- ISSUE 2/2010
- Copyright and Credits
- Guest Editorial
- Feature: Deadly Omissions
- Flight Operations
- Maintenance and Certification
- Accident Synopses
- Recently Released TSB Reports
- Regulations and You
- Debrief: Stick to the Basics: Stable Approach and Sterile Cockpit
- Take Five: Underwater Egress
- Full HTML Version
- PDF Version
- Area Navigation in Canada
- EMS Helicopter Crew Caught by Black Hole Illusion
- Helicopter Safety Helmets—A Hard S(h)ell
- Low Usage of Head Protection by Helicopter Pilots
by Ian Johnson, Civil Aviation Safety Inspector, Aerodromes and Airspace Standards, Standards, Civil Aviation, Transport Canada
Airborne navigation has progressed from maps, watches and sextants, to ground-based navigation aids (NAVAID) (non-directional beacons [NDB] and VHF omnidirectional ranges [VOR]), to self-contained navigation systems such as inertial navigation systems (INS) and space-based systems (e.g. GPS). A minimum navigation performance specification (MNPS) for the North Atlantic was published in 1979 by the International Civil Aviation Organization (ICAO), marking the beginning of navigation harmonization. The intent was to standardize the navigation performance of aircraft crossing the Atlantic from North America to Europe in order to manage air traffic in a safe and efficient manner and increase safety. By using managed Mach cruise speeds and specifying a level of navigation-system accuracy (initially, the required position accuracy allowed a 60-NM across-track by 60-NM along-track spacing between aircraft), aircraft could be spaced more effectively, thereby saving air operators time and fuel. As the skies became more crowded over the years and the distances travelled increased, greater accuracy in navigation became necessary not only for oceanic airspace but also for domestic airspace. The earlier tolerance for navigation error gave way to the “be exactly at this position, at this time” necessity of today’s busy airspace. This has led to the development of additional navigation specifications for specific types of airspace.
Initially, civil aviation authorities regulated aircraft navigation capability by requiring the carriage of specific navigation units (e.g. VOR or distance-measuring equipment [DME]). Then area navigation (RNAV) system use became commonplace in the 1970s. These early units used input from long-range systems (OMEGA, LORAN) and ground-based NAVAIDs to fix positions. As costs decreased, stand-alone inertial navigation systems (INS) began to be widely utilized and positional accuracy increased significantly. With this greater level of accuracy and reliability, highly sensitive systems utilizing multiple sensor inputs were developed and put into service. Satellite navigation constellations, inertial reference platforms, and ground-based NAVAIDs are all integrated by flight management systems (FMS) today to determine the position of an aircraft. An example of a stand-alone sensor with integrated capabilities available would be a combination GPS-inertial reference unit (IRU).
Early navigation practices meant an aircraft’s position could be in error literally by miles. Today’s systems can establish a position to significantly less than a mile. These technological advances have created many different levels of possible system accuracy, redundancy, and performance monitoring. RNAV progressed to required navigation performance (RNP), which has now evolved into the ICAO performance-based navigation (PBN) concept. RNP and RNAV are sub-specifications of PBN; RNP has additional technical requirements above and beyond RNAV. In order to have a consistent global approach to navigation, standards are being harmonized through PBN. Rather than specifying the exact navigation equipment aircraft need to carry, ICAO has created PBN specifications. This means that a navigation specification will state the accuracy, integrity, continuity, performance monitoring and alerting, and signal in space required. The system accuracy required is stated after the type of specification, for example, RNP 4, RNAV 5. The 4 and 5 represent the +/- NM along-/across-track accuracy performance the aircraft’s navigation system must meet. An RNP-type navigation system will continuously monitor its position and alert crew members if the aircraft has the potential to stray outside of allowable airspace boundaries. The airspace boundary is an area equivalent to twice the RNP value. For example, the RNP-4 lateral boundary is a corridor 8 NM in width.
