FCST BY 160800Z

1.8. Aids to Navigation

1.8.1. Not applicable.

1.9. Communications

1.9.1. Not applicable

1.10. Aerodrome Information

1.10.1. The heliport consists of final approach and take-off area 16H/34H, multiple taxiways and six helipads.  The aircraft was operating on Ramp 1, which was lit by standard aerodrome lighting.  Ramp 1 is the inner apron used for ground operations and includes eight helicopter spots and one additional spot designated for rotors running refuelling; see HF1 in Figure 3.  Several power carts were positioned near Spot 1.

Parking of Aircraft Maintenance Support Equipment (AMSE)

1.10.2. At the parking spot where the accident took place, the AMSE was located 16 feet from the outer parking circle, which has a diameter of 93 feet.  Due to the positioning of the marshaller and the proximity of the AMSE and ground support equipment (GSE), the crew opted to stop short of Spot 1.

1.11. Flight Recorders

1.11.1. The Sea King does not have conventional flight data or cockpit voice recorders.  The aircraft was equipped with an IPVMS in 2003 in order to capture data for analysis of the Sudden Uncommanded Transient Loss of Torque phenomenon that affected the fleet at that time.  The IPVMS is an onboard video recorder that records images from four separate cameras, three focused on the instrument panels and one providing a generic overview of the aircraft cockpit.  This last video includes an audio feed that records the aircraft interphone-radio control system in mono format.  The IPVMS is not designed to be crash survivable but the information is recorded onto an onboard hard drive and has six to 10 seconds of information stored in volatile memory that is lost when the power is removed.  The IPVMS video was reviewed, and contained all but the last four seconds of the accident.

1.12. Wreckage and Impact Information

1.12.1. The aircraft salvage process was conducted by the 12 Wing Shearwater Recovery and Salvage Team with fire fighters in attendance.  The aircraft was first secured, de-armed, defueled and hoisted in support cradles onto a flatbed trailer.  It was then secured in F Hangar and an extensive foreign object debris walk was carried out to recover the accident debris.

1.13. Medical

1.13.1. The aircrew were examined post-accident by the duty flight surgeon.  Toxicology was then shipped to the Civil Aerospace Medical Institute and to a local facility in Halifax for analysis, and the results from both did not detect any substances hazardous to aviation.  Work, rest, and sleep cycles were collected to assess whether fatigue was contributory.

Crew Duty Day

1.13.2. The MHC was scheduled for two flights that day; briefing first at 1315 for an 1800 take-off time and then again at 2230 for a 2345 take-off time.  Had the accident mission flown its planned profile, the MHC’s crew day would have reached a minimum of 13 hours.  The 1 CAD Orders state that the maximum crew day is 16 hours regardless of the flight’s time of day or night.  The accident flight was the first flight of the day for the MHCP.

1.14. Fire, Explosives Devices, and Munitions

1.14.1. There was no fire.  The survival packs and life rafts contained CO2 cylinders and flares and there was compressed nitrogen in the emergency blow-down bottles for the landing gear and the float bags located in the sponsons.  The aircraft contained two sonobuoys, six C2A2 smoke markers and several explosive cartridge actuating devices in the crash position indicator, engine fire extinguishing bottles, the main probe, the tail probe, the hoist and the sonar.  There were approximately 2,000 pounds of fuel on board.

1.14.2. Defueling the aircraft was delayed until the investigation viewed, gathered evidence and inspected the aircraft in its final resting place.  Subsequently, the aircraft was levelled and defueled.

1.15. Survival Aspects

1.15.1. The 12 Wing Emergency Response Plan (ERP) was actioned.  The accident response was exceptionally fast, attributable to the fact that hot refuelling was being conducted nearby.  The fire truck proceeded towards the accident while the rotor blades were still turning and arrived on scene within 15 seconds.

1.15.2. The accident was survivable.  The cockpit and all crew positions within the airframe maintained survivable volumes.  The deceleration forces were small and well within the tolerance level of the human body.  The aircraft fell onto its left side and reduced the available opening of the lower personnel door, making the aircrew escape more challenging.  All four crew members egressed from the aircraft on their own.  The marshaller and the attending technician suffered no injuries.

Aviation Life Support Equipment (ALSE)

1.15.3. The crew wore long underwear, flight suits, flight boots, Nomex flying gloves with liners, SPH-5 helmets (each with Night Vision Goggles (NVG) in the raised or up position) and Life Preserver Survival Vests.  The helmets, goggles, and vests were subsequently inspected by ALSE technicians and found to be serviceable with the exception of the AESOP's helmet.  This helmet had a small nick that penetrated deep enough to see the white inner structure, which could have occurred during the accident.

Medical Care

1.15.4. In the event of serious injury or the need for after-hours medical care, 12 Wing relies on support from Halifax Regional Health Authority facilities.  The 12 Wing ERP directs the Wing Operations Duty Officer to contact the Nurse Liaison Officer, CF Health Services Centre – Atlantic, to pass information between the Wing Operations Center and the civilian hospital.  There is no direction within the 12 Wing ERP to contact a duty doctor or Flight Surgeon.

