June 18, 1986: Grand Canyon Airlines, Inc. / Helitech Inc., deHavilland DHC-6 (N76GC) / Bell 206B III (N6TC) Mid-Air Collision, Grand Canyon, AZ
June 18, 1986. The morning was clear and sunny when a deHavilland DHC-6-300 Twin Otter "Vistaliner" (N76GC) operated by Grand Canyon Airlines departed for it's hour long air tour. On board were 18 passengers, many of whom were Dutch citizens booked through a tour company promoted by American Express. The two crew members were seasoned air tour pilots with several years flying the Grand Canyon.
Less than a mile north of the airport, a Bell 206B Jet Ranger helicopter (N6TC) operated by Helitech Inc. was preparing for a 40 minute tour flight with four passengers. The pilot of the helicopter was also highly experienced.
Both flights proceeded normally on their prescribed air tour flights even though no set regulations or standardized routes existed at the time. All flights within the airspace of Grand Canyon in regards to routes and altitudes were conducted by a "gentleman's agreement" with the various air tour companies. A suggested five hundred foot altitude separation of helicopters and airplanes was the safety cushion.
At about 9:30 AM, the two flights were approaching a geologic formation known as Mencius Temple. The Twin Otter, call sign "Canyon 6" from the west and the Bell Jet Ranger, call sign "Tech 2" from the north. For reasons undetermined to this day, both aircraft collided in a horrific impact at an altitude of 6,500 feet. The collision separated the main rotor mast from the helicopter while the disintegrating rotor blades tore into the Vistaliner's tail section causing it to separate in-flight. Both airplane and helicopter pitched over and fell inverted onto the southwestern slope of Mencius Temple. All 25 persons on both aircraft perished, making this accident the second deadliest air disaster in the Grand Canyon to date.
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HISTORICAL SUMMARY:
Unlike the June 30, 1956 accident, the wreckage from this collision was for the most part entirely removed from the national park. The wreckage materials from both airplane and helicopter were taken to a private property location near the town of Tusayan, Arizona and discarded.
During 1990, I was given permission by the land owner to take what I wanted as he was frustrated by the salvage company that never removed the wreckage. Within the debris I found many identifiable personal effects which were overlooked by the initial recovery efforts. I was able to return these items to very grateful surviving family members. The other fragments of wreckage that I have collected and documented provide a tangible historical record to this tragic event in the aviation history of Arizona.
In November 2010, I hiked into the crash site area from the Grand Canyon's North Rim. It was an opportunity to actually see the accident site first hand and to document any remaining wreckage. The crash sites are located on the Tonto Plateau nearly 1,200 feet above the Colorado River and almost 6,000 feet below the canyon's North Rim. The area is designated by the National Park Service as "Wild" since there are no trails, no services, and very few water sources.
This accident was a catalyst event that led the Federal Aviation Administration (FAA) to require that all turbine commercial passenger aircraft be required to have Traffic Collision Avoidance Systems (TCAS) installed. This accident also led the FAA to develop a rules and regulations for standardizing air tour routes and altitudes within the Grand Canyon National Park as well as other selected national park boundaries. The result was an increase in air safety and a reduction of aircraft noise levels within the park.
One of the last items I located at the impact site of "Canyon 6" was this small silver charm or pendant.
THE COLLISION DEBRIS FIELD
Over 2,300 feet of sloping open terrain separated the impact sites of "Canyon 6" and "Tech 2".
With the mid-air collision occurring at roughly 3/4 of a mile above the surface, fragments from both aircraft fell over a wide area on the Tonto Plateau east of the Tuna Creek drainage.
During my short time at the site, I was able to document the locations of a few fragments from both aircraft in this area.
This fuselage bulkhead or rib fragment from "Canyon 6" came from the aft fuselage when the helicopter's main rotor blades tore through the area behind the aft baggage compartment of the Twin Otter.
As a result of this collision damage, the entire tail section of "Canyon 6" separated from the fuselage in-flight causing a complete loss of control.
A fire damaged fragment of the Twin Otter's engine nacelle was identified by the round fire bottle disc indicator. It was located 480 feet from the "Canyon 6" main impact site.
A burned and melted fragment so far from the impact site puzzled me at first since the accident investigation revealed there was no fire at the time of collision.
It was surmised that the fragment most likely fell to this location as the aircraft wreckage was being removed by helicopter during salvage operations.
