Skip Ribbon Commands
Skip to main content
Aviation Accident

Quick Launch

NTSB Identification: WPR15FA215
14 CFR Part 91: General Aviation
Accident occurred Saturday, July 11, 2015 in Twin Sisters Mtn, WA
Probable Cause Approval Date: 11/17/2016
Aircraft: PIPER PA 22-160, registration: N9712D
Injuries: 2 Fatal.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

The noninstrument-rated private pilot was making a cross-country flight over mountainous terrain. Radar data showed the airplane flying in a northwesterly direction and climbing to an altitude of about 10,500 ft mean sea level (msl). About 38 minutes into the flight, the airplane's altitude started to decrease as it continued in a northwesterly direction, and, 6 minutes later, its altitude was 7,500 ft msl. The last radar return occurred 1 minute later at an altitude of 6,000 ft msl. The wreckage was located at the 6,000-ft level of a mountain ridgeline in the vicinity of the final radar return. Photographs of the wreckage revealed that the damage to the airplane was consistent with controlled flight into the terrain. The wreckage was not recovered from the accident site, and no follow-up examination was accomplished.

Weather radar imagery indicated that rain showers moved into the area from the south-southeast as the airplane approached the accident site. These showers extended from about 19,000 ft msl down to ground level. Although no direct weather observations of the accident location were available, the airplane's descent as it approached the site is consistent with an attempt by the pilot to maintain visual meteorological conditions while operating amidst rain and clouds that likely obscured the terrain.


The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
  • The noninstrument-rated pilot's continued visual flight into instrument meteorological conditions, which resulted in controlled flight into mountainous terrain.