S. Lake Tahoe, CA, USA
N8938C
Piper PA-28-140
The single engine airplane appeared to be returning to the airport shortly after takeoff when witnesses saw it descend into trees. The pilot radioed his intentions to perform a downwind departure from runway 18. Approximately 3 minutes later, the pilot made his final radio transmission, stating that he was turning left crosswind. Witnesses reported seeing the airplane in a right turn about 20 feet above the treetops, with a slightly nose low attitude. The airplane then rolled to a level attitude, heading in a northerly direction, and started to descend just prior to its collision with trees. Witnesses also reported hearing the engine at what they described as a high power setting initially, then it dropped to a lower sounding power setting just before the airplane contacted the trees. Postaccident inspection of the airframe and engine revealed no evidence of a mechanical failure or malfunction. The airport is located in a mountain valley with rising terrain immediately to the west, south, and east, and a lake to the north. The elevation is 6,264 feet. The winds were from the south at 16 knots gusting to 31. The density altitude was calculated to be 8,445 feet. Using the airplane's pilot operating handbook (POH) performance charts, the pilot could expect the airplane to be able to maintain a 220 foot per minute rate of climb at 89 miles per hour for this density altitude. The POH published stall speed for zero angle of bank and zero flaps is 55 miles per hour. Advisory Circular AC 00-57 states, "Aircraft that engage in low-level flight operations over mountainous terrain in the presence of strong winds (20 kt or greater at ridge level) can expect to encounter moderate or greater turbulence, strong up-and-downdrafts, and very strong rotor and shear zones." Information available at the airport states that downdrafts are often encountered near the runway abeam the terminal building and west of the golf course, which is along the crosswind and downwind routes for runway 18 departures. The pilot probably encountered turbulence and downdrafts, a reduced rate of climb, and rising terrain to his left shortly after takeoff. It is likely he elected to return to the airport for landing, but was unable to maintain altitude during the turn due to the turbulence/downdrafts, and collided with trees.
HISTORY OF FLIGHT On August 5, 2007, at 0945 Pacific daylight time, a Piper PA28-140, N8938C, collided with terrain shortly after takeoff while attempting to return to South Lake Tahoe Airport, South Lake Tahoe, California. The airplane was operated by the private pilot under the provisions of 14 CFR Part 91. The passenger was seriously injured, the pilot was killed, and the airplane was substantially damaged. Visual meteorological conditions prevailed, and no flight plan had been filed. (Unless otherwise noted, all times in this report are Pacific daylight time based on a 24-hours clock.) The Safety Board investigator reviewed radio transmissions from the accident airplane that were recorded by the South Lake Tahoe unicom radio equipment. At 09:41:50 the pilot announced his takeoff and intention to make a left down wind departure from runway 18. At 09:44:56 the pilot made his final radio transmission stating the he was turning left cross wind. A witness reported seeing the airplane in a right hand turn about 20 feet above the tree tops, with a slightly nose low attitude. The airplane then rolled to a level attitude heading in a northerly direction and started to sink with the wings rolling left and right just prior to its collision with trees. Other witnesses also reported hearing the engine at what they described as a high power setting initially, then the engine sound dropped to a lower sounding power setting just before the airplane contacted the trees. Witnesses also described very windy and gusty conditions in the vicinity. The passenger of the accident airplane could not recall any of the events relating to the accident. An employee on duty for the local FBO told the Safety Board investigator that the pilot did not request fuel services stating that he wanted to be lightly loaded for the departure. PERSONNEL INFORMATION A review of Federal Aviation Administration (FAA) airman records revealed that the pilot, age 36, held a private pilot certificate issued on October 27, 2000, with a single engine land rating. The pilot did not hold a current medical certificate. The pilot had applied for a third class medical certificate on June 6, 2007, where he related having being diagnosed with a kidney stone in March 2006. The attending Aviation Medical Examiner (AME) deferred issuance of a medical certificate pending further examination. The FAA Aerospace Medical Certification Division denied the pilots medical application, as stated in a letter dated September 7, 2007, based on incomplete information provided to the FAA in regards to the pilot's kidney stone diagnosis. The pilot reported total flight experience as 600 hours on his June 6, 2007, FAA medical certificate application. An examination of the pilot logbook indicated that he had accumulated 105.4 hours. His most recent flight prior to the accident, as recorded in his logbook, was a biennial