The location of the fire bottle disc indicators on the left wing of a Twin Otter.
A close-up photo of the fire bottle disc indicators on the aft part of the engine nacelle.
Finding fragments of window plexiglas in the debris field usually indicates that the aircraft cabin was breached in the collision.
Having previously found evidence that the helicopter main rotor blades tore into the passenger cabin near seat row 7. This window fragment probably came from the left side window on the aft entrance door.
Searching a mid-air collision debris field can be a confusing endeavor when similar aircraft are involved. In the case of a helicopter and airplane, the wreckage materials often have a very different type of structure making separate identification easier.
This aluminum tube assembly was found 1,266 feet north of the main impact site of "Tech 2". The assembly was sheared by a tremendous force at both ends and was bent in the middle. I knew it was not from the Twin Otter since there is no such component on the aircraft.
I researched the Bell 206 helicopter and the components that were primarily affected by the collision. The main rotor head assembly of the Bell 206 has two rods extending to the main rotor head. They are called "Pitch Links".
This photograph of a Bell 206 Jet Ranger main rotor assembly illustrates the location of the two main rotor pitch links.
This entire assembly and the main rotor mast in between the two links broke apart and sheared from "Tech 2" after the collision.
This "UP" arrow decal on the reverse side of the tube positively identified the fragment as a helicopter main rotor pitch link assembly.
"Canyon 6's" Nose Wheel Steering Actuator was discovered near the Tuna Creek drainage by a hiker in 2006.
The presence of the hydraulic actuator in the debris field gives a clear idea of the severe damage inflicted by the helicopter's main rotor blades.
The entire nose landing gear and wheel assembly of "Canyon 6" was sheared off the aircraft during the collision. Apparently the actuator was pulled out with it. (Photo courtesy of Larry Antonelli)
With the aircraft radome removed during maintenance, this photograph of a Nose Wheel Steering Actuator (circled) illustrates it's location on the Twin Otter.
The steering actuator shown installed on the Twin Otter.
The actuator allows the pilot to turn the nose wheel during ground taxi operations,
The shape of this small fiberglass fragment does not match any component on the Twin Otter, but does match the shapes and bends of the fiberglass engine and transmission cowlings on the Bell 206 Jet Ranger helicopter.
MAIN IMPACT SITE OF "TECH 2"
Seconds after the collision, a massive imbalance in the fragmenting rotor blades caused the main rotor assembly to separate. The helicopter rolled inverted into a free-fall of 3,000 feet onto this rocky slope on the eastern edge of Tuna Creek.
Similar to the main impact site of "Canyon 6", the crash site of "Tech 2" is marked by a burn area with small fragments lying on the surface.
A majority of the wreckage was removed shortly after the accident to the dump site on the canyon's South Rim.
Locating the crash site of "Tech 2" was a challenge to find. I knew the impact site would be very small and difficult to find.
After walking the area for a half hour, I began to see reflections of broken glass and debris in the distance.
This flexible wristwatch band was located in the burn area.
The watch band, manufactured in Germany, had numerous patent numbers and wording on each link. There were three passengers from West Germany traveling on "Tech 2" when it collided with "Canyon 6".
This outcrop of boulders caught my attention as I examined the crash site of the air tour helicopter. I began to notice the chipping and scarring on their surfaces. (The summit of Mencius Temple in the background).
In addition to the chips and scarring from the helicopter impact, I also noticed the presence of paint and metallic transfers on the surface of the boulders.
Additional metallic transfer marks were found on an adjacent boulder. The NTSB's accident report failed to mention contact with these boulders.
A piece of blue tinted Plexiglas probably came from one of the small tinted overhead windows on the helicopter.
A small animal midden was noticed at the base of the boulder pile. Amid the animal's nesting material were dozens of small wreckage fragments from the helicopter.
Compared to the impact site of "Canyon 6", the burn area of "Tech 2" was much smaller in size at about 15 feet in diameter with additional debris extending 20 feet by 40 feet.
Evidence found at the site also showed that the post crash fire was not as intense as compared with the impact site of "Canyon 6".
A fragment of the helicopter's metal floor panel displayed no evidence of fire damage.
A close examination of the burn area of "Tech 2" revealed evidence of fire damage in the form of melted aluminum. This was the only area at the site where this was noticed.
This cockpit annunciator warning light was found at the impact site. unfortunately it was too far damaged to identify what system on the helicopter it supported.
