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N46951 accident description

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Tail numberN46951
Accident dateMarch 19, 1994
Aircraft typeInterstate S-1B1
LocationSan Antonio, TX
Additional details: None

NTSB description

HISTORY OF THE FLIGHT

On March 19, 1994, at 1351 central standard time, a midair collision occurred between a Taylorcraft DCO-65 (commonly referred to as an L-2), N596BH, and a Interstate S-1B1 (commonly referred to as an L-6), N46951, over San Antonio, Texas. The airplanes, owned and operated by the Alamo Liaison Squadron, were being flown by two commercial pilots. There was no flight plan filed and visual meteorological conditions prevailed. All four occupants aboard both airplanes received fatal injuries. There were no injuries to persons on the ground.

The two airplanes involved in the collision, plus a third (a Piper J-3; commonly referred to as an L-3), were involved in a photographic mission over downtown San Antonio. According to the J-3 pilot, the flight of three was briefed for a formation flight in the local area for the purpose of photographing the J-3, using the skyline of San Antonio as a back drop. He stated that the briefing included the type formation, separation to be maintained, and emergency procedures. He stated that the Interstate, N46951, was leading the flight with the Taylorcraft, N596BH, flying in the left echelon position, and the L-3 flying in an extended right echelon position. A photograph, taken by a tourist shortly before the collision, showed the airplanes in that formation with about a two wing span separation between each. There were no lead changes during the flight. The three aircraft were in radio communication with each other. There were no provisions in the briefing for signaling the turns. The photographer was aboard the Interstate.

According to witnesses, the flight departed the group's facilities at Cannon Field, south of San Antonio, at 1330, and flew directly to an area about one mile southeast of the downtown area. During a post-accident interview, the third pilot stated that they executed two left hand orbits at 2,700 feet MSL and were beginning a third to line up for a photo pass when the collision occurred. In a later written statement, he said that the lead airplane began a left turn, but he was not sure why, as he thought the required photos had been taken. He further stated that during the turn he noticed the Taylorcraft closing on the Interstate. In his written statement, the third pilot said "I was astonished to then see the L-2 (Taylorcraft) collide with the port side of the L-6 (Interstate) while the L-2 was in a left bank. The L-2 was roughly parallel to the level L-6 and in a left bank nose high attitude on contact." During the interview, he said that it appeared to him that contact was made between the wings and the empennages of the airplanes. During the oral interview following the accident, the third pilot was asked what he thought caused the accident. He stated that the lead aircraft initiated the turn and possibly the Taylorcraft "did not turn."

He further said that after the airplanes separated, he lost sight of the Interstate and watched the Taylorcraft enter a right spin. Following the collision, the Interstate impacted the shoulder of a highway and the Taylorcraft impacted in a street and slid into the front of a warehouse and erupted in flames.

WITNESSES

Several ground witnesses submitted oral descriptions to the San Antonio Police Department and two additional witness statements were obtained from the tower controller who had handled the flight and a tourist who observed the accident. All of the statements and descriptions coincided with the observations of the third pilot.

PERSONNEL INFORMATION

Taylorcraft N596BH: The pilot was a retired U.S. Air Force pilot who had several years of formation flight experience and training. According to the Pilot/Operator Aircraft Accident Report filed by the operator, he had accumulated a total of 81 hours in the accident airplane and held a current biennial flight review. The passenger aboard this airplane also held a pilot's certificate issued in 1968; however, he had not held a current medical certificate since 1974.

Interstate N46951: The pilot was a retired U.S. Air Force pilot who also had several years of formation flight experience and training. He had accumulated a total of 414 hours in the accident make and model and held a current biennial flight review. According to information provided by the operator, all three pilots involved in the accident had flown a formation flight together on the Saturday prior to the accident.

AIRCRAFT INFORMATION

Taylorcraft N596BH: The total time on this airplane could not be determined due to the lack of maintenance records. The airplane had been rebuilt by the operator on April 29, 1989, and had accumulated a total of 165.4 hours since the rebuild. It was determined that the airplane was last refueled prior to the flight and was within the prescribed limits for weight and center of gravity.