The basic navigation categories are as follows:
Area navigation (RNAV)—A method of navigation that permits aircraft operation on any desired flight path within the coverage of station-referenced NAVAIDs, within the limits of the capability of self-contained aids, or a combination of both.
Required navigation performance (RNP) system—An RNAV system that supports on-board performance monitoring and alerting.
Performance-based navigation (PBN)—RNAV based on performance requirements for aircraft operating along an air traffic system route, on an instrument approach procedure, or in a designated airspace.
Certain levels of navigation performance are infrastructure-based, meaning the number of DME or VOR/DME facilities available affects the aircraft system’s ability to resolve its location. A navigation system may be capable of an accuracy level of only 2 NM, due to the number and proximity of facilities. Yet given enough facilities, the same system may provide an accuracy level of 1 NM. For example, because the RNAV-1 and RNAV-2 specifications can be dependent on infrastructure, the two specifications are combined into one by ICAO and the Federal Aviation Administration (FAA): RNAV 1/2. The use of satellite systems provides a unique capability independent of ground-based infrastructure. RNAV or RNP arrivals or departures can be implemented at airports that have either minimal or non-existent ground-based NAVAIDs—potentially a much more cost-effective way to provide approach services.
With the advent of reliable and accurate navigation systems for commercial and private aircraft, operators can now take advantage of these capabilities in certain en-route and terminal airspaces. Specifications currently in place or being developed are:
|Area of application||Navigation accuracy (NM)||Designation of navigation standard (current)||Designation of navigation standard (new)||Requirement for performance monitoring and alerting||GNSS required|
(RNP 10 label)
|Oceanic/Remote||4||RNP 4||RNP 4||Yes||Yes|
|En route-Continental||5||B-RNAV||RNAV 5||No||No|
|En route-Continental and Terminal**||2||US RNAV “A”||RNAV 2||No||No|
|Terminal**||1||US RNAV “B”P-RNAV||RNAV 1||No||No|
|Terminal||1||Basic RNP 1||Yes||Yes|
|Terminal||1||Advanced RNP 1||Yes||Yes|
|1/0.3 or less||RNP AR APCH||Yes||Yes|
RNAV and GPS procedures have been in effect in Canada for some time now, and operators are aware of their benefits. Operators are currently using PBN arrivals, approaches, and departures at various airports to reduce flight time, fuel burn, carbon emissions, and noise footprints. RNP procedures into mountainous airports have the potential to enable lower weather minima than those possible with traditional NAVAIDs.
In the future, PBN will enable continuous descent arrivals (CDA) and required time of arrival (RTA) approaches (i.e. the flight will be cleared to arrive at the runway threshold within a specific window of time). It has the potential to increase efficiencies at high-volume airports and provide better access to smaller airfields. Combined with automatic dependent surveillance-broadcast or -contract (ADS-B and ADS-C, respectively) and controller-pilot data link communications (CPDLC), PBN specifications could allow higher traffic densities on oceanic or remote routes. PBN’s inherent potential to optimize flight routes, improve flight safety, and also reduce emissions makes it an attractive tool for aviators in Canada.
1. ICAO Performance-Based Navigation Manual, ICAO Doc 9613
2. TC Advisory Circular (AC) 123R “Use of Global Positioning System for Instrument Approaches”
3. FAA AC 90-105 “Approval Guidance for RNP Operations and Barometric Vertical Navigation in the U.S. National Airspace System”
4. FAA AC 90-101 “Approval Guidance for RNP Procedures with SAAAR”
1. Transport Canada Aeronautical Information Manual (TC AIM)
2. AIP Canada (ICAO) COM section.
On February 8, 2008, a Sikorsky S-76A MEDEVAC helicopter departed Sudbury, Ont., for Temagami, Ont., to meet a land ambulance. At approximately 22:02 Eastern Standard Time (EST), while on final approach to the Temagami Snake Lake Helipad in night visual meteorological conditions (VMC), the helicopter crashed in the forested area at the edge of the lake. The helicopter came to rest on its left side and was substantially damaged. Three of the four occupants received serious injuries and were transported to the hospital. This article is based on the Transportation Safety Board of Canada (TSB) Final Report A08O0029.