1.16. Test and Research Activities

1.16.1. The 12 Wing Dynamic Trainer is a replica of the Sea King flight control system and represents the functional dynamics of primary and auxiliary (PRI/AUX) hydraulic servo cylinders and automatic stabilization equipment (ASE) function as they relate to cockpit flight control movements of the main and tail rotor blades.  The dynamic trainer was used by the investigation to understand the flight control system, malfunctions, cockpit indications and collective travel.

1.16.2. The 12 Wing Operational Flight and Tactics Trainer is a system of linked procedural training devices intended for instruction on Sea King basic flight and specialist tactics training.  The pilot position motion platform presents a reasonable approximation of actual Sea King flight control characteristics but has no exterior visual aids.  It was used, along with testing on actual aircraft, to estimate torque and collective positions/movement for various aircraft scenarios, including collective travel, amount of forward cyclic required to roll the aircraft forward on its wheels, hydraulic and ASE hardovers, flex shaft failure, and collective upload.

1.17. Organizational and Management Information

1.17.1. Not applicable

1.18. Additional Information

1.18.1. Nil.

1.19. Useful or Effective Investigation Techniques

1.19.1. The 12 Wing closed circuit television cameras captured the accident on two cameras (Figure 4).  The IPVMS captured video and audio of the previous flight, the crew change and the accident crew’s taxi up to approximately four seconds before the initiation of the accident.  Both videos were of poor quality but examination of individual frames allowed investigators to conduct accident analysis.

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2.  ANALYSIS

2.1. General

2.1.1. Factual information was reviewed and analyzed for issues relevant to the accident and for unrelated safety issues.  The investigation explored potential engine and transmission malfunctions and landing gear failures, but subsequently focussed on flight control systems, aircrew actions and related human factors.  Specifically, the investigation looked at:

a. Transfer of control procedure;

b. Collective upload;

c. The combination of a forward tip path plane, locked wheels and a collective movement that led to the incipient longitudinal pitchover; and

d. Flight control inputs that arrested the pitch forward but severed the tail.

2.1.2. Contributing factors such as personnel fatigue and distraction were also analysed.  The investigation also examined the debris field, emergency response plan and ramp layout.

2.2. Collective Transfer

2.2.1. The IPVMS system recorded the conversation between the two pilots and their cockpit actions.  The video showed the MHCP lock the tail wheel and then stop short of the parking spot.  The MHC started loosening his left shoulder strap with his right hand.  The MHCP then moved his left hand to the cyclic and waved through the open window with his right hand to the marshaller.  Just before the recording ended, the MHC could be seen loosening his right shoulder strap with his right hand.

2.2.2. Analysis of the video, Figure 5, clearly showed that the MHCP released the collective while the MHC unstrapped.  Post-accident, the MHC demonstrated to the investigation his unstrap procedure and how he used both hands to loosen the shoulder straps.

2.2.3. The National Defence Flying Orders [2] require that the transfer of aircraft control shall not be affected until the recipient states, “I have control.”  The MHCP stated, “Your collective,” making it clear he wanted the MHC to take control of the collective; however, the IPVMS analysis determined that the MHCP released the collective without the MHC stating he had control of the aircraft or collective.  Based on this analysis, the investigation concluded that neither pilot was guarding the aircraft’s collective control at this point.

2.2.4. The CH124 Sea King Standard Manoeuvre Guide (SMG) [3], page 1-8, paragraph 16, states, “CF Flying Orders govern transfer of control for multi-place aircraft.  These procedures apply to helicopters engaged on the ground and in the air.”

2.2.5. Testimony suggests transfer of collective control is required so that a Sea King pilot occupying the right seat can manipulate the throttles, tail wheel pin, and rotor and wheel brakes with their left hand; while their right hand guards the cyclic and adjusts the beeper trim as required.  In preparation for a shutdown, it is standard and documented practice in the MH community for the pilot to give control of the collective to the left seat pilot once the aircraft has completed its taxi to the parking position.  The only other instance where transferring control of the collective to the left seat pilot is documented (i.e. approved) is during rotor engagement.

2.2.6. Evidence collected indicates an excessive and unregulated use of partial transfer of controls by MH pilots.  Partial transfer of control, rather than full transfer of control, can result in a situation wherein it is not clear who has control of the aircraft.  For example, who has aircraft control, the pilot with the cyclic or the pilot with the collective?  The investigation found that the procedures associated with partial transfer of control are unsafe because they are mainly not documented, subject to interpretation and can easily lead to confusion.  If partial transfer of control is to be used, it should be documented and it must be done using clear direction and procedures.

2.3. Aircraft Collective Upload

2.3.1. The application of power (collective pitch increase) was confirmed by review of the ramp camera video, which showed first the rotor disk coning upwards and then the aircraft pitch forward. 

2.3.2. The AOI Description and Maintenance Instructions, Part 6 – Hydraulics, paragraph 24, page 6-2-18, directs that once the collective is brought to a mid-position and released, the “stick should remain in position with a maximum effort of approximately ¼ pound applied at grip.”  The ¼ pound of force is not measured quantitatively, but estimated subjectively by a Maintenance Test Pilot. There are no tools currently available and/or used to measure this force.

