NTSB Factual Report

HISTORY OF FLIGHT

On August 24, 2013, about 1630 Pacific daylight time, a Piper PA-28-140 airplane, N32582, was substantially damaged when it impacted terrain shortly after takeoff from Mountain Valley airport (L94), Tehachapi, California. The pilot/owner and one passenger received minor injuries, and one passenger received serious injuries. The personal flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no Federal Aviation Administration (FAA) flight plan was filed for the flight.

The owner/pilot based the airplane at Fullerton Municipal airport (FUL) Fullerton, California, which was situated on flat terrain, at an elevation of about 100 feet above mean sea level (msl). Both passengers were also pilots, and the three planned to fly from FUL to L94, where they would participate in sailplane soaring activities for the day, and then return to FUL in the late afternoon. The flight to L94 and the day's soaring activities were uneventful. The owner/pilot occupied the left seat and functioned as the pilot-in-command (PIC) for the flight to L94, and for the return trip to FUL as well.

For the return trip to FUL, the PIC conducted the preflight inspection, which was uneventful, as were engine start, taxi-out to runway 27L, and the engine run-up. The PIC reported that, due to the airport's high field elevation, he leaned the mixture for the takeoff, and that the takeoff roll and initial climb were uneventful. Per the established L94 procedures, the PIC turned a left (southbound) crosswind leg to remain clear of sailplane traffic. As the airplane turned onto the crosswind leg, it appeared to cease climbing, and reportedly began sinking. The PIC ensured that the throttle was full forward and that the mixture was properly set. The PIC did not perceive or observe any engine abnormalities, but he was unable to simultaneously maintain adequate airspeed and prevent the airplane from sinking.

The airplane impacted terrain nose gear first, about 1/2 mile southwest of the departure end of 27L. It struck a chain link fence and came to rest about 170 feet from the initial ground impact point. The ground scar was aligned on a magnetic heading of approximately 210 degrees. The nose gear separated, and the left wing sustained substantial damage, but the cabin was intact.

PERSONNEL INFORMATION

Owner/Pilot (PIC)

The pilot/owner (PIC) held a private pilot certificate with an airplane single engine land rating. He reported that he had a total flight experience of approximately 500 hours, including about 250 hours in the accident airplane make and model. His most recent FAA third-class medical certificate was issued in November 2009, and his most recent flight review was accomplished in March 2013. The PIC reported that he had never operated into or out of L94 prior to this flight, and that he had only flown into or out of a high elevation or high density-altitude airport one time. That airport was Big Bear City (L35), Big Bear, California, which was situated at an approximate elevation of 6,700 feet msl.

The PIC did not use the available shoulder harness for the departure from L94. When questioned by the NTSB why he decided not to use his shoulder harness, the PIC responded that he did not expect the flight to be involved in an accident.

Right Front Seat Passenger

According to the PIC, the right seat passenger held a flight instructor certificate, but his only role in the flights to and from L94 was as a passenger. According to a witness at L94, the right seat passenger was the only one of the three who performed as PIC in the sailplanes on the day of the accident.

The right front seat passenger did not use the available shoulder harness for the departure from L94. That passenger sustained facial fractures, and had several vertebrae fused as a result of the accident.

Rear Seat Passenger

This passenger was seated in the right rear seat for both legs of the trip. He held a private pilot certificate with an airplane single-engine land rating. He reported that he had a total flight experience of about 425 hours, and that he had flown with the accident PIC about 15 hours total. He reported that he did not have any experience operating out of high elevation or high density-altitude airports. He made the acquaintance of the accident PIC via the front seat passenger.

AIRCRAFT INFORMATION

FAA information indicated that the airplane was manufactured in 1974, and was equipped with a Lycoming O-320 series engine. Maintenance records indicated that the airplane had a total time in service of approximately 3,870 hours. The records indicated that the engine was overhauled in January 1996, when the tachometer registered 2,600 hours, and that the most recent annual inspection was completed in May 2013.

METEOROLOGICAL INFORMATION

The 1635 automated weather observation at Tehachapi Airport (TSP), Tehachapi, California, located about 2 miles northwest of L94, included winds from 310 degrees at 14 knots, visibility 10 miles, clear skies, temperature 28 degrees C, dew point 4 degrees C, and an altimeter setting of 29.95 inches of mercury.

The PIC and pilot-rated rear seat passenger both reported that they estimated the surface wind at L94 to be approximately aligned with the runway, at a speed of about 15 knots.

Calculations based on recorded meteorological information indicated that the density altitude for L94 about the time of the accident was approximately 6,700 feet.

AIRPORT INFORMATION

L94 functioned primarily as a sailplane port. It was situated at an elevation of 4,220 feet msl, near the southeast perimeter of a geographic bowl a few miles in diameter. The airport was not equipped with an operating air traffic control tower, but a dedicated common traffic advisory frequency (CTAF) was designated for and used by the pilots operating at the airport. Separation of sailplane and powered aircraft traffic was accomplished primarily by having them use separate runways, with opposite direction traffic patterns. On the day of the accident, powered aircraft utilized 27L and left-hand traffic, while sailplanes utilized 27R and right hand traffic.

