Hollywood, MD, USA
N7475
SLINGSBY CAPSTAN TYPE 49B
According to the glider pilot/owner, he purchased the glider 1 week before the accident and flew it with the previous owner for about 1 hour at the time of purchase. He assembled the glider with the assistance of the tow plane pilot and completed all post-assembly checks before they were joined by his copilot. The pilot and copilot then performed the before-takeoff checks outside the aircraft, confirmed operation of the tow release mechanism, and verified that the spoilers were closed. During the initial climb, the glider pilot noticed that the glider was not climbing, and he and his copilot, a more experienced glider pilot, discussed relative position to the tow plane in order to avoid wake turbulence and improve climb performance. About 200 feet above ground level and over the trees beyond the departure end of the runway, the glider pilot observed the tow plane's rudder "waggle" back and forth, and his copilot shouted, "Release! Release! Release!" The glider pilot released the glider from the tow plane and entered a left turn to the north for a forced landing on the divided highway east of the airport. The copilot joined him on the flight controls before the glider overshot the highway and collided with trees on the east side of the roadway. The tow plane pilot provided a similar recounting of the events. He explained that, before the flight, the proper signals for “too fast” or “too slow” were discussed but no others. He added that he had discussed signaling with the glider’s copilot many times previously but that they had not recently discussed the rudder-wag signal, which means “check spoilers.” After takeoff, he noted that the tow plane’s performance was as expected, but the climb rate was not. He checked the glider in his rearview mirror and noted that the spoilers were deployed. The tow plane pilot provided the internationally recognized (in the glider community) rudder-wag signal, and, instead of stowing the spoilers, the glider released from the tow. Postaccident examination of the glider revealed no mechanical deficiencies. The pilot/owner stated that he knew the meaning of the rudder-wag signal, but responded to the callout from his copilot. He further stated that he believed the spoilers were stowed during preflight and before-takeoff checks, but he did not confirm that the control was locked in its detent prior to takeoff.
HISTORY OF FLIGHT On July 15, 2011, about 1535 eastern daylight time, a Slingsby T-49B glider, N7475, was substantially damaged when it collided with trees while maneuvering for landing in Hollywood, Maryland. The glider had released from tow immediately after takeoff from St. Mary's County Regional Airport (2W6), Leonardtown, Maryland. The certificated commercial pilot was seriously injured, and the certificated private pilot was fatally injured. Visual meteorological conditions prevailed, and no flight plan was filed for the personal flight that was conducted under the provisions of Title 14 Code of Federal Regulations Part 91. The glider pilot provided a comprehensive written statement, and a brief interview following the accident. According to the glider pilot/owner, the glider was purchased a week prior to the accident, and he had accrued about 1 hour of flight time in the glider with the previous owner at the time of purchase. He assembled the glider with the assistance of the tow plane pilot, and all post-assembly checks were completed prior to being joined by the copilot. The pilot and copilot then performed the before-takeoff checks "outside the aircraft," confirmed the TOST tow release operation, and "confirmed trim and spoilers closed." The glider was positioned on the grass between runway 11 and the parallel taxiway for takeoff. The glider and the tow pilot exchanged ready-for-takeoff signals and the takeoff was performed by both aircraft without incident. During the initial climb, the glider pilot noticed the glider "wasn't climbing" and he and his copilot, a more experienced glider pilot, discussed relative position to the tow plane in order to avoid wake turbulence and improve climb performance. About 100 feet above ground level (agl), and over the trees beyond the departure end of the runway, the glider pilot observed the tow plane's rudder "waggle" back and forth, and his copilot shouted, "Release! Release! Release!" The glider pilot pulled the TOST release handle, released the glider from the tow, and entered a left turn to the north, for a forced landing on the north/south divided highway east of the airport. The copilot joined him on the flight controls before the glider overshot the highway, and collided with trees on the east side of the roadway. In an interview, the tow plane pilot provided a similar recounting of the events. He had accompanied the glider pilot/owner to the purchase of the glider, and had agreed to perform the tow "between friends," with no compensation. He stated that the plan for the day was to take turns towing and gliding, as the copilot in the glider was also an experienced tow pilot. The tow plane pilot stated that he and the glider pilot/owner assembled the glider in 45 minutes, and that he observed the pilot as he completed his preflight checks, and assisted him as he confirmed control continuity and proper response of the control surfaces to the control inputs. The tow plane pilot remembered the deployment of the spoilers during the preflight, but he did not recall if they were deployed during the before-takeoff routine. They discussed the proper signals for “too fast” (glider yaw), or “too slow” (glider wing rock), but no other signals were discussed. According to the tow plane pilot, he did not discuss the “wing rock or rudder wag” signals from the tow plane to the glider. He added that the copilot of the glider was also an experienced tow plane