The entire region was experiencing localized light to moderate snowfall on the evening of the occurrence and it was uncertain as to whether the flight would be able to land in Temagami.
The captain was the pilot flying (PF) and was certified and qualified for the flight in accordance with existing regulations. He had approximately 3 107 hr total flying time and 2 267 hr on the Sikorsky S-76A. Records indicate that he had received all of the company’s required training, including night visual flight rules (VFR)/instrument flight rules (IFR) and controlled flight into terrain (CFIT) with specific training for black hole approaches (visual spatial disorientation). The captain had been to this location once in the past, on a day VFR flight.
The first officer was the pilot not flying (PNF) and was certified and qualified for the flight in accordance with existing regulations. The first officer was hired in July 2007, and had all the required training. He was fairly new to emergency medical services (EMS) operations and had never been to this location.
On the night of the occurrence, the helicopter departed Sudbury at approximately 21:40 EST on a short flight to the Snake Lake Helipad in the town of Temagami, located approximately 60 NM to the northeast. The helicopter climbed to 2 500 ft and proceeded to Temagami. Throughout the initial portion of the flight, the visibility was found to be no less than 4 to 5 SM and improved as the flight progressed. The flight was uneventful and both pilots spent most of the time discussing procedures and co-ordinating the patient pick-up with dispatch. During the last 1.5 min of the approach, the PF was explaining to the PNF what he was doing, step by step, and what to watch for during night approaches, including black hole illusions.
The Snake Lake Helipad is located on the northeast edge of town. According to the operator’s landing site directory for the Sudbury/Moosonee district, the Snake Lake Helipad is at a field elevation of 997 ft above sea level (ASL) and has a 100 by 100 ft asphalt-surfaced pad with retro-reflective cones around the perimeter and with lead-in cones at 220° magnetic (M) from the pad. Four of the perimeter cones can be equipped with e-flares to aid in visibility. These must be requested by the flight crew and are placed and activated by ground EMS personnel. They were not requested on the night of the occurrence.
The directory cautions of the following hazards:
- wires under, along east and north sides of the approach/departure sector;
- large hills south, east, and north of the site;
- tower west and fire tower south of the site;
- ball park east of helipad.
Additionally, there is a single house located beside the ball diamond, which has typical outside door entrance lights.
The helicopter approached the helipad from the southwest on a heading of approximately 048°M and entered the trees near the edge of the lake approximately 814 ft horizontally from the helipad.
The trees on the approach averaged 40 ft in height. The helicopter impacted trees that were located on the downward slope of the hill, at approximately 70 ft horizontally from the shore, where the height of the hill is approximately 10 ft higher than the helipad. As such, the average tree tops were approximately 50 ft higher than the helipad. The descent into the trees was near vertical with very little horizontal momentum and the nose of the helicopter came to rest approximately 15 ft from the shore. The helicopter’s rotor diameter was 44 ft and the damage to the trees was mostly within this diameter. The rotor blades were completely destroyed. During the descent, a tree passed through the left landing gear bay, the main battery, and continued through the engine deck and exhaust collector of the right engine. There was evidence of heat and scorching on the tree consistent with the heat of a running engine, but no post-crash fire.
Click on image to enlarge
A detailed examination of the helicopter revealed no discrepancies that would have affected its flying characteristics. No damage was found that would have prevented the engine from running.
