Bridgeport, CA, USA
N6106H
Piper PA-28-161
The airplane collided with mountainous terrain while attempting to traverse the mountains at a density altitude approaching the climb capability limit of the airplane. The pilot reported that after departure he conducted circling climbs over the traffic pattern to gain altitude before heading west toward rising terrain to cross the Sierra Nevada Mountain range. He stated that he did not remember exactly what altitude he climbed to, but estimated that it was around 9,000 to 9,500 feet mean sea level (msl). The pilot flew the airplane between two mountain peaks, which were separated by a 1-mile trough. As the airplane was flying between the peaks, it encountered a downdraft that sent the airplane in a nose down pitch attitude. The pilot attempted to recover, but found the engine could not produce enough power to attain a positive climb rate. The pilot leveled off the airplane and attempted to turn it to the left, but heard the stall warning horn sound. The pilot then tried to turn the airplane to the right, but the stall warning horn sounded again. The pilot pulled the nose up before the airplane impacted the ground. The Federal Aviation Administration inspector, who performed a post-accident examination of the airplane, reported that there was nothing wrong with the airplane that would have prevented its normal operation. The approximate density altitude at the accident site was calculated to be 12,300 feet, which according to the airplane information manual, would only allow a 60-foot-per-minute climb rate.
On July 11, 2004, at 1415 Pacific daylight time, a Piper PA-28-161, N6106H, impacted mountainous terrain near Bridgeport, California. The private pilot, the sole occupant, was not injured. The airplane sustained substantial damage. The rental airplane was registered to a private individual and operated by Ocean Air Flight Services, Inc., Watsonville, California, under the provisions of 14 CFR Part 91. Visual meteorological conditions prevailed, and a visual flight rules flight plan had been filed for the cross-country flight. The personal flight departed Bridgeport approximately 15 minutes prior to the accident, and was destined for Columbia, California, where the airplane was to be refueled prior to continuing to Watsonville. During a telephone interview conducted by the National Transportation Safety Board investigator-in-charge, the pilot reported that in light of the rugged terrain and mountainous peaks reaching over 11,000 feet in the proximity of the airport, he discussed his departure route with local pilots prior to departure. During his arrival into Bridgeport, he experienced turbulence and suspected the return flight would be bumpy. The pilot departed Bridgeport and began circling climbs over the traffic pattern to gain altitude before heading west to Columbia. The pilot stated that he did not remember exactly what altitude he climbed to, but estimated it was around 9,000 to 9,500 feet mean sea level (msl). He flew the airplane almost due west instead of the 240-degree straight-line route to his destination. The pilot flew the airplane between two mountain peaks, which were separated by a 1-mile trough. As the airplane was flying between the peaks, it encountered a downdraft that sent the airplane in a nose down pitch attitude. The pilot attempted to recover, but found the engine would not produce enough power to attain a positive rate of climb. The pilot leveled off the airplane and attempted to turn it to the left, but heard the stall warning horn sound. He then tried to turn the airplane to the right, but the stall warning horn sounded again. The pilot pulled the nose up before the airplane impacted the ground. The airplane came to rest in an upright position with the left main landing gear and nose gear collapsed. The pilot shut everything off and exited the airplane. He later departed the area in an attempt to hike down toward the departure airport, which was approximately 8 to 10 miles to the east of the accident site. Review of photographs taken by forest service personnel revealed that the nose and left landing gear, firewall, and the left wing and flap sustained structural damage. The propeller blade tips curled forward. Forest service personnel noted what they thought were numerous propeller strike marks (gouges perpendicular to the airplane's direction of travel) along a 75-foot stretch of ground. Forest service personnel further reported that the elevation of the accident site was approximately 9,700 feet. A Federal Aviation Administration (FAA) safety inspector examined the airplane once it was recovered from the mountain. The FAA inspector did not note any anomalies with the airplane that would have prevented its normal operation prior to the accident. At 1352, the weather observation facility located at the Mammoth Yosemite Airport, Mammoth, California (located 42 nautical miles south-southeast of the accident site at an elevation of 7,128 feet msl), reported the wind as calm; visibility 10 statute miles, clear sky; temperature 27 degrees Celsius; dew point -05 degrees Celsius; and an altimeter setting of 30.25 inches of mercury. The remarks section of that weather observation reported the density altitude as 9,700 feet. The Bridgeport Bryant Airport elevation is 6,468 feet msl. The calculated density altitude at the accident site around the time of the accident equated to an approximate value of 12,300 feet. Review of the PA-28-161 Information Manual's Performance Section revealed that at a density altitude of 12,300 feet, the rate of climb (with a leaned mixture setting and 79 knots indicated airspeed) would have been 60 feet per minute. According to the pilot's written statement, the pilot accumulated a total of 130.6 hours of flight hours, of which 13.0 hours were accumulated in the accident airplane make and model. The pilot reported that he had obtained mountain flying training prior to the accident flight and "thought he was prepared." According to Mountain Flying LLC's website (www.mountainflying.com), pilots should approach mountain ridges at a 45-degree angle to provide the option of escaping toward lowering terrain if the pilot finds themselves in a position where they will be unable to clear the terrain. In the event a pilot finds himself/herself in a position that requires a course reversal away from rising terrain, it should be conducted at a point where sufficient airspeed can be maintained to perform the maneuver. If a pilot encounters an unexpected downdraft, he/she should have left themselves enough terrain clearance to turn away from the downdraft and fly out of the situation.
the pilot's failure to attain an adequate altitude to clear mountainous terrain during a high density altitude condition.
Source: NTSB Aviation Accident Database
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