Jacumba, CA, USA
N684SD
ALLSTAR PZL GLIDER SZD-54-2 PERKOZ
The pilot and passenger took off in the dual control-equipped glider, which used a ground-based winch launch system. Witnesses reported that the ground roll, rotation, and initial climb were uneventful with the glider maintaining a high, nose-up pitch attitude, consistent with the first phase of a winch launch. The pilot made an appropriate airspeed call to the winch operator by radio, and, a few seconds later, while the glider was about 150 to 300 ft above ground level (agl), which was well short of the typical release altitude of between 1,000 and 1,500 ft agl, the glider released from the towline. The glider maintained the same pitch angle and then banked right with an accompanying full-right rudder deflection. The glider's nose then dropped, and the glider began a right spin toward the ground and then impacted terrain in a nose-down attitude. Postimpact examination did not reveal any anomalies with the airframe that would have precluded normal operation. The towline weak-link was intact, and the towline was continuous to the winch. The glider's line release mechanism, which could be controlled by both occupants, was functional. Given the lack of mechanical malfunction, it is likely that one of the occupants initiated the release of the glider. The pilot, who was located in the aft seat, flew gliders regularly and was well acquainted with the airport environment, winch procedures, and accident glider operation. The passenger held an airline transport pilot license; he did not have experience flying gliders and was a passenger in the same glider earlier that day for an introductory flight. Although the pilot's autopsy determined that he had a mildly enlarged, dilated heart and the passenger's autopsy determined that he had coronary artery disease that had been treated with a stent, neither occupant's autopsy revealed any conclusive evidence to support impairment around the time of the accident. However, toxicological analysis revealed that the vitreous urea nitrogen levels for both occupants were twice the normal levels and that their creatinine levels were normal; such results can occur in the presence of dehydration. It is possible that the high temperature (112 degrees F) that day resulted in both occupants experiencing the effects of heat stress and dehydration. Further, individuals with cardiovascular disease and dehydration may be prone to decreased cardiac output, which results in dizziness and/or degraded cognitive function. Enough runway and overrun area remained to provide the pilot ample opportunity to perform an uneventful landing straight ahead even at the low altitude at which the glider was released. In fact, the glider club operating procedures called for a landing straight ahead following a glider release below 400 ft. The premature release and subsequent right banking turn at low altitude indicate that an unusual event likely occurred within the cabin; however, insufficient evidence existed to reach a definitive conclusion as to what occurred, including to what extent either occupant was impaired due to dehydration.
HISTORY OF FLIGHT On June 29, 2013, at 1229 Pacific daylight time, an Allstar PZL Glider, SZD-54-2 Perkoz, N684SD, collided with the ground during the initial climb of a winch launch at Jacumba Airport, Jacumba, California. The glider was registered to, and operated by, Associated Glider Clubs of Southern California, under the provisions of 14 Code of Federal Regulations Part 91. The private pilot and airline transport pilot rated passenger sustained fatal injuries; the glider was substantially damaged. The local flight departed Jacumba, at 1228. Visual meteorological conditions prevailed, and no flight plan had been filed. The Vice President of the glider club reported that he flew the glider earlier in the day with the same passenger who was on board for the accident. The passenger had expressed interest in joining the club, and it was an introductory flight. For that flight, they utilized the winch for the launch, and the takeoff and flight were uneventful, with the glider performing normally. For the accident flight the pilot (who was the Club President) offered to take the passenger up for a second flight. This was to be the pilot's first flight of the day, and by now the wind velocity had dropped and minimal lift conditions were present. He indicated that they would therefore perform a flight within the immediate vicinity of the airport. The passenger sat in the front seat, and the glider was towed back to the launch position at the east end of runway 25, and connected to the towline. Witnesses observed the launch sequence, reporting that the ground roll, rotation, and initial climb were uneventful with the glider maintaining a high nose-up attitude consistent with the first phase of a winch launch. The pilot made an airspeed call of "55" to the winch operator by radio. Immediately after the radio call, and at an altitude of between 150-300 feet, the towline drogue parachute inflated indicating either a line release at the glider, or a break of the weak-link. The glider's pitch angle remained the same and the glider then banked to the right, with an accompanying full right rudder deflection. The nose then dropped and the glider began an erect right spin, colliding with the ground in a nose-down attitude after about 270 degrees of rotation. Following the accident the towline was examined. It remained continuous to