CEN12FA378

The pilot’s failure to maintain adequate airspeed during an emergency situation, which resulted in an aerodynamic stall and subsequent impact with terrain. Contributing to the accident was the pilot’s acute coronary event, which resulted from his severe coronary artery disease, prior physical exertion, and the stress of the emergency situation.

A witness reported that, before launch, the pilot installed the tail dolly on the glider, and the ground crew then assisted him pull the glider near the normal launch position about midfield. Another witness reported that the pilot then assisted the passenger and the lapchild into the front seat of the glider and ensured that the restraints were properly latched and snug. The pilot then got in the rear seat, and he secured his own lap belt and shoulder straps. Several witnesses noticed that, after takeoff, the tail dolly was still attached to the glider, and the glider operations dispatcher made a radio call to "abort...abort...abort." The takeoff continued, and several witnesses observed both the tow plane and the glider lift off normally. When the tow plane was about 50 feet above ground level (agl), the glider suddenly pitched nose up about 45 degrees, and the tow plane disconnected from the glider and turned left. The glider subsequently turned right and continued to climb steeply until it was about 150 to 200 feet agl. The glider then began what appeared to be a controlled left turn with the nose level. While the glider was turning, witnesses saw it suddenly pitch nose down and descend. Wreckage evidence showed that the glider impacted terrain at a 30- to 45-degree nose-down angle. The glider's rapid, near-vertical descent is consistent with the pilot's loss of control of the glider because of an aerodynamic stall. An on-scene examination of the wreckage revealed no evidence of preimpact mechanical malfunctions or failures that would have precluded normal operation. Two other pilots reported that they had previously inadvertently made takeoffs in the same model glider with the tail dolly still attached. Both of them reported that the flight characteristics did not change in that condition. A postaccident weight and balance calculation showed that the glider's weight and balance were still within the allowable range with the addition of the tail dolly. At the time of the accident, the pilot had cardiac hypertrophy and severe coronary artery disease. His physician had examined him 3 days before the accident and had ordered several tests. It is likely that, if the pilot had undergone a stress test, he would have failed it, and further evaluation would likely have led to a coronary artery bypass graft operation in the following few days. The pilot's wife reported that the pilot had spent the day of the accident engaging in strenuous activity, including teaching students and moving the glider around. Given the extent of coronary artery disease found on the pilot's autopsy, it is likely that the pilot's sudden awareness of the emergency situation (takeoff with the tail dolly attached) and physical exertion before the flight led to an acute coronary event and that this event contributed to his loss of control.