2.3.3. The adjustment is typically made to provide a very slight collective upload that does not exceed ¼ pound at the grip.  Co-incidentally, the investigation learned that the introduction many years ago of this ¼ pound of “upload” was likely the result of one Maintenance Test Pilot’s personal preference that eventually became a standard practice despite the lack of any formal documentation. 

2.3.4. The MHC of the aircraft's previous flight stated that the aircraft had a noticeably faster upwards motion of the collective (caused by the upload), which he considered to border on unserviceable.  He then demonstrated his interpretation of an average upload compared to that of CH12435, which was noticeably faster.

2.3.5. Post-accident, CH12435’s collective upload was evident once the aircraft was placed on a hydraulic test stand.  The collective up-motion could be initiated by bumping the collective (such as when reaching for the parking brake, by hitting it with the left pilot's boot, or through a springing action created by first holding it down and then releasing it quickly).  The upward motion was quick; investigation video recorded the collective rise from full down to full up to take two seconds (five seconds would be considered normal).

2.3.6. When parked with rotors running, the Sea King rotor speed is maintained at 100% RPM with engine power adjusted through the Fuel Control Unit (FCU) to maintain rotor speed.  The collective had an upload, which made the collective lift on its own when released, thereby applying lifting power to the rotor disk because the engines maintain the rotor speed at 100% RPM.  There was neither collective friction applied nor a means to hold the collective down while parked.  Together these factors combine to make the aircraft ready to fly away on its own if left unchecked.

2.3.7. Outside of continuous pilot positive control, an inadvertent collective lift can be prevented in two ways.  One is by adjusting the open-loop to a completely neutral position with neither upload nor download.  Collective friction can also be used to the same end, but it is not typically engaged for ground operations.  The investigation concluded that Sea King maintenance procedures should emphasise that the collective be set with neutral upload to make the aircraft more resilient to uncommanded collective movements, both on the ground and in flight.

2.3.8. The investigation determined that the horizontal component of the lift vector generated by the raised collective, given the forward cyclic and locked brakes, created an incipient longitudinal pitchover condition through a turning moment about the lateral axis through the wheels.  With the upload causing substantial collective movement, even a momentarily unguarded collective could lead to pitchover.

2.4. Dynamic Rollover vs Longitudinal Pitchover

2.4.1. Dynamic rollover is an uncontrolled rolling motion around any part of the landing gear when the lifting force is equal to or greater than weight, a rolling moment is introduced, and the center of gravity moves beyond the pivot point.  Dynamic rollover occurs in the lateral plane, because the distance from the center of gravity to the side of the landing gear is much less than the distance to the front of the landing gear, and the landing gear is designed to slide/roll forward but not sideways.  Many of the elements that cause dynamic rollover were present in this accident but in the pitch plane of motion.  In this particular case, the pivot point was the front landing gear with brakes applied, and the other pertinent forces were lift and weight.  The lift vector increase supplied sufficient moment to cause the aircraft to pitch forward around the pivot point (Figure 6).  As the center of gravity never moved beyond the pivot point, the motion did not progress to full rollover but rather it was arrested at the incipient stage when the aircraft became airborne and the pilot pulled back on the cyclic.

2.4.2. As the rotor of the Sea King is high, a small angle change in the rotor disk plane will incur a large variation in the moment arm to the pivot point (Figure 6).  This characteristic, combined with the forward gear being located near the center of gravity, makes the Sea King more susceptible to this forward pitchover condition.

2.4.3. Instructions for take-off and landing within the SMG emphasize careful handling to prevent dynamic rollover during slope / off-level operations.

2.4.4. The MH community is aware of the conditions that could lead to a longitudinal pitchover given the number of warnings and cautions in the SMG concerning tip path plane position, use of brakes, abrupt movement of controls, and transfer of control.  In addition, an informal survey of current and former MH aircrew revealed 20 occurrences where the tail wheel was inadvertently lifted off the ground during parking or taxi operations (nine were reported within the Flight Safety system, 11 were not).  Of these occurrences, inadvertent or misuse of the flight controls and/or parking brakes, mechanical failures of the brakes, seizing or hot brakes and improper transfer of control were contributing factors.

2.4.5.  A Longitudinal pitchover in this situation required three elements:

a. Forward tip path plane position;

b.  Locked brakes that provide an axial point of rotation (in this case directly forward); and

c. Excessive torque (application of power).

2.5. Tip Path Plane

2.5.1. A helicopter tip path plane is defined as the path described by the helicopter blade tips during their rotation (Figure 7).  For the aircraft to move forward, the tip path plane must also be tilted forward so that there is a forward vector created by the lift force of the rotor disc.

2.5.2. The taxi speed is controlled by cyclic, which adjusts tip path plane position, and collective, which adjusts power/lift.  Forward cyclic or increased collective increases taxi speed, while a centralized cyclic or decreased collective reduces taxi speed.  Of note, Sea King taxi procedures are detailed in the SMG, Part 1 – Ground Procedures and Forms, Taxiing, paragraph 18, page 1-8.  A caution preceding this paragraph advises of the hazards involved with taxiing and describes what may result:

"A too low tip path with excessive torque application or applying torque against aircraft brakes may result in the tail wheel lifting from the ground and the possibility of striking the aircraft nose on the taxiway surface."

