Incident
On an unspecified date, Flight 114 was conducting a VOR/DME-3 approach near Las Vegas. Weather conditions at the time included an indefinite ceiling of 500 feet, sky obscured, visibility of 900 meters, and light snow. During the approach, the aircraft descended below the prescribed altitude minima. At a point 9.7 DME from the VOR, at an elevation of 3,575 feet mean sea level (MSL), the airplane struck rising terrain and was destroyed.
Approach Procedure
The VOR/DME-3 approach procedure had become effective on October 3, 1964, but no approaches using this procedure had been flown until November 15. The approach chart depicted a segment from the 15-mile fix to the 6-mile fix with no descent information on the profile section. However, the profile section showed a solid horizontal line between the 6-mile fix and the 3-mile fix, annotated with an altitude of 3,100 feet MSL. The chart legend defined this solid line as “Flight Path,” which implied that a descent to 3,100 feet was proper once the fix to which the flight had been cleared was reached.
Investigation
The investigation determined that the captain misinterpreted the approach chart. At the point of impact, the aircraft should have been at an altitude of 4,300 feet MSL, but it was at 3,575 feet MSL. The premature descent below the obstructing terrain was a direct result of this misinterpretation.