This cast aluminum fragment could have come from either the helicopter's engine gearbox or transmission case.
A small burned logo emblem located at the site was once attached to the top of a passenger's seat belt buckle. The original lettering on the emblem was "bh" for helicopter manufacturer "Bell Helicopter".
This rock cairn located near the crash site of "Tech 2" was placed by Scott Thybony (brother of helicopter pilot John Thybony) during his near disaster solo hike to the site in August 1986.
The trip he made in the middle of summer nearly cost Thybony his life when he ran out of water. Thybony, suffering from severe dehydration was able to find a large section of main rotor blade that was key to the accident investigation.
SCOTT THYBONY
Scott Thybony contributed a wealth of knowledge and information that made my trip to this crash site possible.
To honor John Thybony's military service in Vietnam, I decided to place an American Flag at the crash site as a memorial.
Looking over the crash sites one last time and with the sun about to set over nearby Scorpion Ridge, I began to make the long hike off the Tonto Plateau.
HIKING OUT - A LONG WAY UP
There is an old saying in the canyon, "Hiking down is optional. Hiking back up is mandatory".
It was nearly a two day endeavor of off-trail hiking to reach the crash sites of "Canyon 6" and "Tech 2". To return, it will take two full days of hiking up the same terrain to make it out safely.
The route was tough to hike down with a heavy water laden backpack, but I was dreading having to negotiate this same route climbing up with the same heavy pack.
There was no getting around the shear exposure of this 60 foot climb up this redwall ledge.
Using some rope I brought along, I raised my pack up each ledge as I made a hand climb up to the next level position. Kind of scary. I tried not to look down too much.
Finally reaching the top of the ledge gave me the opportunity to take this photo looking down at my route up.
The canyon walls were steep in this section, but the pour-offs in the creek bed were vertical and impassable. The upper sides of the canyon are the only option of travel.
The route back up Flint Creek through the Coconino, Toroweap, and Kaibab rock layers was steep and a bit challenging.
BACK ON THE NORTH RIM
It's always a good idea to wear gloves and long pants when you have to hike through thickets of New Mexican locust. The thorns of this plant will literally rip you to shreds.
The thorns of the New Mexican locust are brutal to both skin and clothes. Kind of like a rose bush with attitude.
After making a long hike to the Point Sublime Road, I finally found my ATV. Gotta love these hand-held GPS receivers!
While I was in the canyon, the rain I experienced on my first night meant even more snow on the North Rim. Hiking this late in the year I was really pushing the weather.
In less than a week after my hike, another winter storm hit the North Rim forcing the Park Service to close the roads till mid-May of next year.
After a cold 13 mile ride back to my truck, my hike was completed, but my trip was far from over.
Even though I am only 15 miles from my home at Grand Canyon (direct line), the canyon itself is a huge obstacle to bypass and will require another 225 miles of driving before I reach the house.
AFTERMATH - LESSONS LEARNED
August 31, 1986, less than three months after the collision at Grand Canyon, Aeromexico Flight 498 with 67 on board collides with a Piper Archer over Cerritos, California. Lives are lost on both aircraft and on the ground.
The Cerritos and Grand Canyon mid-air collisions prompted the FAA to eventually require commercial operators install electronic collision avoidance equipment. (NTSB Photo)
NTSB HEARINGS - WASHINGTON D.C.
A series of hearings were conducted by the National Transportation Safety Board (NTSB) in the wake of the accident. Prior aircraft accidents were studied as well as the effects of aircraft noise within the national park.
The end result was the establishment of Special Federal Aviation Regulation 50 (SFAR 50) in March 1987 and the passage of the National Parks Overflights Act in August of that year.
Much like the famous 1956 mid-air collision at Grand Canyon, the 1986 collision also caused politicians in Washington D.C. to act quick.
In December 1986, the FAA proposed rules and guidelines regarding flights over Grand Canyon National Park. Taking into consideration safety and noise reduction, regulated air tour routes and altitudes were established.
Since 1987, both general aviation and commercial operators alike must follow specific routes, altitudes and procedures on this chart while flying over the Grand Canyon.
Today, all turbine powered air tour aircraft flying the Grand Canyon are equipped with the required Traffic Collision Alert System (TCAS).
The advent of TCAS technology, concise communication and a pilot's situational awareness of his/her surroundings are the only safeguards to prevent another tragic collision over the Grand Canyon.
(THE END)