The helicopter was equipped with an enhanced ground proximity warning system (EGPWS), dual Garmin GNS 530 global positioning system (GPS)/Navigation/ Communication units, a Latitude Technologies SkyNode satellite tracking system, and a cockpit voice recorder (CVR). These components were removed and analyzed. There were no operating abnormalities with the helicopter or engines prior to impact, and the helicopter was on the proper descent profile until it reached 500 ft above ground level (AGL) and 0.5 NM from the helipad, 21.5 s before impact. The PF perceived that the helicopter was too high and corrected accordingly. Simultaneously, the cockpit area microphone picked up the sound of the rotor RPM increasing slightly, then decreasing just prior to impact. The rotor RPM recording also confirmed an increase and decrease in rotor RPM just prior to impact. The PNF did not question the PF’s deviation from the proper descent profile, nor did he make any further speed or altitude calls after the deviation.
According to a study by the United States Air Force, titled Running Head: BLACK HOLE ILLUSION, spatial disorientation is defined by Gillingham as: “an erroneous sense of one’s position and motion relative to the plane of the earth’s surface.” The study also states:
Visual spatial disorientation (SD) is often cited as a contributor to aviation accidents. The black hole illusion (BHI), a specific type of featureless terrain illusion, is a leading type of visual SD experienced by pilots. A BHI environment refers not to the landing runway but the environment surrounding the runway and the lack of ecological cues for a pilot to proceed visually. The problem is that pilots, despite the lack of visual cues, confidently proceed with a visual approach. The featureless landing environment may induce a pilot into feeling steep (above the correct glide path) and over-estimate their perceived angle of descent (PAD) to the runway. Consequently, a pilot may initiate an unnecessary and aggressive descent resulting in an approach angle far too shallow (below the correct glide path to landing) to guarantee obstacle clearance.
There were no anomalies found with the helicopter that would have contributed to the accident. Therefore, this analysis focuses on the operation of the helicopter.
The Snake Lake Helipad is a classic black hole approach helipad. Temagami itself is a small community and the helipad is on the northeast edge of town. The approach is flown over the town and past all the lights with a relatively featureless landscape forward. The only visible lights are those of the house beside the ball diamond. On the terrain along the approach path, a small hill begins to rise approximately 2 430 ft horizontally from the helipad. The maximum rise is approximately 20 ft, which then gently slopes back down to the lake surface 723 ft horizontally from the helipad. The mature trees along the flight path would further increase the obstacle height another 40 ft. However, the steep approach angle of 8° into the landing site would have provided for adequate clearance above the trees to land safely.
The black hole approach requires diligent monitoring of the helicopter’s instruments. The flight crew followed most of the standard operating procedures (SOPs) during the approach and appropriate calls were made. In this case, the PNF was monitoring the airspeed, altitude and distance to the helipad. He relayed this information to the PF regularly. The PF, flying a visual approach, utilized the information from the PNF in addition to the visual cues for reference. However, the PF’s radar altimeter was not set to 150 ft as called for by the operations manual. This would have provided an additional cue to the flight crew that the helicopter was approaching the ground too soon during the descent into the helipad. Meanwhile, the helicopter was on a stabilized approach with the proper 8° descent profile, as required by the operations manual and the SOP.
During the 1.5 min of the approach, the PF’s attention was split between flying the approach and explaining why things were happening and what to watch for during a black hole approach. This likely distracted the pilots from the task at hand. In this case, the PF acknowledged a 0.5 NM and 500-ft call, an on-profile condition, but visually perceived that the helicopter was too high and, therefore, increased the rate of descent. This coincides with the increase in the rotor RPM—an indication that the collective is being lowered, decreasing the load on the rotor blades and increasing the descent rate. This was followed by a decrease in rotor RPM as the collective was raised, increasing the load on the rotor blades and decreasing the descent rate just prior to impact. At no time did the PNF question the PF’s deviation from the proper descent profile nor did he make any further speed or altitude calls after the deviation.
Based on the available information, a descent from 500 ft to impact in less then 21.5 s equates to a descent rate of more than 1 400 ft/min—well in excess of the recommended maximum descent rate of 750 ft/min. The increased descent rate caused the helicopter to descend into the trees before either crew member realized what was happening.