2.5.3. The SMG directs pilots to visually position the tip path plane ¼ to ⅓ of the way down the windshield.  In this position, and with the recommended torque applied, the helicopter will taxi at a normal taxi pace.  A low torque value, such as 20%, will yield a slow taxi pace.  Taxi speed can be increased by increasing torque or adjusting the tip path plane to an increased forward position, or a combination of both.

2.5.4. Both the MHC and MHCP felt the aircraft was being taxied slowly back to the ramp.  A review of the ramp video supports a slow taxi speed.  The IPVMS cockpit video showed the aircraft taxied with 20% torque (which is sufficient once the aircraft is moving), not the 30-40% torque recommended in the SMG.  The investigation concluded that the tip path plane was within the normal range of ¼ to 1/3 of the way down the windshield.

2.6. Locked Wheels

2.6.1. The parking brake was set just prior to the accident, locking the wheels on the MLG.  Both the MHC and MHCP described that once the aircraft came to a stop, the MHCP moved his left hand forward and set the parking brake.  The MHC was about to assist the MHCP with this task, but then proceeded to unstrap once he saw that it was accomplished successfully.

2.6.2. Post-accident inspection confirmed that the brakes were serviceable.  The locked wheels provided the pivot point for the forward rolling moment. 

2.7. Movement of the Controls

2.7.1. The SMG, Part 2 – Normal Flight Operations, paragraph 45, page 2-7, provides a caution to the Hover Landing Procedures that states:

"During landings and ground operations, it is possible, by abrupt movement of the collective pitch lever to the down position and the cyclic stick to the aft position, to cause the main rotor blades to strike the tail section.  To prevent this, avoid abrupt movements of the collective and cyclic controls while the wheels are in contact with the ground."

2.7.2. Once the MHC detected the forward pitching motion of the Sea King, he pulled the cyclic back and lowered the collective.  This caused the main rotor blades to strike and sever the tail section. When the tail section was severed, and in conjunction with the high torque setting, the aircraft started rotating in a way that it was impossible for the crew to maintain positive control of the aircraft.

2.8. Distraction Due to Pressing

2.8.1. At the time of the accident, both pilots were distracted.  The MHC likely had a rushing or pressing mindset attributable to an administrative delay at the end of an already long crew day.  The two pilots were the only two MHCs at the squadron that week and needed to refresh their night currencies prior to flying with other MHCPs.  In order to accomplish this objective at the end of an already lengthy period of wakefulness, the crew still had to wait for the MHC to go in to the hangar, re-sign the paperwork, return to the aircraft, strap in, taxi out, then complete their mission as planned.

2.8.2. A pressing mindset can cause crews to go through checks quickly, possibly missing key items.  It can also distract from situational awareness, as their mind is focused on what they must do next rather than scanning their environment now.  Due to the requirement to re-sign the electronic records, the MHC proceeded to unstrap and was not aware that the MHCP had attempted to transfer to him the collective control.  The investigation found that the MHC was distracted due to pressing during the parking sequence.

2.8.3. Approaching Spot 1, the crew noticed that the marshaller was positioned between the spot and the parked AMSE equipment.  Anticipating the requirement to taxi after the MHC had completed the flight authorizations, the crew elected to stop short of the spot in order to provide a safe distance from the AMSE equipment.  This distance was required so that the aircraft could move forward in order to unlock the tail wheel and allow the aircraft to turn while taxiing.  As the MHCP stopped the aircraft, the marshaller continuously motioned for the aircraft to advance to the center of the spot.  The investigation found that the conflict between the MHCP's desire to stay clear of the power carts and the marshaller’s intent for the aircraft to move forward to the spot distracted the MHCP from a proper transfer of control procedure and a lapse in monitoring the flight controls during the parking sequence.

2.9. Distraction Due To Fatigue

2.9.1. Both pilots’ sleep/wake histories were collected and analyzed to determine the presence of fatigue and its contribution towards degrading human performance in this occurrence.  Detailed analysis of fatigue and associated 1 CAD crew rest orders is contained at Annex B.

2.9.2. The MHC and MHCP had both been awake for over 14 hours at the time of the accident.  Based on the Fatigue Avoidance Scheduling Tool (FAST), the MHC’s predicted cognitive effectiveness at the time of accident was 85% and rapidly degrading, as illustrated by the steep slope of the graph in Figure 8.  A cognitive effectiveness of 85% is equivalent to a blood-alcohol content (BAC) of 0.05%.

2.9.3. Had this flight continued as planned, the FAST model predicted the average person’s cognitive impairment to be equivalent to a BAC of almost 0.08% during the landing phase.  FAST modeling also shows that 10% of the RCAF aircrew population would have been operating at a much more severe level of cognitive impairment, as depicted by the dotted blue line in Figure 8.  The FAST analysis also predicted a cognitive impairment lapse rate of 2.3 for the average person, meaning that they were 2.3 times more likely to make an error than a fully rested person.