pilot, and that they had discussed signaling many times previously, but that they had not recently “discussed the rudder wag” signal. According to the tow plane pilot, the accident flight was the first flight for the glider at 2W6. They set up in the grass between the taxiway and the runway for an easterly departure. They did not employ a “wing runner” to assist, but the initial takeoff was performed with no anomalies, with the glider successfully leveling its wings very shortly after departure, as verified in the tow plane rearview mirror. The tow plane was producing power as expected and the takeoff was smooth, but the tow plane pilot noted a slow rate of climb after the initial takeoff, and thought that maybe it was due to towing a glider to which he was not accustomed and to the slightly-high tow position. The tow pilot reported that the airplane's climb rate after takeoff was 100 to 200 feet-per-minute with full engine power, and not improving. While passing the north/south highway, the tow plane pilot checked his rearview mirror to inspect the glider behind him, and observed the spoilers were at least partially deployed above and below each wing. The spoilers were prominent, because they were flat, vertical “boards” painted red against a white wing background to make their position easily identifiable. The tow plane pilot rapidly “wagged the rudder” while keeping the tow plane wings level to signal the glider pilot to “check his spoilers.” The rudder wag is a published signal, widely used in the glider community, to communicate the "check-spoilers" message. He estimated that both aircraft were approximately 200 feet agl, and 1/2 mile beyond the departure end of the runway, when he gave the signal. At that moment, the glider released from the tow, banked to the North, and struck trees adjacent to the highway while appearing to try to get to the divided highway median. The tow plane pilot returned to the airport, landed and responded to the scene by car. PERSONNEL INFORMATION The glider pilot held a commercial pilot certificate with ratings for airplane single-engine land and sport pilot (glider). He also held a mechanic certificate. The pilot reported 1,471 total hours of flight experience, of which 21 hours were in gliders. He had one hour of experience in the accident glider. His most recent Federal Aviation Administration (FAA) second-class medical certificate was issued on March 28, 2011. The copilot held a commercial pilot certificate with ratings for airplane single-engine land, instrument airplane, and glider. The copilot's logbook was not recovered. However, the tow plane pilot said a recent review of the copilot's logbook revealed over 800 total hours of flight experience, of which 165 hours were in gliders. The copilot's most recent FAA second-class medical certificate was issued September 30, 2011, and he reported 910 total hours of flight experience on that date. The tow plane pilot held a commercial pilot certificate with ratings for airplane single-engine land, single-engine sea, and glider. The tow plane pilot reported 2,250 total hours of flight experience, of which 590 hours were in gliders. He had 242 hours of experience in the tow plane. His most recent FAA second-class medical certificate was issued on March 5, 2010. AIRCRAFT INFORMATION According to FAA records, the glider was manufactured in 1968. A review of the glider's maintenance logs revealed that its most recent annual inspection was completed June 14, 2011, at 642 aircraft hours. The glider was not equipped with a communication radio, and neither was there a hand-held radio in use during the accident flight. According to FAA records and the tow plane pilot/owner, the tow plane was manufactured in 1960. Its most recent annual inspection was completed November 11, 2010 at 4,933 hours. METEOROLOGICAL INFORMATION At 1537, the weather conditions reported at 2W6, at 142 feet elevation, included clear skies, visibility 10 miles, temperature 26 degrees C, dew point 12 degrees C, and an altimeter setting of 30.12 inches of mercury. The wind was from 140 degrees at 7 knots. WRECKAGE AND IMPACT INFORMATION A Safety Board aircraft systems investigator examined the glider at the accident site on July 15 and 16, 2011. The glider was located approximately one-half mile from the departure end of runway 11 and was lodged in a tree approximately 80 feet above the ground. The cockpit canopy was found on the ground. The right wing was still intact with some twisting present close to the root end. The left wing was broken off approximately 4 feet from the root. The remainder of the left wing was suspended in the tree and was attached to the glider by flight control cables. The tail section of the glider was essentially intact. The spoilers on the right wing extended to a position consistent with full extension. Once the glider was removed from the tree, the spoiler extension was found to be approximately 5 inches, but the lower spoiler was compressed into the wing, and the upper spoiler retracted slightly, as the glider was placed on the ground. Full extension of the spoilers (as measured when they were extended by hand on the ground) was approximately 8.5 inches. Flight Controls The cockpit was configured with side-by-side seating and contained dual controls. Both the left and right control columns were present. The left column was still attached, while the right column was found unattached in the cockpit. The control column to the elevator turnbuckle joint was found fractured in a manner consistent with overstress. Control continuity was established from the cockpit to the elevators. The aileron interconnect rod was broken at the turnbuckle joint between the interconnect rod and the left control column. Control continuity was established from the cockpit to the right side aileron. Continuity to the left side aileron