Flight Operations


Missed Engine Cover Still Installed Brings Down Helo

On August 6, 2008, an MD369D helicopter was operating near Alice Arm, B.C. The helicopter took off at about 07:09Pacific Daylight Time(PDT) for the first flight of the day, with one pilot and three passengers; it was headed to a drill site up the Kitsault River valley. As the helicopter departed in a shallow left climbing turn, it emitted an unusual sound, reached about 150ft above ground level(AGL), then suddenly banked 90° to the right and fell to the ground. It broke up on impact and all four occupants suffered fatal injuries. The investigation by the Transportation Safety Board of Canada(TSB) is complete, and the following is based on TSB Final ReportA08P0244.

Other factual information
The pilot had 38 years of flying experience and had accumulated over 11000hr of flight time. The work schedule was relatively light. Prior to this tour of duty, the pilot had been off for 10days. This was well within the limits of duty time, and he had a quiet, restful evening before the accident flight.

There was an apprentice aircraft maintenance engineer(AME) on site to help with elementary tasks on the helicopter. He would normally look over the helicopter at the end of the day and secure it for the night. This included installing a synthetic heavy material cover(doghouse cover) over the engine intake and around the main rotor control system, and tying down the main rotor. He would normally get up in the morning to remove the cover and untie the rotor, among other things. A couple of days before the accident, the pilot suggested that the apprentice need not get up early, and that he would prepare the helicopter for the day’s flying. On the last two nights, the apprentice did not tie the rotor down, but he did install the cover.

The cover did not have any straps or physical barriers that fall at or below human eye level. Once the pilot gets into the helicopter, there are no visual clues of the cover’s installation. Before this occurrence, it was expected that the engine would not start with the cover installed, but we now know that as soon as the rotor started turning, the cover opened enough to let in sufficient air for the start.

Photo 1: Doghouse cover

Photo 1: Doghouse cover

On the morning of the accident, the pilot was up at the usual time, but stayed at the lodge a little longer and arrived at the helipad later than normal. Two of his passengers arrived before him that day. When the third passenger arrived at the helipad, the pilot was loading the other passengers’ equipment. They loaded some more equipment, embarked the helicopter and departed immediately after. Examination of the helicopter wreckage at the accident site revealed the cover tightly wrapped around the main rotor control system, around the swashplate (see Photo2). Nearly all the control linkages (pitch change rods) were broken and the damage was not consistent with that normally found from crash impact forces. Rotor blade damage was consistent with low rpm at impact. Tree damage and scars at the accident site were consistent with a vertical descent, and no rotorrpm.

Photo 2: Doghouse cover wrapped between controls

Photo 2: Doghouse cover wrapped between controls

It is clear that the removal of the cover was missed during flight preparation and that the cover damaged the main rotor controls while the rotor was turning. Also, rotor rpm was likely lost due to the binding effect that the cover had as it squeezed between the stationary and rotating components of the swashplate assembly. This rendered the helicopter uncontrollable after the takeoff, and it collided with terrain.

To determine how this item could be missed, the following analysis focuses on human factors.

Because humans are easily distracted and our memories are less than perfect, we use training, routine, checklists, visual cues, and physical defence barriers to help us carry out required tasks.

There were no physical barriers to prevent the pilot from operating the helicopter with the cover installed. When the cover was installed without the main rotor being tied down, two things happened. The physical barrier and visual cues were removed. Since the pilot arrived at the helipad after some of his passengers, it is possible he was distracted from his normal routine by the need to assist them loading their equipment. Also, mental imprinting of the task to remove the cover could have been lessened by the practice of having someone else installit.

In summary, anomalies in the pilot’s routine and the lack of physical barriers likely caused him to miss removing the cover before the flight.

Photo 3: Modified doghouse cover

Photo 3: Modified doghouse cover

The TSB final report lists the following three findings as to causes and contributing factors:

  1. The doghouse cover was not removed before flight and it wrapped around the flight controls linkage, damaged the linkage, and rendered the helicopter uncontrollable.
  2. The helicopter fell in an uncontrolled state, with reduced rotor rpm, until it collided with terrain.
  3. Anomalies in the pilot’s routine and the lack of physical barriers likely caused him to miss removing the cover before the flight.