Findings as to causes and contributing factors
- The PF was likely affected by visual spatial disorientation and perceived the approach height of the helicopter to be too high. While correcting for this misconception, the helicopter descended into trees 814 ft short of the helipad.
- The pilots were likely distracted during the critical phase of the approach and did not identify that the helicopter had deviated from the intended approach profile and recommended descent rates.
Findings as to risk
- The right rear aft-facing paramedic seat lap belt attachment barrel nut was worn in the groove where the seat belt attaches, weakening the barrel nut’s structural integrity, thereby increasing the risk of failure.
- The helicopter crashed on its side, placing an abnormal side load on the right rear aft-facing paramedic seat lap belt attachment barrel nut, thereby causing it to fail.
Safety action taken
Following the occurrence, the supplemental type certificate (STC) holder for the EMS interior utilized in the S-76, issued Service Bulletin No. SB-EMS76-1. This service bulletin identified the affected helicopters and called for the replacement of the existing lap belt attachment barrel nut with a steel shackle. All affected helicopters have complied with the service bulletin.
by Rob Freeman, Program Manager, Rotorcraft Standards, Operational Standards, Standards, Civil Aviation, Transport Canada
In 1913, two American Army Signal Corps aviators were involved in a crash of their aircraft. It was later determined that the use of a steel helmet prevented one of them from suffering serious injuries. The investigation team recognized the potential of safety helmets for aviators, and ran with it. In fact, a steel helmet was designed for experimental use in aircraft near the end of World War I. From that uncertain genesis, you never see a military helicopter pilot anywhere in the world today without a helmet.
In the intervening years, we have seen many different types of helmets designed, developed, and accepted as an effective preventative measure. The list is long and inclusive of almost all activities where the participant is exposed to head injury—from construction workers and hockey players, to Formula One drivers, and many others. Why? Helmets work. They save heads and, subsequently, lives. And yet, their overall use by commercial and private helicopter pilots in the civilian market is conspicuously low, as verified by surveys and accident statistics. Agreed, there are some pockets of usage and acceptance in Canada—such as for aerial work, and by police and EMS operators, government pilots, heliskiing operators and individual, progressive companies—but for many Canadian operators and their pilots, helmet use is still rare.
As noted above, helmets, and the official recognition of their contribution to aviation safety originally occurred almost 100 years ago. There are light-weight, high-tech helmets specifically developed for helicopter use on the market now, incorporating active noise suppression, superior communications, and other desirable innovations that contribute to physical health and comfort, as well as accident protection. Availability and technology are not the issue. So what gives? Why are so many of our associates still flying around with semi-naked heads? The traditional list of excuses for not wearing helmets includes, but is not limited to, the following:
- Peer pressure. You start in a new company and are anxious to fit in, and no one else wears a helmet. I was once asked disdainfully by a group of grizzled veterans when I showed up on the job site with a helmet if I was a rookie or an ex-military pilot. Although no explanation for these two unrelated categories was offered, apparently neither group was desirable in a real man’s operation. Does this sound familiar? How are helmets perceived in your company? Is the safety culture supportive or dismissive?
- Company pressure. More than one operations or marketing manager has suggested that their pilots not wear helmets, as it frightens the passengers by implying that helicopter flight is a high-risk activity and is therefore bad for business.
- Comfort, fit, and helmet weight. These complaints often stem from the fact that used helmets were purchased from various sources such as military surplus and were never properly fitted for the current user. Pressure, hot spots, and neck pain resulted. And earlier designs were heavy.
- Feeling of restriction. Some pilots genuinely suffer claustrophobia when wearing helmets. Luckily, they are few in number, but their dilemma is legitimate. (There are a few newer models of light-weight helmets with less side-panel coverage that might provide a solution for these folks.)
