What happened
On the morning of June 18, 1986, two sightseeing aircraft collided at an altitude of 6,500 feet msl over the Tonto Plateau area. The first aircraft, a DHC-6 (Twin Otter) registered as N76GC, operated by Grand Canyon Airlines, had departed from Grand Canyon Airport's runway 21 for a scheduled tour. Shortly after this departure, a Helitech Bell 206B (Jet Ranger), registration NGTC, took off from a heliport in Tusayan, Arizona, to begin an on-demand flight.
The collision occurred during the flight phase of both aircraft while operating under visual meteorological conditions. The impact resulted in 25 fatalities, accounting for every passenger and crew member aboard both vessels. Specifically, the Twin Otter was carrying 18 passengers and 2 crew members, while the Bell 206B carried 4 passengers and 1 crew member.
Findings
Investigators were unable to reconstruct the specific flight paths of the two aircraft due to the absence of radar data, flight data recorders, and cockpit voice recorders. Consequently, it could not be determined why the pilots failed to perform the necessary see-and-avoid maneuvers to prevent the collision.
Significant regulatory and oversight issues were identified during the investigation. It was noted that the Federal Aviation Administration (FAA) lacked oversight regarding the specific routes and altitudes used by local scenic tour operators in the Grand Canyon area. Additionally, the National Park Service had been influencing flight paths as part of a noise conservation study; these adjustments caused rotary-wing routes to converge with fixed-wing paths at the accident site. Other identified safety concerns included a lack of regulations regarding pilot duty times and the absence of requirements for pilots to use intercom systems during narrated tours.