Safety action taken
As a results of this occurrence, the operator implemented procedures requiring that blade tie-downs be installed whenever the doghouse cover is installed. Also, the covers have been modified with tape/straps that hang down and are to be placed in the front doors.

The manufacturer of the doghouse (Aerospace Filtration Systems Inc.) has taken safety action in modifying the cover (see Photo 3).

Closing comment from the lead investigator to the Aviation Safety Letter (ASL): "I would hope that the ASL readers don’t think this was just a stupid error. This cover was missed by a very well-respected and careful pilot. If it happened to him, it can happen to any of us. It is also important for all operators to get that message. Our analysis looked at human factors to determine how a fastidious, experienced pilot could miss such a basic and critical item."

Night Vision Goggles Blind to LED Lights

by Stéphane Demers, Civil Aviation Safety Inspector, Rotorcraft Standards, Standards, Civil Aviation, Transport Canada

Aviation eats up technology at an ever-increasing speed. Today, we see numerous technological advances being adapted from the military and from other areas into a broad spectrum of aviation-related applications.

Night vision goggle(NVG) technology is becoming mainstream, especially in the rotorcraft community. The ability to have a discernable horizon, see terrain details that were previously masked by darkness, and greatly increase night-operation safety makes the decision to use NVGs a wise choice. Pilots who use NVGs regularly now consider unaided night operations more of an emergency measure and would reluctantly fly without them.

Light emitting diode(LED) lights are another great tool, and their use is fast becoming the norm. In the past two to three years, these little lights have made their way into all forms of lighting fixtures, from tiny flashlights to automotive lights. In aviation, LED lights are now being used for obstruction and aircraft lighting. LED bulbs have a terrific appeal because they last much longer, and their size allows for more flexibility in designing navigation lights and beacons.

Ironically, we have inadvertently combined two technologies without fully calculating their impact on each other. In the past year, I have received numerous complaints from military, police, and emergency medical services(EMS) pilots indicating that their NVGs could not discern LED lights.

I first encountered this problem while working as a heliport inspector in Alberta, testing portable lighting systems for heliports. During testing, the pilots reported being unable to see green LED. We initially believed the colour was causing the problem: NVGs tend to make everything appear in greenish hues, and so we thought they must be drowning out the green LED.

Within weeks of our testing, we received other calls, but now about red and white LED lights. A military crew operating near a wind farm in Ontario reported that their NVGs could not see the red obstruction lights on the windmill towers. Some Royal Canadian Mounted Police(RCMP) pilots had reported being unable to see red LED lights on towers and on some automobiles; red LED Christmas lights were also invisible.

As the problem became more widespread, we contacted the National Research Council Canada(NRC) in Ottawa, Ont., to look into the matter. Dr. Gregory Craig confirmed that the NRC crews had made the same observation in their work. Dr.Craig provided the following numbers on NVG sensitivity and the LED spectrum (all measured in nanometres). The bottom line is this: The most commonly used LED lights peak at 623nm; NVGs begin "seeing" at 645nm and peak between 660-850nm.

Night vision goggles are becoming mainstream

Photo: Jeff Calvert

Night vision goggles are becoming mainstream

Some LED lights peak at around 660nm and would thus be visible to NVGs. However, it is unclear how prevalent their use is. The easy answer would be to simply use 660nm LED lights. However, current regulations do not specify this nanometre reading as a requirement.

Furthermore, current obstruction lighting regulations do not require towers of lower than 300ft to be lit unless they are an obvious hazard to aviation-such as very close to an airport or along an air route. This regulation has some flaws as it was conceived with fixed-wing operations in mind. However, the heaviest use of NVGs occurs away from those areas and often at or below 300ft. As NVGs gain popularity, more fixed-wing aircraft will undoubtedly be using them. It may also be possible to see pipeline, wildlife, anti-poaching patrol, police, or even spray aircraft using them, all of which operate at or below 300ft as required by their missions.

