NTSB Factual Report

HISTORY OF FLIGHT

On January 14, 1995, at 1136 Pacific standard time, a Cessna 182R, N9706E, was destroyed by ground impact in mountainous terrain while maneuvering near Wrightwood, California. The aircraft was owned and operated by the Civil Air Patrol (CAP) and was on a search and rescue (SAR) mission as a public use aircraft. Visual meteorological conditions were prevalent at the time and a composite VFR/IFR flight plan had been filed for the operation. The certificated commercial pilot, his observer, and scanner sustained fatal injuries. The flight originated from Cable Airport, Upland, California, at 1029 on the day of the accident.

The crew was conducting a search and rescue (SAR) as assigned by the California Wing of the CAP. CAP operations conducted a mission briefing for three SAR aircraft and made grid assignments in the search area. All three aircraft departed IFR, and after breaking out in VFR conditions, initiated searches in their assigned areas. At 1111, the pilot reported "ops normal" to CAP operations. Another CAP aircraft, which was conducting a grid search in an area adjacent to and west of the accident site, reported hearing an emergency locator transmitter (ELT) signal at 1136. The CAP reported that the minimum altitude for conducting searches is 500 feet agl.

PERSONNEL

The pilot was a CAP trained and qualified search and rescue pilot. He received his initial check flight on September 10, 1983. A review of his training records showed he had received satisfactory entries including "mountainous terrain procedures," such as "wind/updrafts/downdrafts" and "mountain wave effects" in his CAP training records. He attended a CAP "mountain clinic" on May 18-19, 1990. His last check flight was conducted on April 4, 1994, and he was rated as "mountainous terrain qualified."

All three occupants of the aircraft were certified pilots. On this mission pilot duties were limited to the PIC.

AIRCRAFT INFORMATION

The aircraft forms and records were reviewed by investigators with no discrepancies noted. The aircraft was equipped with fully functioning dual controls.

METEOROLOGICAL CONDITIONS

The pilot was given a verbal weather briefing by the CAP operations officer based on weather obtained through a direct user channel access terminal (DUAT). Localized weather conditions including downdrafts and turbulence in the vicinity of mountainous terrain were noted by witnesses flying near the accident location.

Two CAP aircraft were searching on grids adjacent to the east and west of the grid occupied by the accident aircraft.

The crew in the grid to the east reported weather in the search area as clear with unrestricted visibility. Cloud layers were visible about 40 miles to the west. Winds were said to be from the west with the top of Mt. San Antonio obscured by clouds. In that area, cloud bases were estimated as 7,500 to 8,000 feet with tops variable from 9,000 to 10,500. While flying a Cessna 206 on a search pattern on the north side of Mt. San Antonio they reported encountering significant downdrafts. During one west to east pass on the leeward side of a ridge, intense downdrafts were encountered and the pilot was forced to turn north and away from higher terrain. They noted that as the morning progressed clouds began moving into the area, hampering their search.

The second crew to the west of the accident site reported being VFR as they entered the search area. They also reported seeing clouds in the vicinity of Mt. San Antonio with bases between 6,000 and 7,000 feet. Conditions were described as smooth with no turbulence until their search path reached the northeastern portion of the grid. The crew noted that as the morning progressed weather in their "search area began to deteriorate."

A flight test engineer who was flying in the vicinity of the accident site and north of the predominant east/west ridgeline, reported light to moderate clear air turbulence and lenticular clouds building up between 1015 and 1100 on the day of the accident. He stated that he returned to the area later that day and then departed when he noted that the conditions had intensified.

COMMUNICATIONS

CAP mission planning included instructions to all crews to establish and maintain air-to-air communication between search aircraft upon their arrival in their assigned search areas. The aircraft was on an assigned transponder code of 0215 and was visible on radar until 1129.

WRECKAGE AND IMPACT INFORMATION

On January 15, 1995, the aircraft was found by aerial search personnel at the 7,700 foot level of the Angeles National Forest, at latitude 34 degrees 18.46 minutes and longitude 117 degrees 39.09 minutes, in an area covered by 80-foot pine trees. The site was near the crest of a ridge on terrain that sloped downward between 45 and 60 degrees. The ground was frozen and covered with about 1-foot of snow and ice. The final position of the aircraft was approximately 4 feet down slope from a visible ground scar. Tree limbs were found within 10 to 15 feet of the wreckage and exhibited evidence of fresh breaks. The terrain at the impact site was rocky and rescuers stated they believed they saw evidence on the ground of a fuel spill in the immediate vicinity of the aircraft.

The aircraft's final position was nose down with the main wings nearly perpendicular to the terrain. The nose was crushed rearward aft of the leading edge of the main wings. Both main wings exhibited extensive crushing along the leading edges extending from wing tip to wing tip. The was no discernable bending or twisting evident with either wing.

The fuselage was collapsed and was found in a near vertical position. The empennage had collapsed and rotated forward over the top of the main wings.

The flight control surfaces were in place; however, the associated control cables were either broken or loose. The instrument panel was destroyed and prevented the establishment of instrument readings and settings, as well as switch positions.

Rescue personnel reported that the No. 2 blade of the propeller had separated and was located several feet from the aircraft. The blade was not found again after the recovery process was completed. The No. 1 blade came out of the hub during the removal of the propeller from the crankshaft. The blade was bent aft and exhibited leading and trailing edge gouges and scaring.

The propeller governor had been partially separated in an aft direction. The governor base plate exhibited impact marks corresponding to individual oil pump gear teeth.

The oil sump was crushed upwards, as was the muffler. Both exhaust manifolds exhibited some crushing. The right intake manifold was fractured and the carburetor had been pulled off. The mounting bolts were found stripped. The carburetor was found with the throttle valve in the closed position and the mixture arm in the lean position. All four engine mounts were fractured. The oil filter, starter, alternator, vacuum pump, and both magnetos had separated and were missing. The rocker covers for No. 1, 2, and 5 were crushed and breached. The crankshaft was displaced rearward into the case and could not be rotated.

According to the Continental Motors representative, no preimpact discrepancies were noted during the inspection of the engine.

MEDICAL AND PATHOLOGICAL INFORMATION

Autopsies were performed by the Los Angeles County Coroner's Office. The results from the toxicological screening of samples submitted to the Civil Aeromedical Institute (CAMI) were negative.

ADDITIONAL INFORMATION

At 1136, a strong but intermittent ELT signal was received by search aircraft and alerted them to the possibility of a downed aircraft. After repeated attempts to contact the accident aircraft by radio failed, a search was initiated based on the ELT signal. According to CAP personnel, the initial lack of ability to DF the signal made it difficult to quickly locate the aircraft. A second aircraft with DF capability joined the search. Due to deteriorating weather delaying the search, the aircraft was not located until 0846 the next morning.

The wreckage of the aircraft was found in an area not accessible by ground recovery equipment. Continued adverse weather conditions, several feet of snow, and the inaccessibility of the area precluded an on-site examination of the aircraft. Recovery was deferred until more favorable environmental conditions resumed and a military aerial recovery unit could be scheduled for retrieval. The aircraft was recovered on July 24, 1995.

The aircraft wreckage was released on September 6, 1995, in writing to the Commander of the California Wing of the CAP.

NTSB Probable Cause

the pilot's loss of aircraft control and subsequent inadvertent stall/spin following an encounter with a localized mountain wave condition and turbulence while conducting a search mission in close proximity to mountainous terrain.