19990501004232A

Grob G-103 glider collided in mid-air with N5171G, a Cessna C305 afct, under unknown circumstances, N47938 was destroyed and the 2 POB suffered fatal injuries, N5171G was also destroyed and the pilot/sole occupant suffered fatal injuries, other circumstances are unknown. (.19) on may 1, 1999, about 1334 eastern daylight time, a Cessna 305A, N5171G, and a burkhart Grob, G-103 twin ii, N47935, were destroyed following a midair collision within 1 mile of the Philadelphia Gliderport, Hilltown, Pennsylvania. The Cessna was in a climb towing a glider, while the Grob was maneuvering. The certificated commercial pilot (Cessna), the certificated flight instructor (Grob) and the certificated private pilot (Grob) received fatal injuries. The Cessna and the Grob were owned and operated by the Philadelphia glider council, located at the Philadelphia Gliderport. Visual meteorological conditions prevailed, and no flight plan was filed for either the local tow flight or instructional glider flight conducted under 14 CFR part 91. The pilot that had towed the Grob aloft stated that they had taken off, at 1325. He recalled that the private pilot, who was receiving instruction in the Grob, was seated in the front seat, and the certificated flight instructor (CFI) was in the rear seat. He reported that the prevailing winds were from the east, and as he towed eastward, the Grob released at 2,500 feet above ground level (AGL). He stated that he returned to the Gliderport and landed without seeing the Cessna. The pilot of a single seat glider who was being towed aloft by the Cessna, stated that after takeoff, and reaching 400 feet AGL, the Cessna turned left to a northerly heading. He stated that the Cessna then started a 10 degree right angle of bank turn. He reported that about 1,000 feet AGL, while turning through a southeasterly heading, he spotted the Grob at his 11:00 o'clock position, about 1,500 feet away, and about 100 feet above his position. He also stated: "the Grob was (coming towards us) in about a 15 degree right angle of bank turn. As we continued, it became apparent to me that the flight path of the Grob and our flight path (single seat glider and the tow plane) would cause a collision if no evasive action was taken." The pilot further stated: "...about 1,200 feet AGL, I pulled the rope release and turned to the right in about a 45 degree angle of bank. After aboutta 60 degrees heading change, I leveled off and looked to my left in time to see the Grob and the Cessna approach and collide. I do not think that either aircraft was taking evasive action. My impression was that the collision occurred about 5 second after I realeased the tow rope. I was probably 100 to 200 yards away from the impact. I believe the Grob and Cessna passed each other right hand side to right hand side. I kept watching the Cessna with a large portion of one wing's leading edge missing. The Cessna spun in the direction of the damaged wing, making about two complete revolutions before impacting the ground almost straight down (nose down attitude). I looked for the Grob in the air, but only saw fluttering debris." The Cessna impacted the terrain next to a residential driveway, at the base of a 40 foot tall pine tree. All the debris was confined to a 20 feet radius from the main wreckage, with the fuselage facing a southeasterly heading. The Cessna's left aileron was found on the roof of a house about 1/4 mile northwest of the main wreckage. The left wing tip and about a 2 foot section of the left wing's leading edge metal were found in a field about 500 feet northwest of the aileron. Imbedded in the 2 foot section was material similar to that utilized for the wing spars of the Grob. The Grob impacted the terrain in an open field about 400 feet northeast of the Cessna's aileron. All the debris from the main wreckage was located in a 30 foot radius. Ground scarring and debris from the Grob were oriented towards the northeast, and the wreckage came to rest in an upright attitude, facing towards the southwest. The left wing and the empannage were intact, but the damage appeared similar to that of terrain impact. The Grob's right aileron was found about 100 feet southwest of the Cessna's aileron. Sections of the Grob's right wing spar were found in the field near the Cessna's left wing tip. On may 2, 1999, a safety board investigator and a federal aviation administration inspector examined the wreckage of the Cessna and the Grob. The cockpits of both airplanes were destroyed, with pieces found throughout their respective impact craters. Flight control continuity was verified for both airplanes. The Cessna's propeller, which contained chordwise scratching and bending, was found in the main crater detached from the engine. The crank shaft was broken, the engine casing was shattered in the bottom front area, and the accessories on the back section of the engine were detached. About 4 feet inboard of the Cessna's right wing tip, was a 2-foot indentation which contained black rubber markings and symmetrical metal scratches. Telephone and electrical power lines, made of wrapped metal wiring and coated with black rubber were located about 25 feet above the wreckage. These lines were found sagging immediately above the wreckage. The electrical and telephone service to the the local homes was lost following he Cessna's impact. The wreckage of the Cessna and the Grob were released to a representative of the Philadelphia glider council on may 2, 1999. (-23)the accident involved a mid-air collision between a Cessna 305 (N5171G) towing a glider, and a second glilder, a Grob 103 (N47938) that was returning to the field. The pilot of N5171G was killed and an instructor and private pilot onboard N47938 were also killed. No injuries on the ground, and there was minor ground damage. (.4)the Cessna was in an approximate 10 degree right bank climbing turn, towing a glider. As the Cessna reached approximately 1,000 feet; the pilot (witness) of the glider being towed saw another glider, a Grob, approaching from his 11:00 position. The Grob was in an approximate 15 degree right bank descending turn. The pilot being towed believed that the Cessna and Grob were on a collision course, and he released from the tow aircraft. He saw the two aircraft collide, and the Cessna spin to the ground. He did not see the Grob after impact, but saw fluttering debris. Both the Cessna and Grob were equipped with communication radios.