- Feeling of invincibility. No one takes off in the morning planning to have an accident. If you are involved in the same work, in the same helicopter type for a long period of time, you may develop a sense of complacency and invincibility. One day is pretty much the same as the next. If you are never going to crash, why bother with a helmet?
- Cost. Depending on the model and installed equipment, a well-equipped helmet can exceed $3000, whereas a good-quality headset, complete with designer sunglasses and a snazzy baseball cap with your favourite team logo is less than a grand. Simply put, what is more important: your head or your “look”?
- Conventional wisdom states that aerial work and remote operations conducted by single-engined helicopters pose the greatest risks to their pilots for mishaps, and those are the areas where helmets should be employed. Medium and large twins, used more for pure transport, are statistically less likely to end up in an accident. Therefore, helmet usage is a lesser concern for these pilots.
The reality: In the past three years, at least one of each of the latest generation of medium to large twin-engined helicopters, with all the latest technology, has suffered a serious or fatal accident somewhere in the world. Although the traditional wisdom would seem to indicate otherwise, there is no “pass” to helmet usage just because you fly a large twin mostly in cruise flight at altitude. If you lose control of the helicopter for whatever reason, you are subject to the same forces on impact as the pilot in the smallest single. One study conducted by the U.S. Army concluded that head injuries occurred in approximately 70 percent of helicopter accidents. And many of these accidents occur at relatively slow speeds, meaning that they are probably survivable, if the crew is properly protected.
It is the secondary impact that causes head trauma and kills. The primary impact is the airframe striking the terrain or water. The secondary impact results from inertia, causing the crew to strike hard fixed objects within the cockpit. Instantaneous, momentary impact forces can easily exceed 50 g—50 times the force of gravity. Without a helmet, no matter how strong you are, or how you brace yourself you cannot avoid the hard secondary impact with your head. Transport Canada (TC) Canadian Aviation Regulations (CARs) mandate seat belts and shoulder harnesses to hold you in your seat. This has greatly reduced chest and limb injuries. Unfortunately, without a helmet, your head is left unprotected and flailing about during an accident sequence.
The Transportation Safety Board of Canada (TSB) Aviation Safety Advisory which follows this article advises that you are six times more likely to suffer a fatal injury if you crash without a helmet. A 1998 Flight Safety Foundation (FSF) study on helmet-visor usage further suggests that, in 25 percent of helicopter accidents where a helmet is worn with the visor down, the visor will significantly reduce facial and—of particular importance to pilots—eye injuries resulting from those secondary collisions. Visors aren’t just for bird strikes. In researching this article, I realized that I personally knew several skilled pilots over the years who died in helicopter accidents, primarily due to unprotected head trauma. How about you? Uncomfortable memories too? These statistics aren’t just for others.
U.S. military services train helicopter crew members to use aviation life-support equipment (ALSE) on every flight and include, minimally, a Nomex flight suit, fire-and chemical-resistant gloves, leather boots, and a helmet with visor. The helmet and visor are considered the most critical because numerous studies show that head injuries are the leading cause of death in U.S. Army helicopter accidents. Although an argument might be made that military missions are different from civilian flying, military accidents that do not involve weapons fire are surprisingly similar to those of their civilian brethren in root causes. There are certainly more similarities than differences.
If an accident occurs and you are unconscious or badly injured, you are of no help to your passengers and significantly reduce their chances for survival. Passengers look to their pilot(s) for leadership and direction after a crash, and they are far less likely to do as well without you. After all, you are the activity authority (flight) figure, you have the survival training knowledge, and you are familiar with the emergency gear, the emergency locator transmitter (ELT), and rescue protocols. An unconscious pilot is just one more demanding burden on the survivors, who may have limited abilities or knowledge and are probably dealing with shock, confusion, and trauma themselves. Your need to perform and provide leadership after an accident has occurred should not be underestimated. Your own survival, as well as theirs, could depend on it.