2.9.4. Annex B provides a detailed look at the elements of fatigue affecting both pilots.  It showed that four of the five spheres of fatigue were present in both pilots at the time of the accident.  Based on the above analysis and the information in Annex B, the investigation found that the performance of both pilots was likely degraded as they exhibited behaviour known to be associated with fatigue.  The supervisors did not know how long the MHCP had been awake prior to duty or the effect of this on his cognitive performance.  The pilots and their supervisors were not provided with the tools to detect the level of risk due to fatigue nor the knowledge of how to mitigate this risk in order to safely accomplish the mission.

2.9.5. With night operations and their inherent elevated risks, the risk posed by fatigue can be reduced, particularly by employing appropriate tools, regulations and strategies:

a. Tools:  The investigation found that neither the crew nor supervisors had access to FAST, which would have provided an objective and scientifically validated measure of the crew’s predicted cognitive performance;

b. Regulations:  Crew rest orders should provide appropriate regulatory oversight to help mitigate and manage fatigue.  Crew rest orders may vary from fleet to fleet, but should be based on scientifically measured and validated data.  After consultation with 1 CAD representatives, the investigation could not identify any data supporting or validating the current 1 CAD crew rest orders.  A detailed review of 1 CAD crew rest orders could improve this regulatory oversight; and

c. Strategies:  An approach, such as a Fatigue Risk Management System (FRMS), many of which are currently in use by the aviation industry, would provide commanders with an awareness of fatigue-related performance degradations that would enable them to take appropriate countermeasures to safeguard all personnel involved in flight operations.

2.10.  Visual Environment

2.10.1. The accident happened at night.  Typically daylight operations provide a certain level of resilience in that pilots may quickly see, understand and react to sudden flight control or aircraft movements.  Night time operations, where there are limited peripheral cues in the darkness, provide a more difficult challenge for detecting movement.  Because of the darkness, neither pilot was able to quickly see and understand the initial aircraft movement and thus take action to control it in a timely manner.

2.10.2. The positioning of the tip path plane is critical for taxi operations; however, it is difficult to see at night.  In this case, the crew was unable to confirm the exact positioning of the tip path plane due to darkness.

2.11. Unlit Collective

2.11.1. The Sea King collective is unlit.  Other aircraft, such as the CH146 Griffon, have collective switches that are easily located by aircrew at night because of their backlighting.  This also provides a visual reference to detect collective movement at night, even with peripheral vision.  It is possible that the collective movement would have been detected by the crew had it been lit.  Lighting the collective would reduce the chance of incorrect collective switch activation and improve situational awareness of the collective position in the dark.

2.12. Other Safety Concerns

Debris Field

2.12.1. The 150,000 m2 debris field was extensive.  There was significant damage to nearby hangars, including components embedded in the hangar walls and doors, a few shattered windows, and a severed interior fire suppression system line.  There was significant potential for injury to ramp personnel given the extent of the debris field and the amount of debris strewn about it.

2.12.2. Of particular concern was a fuel tank adjacent to the crash site between 12 AMS and 423 Sqn (Figure 9) that narrowly missed being pierced by a piece of the tail rotor drive shaft.  The tank fed an emergency generator that supported the adjacent hangars.  Although it was installed in accordance with airfield design regulations, there was no regulation found dictating a distance the tank should be from the flight line.  The investigation concluded that measures, such as relocating the tank or protecting it from potential flying debris, should be taken to reduce the risk of its rupture.

Ramp Layout

2.12.3. A review of the parking and storage of AMSE and GSE on the ramp area next to the hangar line indicated that there was no organized or coordinated system in place.  The maintenance manual [4] explains that in order to park, the Sea King helicopter should be located “more than one rotor blade distance from other helicopters or objects.”  There is no reference point given for the one rotor blade distance, which could be measured from the center of the hub, the structure of the airframe, or the edge of the rotor disc.  Testimony indicated that no one could identify any directions or regulations concerning storage or parking of AMSE and GSE near helicopter spots.

2.12.4. Although the aircraft eventually came to rest near the center of the spot (Figure 10) the crew initially stopped short of it.  Had the crew stopped at its center, due to the Sea King’s taxi turning radius it would have been difficult, if not impossible, for the helicopter to depart with the AMSE located directly in front.  The investigation found that in order to facilitate safe taxi and ramp operations, AMSE should be positioned a distance from the spots to allow the aircraft freedom to taxi away and that this should be determined and clearly explained in the appropriate orders, with appropriate marking made on the ramp for positioning of this equipment.  Furthermore, training and directives for marshallers should be reviewed to ensure that aircraft positioning and taxi requirements are explained and understood.

Emergency Response Plan

2.12.5. The Duty Doctor collects routine toxicology, medical history, and other important information prior to the investigation team’s arrival on scene.  Any additional aviation-specific medical requirements are addressed by the Flight Surgeon during normal duty hours.  However, the 12 Wing ERP only directs the Nurse Liaison Officer to be contacted; there is no direction to contact either the Duty Doctor or the Flight Surgeon.  Therefore, the ERP should be modified to also notify both the Duty Doctor and the Flight Surgeon.