The location of the airport resulted in aircraft departing from runway 27L and following the left-hand traffic pattern to fly towards and over nearby rising terrain, while straight out or right-hand traffic patterns from runway 27L would result in aircraft overflying, for several miles, terrain that was approximately the same elevation as the airport.

FLIGHT RECORDERS

A Go-Pro camera and a handheld GPS were recovered from the airplane, and sent to the NTSB Recorders Laboratory for data download. Neither device contained any data from the accident flight, and both were returned to their respective owners.

WRECKAGE AND IMPACT INFORMATION

The airplane impacted flat, slightly inclined, dry grass and compacted earth open area. The impact site was about 2,200 feet beyond the departure end of 27L, and offset about 1,770 feet southwest of the extended runway centerline. The elevation of the impact site was about 4,380 feet msl, which was about 160 feet higher than the runway.

A ground scar extended for about 110 feet, on a magnetic heading of 210 degrees, before it intersected an east-west chain link fence. The fence partially failed, and served as an arresting system for the airplane. The airplane came to rest partly ensnared by the fence, about 60 feet beyond the fence line. The airplane was upright, but was pitched about 15 degrees nose down, due to the separation of the nose landing gear.

On-scene examination of the airplane, engine, and propeller did not reveal any pre-impact mechanical anomalies or deficiencies that would have prevented continued operation and flight.

The airspeed indicator arcs were in compliance with the manufacturer's published values. There were no indications that the airspeed indication system was inaccurate, but the accuracy of the airspeed indicating system was not verified subsequent to the accident.

ADDITIONAL INFORMATION

Takeoff and Climb Performance Information

According to the PIC, before the trip, he conducted weight and balance calculations, but he did not conduct any evaluation of the takeoff or climb performance from FUL. Prior to departure from L94, he obtained weather information via his smartphone, but he did not calculate the density altitude, nor did he conduct any takeoff or climb performance evaluations for that departure.

In an interview with the investigator, the PIC explained that his rationale for not conducting a takeoff and climb performance analysis for the L94 departure was that he had previously flown the airplane from an airport with a significantly higher field elevation than L94. In that same interview, the PIC appeared to be unaware of the concept of density altitude, and in particular, the effect of ambient temperature on density altitude and airplane performance.

The circumstances of the accident, combined with the lack of any observed pre-accident mechanical deficiencies, prompted a review of the manufacturer's takeoff performance data in order to determine the airplane capabilities. Based on PIC interviews and physical evidence, the actual takeoff configuration (0 degrees flaps, air conditioning off) was in accordance with the manufacturer's published guidance.

According to the manufacturer, the best angle of climb speed was 78 mph, and the best rate of climb speed was 89 mph. The investigation did not determine the accuracy of the airspeed indicating system, or the operating speed(s) used by the PIC.

Based upon the combination of PIC-provided information, physical evidence, and airplane weight and balance records, the airplane was determined to be within its allowable weight and balance envelope for the departure from L94. The estimated gross weight for the takeoff was 2,117 lbs, which was 34 lbs below the maximum allowable value.

The manufacturer's takeoff and climb performance charts only considered density altitude and airplane weight; they did not account for wind, humidity, runway slope, runway surface, or any other variables affecting performance. According to the charts and the calculated airplane weight, the predicted takeoff ground roll was about 1,500 feet, and the distance to 50 feet above ground was about 3,300 feet. The predicted rate of climb, using the manufacturer's best rate of climb speed of 89 mph, was about 310 feet per minute (fpm).

A climb rate of 310 fpm at an airspeed of 89 mph yields a zero-wind climb angle of about 2.2 degrees, which is approximately 1 foot of altitude gain for every 25 feet of horizontal travel, or a slope (gradient) of about 4 percent. Idealized, zero-wind calculations that did not account for any altitude loss in a 90 degree left turn (from upwind to crosswind) indicated that the airplane would have achieved a net altitude gain of 275 feet, which would place the airplane at 115 feet agl at the impact location. Those calculations did not account for any variations in airplane, engine, propeller, or pilot performance, and did not account for any vertical air motions such as thermals or up- and down-drafts.

Factors Affecting Performance

Airframe, engine, and propeller performance can be adversely affected by the components' overall condition, which is influenced by factors such as wear, improper adjustment, damage, and cleanliness. Although no obvious deficiencies associated with those factors were observed, the investigation did not accomplish a detailed determination of those factors, or their effect on airplane performance.

In addition, improper adjustment or operation by the PIC, including variables such as engine mixture and airspeed control, can adversely affect airplane performance. No data was available to enable the investigation to positively determine whether the mixture was properly set, or what airspeed profile was flown by the PIC.

Terrain Elevation Information

As noted, L94 was situated near the perimeter of the southeast quadrant of a geographic bowl. Review of terrain elevation data below the runway 27L left-hand traffic pattern revealed uphill terrain slopes of at least 10 percent, and significantly higher slopes just southwest of that traffic pattern. In contrast, terrain beneath either a departure path straight out from runway 27L, or a right-hand traffic pattern, remained at approximately the airport elevation for several miles.

NTSB Probable Cause

The pilot's failure to conduct predeparture airplane performance planning for a departure from a high density altitude location, which resulted in his selection of a flightpath toward rising terrain that the airplane was not capable of outclimbing.