could not be determined due to damage to the left wing. The control cables and rudder pedal connections were all present and connected, however the rudder pedals themselves were no longer in the proper positions due to impact damage. The tow cable release knob was checked and found to move freely, and was spring-loaded to the retracted (hook closed) position. The corresponding movement of the hook when the cable release knob was pulled could not be checked. The before-takeoff checklist was placarded in the cockpit. The third item on the checklist was to verify that the spoilers were in the closed position. The elevator trim lever was found in the full forward (nose down) position. The corresponding trim tab position on the elevator could not be determined. The left spoiler handle was attached to the spoiler interconnect rod, and the pin on the left side of the spoiler interconnect rod was still engaged in its socket. The right hand spoiler interconnect rod socket was not present, and the pin was free floating. When the pin was restrained in a position approximating that of the socket (by comparison with the left side), there was no interference between the spoiler control mechanisms and the wood frames in the cockpit. The spoiler interconnect rod was still attached to a push-pull rod leading to a set of bell cranks aft of the cockpit. The right spoiler push-pull rod in the wing was still connected, and the entire right spoiler system moved in the proper sense when the cockpit controls were moved. The spoiler linkage to brake interconnect was connected and appeared to be functional – the brake paddle appeared to move against the tire when the spoiler control handle was moved aft. Spoiler system control continuity on the left side was present up to the pinned joint between the fuselage and wing. The pin was present in that joint. When the spoiler control handle was moved aft in the cockpit, the right hand spoiler extended to the full extended position, and when the control was moved forward, the spoilers moved towards the retracted position. The spoilers would not fully retract; they would only retract to a position where 7/8 inch of spoiler was still extended. The source of the interference preventing full retraction could not be determined. The left spoiler interconnect linkages, which connected the upper and lower spoiler panels, exhibited signs consistent with overtravel. The foam cores of the spoiler panels showed compression (between ¼ and 5/8 inch) consistent with the linkages moving past the 90-degree (right angle) position. Also, when the linkages were placed in their maximum extended position, there was approximately 1/8 inch of unpainted metal showing, a position also consistent with overtravel. Cockpit The readings noted on the cockpit instruments were: Electronic turn and slip indicator – full left slip and turn needle centered. Bank indicator – full left ball Mechanical uncompensated variometer – 0 ft/min Electric TE variometer with audio – 0 ft/min (number 2 selected) and 5, 10, 20-switch was set to off Altimeter - -160 ft Airspeed indicator – 68 kts All electrical switches were off The right seat pan was broken. The right outboard seat belt attachment point was slightly pulled out, and the left attachment point appeared undamaged. The left seat was not present in the glider. The seatbelt was found buckled with its webbing intact, but the attachment points for the seat belt were separated from the cockpit structure. None of the left hand seat belt attachment points showed any signs of damage, the failures were all in the cockpit backing structure. The right hand seat back rod was noted to be in the full aft position. The left hand seat back rod was noted to be in the position second from the front. Both static ports were noted to have their respective tubes present but not attached. MEDICAL AND PATHOLOGICAL INFORMATION The Office the Chief Medical Examiner, Baltimore, Maryland performed the autopsy on the copilot. The cause of death was listed as “multiple injuries.” The FAA Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed forensic toxicology on specimens from the copilot. The toxicology report stated no ethanol was detected in the liver or the muscle, and Pioglitazone was detected in the blood and urine. According to the U.S. National Health Library, Pioglitazone was used with a diet and exercise program and sometimes with other medications, to treat type 2 diabetes. A review of the copilot’s FAA medical records, as well as the autopsy report, revealed that the pilot’s health should not have posed a significant hazard to flight safety. ADDITIONAL INFORMATION According to the Soaring Safety Foundation, the Recommended Standard Soaring Signals include: WARNING – SPOILERS OUT – "waggle rudder." According to both the glider pilot and the tow plane pilot, the "increase speed" and "decrease speed" signals were discussed prior to takeoff, but none of the others. According to the towplane pilot, “We should placard those signals in each aircraft so we don’t forget them.” As a result of this investigation, the tow plane pilot published standard operating procedures (SOP) for glider operations at St. Mary's County Airport. The SOP included a detailed diagram on the internationally recognized in-flight signals. As the director of operations for a Soaring 100 event, he wrote the SOP and distributed hand-outs that included a review of the in-flight signals.
The glider pilot’s improper response to the “check spoilers” signal from the tow pilot. Contributing to the accident was the glider pilot’s failure to confirm that the spoilers were closed and locked before takeoff, and the glider copilot’s improper crew coordination response to the “check spoilers” signal from the tow pilot.
Source: NTSB Aviation Accident Database
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