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 3. CONCLUSIONS

3.1. Sequence of Events

3.1.1. The relevant sequence of events was assessed to be as follows:

a.  The parking brake was set when the aircraft was stopped prior to the parking spot;

b.  The MHCP was pre-occupied with the marshaller;

c. The MHC had a pressing mindset;

d. Both pilots had degraded performance due to fatigue;

e. Control of the collective was transferred from the MHCP to the MHP without confirmation;

f.  Collective upload caused the unguarded collective to rise;

g.  Movement of the unlit collective was not noticed;

h.  Incipient longitudinal pitchover occurred when the aircraft pitched forward about the pivot point created by the locked main landing gear;

i. The aircraft became airborne;

j. The MHC rapidly lowered the collective and moved the cyclic aft to arrest aircraft rotation; and

k. The blades severed the aircraft tail, and the aircraft rolled onto its left side.

3. 2. Findings

Findings Concerning Equipment

3.2.1. The Sea King collective open loop spring is typically adjusted so that there is a very slight collective upload. (2.3.3)

3.2.2. CH12435 had an upload set in the collective, causing the collective to rise easily, quickly and significantly if unguarded and/or jarred.  (2.3.4)

3.2.3. Vital 12 Wing systems, such as fuel tanks, were not adequately protected from debris. (2.12.2)

Findings Concerning Procedures

3.2.4. As indicated by the attempted transfer of collective control and the lack of confirmation by the MHC, the MHCP employed a commonly accepted yet undocumented procedure for partial transfer of control that is not in accordance with National Defence Flying Orders.  (2.2.3 & 2.2.4)

3.2.5. AMSE was parked on the ramp in such a manner as it precluded a normal turning radius for departing aircraft using parking Spot 1. (2.12.4)

3.2.6. The pilots were pre-occupied with the marshaller, who motioned for the aircraft to proceed to a parking spot that the pilots deemed unsuitable because of the close proximity of AMSE equipment. (2.8.3) 

3.2.7. There was no direction within the 12 Wing ERP to contact either the Duty Doctor or the Flight Surgeon. (2.12.5)

Findings Concerning Personnel

3.2.8. The MHC and MHCP were awake for over 14 hours at the time of the accident, which made them twice more likely to make an error than a fully rested person. (2.9.3)

3.2.9. The accident occurred at night time, in darkness and during the circadian rhythm trough.  (2.9, 2.10.1)

3.2.10. The approach used to establish current crew rest orders appears to have been inconsistently applied to RCAF fleets and exclusively to aircrew. (2.9.5, Annex B)

3.2.11. The crew duty day for MH aircrew is not reduced for night time or NVG operations as they are for other communities. (Annex B)

3.2.12. Neither the pilots nor their supervisors had tools to detect the level of fatigue risk prior to the accident flight. (2.9.4)

3.3. Cause Factors

Active Cause Factors

3.3.1. The MHCP released the collective after passing control without getting acknowledgement from the MHC.

3.3.2. Due to reduced visual cues impairing their situational awareness, the pilots were unable to recognize and react in a timely manner to the incipient longitudinal pitchover.

Latent Conditions

3.3.3. The MHC was pre-occupied with an administrative delay at the end of a long day while the MHCP was pre-occupied with a marshaller motioning for the aircraft to move forward to an unsuitable parking spot. (2.8)

3.3.4. The MHC and MHCP exhibited behavior, known to be associated with fatigue, which may have contributed to this accident. (2.9)

3.3.5. Although Sea King maintenance documentation limits the force applied to the collective to ¼ pounds in order to maintain a neutral position, the aircraft had an upload exceeding this limit.  Currently, technicians have no tool to measure this force. (2.3)

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4. PREVENTIVE MEASURES

4.1. Preventive Measures Taken

4.1.1. AMSE parking lines were painted in front of the hangar to ensure that AMSE equipment will not interfere with parking spots. (2.12.2 & 3.2.6)

4.2. Preventive Measures Recommended

4.2.1. 1 CAD / MH SET to ensure that the transfer of aircraft control procedure described in the SMG either reiterates the National Defence Flying Orders direction or authorizes and provides clear direction on the partial transfer of control. (2.2.6 & 3.3.1)

4.2.2.  DAEPM (M) 3 to establish Sea King maintenance procedures to accurately measure collective loads within acceptable tolerance limits. (2.3.2 & 3.3.5)

4.3. Other Safety Measures Recommended

4.3.1. 12 Wing / 12 AMS amend training and directives for marshallers to ensure that aircraft positioning and taxi requirements are explained and understood. (2.12.4 & 3.3.3)

4.3.2. 12 Wing / WOps amend Wing orders to stipulate that AMSE be parked to facilitate a normal turning radius for parked aircraft exiting the ramp. (2.12.4 & 3.3.3)

4.3.3. 12 Wing / WOps amend the Wing ERP to include contacting the Duty Doctor and, when available, the Flight Surgeon. (2.12.5 & 3.2.7)