Interstate N46951: The total time on this airplane could not be determined due to the lack of maintenance records. It had been rebuilt on April 30, 1989, and had accumulated 254.7 hours since the rebuild. It was determined that the airplane was last refueled prior to the flight and was within the prescribed limits for weight and center of gravity.

METEOROLOGICAL INFORMATION

The weather observation taken at the San Antonio International Airport at 1414, reported the surface winds as being from 160 degrees at 9 knots, with no gusts. The third pilot stated that he did not recall any adverse winds or gusts and that there was only minor turbulence from thermals.

COMMUNICATIONS

The lead pilot was handling air traffic control communications for the flight. The other two airplanes were equipped with hand held radios for communications between the formation. The third pilot stated that he did not hear any transmissions between the airplanes after the collision.

WRECKAGE AND IMPACT INFORMATION

Taylorcraft, N596BH: The airplane impacted in the middle of a street about 1/2 mile north northwest of the location of the Interstate wreckage. Imprints from both wings, the propeller, and the engine indicated that the airplane had struck the ground vertically. Following initial impact, the wreckage slid 24 feet through the street and came to rest against the front doors of a Quonset style warehouse. Witnesses stated that the airplane "exploded" on impact. The engine disintegrated on impact and numerous internal components were found throughout the impact area.

The forward section of the fuselage was deformed and accordioned aft to a point just behind the aft seat. All of the flight controls were accounted for at the accident site. The right wing was found laying on top of the left wing, folded under the inverted fuselage. The empennage, forward of the horizontal stabilizers was twisted to the right. Examination of the right horizontal stabilizer revealed several indentations that were angular in nature and inconsistent with the deformation found on the left stabilizer.

Interstate, N46951: The airplane impacted on the shoulder embankment of an interstate highway on a measured heading of 180 degrees. The main impact crater was about 18 inches deep and the propeller was found in the bottom of the crater. The main wreckage, minus the left wing, was found 21 feet from the crater on a measured heading of 210 degrees. The left wing had separated and was located about 300 feet north of the wreckage. Fuel spill distribution was oriented from between 180 degrees and 220 degrees and extended away from the crater for approximately 120 feet. All of the flight controls were accounted for at the accident site.

The separated left wing had burned on impact. The outer 1/2 of the left wing showed evidence of compression buckling on the five outboard ribs and at mid span there were two compression dents and a gouge with a missing piece of metal that was not found. Scratches were found along the outboard section of the leading edge. The scratches originated at the leading edge and ran back to the forward spar on the upper surface of the wing. The scratch marks ran 22 degrees tangent to the chord line of the wing from outboard toward inboard. An angular indentation was found at the rounded tube that formed the left wing tip. Both struts for the wing were accounted for at the accident site. The major portion of the forward strut remained attached to the airframe and the aft strut was found attached to the separated wing. Both of the wooden spars on the left wing were found broken near the inboard section.

MEDICAL AND PATHOLOGICAL INFORMATION

Autopsies and toxicology studies were ordered on both pilots. The autopsies were performed by the Bexar County Medical Examiner's Office. There were no significant findings on either pilot. The toxicology studies were performed by the FAA Civil Aeromedical Institute (CAMI). The samples from the pilot of the Taylorcraft were positive for 22.00 mg/dl of ethanol which was detected in the urine. It was the opinion of the CAMI director of toxicology that the ethanol was a result of post-mortem production.

FIRE

Taylorcraft N596BH: According to the third pilot and ground witnesses, the airplane exploded and burst into flames on ground impact. The airplane subsequently slid across a street and driveway and came to rest against a warehouse. With the exception of the tubular structure, the entire airplane was consumed by the post-crash fire. The front portion of the warehouse was also involved in the fire.

Interstate N46951: There was no evidence of in flight or post- crash fire on the main wreckage of the airplane. However, a post-crash fire developed in the separated left wing when it struck the ground.

ADDITIONAL INFORMATION

Wreckage Releases: Both wreckages were released to the owner/operator's representative on March 21, 1994. All of the retained records were returned on March 24, 1994.

SEE NARRATIVE FOR FTW-94-F-A102A.

(c) 2009-2011 Lee C. Baker. For informational purposes only.