Date & Time: Dec 2, 2013 at 2010 LT
Operator:
Registration:
N831BC
Flight Type:
Cargo
Survivors:
No
Schedule:
CSQ405
MSN:
AC-654B
YOM:
1986
Flight number:
Santo Domingo - San Juan
Crew on board:
2
Crew fatalities:
2
Pax on board:
0
Pax fatalities:
0
Other fatalities:
0
Total fatalities:
2
Circumstances:
Aircraft was destroyed during a rapid descent to terrain near La Alianza, Puerto Rico. The captain and the first officer were fatally injured. Night visual meteorological conditions prevailed. The international cargo flight was operating on an instrument flight rules flight plan between Las Americas International Airport (MDSD), Santo Domingo, Dominican Republic, and San Juan International Airport (TJSJ), San Juan, Puerto Rico, under the provisions of 14 Code of Federal Regulations Part 135. According to the operator, the accident flight occurred during the return leg of a round trip between TJSJ and MDSD. Prior to the outbound flight, "normal dispatch requirements were met," and the airplane took on fuel at TJSJ for both legs. The airplane departed MDSD on the accident flight at 1936. A review of radio transmission tapes indicated that the crew first contacted the FAA San Juan Combined En route Approach Control (CERAP) facility at 1949, 13 nautical miles west of MELLA intersection at 11,000 feet. At 2002, the crew was told to descend to 7,000 feet at "pilot's discretion," and at 2008, the crew was advised to change frequency to the next CERAP sector controller. The crew subsequently contacted the next controller, "leaving one one thousand, descending to seven thousand." The controller then advised the crew to maintain 3,000 feet, expect the ILS (instrument landing system) approach, proceed direct to the "TNNER" fix, and that information "Tango" was in effect. After a crew member read back the information, there were no further transmissions from the airplane. Preliminary radar data revealed that after MELLA, the airplane proceeded toward TJSJ along a heading of about 085 degrees true, crossing the west coast of Puerto Rico just south of the town of Stella. The airplane maintained 11,000 feet until 2007, and had descended to 8,300 feet by 2010:08. It then made a 20-degree turn to the left, and by 2010:13, had descended to 7,300 feet. It subsequently made a 45-degree turn to the right, and had descended to 5,500 feet by 2010:18. There were no additional verifiable altitude positions. Descent calculations between 2010:08 and 2010:13 indicated a rate of descent of about 12,000 feet per minute (fpm), and between 2010:13 and 2010:18, over 21,000 fpm. Preliminary ground speed calculations indicated about 290 knots. There was no cockpit voice recorder or flight data recorder onboard the airplane. Weather, recorded at TJSJ, 33 nm to the east, at 1956, included wind from 170 degrees true at 5 knots, visibility 10 miles, a few clouds at 7,000 feet, and scattered clouds at 10,000 feet. An NTSB review of radar images at the time of the accident revealed no precipitation in the area. U.S. Naval Observatory data indicated that sunset occurred at 1749 and that the end of civil twilight occurred at 1813. Wreckage was scattered over a large area that included a pasture and the hillsides that partially surrounded it. General dimensions of the wreckage field were about 1,900 feet in length and 600 feet in width at its widest point, oriented toward 178 degrees true. The wreckage field commenced in the vicinity of 18 degrees, 23.07 minutes north latitude, 066 degrees, 35.30 minutes west longitude, with lighter materials, including the airplane's radome. The field narrowed toward its end, with the heavier materials such as the airplane's two engines located close to each other in the vicinity of 18 degrees, 22.77 minutes north latitude, 066 degrees, 35.29 minutes west longitude. There was no impact crater; only airplane remnants scattered throughout the wreckage field. Significant remnants included, from north to south: the upper right cockpit area, and to the left and further south of that, the outboard portion of the left wing. Farther south was the left side of the cockpit, and near that, toward the center of the wreckage field, was the empennage. To the right of the empennage was the right wing, and farther to the south, on the left side of the wreckage field, was the remainder of the left wing. Beyond that, but before the engines, was the airplane's nose section, which included many of the cockpit controls. There was no evidence of an inflight fire or explosion. All three landing gear remained with their respective housings. The right wing was found upside down, with the landing gear extended and the drag brace assemblies locked over center. The main part of the left wing was also found upside down, but with the landing gear retracted and loose in the wheel well. Extending the landing gear by hand revealed housing deformations and tire marks consistent with the gear having been extended in flight. The nose landing gear was found partially extended in the airplane's nose section, which came to rest on its side. When the nose section was rolled upside down, the landing gear fell back into the wheel well. However, when the landing gear was extended by hand, housing deformation and tire marks found were consistent with the landing gear having been extended in flight. The cockpit landing gear handle, which could only be pulled upward, but not moved forward or aft, was found in the "gear down" position. There was evidence of fuel in both wings. Although extensive on-site photographs were taken, the size of the wreckage field as well as the muddy terrain and wet weather precluded complete documentation of flight control continuity. The wreckage was recovered and containerized, and is expected to arrive at a storage facility in Houston, Texas, by late January 2014. After its arrival, the investigative team will reconvene to complete the documentation.