The Airport/ Facility Directory, Southwest U. S., indicated that runway 18/36 at the TE71 airport was 4,000 feet long and 125 feet wide. The runway surface was composed of turf. Gliderport communications are available on a frequency of 123.5 MHz. An autopsy was performed on the pilot by the Galveston County Medical Examiner's Office, Texas City, Texas. Forensic toxicology was performed on specimens from the pilot by the FAA, Aeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma. The toxicology report was negative for ethanol and was negative for drugs. The Chief Medical Officer for the National Transportation Safety Board reviewed the pilot's FAA blue ribbon medical file, the FAA medical review, the autopsy findings, the toxicology results, the NTSB database for information regarding a previous glider accident, and the investigator's report. According to the FAA blue ribbon medical file, the pilot initially received a third class medical certification in 1965. He reapplied and was granted a third class medical certificate in 1983 and biannually thereafter. When the pilot applied for medical certification in 1989, he reported 81 total hours of flight time and a new diagnosis of diabetes. He also reported having a glider accident in August, 1989 in which he suffered a T12 compression fracture. A review of the NTSB accident database regarding that accident revealed that the pilot's glider experienced an inflight breakup due to severe turbulence and the pilot parachuted to safety from 6,500 feet. As a result of his diagnosis of diabetes, in 1990 the pilot was awarded a special issuance third class medical certificate, limited to one year. The pilot did not apply for medical certification after 1990. Glider pilots do not require medical certification by the FAA. According to the autopsy, in addition to the finding of the cause of death, it also identified significant natural disease in the heart. It weighed 450 grams (normal for a man of his height is 340, plus or minus 40 grams). In addition, the left main coronary artery and left anterior descending artery were markedly calcified and had areas with more than 90 percent stenosis from atherosclerotic plaque. The right coronary artery had mild calcification and areas of about 90 percent stenosis. No obvious acute occlusions and no other significant natural disease were identified. Personal medical records indicated that at the time of the accident, the pilot was being treated with a number of medications for diabetes, hypertension, high cholesterol, and osteoporosis. He visited his primary physician on June 14, 2012, three days before his fatal accident, complaining about intermittent episodes of "tiredness" in both arms without an obvious cause. His physician considered a number of possible causes, including coronary artery disease, and requested a number of blood tests as well as a stress test. The stress test had not yet been performed when the glider crashed. The pilot's chronic conditions were considered to be moderately well controlled: his blood pressure was measured at 130/80 (below 140/90 is desired) and lab tests revealed a hemoglobin A1C of 7.9 percent. (Hemoglobin A1C is a test of 2 glucose control in the preceding 5 to 6 weeks; normal is below 6.4 percent, up to 7.0 percent is considered good control and over 9.0 percent is considered poor control.) According to the FAA-H-8083-13A, Glider Flying Handbook: (page 8-11) If an inadvertent release, towline break, or a signal to release from the tow plane occurs at a point at which the glider has insufficient runway directly ahead and has insufficient altitude (200 feet above ground level AGL) to make a safe turn, the best course of action is to land the glider ahead ... If the inadvertent release, towline break, or signal to release from the tow plane occurs after the towplane and glider are airborne, and the glider possesses sufficient altitude to make a course reversal … a minimum altitude of 200 feet above ground level is required to complete this maneuver safely. Such factors as a hot day, weak tow plane, strong wind, or other traffic may require a greater altitude to make a return to the airport a viable option. According to test result notations in the manufacturer's documentation of an internal technical flight conducted in 1999, the glider stalled at 35 knots in a landing straight flight stall, and stalled at 37 knots in a landing turn stall. According to instructions in the Aircraft Flight and Maintenance Manual (AFMM): Section 3.2. Spin Recovery; the height loss for a spin turn is approximately 262 to 295 feet with a speed at spin recovery of approximately 81 to 86 knots. According to FAA Advisory Circular AC No: 61-67C; Subject: Stall and Spin Awareness Training: Chapter 1: " … The possibility of inadvertently stalling the airplane by increasing the load factor (i.e., by putting the airplane in a steep turn or spiral) is much greater than in normal cruise flight … Excessively steep banks should be avoided because the airplane will stall at a much higher speed … If the nose falls during a steep turn, the pilot might attempt to raise it to the level flight attitude without shallowing the bank. This situation tightens the turn and can lead to a diving spiral. … If recovery from a stall is not made properly, a secondary stall or a spin may result. A secondary stall is caused by attempting to hasten the completion of a stall recovery before the aircraft has regained sufficient flying speed ... 14 Code of Federal Regulations 91.107 requires that each person must occupy an approved seat with a safety belt, except that a person may be held by and adult who is occupying an approved seat, provided that the person being held has not reached his or her second birthday and does not occupy or use any restraining device. Two other pilots reported that they had previously inadvertently made take-offs in the IS-28B2 glider with the tow dolly still attached. Both of them reported that there was no change in the flight characteristics in that condition except for a "whistling noise". One of the pilots said the glider actually handled better with the tow dolly attached. According to a postaccident sample weight and balance calculation by the operator; the center of gravity (CG) with all three passengers and without the tow dolly was 27.59 percent MAC. Adding the weight of the tow dolly shifted the CG to 30.96 percent MAC. The allowable range was from 22 to 47 percent MAC. The closest official weather reporting station was at Sugar Land Regional Airport (SGR), Sugar Land, Texas, located 19 miles east from the accident location, At 1653, the automated weather observation station at SGR reported wind from 120 degrees at 6 knots; broken clouds at 7,000 feet, temperature 31 degrees Celsius (C), dew point temperature 19 degrees C, and an altimeter setting of 29.88 inches of Mercury. The impact location was about 3,500 feet south of the take-off position at TE71, and about 400 feet west of the extended runway centerline. The glider came to rest upright in a slightly nose down attitude in 3-foot tall cotton in a flat farm field. A ground impact crater corresponding to the nose impact was found under the nose of the glider. The nose and front cockpit section showed impact crushing damage and were bent slightly to the right and bent up about 45 degrees from the horizontal. The aft fuselage and empennage were oriented to about 160 degrees. There was a ground impact mark oriented to about 230 degrees which corresponded to the leading edge impact damage on the right wing which was oriented to about 260 degrees from the fuselage. The outer portion of the left wing was bent aft about 40 from left wing. The leading edges of both wings had impact crushing damage of about 30 to 40 degrees from the horizontal. The landing gear was fully extended. Both flaps were in the Flaps 1 position. All four spoilers were