The fact is, all helicopter pilots should be wearing helmets—with visors installed and selected down, whenever possible. The numbers speak for themselves. So what is the answer? How do we get a buy-in and get Canadian heads and helmets together? When motorcycle head injuries spiked some years ago and large numbers of injured riders suddenly needed expensive, continuous, and high-tech medical care, provincial transportation authorities introduced mandatory helmet regulations. The loss of individual freedom of choice was considered less important than the soaring medical costs of treating severe, chronic injuries on a lifetime basis. Remember: unlike other injuries, brain trauma may be irreversible. The injury and its consequences may be with you for the rest of your life, provided that you survive to begin with.
Should TC introduce regulations for mandatory helmet usage? Under the current government’s Cabinet Directive on Streamlining Regulations, TC may consider regulatory action only when absolutely necessary. Other alternatives must be considered first. In this case, with relatively low numbers of pilots affected, a more consultative approach with industry in accordance with the Canadian Aviation Regulation Advisory Council (CARAC) Charter is mandated before any regulatory action can be undertaken. However, when Safety Management Systems (SMS) arrive, individual operators will be required to do operational risk assessments to identify existing hazards and mitigate them. And this is definitely a hazard. In the meantime:
- Various associations such as the Helicopter Association of Canada (HAC), Air Transport Association of Canada (ATAC), Association québécoise des transporteurs aériens (AQTA), and others such as the insurance industry could act as champions for this safety initiative, particularly if identified as a best practice by the associations’ memberships.
- Individual operators and their safety managers can encourage or underwrite the time-payment purchase of helmets. In fact, a single paragraph inserted in the company operations manual—mandating the use of helmets by all company pilots—would suffice, provided that the operator were willing to underwrite or otherwise assist in their purchase.
- Alternatively, each pilot can take responsibility for his or her own well-being. Nothing prevents individuals from purchasing and using helmets themselves, without official action at any level. You might even be able to negotiate a deal if several pilots in the same organization place a bulk order!
This is one proven but overlooked safety innovation that greatly increases accident survivability and resulting quality of life, and it is fully supported by TC. To paraphrase those quirky television credit-card commercials: “What’s on your head?
Source: Flight Safety Foundation, Helicopter Safety, Volume 24, Number 6, November–December 1998.
Article: Helmets with Visors Protect Helicopter Crews, Reduce Injuries
Authors: Clarence E. Rash, Barbara S. Reynolds, Melissa Ledford, Everette McGowin, III, John C. Mora, U.S. Army Aeromedical Research Laboratory, Fort Rucker, Alabama
The following is an Aviation Safety Advisory from the Transportation Safety Board of Canada (TSB).
On March 12, 2009, a Sikorsky S-92A helicopter with 16 passengers and 2 flight crew on board was en route from St. John’s, N.L., to the Hibernia oil production platform when, 20 min after departure from St. John’s, the flight crew noticed an indication of low oil pressure to the main gearbox. The crew declared an emergency and diverted the flight back to St. John’s. Approximately 30 NM from St. John’s, the helicopter impacted the water and sank in 178 m of water. There was one survivor and 17 fatalities. Although not fatally injured during the impact sequence, both pilots received severe injuries due in part to striking their heads/faces against the instrument panel. Neither pilot on the occurrence flight was wearing head protection.1 The TSB investigation into this occurrence (A09A0016) is ongoing.
While the Canadian Aviation Regulations (CARs) do not require that helicopter pilots wear head protection, approximately 10 percent of the operator’s pilots were routinely wearing head protection at the time of the occurrence. Whether or not this percentage represents an industry-wide norm for head protection usage is unknown. However, the majority of pilots surveyed during the A09A0016 investigation cited discomfort as the reason they did not wear head protection. In addition, very few pilots had fully considered that partial incapacitation due to a head or face injury could compromise their ability to help their passengers after an accident. On May 8, 2009, the operator implemented a cost-sharing program aimed at increasing the use of head protection. Management agreed to cover a portion of the cost for any pilot wishing to purchase a prescribed make and model of head protection. The operator stated that approximately 50 percent of its pilots have participated thus far, and it anticipates 75 percent participation.