the winch, and the Tost ring, weak-link, and parachute were intact and undamaged. PERSONNEL INFORMATION Pilot The 54-year-old pilot held a private pilot certificate with ratings for gliders issued in March 2002. No personal flight records were recovered; however, according to the club vice president, the pilot had undergone a flight review on September 22, 2012. He flew regularly, and was current in the accident glider. He did not hold an FAA medical certificate, nor was he required to per Federal Aviation Regulations. Pilot Rated Passenger The 63-year-old pilot-rated-passenger held an airline transport pilot certificate with ratings for airplane multiengine land, and private privileges for airplane single engine land. He applied for the airline transport pilot certificate in August 2007, at which time he reported 4,499 total hours of flight experience. He reported prior military flight experience as an A-6E pilot for the US Navy, and on his most recent application for an FAA medical certificate he reported 1,100 hours of civilian flight time. He was issued an FAA first-class medical certificate on January 25, 2013, with the limitation that he wear corrective lenses for near and distant vision. GLIDER INFORMATION SZD-54-2 Perkoz was a two-seat glider with a structure combined of glass and carbon epoxy laminate. The cabin was configured in a tandem arrangement, with dual flight controls (including tow release). The glider was manufactured in Poland in 2010, and was imported into the United States where it was registered by the operator under the experimental classification - exhibition category, in April 2011. According to maintenance logbooks, it had undergone a condition inspection, which was completed on June 7, 2013. At that time, it had accumulated a total flight time of 133.85 hours, over the course of 203 flights. The glider was approved for winch-launch utilizing the belly hook only, with a recommended winch-launch airspeed of 53 to 59 knots. METEOROLOGICAL INFORMATION The closest weather reporting station was located in Campo, California, about 17 miles west of the accident location, and at an elevation of about 2,600 feet. At 1252, the station reported wind from 260 at 10 knots, gusting to 19; temperature of 102 degrees F, dew point 43 degrees F; and an altimeter setting at 29.89 inches of mercury. The resultant density altitude was about 6,000 feet. The medical examiner investigator who responded to the accident site reported that the temperature was 112 degrees F upon his arrival at 1450. AIRPORT INFORMATION Jacumba Airport was comprised of a single gravel runway, 2,508 feet long, by 100 feet wide and oriented on a 07/25 heading. The airport was situated at an elevation of 2,844 feet mean sea level. A gravel overrun of about 1,000 feet in length extended beyond the departure end of runway 25, and the terrain within the immediate vicinity of the airport was composed of flat fields and brush. WRECKAGE AND IMPACT INFORMATION The glider came to rest on a westerly heading on the north runway apron about 1,200 feet beyond the initial launch position, and 1,500 feet short of the winch. Both occupants were situated within the confines of the cabin, which was fragmented through to the wing leading edges. Both wings remained attached to the fuselage, with the left wing snapped and bending down at the root of the aileron, about 2-feet outboard of the aerodynamic brake. The empennage had detached from the tailcone, which remained partially attached to the aft cabin bulkhead. MEDICAL AND PATHOLOGICAL INFORMATION A postmortem examination was conducted on both occupants by the San Diego County Medical Examiner's Office. The cause of death in both cases was reported as the effect of multiple blunt force injuries. The FAA Civil Aerospace Medical Institute (CAMI) performed toxicological tests on specimens recovered by the pathologist. Pilot According to the autopsy report, the pilot exhibited mild cardiomegaly (heart weight of 470 grams) with biventricular dilatation. No other natural disease was identified. CAMI toxicology results indicated acetaminophen in the urine (120 (ug/ml, ug/g). Acetaminophen is an over-the-counter pain and fever control medication. The pilot's autopsy vitreous chemistry panel reported: Glucose 5 mg/dL (Normal < 200) Chloride 118 mmol/L (Normal 105-135) Creatinine 0.6 mg/dL (Normal 0.6-1.3) Potassium 15.7 mmol/L (Normal < 15) Sodium 134 mmol/L (Normal 135-150) VUN (vitreous urea nitrogen) 42 mg/dL (Normal 8-20) Pilot Rated Passenger According to the autopsy report, the passenger had coronary artery atherosclerosis with a stent installed at the mid left circumflex coronary artery. The pathologist did not detect changes in the heart muscle consistent with new or old ischemia (heart attack). FAA medical records indicated that he had a history of chest pain due to ischemia, which was treated by the stent in 2003. His medications included Ramipril, a prescription blood pressure control medication, aspirin, and ezetimibe/simvastatin a combination of two prescription cholesterol control medications marketed as Vytorin. He had passed his most recent follow up nuclear stress test on December 10, 2012. CAMI toxicology results indicated famotidine in the liver. Famotidine is an over-the-counter acid reducing medication. The pilot's autopsy vitreous chemistry panel reported: Glucose 6 mg/dL (Normal < 200) Chloride 118 mmol/L (Normal 105-135) Creatinine 0.9 mg/dL (Normal 0.6-1.3) Potassium 22.7 mmol/L (Normal < 15) Sodium 128 mmol/L (Normal 135-150) VUN 32 mg/dL (Normal 8-20) According to the NTSB Medical Officer, elevated VUN with normal creatinine can occur in the presence of dehydration. Individuals with cardiovascular disease and dehydration may be prone to decreased cardiac output resulting in dizziness and or degraded cognitive function. TESTS AND RESEARCH The glider was recovered from the accident site and examined by the NTSB investigator-in-charge. A complete examination report is contained within the public docket. Cabin The fragmented forward cabin included the remnants of the flight controls, cabin skins, seats, and the canopy. The rudder, elevator, and aileron control assemblies within the cabin sustained significant crush and fragmentation damage; inspection revealed the damage was consistent with impact forces. Impact damage prevented an accurate assessment of the trim positions, and no cabin balancing masses were located. Wings The right wing outboard leading edge sustained crush damage in an aft direction. The outboard portion of the left wing exhibited similar crush damage, as well as a tear in the upper skin along the spar. The spar rigging points on both the wings and fuselage were intact. Rotation of the aileron trunnion at both wing roots resulted in smooth movement of the aileron pushrods at each of the aileron roots. The outboard pushrods were continuous to their associated bellcranks, which remained attached to the wing spars. Both ailerons remained attached at their hinges. Both aerodynamic brakes were in the partially extended position at the accident site, but had retracted during the wreckage recovery. Both extended and retracted smoothly when the wing root brake trunnion was rotated. The lack of damage observed to the brakes was consistent with them being in the retracted position at impact, with impact forces causing them to partially extend. Empennage The empennage remained largely intact, with both the elevator and rudder pushrods sustaining bending damage, separating them at the tail break. The rudder remained attached to the vertical stabilizer at its hinge points and moved freely. Movement of the rudder resulted in smooth longitudinal movement of its associated pushrod at the tail break. The elevator remained attached to the horizontal stabilizer, and sustained minimal damage. Both elevator balance weights had separated from the tips, and movement of the elevator resulted in smooth uninhibited movement of the elevator control horn/fork. The associated elevator control lifter remained attached to its bellcrank in the tailcone, with its pushrod intact to through to the tail break. Tow Hook System The tow hook release system had separated completely from its respective airframe mounting points, but remained interconnected and functional. The forward and aft yellow release control handles were continuous to the nose and belly release mechanisms. Both release handles were pulled, and the nose and belly hooks opened and closed appropriately. Winch The glider winch was manufactured by Roman's Design, and was a single-drum type powered by a 325-horsepower diesel engine. The winch line was a 3,800 feet long "synthetic" fiber rope, attached to the glider with a weak link, release parachute, and Tost ring. The glider's maximum winch takeoff speed in the accident configuration was 59 knots. ADDITIONAL INFORMATION The FAA Glider Flying Handbook (FAA-H-8083-13) states the following with regard to normal, into-the-wind ground launch, "As the launch progresses, the pilot should ease the nose up gradually...while monitoring the airspeed to ensure that it is adequate for launch but does not exceed the maximum permitted ground launch tow airspeed. When optimum pitch attitude for climb is attained, the glider should be approximately 200 ft AGL. The pilot must monitor the airspeed during this phase of the climb-out to ensure the airspeed is adequate to provide a safe margin above stall speed but below the maximum ground launch airspeed. If the towline breaks, or if the launching mechanism loses power at or above this altitude, the pilot has sufficient altitude to release the towline and lower the nose from the climb attitude to the approach attitude that provides an appropriate airspeed for landing straight ahead." According to pilots familiar with the Jacumba Airport winch procedures, the towline is generally released by the pilot once the glider has reached an altitude of between 1,000 and 1,500 feet agl. The club's standard procedure should the line fail below 400 feet, is to land straight ahead. Weight and Balance According to the coroner, the passenger located in the front seat weighed 189 pounds, and the pilot in the rear seat weighed 235 pounds. No luggage was on board, therefore according to the glider's flight manual, with a basic empty weight of 829.37 pounds, it was loaded within 36.33 pounds of its maximum gross weight of 1,289.7 pounds (when operated in the utility category). In this configuration, the glider was not required to be carrying balancing masses, and none were installed.
The premature release of the towline from the glider and the glider’s subsequent right banking turn at low altitude for reasons that could not be determined because postaccident airframe examination did not reveal any evidence of a mechanical malfunction or failure that would have precluded normal operation.
Source: NTSB Aviation Accident Database
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