N127AL

HISTORY OF FLIGHT

On November 28, 2009, at 1101 Pacific standard time, a Piper PA-25-235 airplane, N7023Z, and a Schleicher ASW-27 glider, N127AL, collided during the landing approach at Crazy Creek Private Gliderport, Middletown, California. The airplane was operated by Calsoar, Inc., d.b.a. Crazy Creek Air Adventures, as a glider tow flight. The glider was operated by the pilot as a local personal flight. Both aircraft were operating under the provisions of Title 14 Code of Federal Regulations (CFR) Part 91. The private pilot onboard the glider, and the commercial pilot onboard the airplane, were killed. Both aircraft were substantially damaged. The airplane and glider departed Crazy Creek at 1056. Visual meteorological conditions prevailed, and no flight plan had been filed.

The airplane departed the airport with the glider in tow. Witnesses then observed the airplane and glider release west of the airport at an altitude of between 2,000 and 3,000 feet mean sea level (msl). The airplane then maneuvered in the vicinity of the release, and turned back towards the airport. After release, the glider tracked to the north along an adjacent ridgeline and shortly thereafter, turned to the southeast back towards the airport. Witnesses described gusting crosswind conditions at the time of takeoff, with one witness reporting that the airplane was being, "knocked around" during climb out.

According to witnesses, both aircraft entered the downwind leg of the single northwest runway about the same time, with the glider on the right downwind leg and the airplane on the left downwind leg. Both aircraft continued on downwind, and turned onto their respective base legs about the same time. As the aircraft turned to final, they collided. One witness reported that neither aircraft performed any abrupt or evasive maneuvers prior to the collision.

The glider was equipped with a Cambridge Aero Instruments Model 302 Direct Digital Variometer. The unit had sustained impact damage and was sent to the National Transportation Safety Board Office of Research and Engineering for data extraction. The data revealed a similar flight track to the witness reports, with the glider climbing to a maximum Global Positioning System (GPS) altitude of 2,405 feet 2 minutes after takeoff. The glider then changed heading to the north, followed by a turn to the southeast. Two minutes later it joined the right downwind for the departing runway at an elevation of 1,614 feet (about 700 feet above runway level). For the next minute, the glider continued on downwind about 1,500 feet north of the runway. The groundspeed during the downwind leg increased from 78 to 83 mph. The glider then began a right turn to the base leg; as the turn progressed, the ground speed increased to 97 mph, and it overshot the runway centerline, while still perpendicular to the approach path. The last recorded position occurred 4 seconds later with the glider at an altitude of 1,214 feet on a heading of about 240 degrees magnetic.

A representative from Calsoar provided photographs of the accident flight taken from the Calsoar facility located on the north side of the runway. The images included the takeoff and post impact sequence. The post impact photograph appeared to have been taken just after the collision, and displayed the airplane relatively intact, flying straight and level on a north heading. The glider was positioned to the south of the airplane, and was flying on an approximate runway heading. The glider's right wing appeared fragmented midspan, with the tail section fractured aft of the cabin and pointing to the north. The airbrakes were in the deployed position.

PERSONNEL INFORMATION

Airplane Pilot

A review of Federal Aviation Administration (FAA) airman records revealed that the 44-year-old pilot held a commercial pilot certificate with ratings for airplane single-engine land, multiengine land, instrument airplane, and glider. The pilot held a third-class medical certificate issued on July 31, 2009 with no limitations or waivers. A complete log of the pilot's flight history was not located; however, on his most recent application for a medical certificate, dated July 31, 2009, he reported a total pilot time of 1,600 hours.

Glider Pilot

A review of FAA airman records revealed that the 63-year-old pilot held a private pilot certificate with ratings for airplane single-engine land, and glider. Family members reported that he had undergone refractive eye surgery about 10 years prior in order to correct his vision of distant objects. Review of the pilot's most recent glider flight logbook revealed that he had completed 163 glider flights since March 2005, 19 of which departed from the accident airport. The logbooks indicated that as of October 10, 2009, he had accumulated 851 hours of total flight time in all aircraft.

AIRCRAFT INFORMATION

Airplane

The airplane was a low-wing type, with the pilot located within an elevated cabin centered just above the trailing edge of the wings. The airplane was primarily white in color, with red and black trim accents on both the outboard section of the right wing, and along the full length of the fuselage side panels.