4.3.4. 1 CAD / A4 Maint assess this accident’s debris damage so that vital 12 Wing systems, such as fuel tanks, are protected should other such events occur.  (2.12.2 & 3.2.3)

4.3.5. 1 CAD / Dir Fleet Rdns amend crew rest orders to ensure they are consistent, scientifically valid, and apply to all RCAF personnel involved in flying operations, regardless of fleet. (2.9 & 3.3.4)

4.3.6. The Airworthiness Authority, with assistance from Airworthiness Medical Authority, implement a Fatigue Risk Management System (FRMS) so that commanders are fully aware of fatigue-related performance degradations and can take appropriate countermeasures for all personnel involved in flying operations.  This FRMS should contain mandatory and recurrent fatigue education, fatigue avoidance software, mandatory reporting of “time awake” prior to commencement of duty, pharmacological fatigue counter-measures as approved by AMA, and the requirement to report fatigue hazards using the Flight Safety reporting system. (2.9)

4.4. DFS Remarks

4.4.1. This accident was clearly preventable.  It is essentially the result of many human factors that combined together to enable this accident.  Over the years, undocumented procedures for transfer of control and setup of collective upload became the accepted norm.  This, coupled with fatigue and a pressing mindset to get the training currencies done, created the alignment of the “holes in the Swiss cheese.”  Fatigue is a factor here, and this report skims the surface of this important contributor to many air accidents.  The report could have dug deeper into many other factors that could lead to increased fatigue such as a shortage of experienced pilots, low YFR, increased need to absorb new-winged graduates and even currencies, regulations and weather.  These could all be seen as latent conditions that put pressure on experienced pilots, particularly at the end of a quarter, to ensure currencies are met.  The fatigue issue is not well understood in the RCAF.  Many believe it is essentially a question of crew rest and only concerns pilots.  It is not.  Transport Canada, civilian operators and now militaries around the world are investing in FRMS by developing policies, guidance, and mitigating measures.  It is time for the RCAF to embrace this concept.

// original signed by //

S. Charpentier
Colonel
Director of Flight Safety

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References

[1] The collective open loop spring is part of the collective auxiliary servo valve open loop assembly. This open loop spring normally supports the weight of the collective lever and linkage so that it remains in any position with little or no external force applied to hold the collective. The collective open loop can be adjusted to compensate for either an upload or download in the collective by turning an adjustment screw in the servo valve open loop assembly. The CFTO C-12-124-AA0/MF-000 directs that the open loop should be adjusted to a neutral position, such that there is neither an upload nor a download force and the collective lever should remain in position with a maximum effort of approximately ¼ pound applied at the grip. The Helicopter Operational Test and Evaluation Facility Maintenance Test Pilot indicated that typically, the technicians will conduct this adjustment to provide a very slight upload in the collective, not to exceed ¼ pound at the grip, as per the preference of most pilots.

[2] B-GA-100-001/AA-000

[3] C-12-124-A00/MB-001

[4] C-12-124-A00/MF-000

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ANNEX A - ABBREVIATIONS AND ACRONYMS 

ABBREVIATION  -  MEANING 

ACSO  -  air combat systems operator

AESOP -  airborne electric sensor operator

AMS -  air maintenance squadron

AMSE  -  aircraft maintenance support equipment

ASE  -  automatic stabilization equipment

C  -  Celsius

ERP  -  emergency response plan

GSE  -  ground support equipment

IPVMS  -  instrument panel video monitoring system

m  -  meters

MH  -  maritime helicopter

MHC  -  maritime helicopter captain

MHCC  -  maritime helicopter crew commander

MHCP  -  maritime helicopter co-pilot

NVG  -  night vision goggles

STRO  -  squadron training and readiness office

Sqn  -  squadron

TACCO  -  tactical coordinator

Z  -  coordinated universal time

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ANNEX B - FATIGUE AND CREW REST

Fatigue

1.  In this accident, a critical error was made during the transfer of control.  In addition, the pilots did not react quickly enough to the resulting incipient dynamic pitchover in order to prevent aircraft damage.  Fatigue likely caused a decrease in their cognitive ability and an increase in reaction time which likely contributed to the accident.

2.   Mental fatigue is a transient decrease in maximal cognitive performance resulting from prolonged periods of cognitive activity.  It may also be described as a decreased level of consciousness and can be dangerous when performing tasks that require constant concentration, such as operating large vehicles.  This cognitive ineffectiveness is equated to blood alcohol content intoxication in the Fatigue Avoidance Scheduling Tool (FAST).

3.  Fatigue is insidious and can affect the fatigued person in five spheres:  problem-solving, memory, attention/vigilance, reaction time and mood.  The investigation analyzed the work/rest/sleep cycles of the MHC and found that he displayed fatigue-related behaviour in four of these spheres:

a.   Problem-Solving:  focussing on a minor problem when there is a risk of a major problem, in that he directed his attention to unstrapping instead of maintaining control of the collective;

b.   Attention or Vigilance:  becoming preoccupied with a single task, in that he focused on the aircraft paper work that was to be completed so they could complete the mission;

c.  Reaction Time:  fatigue affecting a person’s ability to respond to emergency stimuli, in that he was unable to recognize aircraft movement and apply appropriate action in time to prevent the accident; and

d.   Mood:  impatience in that he felt the MHCP was taxiing too slowly.