flight review on October 20, 2006. The last three pilot logbook entries were for biennial flight reviews (BFR) on October 14, 2002, October 11, 2004, and October 10, 2006. The accident pilot's CFI stated that the pilot normally logged his flights in an aircraft flight-expense log kept on the airplane, that the total flight time in his personal logbook was probably inaccurate, and that the flight time he reported in his FAA medical certificate application was probably more accurate. AIRCRAFT INFORMATION The airplane was Piper PA-28-140, which is a single engine, 4 occupant, low-wing, fixed tricycle landing gear airplane, which had been purchased by the pilot on March 15, 2007. The airplane serial number was 28-7625136. The engine was a Lycoming O-320-E2A with a fixed pitch Sensenich propeller. A review of the airplane maintenance logbook revealed a total airframe time of 5,101 hours at the last annual inspection, dated October 10, 2006. The engine logbook documented the engine time since major overhaul (SMO) was 809.4 hours at the last annual inspection. Aircraft Performance Utilizing the Piper Cherokee Pilot Operating Handbook (POH) and the weight and balance documents that were located in the airplane, airplane weight and climb performance was calculated. The airplane weight at the time of the accident was estimated to be 1,965.18 pounds using the pilot's weight and bags at 210 lbs, passenger estimated weight and bags at 140 lbs, and a half load of fuel (25 gallons). The airplane's weight and balance was determined to be within allowable limits per the POH. The density altitude was calculated utilizing a density altitude chart provided in the POH, airport elevation of 6,260 feet, and outside air temperature (OAT) of 69 degrees F. The result was a density altitude of 8,445 feet. The best rate of climb was found to be 220 feet per minute utilizing the climb performance chart in the POH, which assumes a max gross weight of 2,150 lbs, zero flaps, full throttle, and airspeed at 89 MPH calibrated air speed (CAS). The Piper Cherokee 140 POH states, "The best rate of climb airspeed at gross weight is 89 miles per hour while best angle of climb is 78 miles per hour. At lighter than gross weight these speeds are reduced." The published stall table lists the stall speed at zero degrees angle of bank and zero flaps as 55 miles per hour. The published maximum sea level rate of climb is 620 feet per minute. METEOROLGICAL INFORMATION The South Lake Tahoe Airport Automated Surface Observation System (ASOS) weather reporting system recorded the weather conditions at 0953 as southerly winds at 16 knots gusting to 31, visibility 10 miles, temperature 69 degrees F, dew point 26 degrees F, relative humidity 19%, and the altimeter setting was 30.10 inHg. The airport manager stated that due to the location of the weather sensing equipment, the reported winds are usually less than what is experienced at other locations in the airport vicinity. AIRPORT INFORMATION The South Lake Tahoe airport is located in a valley basin. The Airport/Facility Directory establishes the airport elevation at 6,264 feet mean sea level (msl), and the runway is oriented in a north-south direction (runways 18 and 36). Mountainous terrain rises up from the basin floor on the western, southern, and eastern sides. Approximately 2.5 miles to the west is a 7,000 foot ridge line, 4.8 miles to the southwest is a 8,817 foot peak, 3.6 miles to the south is a 7,623 foot peak, 4.2 miles south east is a 8,978 foot peak, and 4.4 miles to the east is a 9,840 foot peak. WRECKAGE AND IMPACT INFORMATION The airplane wreckage was located about 50 yards west of Elks Club Drive, South Lake Tahoe, at an elevation of 6,316 feet msl. The immediate vicinity was level terrain populated with mature 100-foot tall pine trees. The initial point of contact with the trees was identified by the top missing from a pine tree 239 feet immediately south of the wreckage. Freshly severed pine tree trunk and branches were at the base of the tree. Along the same bearing line; 117 feet from the wreckage, was a pine tree that had been severed 43 feet above the ground, with freshly broken tree trunk at the base. The severed section of trunk exhibited a 2-foot long oval abrasion and a branch that had been sliced squarely in cross-section. A pine tree 60 feet from the wreckage exhibited a witness mark approximately 100 feet up and the right stabilator was identified at the tree base. The main wreckage was oriented on a bearing of 300 degrees magnetic laying on its right side. The engine was attached to the firewall; the propeller was not present on the engine. Black soot and charring was evident on the left side of the fuselage around the engine compartment and left side of the cockpit. The nose wheel was folded back into the firewall and left side cockpit floor. No evidence was found to suspect that the occupied space in the cockpit had been compromised. The throttle and mixture were in intermediate positions on the engine control quadrant. The engine exam revealed no evidence of mechanical failure or malfunction. Both wings had been cleanly separated at the wing root. The wing spar fracture locations were characterized by bright surfaces, granular in texture, and 45 