As Transport Canada Civil Aviation(TCCA) and the NRC continue to work together and with other interested agencies, it is important to get the word out to industry that obstructions may not be lit even when you think they should be. For those using NVG technology, be aware that you may not see LED lights on towers or even on another aircraft.

So, going night flying anytime soon? Check NOTAMs, plan your route carefully, do a dry run during daylight hours (if possible), and mark obstructions on your map or in your global positioning system(GPS). And remember that while your NVGs are a great tool, they do not exactly turn night into day. So keep vigilant, and take the odd peek outside under your nogs just to spot those elusive LED lights.

I’ll Just Sneak Through Here...They’ll Never See Me if I Stay Low

by Bob Grant, Civil Aviation Safety Inspector, Airspace Standards and Procedures, Standards, Civil Aviation, Transport Canada

Of all human failings, the most insidious and probably the most common is "If I had it to do over again, I would have done it differently." But, unfortunately, we can never should have, would have, could have the next day.

The pilot was delayed, the departure time was set back, and the schedule was now very restrictive. He could make the trip before dark if he took the direct route through the hills to the north of a large metropolitan area. Getting to destination before nightfall was essential as he had an early evening sales appointment that his boss said he could not miss. There was no room for compromise.

The weather was forecast to be fairly good en route with lowering ceilings and visibility in the hills to the north. He could alter his track a bit to the south to stay in the lower terrain if he ran into weather problems. He’d increase his speed a bit and still make destination on time. There was one more problem, and it was a big one. NOTAMs revealed that a 30-NM restricted area had been created around the international airport of the metropolitan area to help provide security for a visiting head of state. Passage through the area was based on a number of requirements, one of them being a serviceable transponder, and his was down for maintenance. He knew there was no point in asking for clearance without a transponder and, as he was being forced toward the restricted airspace by deteriorating weather, he was compelled to make a decision that he would live with for the rest of his life.

He elected to descend. His rationale was that air traffic control radar wouldn’t be able to see him and he would get through the area quickly and be on his way. His rationale was flawed. ATC had a backup. The military was present to provide security identification and possible enforcement. His track was observed, and a fighter aircraft was dispatched to escort him out of the restricted area.

He was about halfway through the top 4NM of the restricted area when his system received a large jolt of reality that would forever affect his life. A large, ominous, dark aircraft appeared off his left wing. The appearance of an aircraft, so close and of this type, had never crossed his mind.

His first and last reaction was to bank hard away from the perceived danger. His last conscious thought was of a crushing substernal chest pain followed by shortness of breath and darkness.

This is a bit of fiction, but could it be true? Unfortunately, yes.

In late 2008, a congress of leaders from Francophone nations was held in Québec City. The federal agency responsible for security at the event asked the Canadian Forces for some air support. During the three-day event, 22 airspace violations were recorded. Military aircraft prosecuted most of these violations. To say that a number of pilots in the Québec area were surprised by visits from military aircraft would be an understatement.

Earlier this year, the President of the United States visited Ottawa. During his short six-hour visit, a commercial helicopter violated restricted airspace that had been established to add security.

Over the past five years, over 400 airspace violations have occurred in Canadian airspace.

People make mistakes-that’s human nature. But post 9/11 security of airspace has increased dramatically, and there is less margin for error. Military presence has increased with more and more intercepts being conducted. If pilots continue to disregard restricted areas, it’s only a matter of time before a very serious occurrence takes place with, perhaps, loss of life. In simple terms, restricted airspace means just that: Don’t go there unless you request and receive permission from the controlling agency.

The Aeronautics Act

Article 5.1

The Minister or any person authorized by the Minister may by notice prohibit or restrict the operation of aircraft on or over any area or within any airspace, either absolutely or subject to any exceptions or conditions that the Minister or authorized person specifies, if, in the opinion of the Minister or authorized person, the prohibition or restriction is necessary for aviation safety or security, is necessary for the protection of the public or is in the public interest.

Canadian Aviation Regulations(CARs)

Orders Prohibiting or Restricting Aircraft Operation

601.18 The Minister may make orders prohibiting or restricting the operation of aircraft over such areas as are specified by the Minister, either absolutely or subject to such exceptions or conditions as may be specified by the Minister.