FAA records indicated that the airplane was issued a restricted special airworthiness certificate for glider towing. Review of the airplane’s maintenance logbooks revealed a total airframe time of 10,356 flight hours with a corresponding engine tachometer time of 3,895 hours at the last 100-hour inspection, which took place on October 13, 2009. The tachometer read 3,909 hours at the accident site.

Glider

The glider was a mid-wing type. Measurements taken at the accident site indicated that while buckled into the pilot's seat, the pilot's head would have been located about 8 inches forward, and 5 inches above the leading edge of the wing. The wing width at the intersection to the fuselage was about 30 inches.

Review of the glider's maintenance logbook revealed a total airframe time of 463 flight hours at the last annual inspection, which took place on October 15, 2009.

METEOROLOGICAL INFORMATION

The closest aviation weather observation station was Charles M. Schulz-Sonoma County Airport, Santa Rosa, California, which was 22 miles southwest of the accident site. An aviation routine weather report (METAR) for Santa Rosa was issued at 1053. It stated: winds from 340 degrees at 13 knots; visibility 10 miles; skies clear; temperature 17 degrees C; dew point minus 2 degrees C; altimeter 30.01 inches of mercury.

At 1054 a METAR was issued for Napa County Airport located 40 miles south of the accident. It stated: winds from 340 degrees at 25 knots, gusting to 35 knots. Additionally,

at 1053 a METAR was issued for Sacramento International Airport located 60 miles southeast of the accident indicating winds from 330 degrees at 25 knots, gusting to 31 knots.

Witnesses at the airport stated that the wind at the time of the accident was from the north at a velocity of between 25 and 35 knots.

The FAA reported that neither pilot had requested weather reporting services from Flight Service Station prior to the accident.

According to the United States Naval Observatory Astronomical Applications Department, the altitude and azimuth of the sun at 1100 in the town of Calistoga, were 28.5 degrees and 164.5 degrees, respectively.

COMMUNICATIONS

The glider was equipped with a Walter Dittel radio transceiver, and a Becker Avionics transponder. The airplane was not equipped with a radio transceiver or a transponder. Neither aircraft was required to be equipped with a radio or a transponder.

The Calsoar facility was not equipped with a radio transceiver, nor was it required to be so equipped.

AIRPORT INFORMATION

The runway was comprised of a 2,000-foot-long, 30-foot-wide asphalt strip. The runway was oriented to the northwest at an elevation of about 975 feet msl and flanked to the south by a parallel 1,400 foot msl ridgeline.

According to a representative from Calsoar, a left hand traffic pattern is considered standard at the airport.

WRECKAGE AND IMPACT INFORMATION

Both aircraft came to rest about 1,300 feet east of the approach end of the northwest runway at an elevation of 980 feet msl. The airplane was located 40 feet north of the runway centerline, with the glider located 400 feet to the southwest. The wreckage path began at approximately the midpoint of the two aircraft, and continued along a magnetic heading of 160 degrees for about 700 feet. The debris path consisted of outboard sections of the glider’s right wing, and a 3-foot-long section of the airplane's right wing tip.

Airplane

The airplane came to rest on its right side, on a heading of about 350 degrees. The entire cabin area sustained crush damage through to the firewall. The engine remained partially attached to its mounts, was upright, and canted 90 degrees to the right of the fuselage centerline. The left wing remained attached at the forward spar, and had become folded forward and parallel to the fuselage. The inboard section of the right wing remained attached to the fuselage, had sustained crush damage along its entire leading edge, and had become folded aft and underneath the fuselage. The right elevator and horizontal stabilizer sustained aft crush damage; the remaining sections of the left horizontal stabilizer remained intact and attached to the tailcone. Both of the airplane's tow cables were in the retracted position.

Glider

The glider came to rest inverted on a heading of about 340 degrees. The left wing remained intact and attached to the fuselage. The inboard 9-foot-long section of the right wing appeared mechanically attached at the root, and was cut from the fuselage by first responders. Fragments of the outboard right wing were located in the wreckage path. The upper surface of the wing fragments exhibited lateral red colored streak marks similar in color to the red paint on the airplanes right wing. A 2-foot-long section of t...