degree fracture surfaces. The right wing was oriented parallel with the right side of the fuselage with the wingtip towards the front of the airplane. The wing had a leading edge indentation one-foot inboard of the wing tip. The right fuel tank had been breached. The left wing was hanging against the fuselage by control cables and the wing root was positioned up against the fuselage. The left fuel tank was approximately half full of fuel (25 gallon capacity fuel tanks). The tail was separated from the empennage, hung by the rudder and stabilator control cables. The left stabilator, vertical stabilizer, and rudder were present. Control continuity was established to all control surfaces. All control cables were intact except for the right aileron primary cable, which was separated near the wing root and exhibited signatures consistent with overload. All cables were attached to their appropriate bell cranks or cockpit control attachment fittings. The fuel selector was found detached from the fuselage. By passing pressurized air through the fuel selector valve it was determined that the fuel selector was set to the left tank position. The emergency locator transmitter (ELT) was identified as a Narco ELT-10. The ELT was found in the armed position. No report of an ELT beacon had been received by FAA or airport personnel. The Safety Board investigator tested the ELT and found it to be functional when switched to the "on" position and activated when subjected to a sudden g-load in the longitudinal axis. Additional information regarding the wreckage as examined on-scene is contained in the official docket of this accident investigation. MEDICAL AND PATHOLOGICAL INFORMATION The Washoe County Medical Examiner's Office, Reno, Nevada, completed the autopsy of the pilot. The autopsy findings listed "multiple blunt force injuries" as the cause of death. The FAA Forensic Toxicology Research Team performed toxicological analysis from samples obtained during the autopsy. The results of the analysis of the specimens were negative for carbon monoxide, cyanide, volatiles, and tested drugs. SURVIVAL ASPECTS There were no reports of an ELT signal immediately after the accident. The ELT was found armed and the connection to the external antenna was not compromised. The ELT was easily activated when tested by investigators. FIRE There was a post accident fire in the engine compartment, which was beginning to spread to the cockpit. Two of the first people on-scene had fire extinguishers and successfully extinguished the fire. Investigators did not locate a fire extinguisher in the airplane that the pilot or passenger could have used. ADDITIONAL INFORMATION Lake Tahoe Airport Pilot Information Sheet/Flyer An airport information sheet had been published by the airport manager that addresses noise abatement procedures, arrival and departure procedures, and a caution for departing runway 18. Copies were available at the pilot briefing area in the airport terminal. The departing instructions for runway 18 state, "NO LEFT TURN OUT under 7,500 MSL - the smaller hill straight ahead has an elevation of 6,640' MSL, PLUS up to 100' trees around the houses. Track the river to the golf course. Circle and climb to 7,500 MSL over the golf course. If not able to climb to 7,500' consider returning to the airport. Advise traffic over UNICOM 122.95." The caution for runway 18 departures states, "CAUTION: Downdrafts are often encountered near the runway abeam the terminal building and West of the golf course near the mountains." Aviation Weather and Mountain Flying Advisory Circular AC 00-6A states the following about high winds in mountainous terrain: "Flying mountain passes and valleys is not a safe procedure during high winds. The mountains funnel the wind into passes and valleys thus increasing wind speed and intensifying turbulence. If winds at mountain top level are strong, go high, or go around. Surface wind may be relatively calm in a valley surrounded by mountains when wind aloft is strong. If taking off in the valley, climb above mountain top level before leaving the valley. Maintain lateral clearance from the mountains sufficient to allow recovery if caught in a downdraft." Advisory Circular AC 00-57 states the following about Hazardous Mountain Winds and Their Visual Indicators: "3.3 Low-level Mountain Flying. Aircraft that engage in low-level flight operations over mountainous terrain in the presence of strong winds (20 kt or greater at ridge level) can expect to encounter moderate or greater turbulence, strong up- and downdrafts, and very strong rotor and shear zones. This is particularly true for general aviation aircraft." Additionally, "….downdrafts over forested areas may be strong enough to force aircraft down into the trees, even when the aircraft is flown at the best rate-of-climb speed. This effect on the aircraft is exacerbated by loss of aircraft performance because of the high-density altitude."
The pilot's inadequate preflight planning/decision, and his failure to maintain clearance from trees during takeoff-initial climb. Contributing to the accident were turbulence, downdrafts, and rising terrain.
Source: NTSB Aviation Accident Database
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