IFR or VFR Flight in Class F Special Use Restricted Airspace or Class F Special Use Advisory Airspace

601.04 (1) The procedures for the operation of aircraft in Class F Special Use Restricted airspace and Class F Special Use Advisory airspace are those specified in the Designated Airspace Handbook.

(2) No person shall operate an aircraft in Class F Special Use Restricted airspace unless authorized to do so by the person specified for that purpose in the Designated Airspace Handbook.

(3) For the purposes of subsection(2), a person specified in the Designated Airspace Handbook may authorize the operation of an aircraft where activities on the ground or in the airspace are not hazardous to aircraft operating in that airspace and access by aircraft to that airspace does not jeopardize national security interests.

What is it about these documents that is so hard to understand? Restricted and prohibited mean just that: Stay out unless you have been granted permission to enter. If you violate restricted airspace, you will be charged under the CARs. Penalties upon conviction range from monetary fines and/or loss of pilot privileges. In addition, depending on the security to be enforced, punishment could be far more severe. I quote the last line from interception procedures issued by the Federal Aviation Administration(FAA) for all aircraft operating in United States national airspace: "BE ADVISED THAT NONCOMPLIANCE MAY RESULT IN THE USE OF FORCE." Similar words were used in 2002 when Canada hosted the G8 Summit in Kananaskis, Alta. The threat of a terrorist situation is real, and so are the counter-measures.

The Winter Olympics will be held in the Vancouver area next February, and special airspace restrictions will be in place to provide appropriate levels of safety and security. For those who, for whatever reason, find themselves inside restricted airspace, rest assured you will be intercepted.

All pilots should know the interception signals, in case something like this happens.

All pilots should know the interception signals, in case something like this happens.

To that end, I’m repeating the information found in part or in total in the CARs, Canada Flight Supplement(CFS), section F on "Interception of Civil Aircraft" and "Signals For Use in The Event of Interception" and the Transport Canada Aeronautical Information Manual(TCAIM).


Interceptions are made only where the possibility is considered to exist that an unidentified aircraft may be truly hostile until definitely proven to the contrary. Intercepted aircraft should maintain a steady course and under no circumstances take retaliatory action such as shining a light on an interceptor or attempt evasive action. Retaliatory action on the part of an intercepted aircraft could be construed as a hostile intent and might result in drastic consequences. Practice interceptions are not carried out on civil aircraft.


The word "interception" in this context does not include intercept and escort service provided, on request, to an aircraft in distress, in accordance with the International Civil Aviation Organization(ICAO) International Aeronautical and Maritime Search and Rescue(IAMSAR) Manual (Doc.9731).

An aircraft which is intercepted by another aircraft shall immediately:

  1. follow the instructions given by the intercepting aircraft, interpreting and responding to visual signals (see following page);
  2. notify, if possible, the appropriate air traffic services unit;
  3. attempt to establish radio communication with the intercepting aircraft or with the appropriate intercept control unit, by making a general call on the emergency frequency 121.5MHz and repeating this call on the emergency frequency 243.0MHz, if practicable giving the identity and position of the aircraft and the nature of the flight;
  4. if equipped with transponder select ModeA Code7700, unless otherwise instructed by the appropriate air traffic services unit.

If any instructions received by radio from any sources conflict with those given by the intercepting aircraft by visual or radio signals, the intercepted aircraft shall request immediate clarification while continuing to comply with the instructions given by the intercepting aircraft.