According to U.S. military research2, the risk of fatal head injuries can be as high as six times greater for helicopter occupants not wearing head protection. In addition, the second most frequently injured body region in survivable crashes is the head.3 The effects of non-fatal head injuries range from momentary confusion and inability to concentrate, to a full loss of consciousness4; these outcomes can effectively incapacitate pilots. Incapacitation can compromise a pilot’s ability to quickly escape from a helicopter and assist passengers in an emergency evacuation.
The U.S. National Transportation Safety Board (NTSB) has acknowledged that the use of head protection can reduce the risk of injury and death. A review of 59 emergency medical services accidents that occurred between May 11, 1978, and December 3, 1986, was completed in 1988. This review resulted in recommendations to the Federal Aviation Administration (FAA) (# A-88-009) and to the American Society of Hospital-Based Emergency Aeromedical Services (# A-88-014) to require and encourage, respectively, that crew members and medical personnel wear protective helmets to reduce the risk of injury and death.
Transport Canada (TC) also acknowledged the safety benefits of head protection use in its 1998 Safety of Air Taxi Operations Task Force (SATOPS) report5, in which it committed to implementing the following recommendation:
- That TC continue to promote in the Aviation Safety Vortex newsletter the safety benefits of helicopter pilots wearing helmets, especially in aerial work operations, and promote flight training units (FTU) to encourage student pilots to wear helmets.
In addition, SATOPS directed the following recommendation to air operators:
- That helicopter air operators, especially aerial work operators, encourage their pilots to wear helmets, that commercial helicopter pilots wear helmets, and that FTU encourage student helicopter pilots to wear helmets.
This helmet was retrieved from an AS350 accident in Atlantic
Region (TSB File A07A0007). The other pilot was not
wearing his helmet and suffered serious head injuries.
The TSB has documented a number of occurrences where the use of head protection likely would have reduced or prevented the injuries sustained by the pilot. Similarly, the TSB has documented occurrences in which the use of head protection reduced or prevented injuries sustained by the pilot. Despite the well-documented safety benefits of head protection, the majority of helicopter pilots continue to fly without it. Likewise, most Canadian helicopter operators do not actively promote head protection use amongst their pilots. The low frequency of head protection use within the helicopter industry is perplexing, given the nature of helicopter flying and the known benefits of head protection.
As shown in this occurrence, without ongoing and accurate communication of the benefits of head protection usage, helicopter pilots will continue to operate without head protection, thereby increasing the risk of head injury to the pilot and consequent inability to provide necessary assistance to crew or passengers. Therefore, TC and the Helicopter Association of Canada (HAC) may wish to consider creating an advocacy program designed to substantially increase head protection use amongst helicopter pilots. Such a program could include, but is not limited to, initiatives that: ensure that helicopterpilot training curricula highlight head protection use, promote the advantages of cost-sharing programs between operators and pilots, and encourage informed debate by publishing articles that promote head protection use in publications such as the TC Aviation Safety Letter (ASL) and HAC newsletters.
1 TSB defines head protection as the use of an approved helmet, complete with visor.
2 Crowley, J.S. (1991) “Should Helicopter Frequent Flyers Wear Head Protection? A Study of Helmet Effectiveness.” Journal of Occupational and Environmental Medicine, 33(7), 766-769.
3 Shanahan, D., Shanahan, M. (1989) “Injury in U.S. Army Helicopter Crashes October 1979–September 1985.” The Journal of Trauma, 29(4), 415-423.
4 Retrieved on 31 August 2009 from www.braininjury.com.
5 Transport Canada publication, TP 13158.
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