Embry-Riddle Aeronautical University

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A Sampling from the Archives:
S. Harry Robertson Papers

Helicopter Crash on the Salt River

Harry Robertson's career has included work in the fields of aviation safety, safety research, crash investigation, and crash investigation education, as well as in the design, development, testing, and production of crashworthy, ballistically tolerant fuel systems used by military aircraft worldwide.

The Robertson papers include accident investigation case files (including over 15,000 photographs); technical papers, reports, and reference material; a video library; and books and periodicals. The selected items on display come from one of the accident investigation case files.

The Accident:

Bell 206 helicopter after accident

On 21 December 1978, a Bell 206 Jet Ranger helicopter was on a powerline patrol for Arizona Public Service (APS) along the Salt River. A tower collapsed due to water action in the flooded river, and the helicopter was struck by a static cable.

As part of the investigation carried out by James Turnbow and Dan Clark, a plan of the accident site was created:

accident site

The investigation concluded that the helicopter "was placed in jeopardy by being positioned inside the general curvature of the Hi-line... and sufficiently close to a straight line between the towers immediately to the east and to the west of the potentially collapsing tower to allow the lines to fall over the aircraft."

In order to avoid a similar accident in the future, the investigation report suggested that if tower collapse is possible an inspection flight should approach

a) from outside of the hi-line curvature
b) from above, or
c) at sufficient distance on the inside of the cord line between adjacent towers to allow a safe clearance in event of a collapse

Alternatively, it was also suggested that the use of binoculars could avoid the need for a close approach.

Additional information on this, and other accident case files, is available in the archives.