Series Intercepting Aircraft Signals Meaning Intercepted Aircraft Responds Meaning
1 DAY - Rocking wings from a position in front and, normally, to the left of intercepted aircraft and, after acknowledgement, a slow level turn, normally to the left, on to the desired heading. Flares dispensed in immediate vicinity.
NIGHT - Same and, in addition, flashing navigational lights at irregular intervals. Flares dispensed in immediate vicinity.
NOTE 1. Meteorological conditions or terrain may require the intercepting aircraft to take up a position in front and to the right of the intercepted aircraft and to make the subsequent turn to the right.
NOTE 2. If the intercepted aircraft is not able to keep pace with the intercepting aircraft, the latter is expected to fly a series of race-track patterns and to rock its wings each time it passes the intercepted aircraft.
You have been intercepted.
Follow me.
DAY - Rocking wings and following.
NIGHT - Same and, in addition, flashing navigational lights at irregular intervals.
Rocking aircraft, flashing navigational lights at irregular intervals and following.
NOTE - Additional action by intercepted aircraft is prescribed in paragraph "INTERCEPTION SIGNALS".
Understood, will comply.
2 DAY or NIGHT - An abrupt breakaway manoeuvre from the intercepting aircraft consisting of a climbing turn of 90degrees or more without crossing the line of flight of the intercepted aircraft. You may proceed. AEROPLANES:
Rocking wings.
Rocking aircraft.
Understood, will comply.
3 DAY - Circling aerodrome, lowering landing gear and overflying runway in direction of landing or, if the intercepted aircraft is a helicopter, overflying the helicopter landing area.
NIGHT - Same and, in addition, showing steady landing lights.
Land at this aerodrome. AEROPLANES:
DAY - Lowering landing gear, following the intercepting aircraft and, if after overflying the runway landing is considered safe, proceeding to land.
NIGHT-Same and, in addition, showing steady landing lights (if carried).
Following the intercepting aircraft and proceeding to land, showing a steady landing light (if carried).
Understood, will comply.


Series Intercepted Aircraft Signals Meaning Intercepting Aircraft Responds Meaning
DAY - Raising landing gear while passing over landing runway at a height exceeding 300m (1000ft) but not exceeding 600m(2000ft) above the aerodrome level, and continuing to circle the aerodrome.
NIGHT - Flashing landing lights while passing over landing runway at a height exceeding 300m (1000ft) but not exceeding 600m (2000ft) above the aerodrome level, and continuing to circle the aerodrome. If unable to flash landing lights, flash any other lights available.
Aerodrome you have designated is inadequate. DAY or NIGHT - If it is desired that the intercepted aircraft follow the intercepting aircraft to an alternate aerodrome, the intercepting aircraft raises its landing gear and uses the Series 1 signals prescribed for intercepting aircraft.
If it is decided to release the intercepted aircraft, the intercepting aircraft uses the Series 2 signals prescribed for intercepting aircraft.
Understood. Follow me.

Understood, you may proceed.
DAY or NIGHT - Regular switching on and off of all available lights but in such a manner as to be distinct from flashing lights.
Cannot comply. DAY or NIGHT - Use Series 2 signals prescribed for intercepting aircraft. Understood.
DAY or NIGHT - Irregular flashing of all available lights.
DAY or NIGHT - Irregular flashing of all available lights.
In distress. DAY or NIGHT - Use Series 2 signals prescribed for intercepting aircraft. Understood.

In closing, it is imperative in today’s security environment for pilots to be cognizant of airspace restrictions and fully aware of the procedures to follow if intercepted. When it comes to restricted airspace, fly smart and fly safe.

Flight in the Vicinity of Convective Weather

by Thomas Smyth, Civil Aviation Safety Inspector, Airline Standards, Standards, Civil Aviation, Transport Canada

Since the earliest days of flight, convective weather has posed many risks to commercial and general aviation. Whereas some convective weather systems present little risk to aviation activities, others are extremely hazardous. The focus of this article will be on the extreme events such as thunderstorms, and specifically during the approach and landing phases of flight.

The summer season in Canada can offer some of the most enjoyable flying conditions of the year. However, the heat of the summer also provides the energy for the formation of powerful air-mass and frontal thunderstorms. The chances of encountering a thunderstorm will largely depend on where you are flying within Canada. The Yukon Territory, Nunavut Territory, Northwest Territories, and British Columbia have the fewest number of thunderstorms each year. Alberta through to Nova Scotia, on the other hand, average 20 to 30days of thunderstorms each year with some localized areas getting more, such as southern Saskatchewan, which may experience daily thunderstorms during the month of July. Thunderstorms are evolving phenomena as they have several stages to their life cycle, which generally last one to two hours. The first stage, called the developing stage, is characterized by updrafts that can be seen as bubbling cumulus cloud with rapid vertical growth. The mature stage follows and is the most likely time for hail, heavy rain, and frequent lightning. The dissipating stage signals the end of the life cycle, but by no means the end of the hazards generated by the thunderstorm since strong winds and lightning can still be present. Pilots should be aware of the characteristics of each stage-along with their associated hazards-and learn to recognize them while flying.

