On July 13, 2012, about 1530 eastern daylight time, a Burkhart Grob G 103 Twin II, N5448G, was substantially damaged when it impacted trees and terrain during a simulated low altitude launch failure after a launch from Philadelphia Gliderport (0PA0), Hilltown, Pennsylvania. The two flight instructors onboard were seriously injured. Visual meteorological conditions prevailed, and no flight plan had been filed for the local instructional flight, which was conducted under the provisions of 14 Code of Federal Regulations Part 91. According to the flight instructor in command (FIIC), the Philadelphia Glider Council was conducting winch launch training for its glider-rated flight instructors who did not have a ground launch endorsement, and for recently-endorsed instructors to gain additional ground winch teaching experience. Prior to beginning flight operations, a group briefing was conducted for participating personnel, including the launch crew and the flight instructors providing, as well as receiving instruction. The gliderport had multiple turf runways, including runway 7/25, which was 2,450 feet long and 300 feet wide. According to the FIIC, the glider was set up on east end of runway 25, and the winch was set up about 4,000 feet away, on the north side of the runway overrun. The FIIC and the flight instructor under instruction (FIUI) had flown multiple launches previously that day, with the FIUI noting that there were simulated rope breaks on his previous two launches at 400 feet above ground level (agl) and 10 feet agl. Both pilots concurred that the accident flight was briefed as a simulated rope break at 200 feet. According to the FIIC, the simulated rope break was expected to result in a landing straight ahead on the runway. The ground roll, takeoff and transition to full climb were “normal,” and about 150 feet, the FIIC pulled the release to simulate a launch failure. The FIUI executed a “normal” recovery from a full climb to straight and level flight at 100 feet and 52 knots. The glider subsequently turned to the left, which was all the FIIC could recall due to head trauma. According to the FIUI, after the FIIC pulled the release, he executed an “assertive round over” and established an airspeed of 54 knots. At that point, he felt that the glider was “considerably” lower than 200 feet agl. He initiated a right turn for a few seconds, then rolled wings level. He recalled that the FIIC said something to him “about having a plan,” and then, a few seconds later, he made the decision to make a 180-degree left turn to land on runway 7. The glider had insufficient altitude and impacted trees. The FIUI also recalled that the FIIC did not take control of the glider and that the FIUI was operating the flight controls when the glider hit the trees and the ground. Witnesses differed on specifics as to what occurred after the release, with one stating that after the glider achieved a 5-degree nose-down attitude, the dive brakes partially deployed, then retracted. The glider then made a slight right turn, followed by a turn to the left, “which appeared to be a low-level return to the field.” The witness was concerned that the glider was going to stall/spin at 100 feet, but it continued in a left turn, then rolled wings level before impacting trees. Another witness saw that after the glider was released, it continued in level flight for about 10 seconds, during which, it started a “gentle” right turn. It then rolled into a “medium bank turn” to the left, “attempting a 180-degree turn to return to the departure runway, this all occurring approx. 100 feet agl.” From the witness’s position, it was clear to him that the glider was not going to clear trees. During the last seconds, the dive brakes, which had been closed during the earlier part of the flight, opened and closed, and the glider disappeared behind the tree line. One of the witnesses also stated that when the simulated rope break occurred, the glider was low enough to open the dive brakes and land straight ahead. Neither flight instructor reported any preexisting mechanical anomalies that would have precluded the glider’s normal operation.