4.   The MHCP exhibited behaviours in three of these spheres:

a.  Problem-Solving:  focussing on a minor problem  when there is a risk of a major problem, in that he was signalling to the marshaller and not able to recognize the aircraft movement;

b.  Attention or Vigilance:  becoming preoccupied with a single task, in that he focussed on communicating with the ground crew and released his hold on the collective in spite of not hearing the MHC’s confirmation that he had control; and

c.  Reaction Time:  fatigue affecting a person’s ability to respond to emergency stimuli, in that he was unable to recognize aircraft movement and apply appropriate action in time to prevent the accident.

5.  The MHC was aware that he was approaching the end of his duty day and was proactive in mitigating this risk by shortening the flight by one hour.  The present CH124 duty day of 16 hours is an optimistic estimation of a pilot’s abilty to perform aviation duties safely and effectively.  This results in an underestimation of associated risk as demonstrated by the FAST analysis (para 2.9.3).

6.   Flight Comment, Issue 2 2013, focussed specifically on fatigue and indicated that fatigue management is a critical requirement in sustained air operations. The pilots and their supervisors were neither provided with the tools to detect the level of risk that fatigue was to play in this accident nor the knowledge of how to mitigate this risk in order to safely accomplish the mission.  They neither knew how long the MHCP had been awake prior to duty nor the effect of this on his cognitive performance.  Additionally, they did not have access to FAST, which would have provided them with an objective and scientifically validated measure of the crew’s predicted cognitive performance.  Lastly, they did not have training on how to employ non-pharmacological and pharmacological fatigue mitigation countermeasures.

Crew Rest Orders

7.  The 1 CAD RCAF Flight Operations Manual, Chapter 2, Section 3, Part 3 - CREW FLYING TIME / DUTY / REST / NON-WORKING DAYS, stipulates crew duty day limits for different fleets.  A summary of selected fleets follows:

a.   Fighter Force:  crew duty day should be reduced from 16 to 12 hours when engaged in NVG flying;

b.   Air Mobility:  crew duty day maximums are reduced by two hours when the mission has a planned departure between 1800 and 0759 local;

c.  Tactical Aviation:  crew duty day is reduced by three hours when activities include night flying; and

d.  Maritime Helicopter:  units shall establish plans for NVG operations that reduce maximum allowable crew duty day.

8.  Fatigue and crew duty days can vary due to the differences between, or the demands of, specific missions or operating fleets.  However, the investigation believes that the approach to establishing current crew rest orders was inconsistently applied between fleets.  The 1 Cdn Air Div Surgeon indicated that the source of the fleet duty day limits was unknown, and that a working group was underway to overhaul the RCAF approach to minimizing fatigue.

9.    Additionally, crew rest orders are specific only to aircrew and not inclusive of other personnel involved in flight operations; fatigue is not selective and its effects on degraded human performance transcend all military occupations.  There is inconsistent direction to reduce crew days to take into account night work, “shift lag,” “jet lag,” low level flight etc.

10.  1 CAD “Crew Rest Orders” do not account for extended periods of wakefulness prior to the commencement of duty.  They assume that the member has just awoken from sleep of high quality and sufficient quantity.  The MHCP had already been awake for approximately 12 hours prior to starting his crew day.  His predicted cognitive performance was already starting to rapidly decline at the start of the mission and would have continued to decline throughout a 16 hour crew day without proper employment of appropriate counter measures.

11.   To manage this risk, the 1 CAD RCAF Flight Operations Manual should address the universal effects of fatigue such as time awake, mandatory fatigue training, use of fatigue counter measures, assessment of flying programs and work schedules using a FAST, and mandatory fatigue hazard reporting.  Flying orders at the appropriate levels should provide additional reductions to crew duty limits for fleet- and mission-specific considerations, such as low level flying or a lack of auto pilot.  Crew rest orders should be reviewed to ensure that they are scientifically valid and apply to all personnel involved in flight operations.

Fatigue Risk Management

12.  Transport Canada states in TP 14575 that the risks associated with fatigue can be managed at the organizational level within a safety management system framework.  This allows the risks associated with fatigue to be managed in a way similar to other hazards.  A Fatigue Risk Management System (FRMS) should be based on an internal risk assessment of the organization and ensure that any fatigue management strategies being implemented are measured, appropriate, and targeted.

13.   Aircrew fatigue monitoring, crew duty orders and FAST are but individual components of what should be a global approach to fatigue management under the auspices of an FRMS.  RCAF personnel are exposed to unique risks as a consequence of their employment.  Fatigue from long duty periods and circadian rhythm abnormalities together with challenging flying and operating conditions can result in cognitive impairment.  Commanders require tools, training and regulations in order to monitor and control risk associated with fatigue-related performance degradations. The RCAF should adopt a comprehensive FRMS so that these risks can be identified, tracked and mitigated to maintain operational capability.

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