During their initial training, pilots are taught about the power and dangers of thunderstorms. They are also taught that aircraft of any size are no match for a thunderstorm, as many accidents have proven. Windshear, microbursts, hail, heavy rain, lightning, and reduced visibility are some of the hazards of thunderstorms that may be encountered during the approach and landing phase of flight. The consequences of flying through such conditions can range from experiencing uncomfortable turbulence to crashing short of the runway. We can reduce the risks of thunderstorms to an acceptable level by giving ourselves the tools to make informed decisions so that we can manage the threat appropriately. These tools include weather information gathered prior to flight and especially en route, onboard weather detection, alternative plans that are devised prior to the flight, and of course, common sense. The objective is to prepare for the flight so that we are not forced into a situation where we need to make a critical decision under a great deal of stress because, as we all know, such decisions are not usually our best.

Whether you are flying using instrument flight rules(IFR) or visual flight rules(VFR), the hazards from thunderstorms during the approach and landing are the same. Let’s look at an example: An approaching thunderstorm will be preceded by a gust front as cold, dense air descends from the expanding storm and strikes the ground, moving outward at speeds that can approach 50kt. The gust front creates medium-to-severe turbulence, which can cause small, general aviation aircraft to momentarily depart controlled flight and larger aircraft to experience some very uncomfortable turbulence. As the thunderstorm and the aircraft move closer to the airport, the level of risk will increase, especially as the aircraft descends for a landing. If caught in a microburst, the aircraft would have great difficulty recovering given its close proximity to the ground. In the recent past, this phenomenon has contributed to several fatal accidents involving large aircraft.

With thunderstorms nearby, even being on the landing roll can bring significant challenges. Rapid changes in wind velocity and direction can change a 20-kt headwind to a 20-kt tailwind very quickly, leading to the aircraft touching down well past the normal touch-down point. The problems of a long landing can be compounded by deteriorating runway conditions because a runway that was dry only minutes before can not only become wet from a heavy downpour, but can reach the point where the runway is considered contaminated (more than 3mm of water). Hydroplaning and loss of directional control, particularly if there is a crosswind, can be expected in these conditions. There have been numerous accidents in which pilots had the good judgment to navigate around storm cells while approaching the airport, but then landed in heavy rain and overran the runway due to contamination of the runway surface by water.

Pilots should also be aware that airports currently do not have the technology to detect if runways are contaminated by water, but can only report that the runway is wet.

Now for the human factors side of this issue: for all the positive characteristics we pilots have, our focus on the final objective can sometimes override common sense. It would be difficult to find a pilot who thought that landing at an airport during a thunderstorm was a good idea, but even with all we know about this topic, it still happens, and often with tragic consequences. Poor decision making can be caused by many factors, such as fatigue, lack of information, and inexperience. To a pilot, a thunderstorm is an obstacle in the way of the ultimate goal of the flight, which is arriving at the destination. When a thunderstorm is encountered en route to the destination, there is usually a way around it. However, when the thunderstorm is positioned close to an airport, and the aircraft is on final approach, it is easy to say "The aircraft ahead of us landed safely; we should be fine as well," because the goal of the flight is so close. Still, the weather conditions can quickly change for the worse, making a successful landing all but impossible. Each situation is unique, and just because you were able to make the approach and landing in similar conditions last time does not mean that luck will be on your side this time.

Windshear- and weather-detection technology that is available for airports and on board aircraft is helping to reduce the risks associated with convective weather by giving pilots and air traffic controllers the information they need to make informed decisions and avoid the potentially catastrophic results of flying into convective activity. Technology, though, is not the final solution to the risks presented by thunderstorms, but along with education and awareness, the risks can be greatly reduced, and flight operations in the vicinity of thunderstorms made as safe as possible.

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