LAX04FA304

Two identically painted American Champion 8KCAB airplanes (N561ER and N562ER) collided in flight while performing a formation aerobatic hammerhead maneuver. The airport was hosting an airshow where the accident pilots were going to perform a formation aerobatic routine. Witnesses observed the two airplanes practicing the routine on several different occasions during the previous months, and had become familiar with it. They said that when the accident happened, a vertical climb was initiated with both airplanes side-by-side, and at the apex of the maneuver, one or both of the airplanes moved out of their normal positions, and they became stacked one on top of the other. After the airplanes initial contact, witnesses observed several additional contacts as the airplanes fell to the ground. Color transfers, damage patterns, and witness marks found that the propeller of N561ER made multiple contacts to the engine compartment and cockpit of N562ER, while contact between the left lift strut of N562ER and the empennage of N561ER damaged and separated the vertical and horizontal stabilizers of N561ER. An airframe and engine examination of both airplanes revealed no mechanical discrepancies that would have precluded normal operation and control.

History of flight

On August 28, 2004, at 0831 mountain standard time, two American Champion Aircraft 8KCAB, N561ER (Riddle 61) and N562ER (Riddle 62), collided in midair while performing formation aerobatics 7 miles east of Ernest A. Love Field (PRC), Prescott, Arizona. Both airplanes were owned and operated by Embry-Riddle Aeronautical University (ERAU) under the provisions of 14 CFR Part 91. Both airplanes were destroyed. The commercial certificated pilot of Riddle 61, the sole occupant, and the airline transport certificated pilot of Riddle 62, the sole occupant, were both fatally injured. The personal flights departed PRC at 0818, with the intent of practicing for an upcoming aerobatic performance. Day visual meteorological conditions prevailed, and no flight plans had been filed for the local area flight.

Both pilots were faculty members at ERAU. The pilot of Riddle 61 was the program Chair for the Aeronautical Science Department. The pilot of Riddle 62 was the school's Chief Flight Instructor. Both were experienced aerobatic pilots, and instructed and mentored the school's aerobatic club.

The pilots were practicing an aerobatic routine at the time of the accident that was to be the highlight of the ERAU sponsored Prescott Air Fair scheduled for October 2, 2004.

The National Transportation Safety Board investigator-in-charge (IIC) interviewed several witnesses who were hunting in the area at the time of the accident. They had observed the accident airplanes perform several times in the past months, were accustomed to the airplanes, and familiar with the routine. The airplanes had completed the routine once, and were setup for the second pass. The witnesses reported that the airplanes completed one maneuver and pulled out low to the ground. While in formation, they maneuvered into a nose up to a vertical attitude. They saw one airplane overtake the other, and a collision ensued. Both airplanes appeared as if they were out of control as they fell to the ground. Immediately after the collision several pieces of both airplanes began to fall to the ground, though the witnesses could not distinguish what parts they were.

The Safety Board IIC, along with an ERAU representative, ascertained from witness interviews that Riddle 61 was in the high and to the right position relative to Riddle 62 during the vertical climb. At the apex of the maneuver one or both of the airplanes traveled out of position in the formation flight and became stacked one on top of the other; Riddle 61 on top, Riddle 62 on the bottom. The airplane's contacted each other, with numerous additional contact made during the descent, until the airplane's separated prior to ground impact.

A flight instructor at ERAU saw both pilots the morning of the accident and said they were both in good humor. He observed the airplanes taxi off the ERAU flight line about 0810.

The Safety Board IIC reviewed the planned routine program located in Riddle 62. According to the ERAU party representative, maneuver 3 was a hammerhead maneuver in formation.

Personnel information

Riddle 61

The operator reported that the pilot of Riddle 61 held a commercial pilot certificate with ratings for airplane single engine land and sea, multiengine land, and instrument airplane. He held a certified flight instructor (CFI) certificate with ratings for airplane single engine land and instrument airplane.

The pilot held a second-class medical certificate issued on October 6, 2003. It had the limitation that the pilot must wear corrective lenses.

The operator reported that the pilot had a total flight time of 4,901.9 hours. He logged 22.5 hours in the last 90 days, and 4.3 hours in the last 30 days, all in the accident make and model. He had an estimated 371.6 hours in accident make and model. He completed a flight review in September 2003.

Riddle 62

The operator reported that the pilot of Riddle 62 held an airline transport pilot certificate with ratings for airplane single engine land, multiengine land, and instrument airplane. He held a certified flight instructor (CFI) certificate with ratings for airplane single engine land, multiengine land, and instrument airplane.

The pilot held a second-class medical certificate issued on December 10, 2003. It had the limitation that the pilot must possess corrective glasses for near vision.

The operator reported that the pilot had a total flight time of 6,707.1 hours. He logged 32.2 hours in the last 90 days, and 17.6 in the last 30 days, of which 10.4 were in the accident make and model. He had an estimated 129.8 hours in this make and model. He completed a flight review in April 2003.

Aircraft information

Riddle 61

The airplane was an American Champion Aircraft 8KCAB, serial number 934-2003. The operator reported that the airplane had a total airframe time of 286.5 hours at the last 100-hour inspection dated July 16, 2004.

A Lycoming AEIO-360-H1B engine, serial number L-31198-51A, was installed on the airplane. Total time recorded on the engine at the last 100-hour inspection dated July 16, 2004, was 286.5 hours.

Examination of the maintenance and flight department records revealed no unresolved maintenance discrepancies against the airplane prior to departure.

Riddle 62

The airplane was an American Champion Aircraft 8KCAB, serial number 935-2003. The operator reported that the airplane had a total airframe time of 264.9 hours at the last 100-hour inspection dated August 6, 2004.

A Lycoming AEIO-360-H1B engine, serial number L-31196-51A, was installed on the airplane. Total time recorded on the engine at the last 100-hour inspection dated August 6, 2004, was 264.9 hours.

Examination of the maintenance and flight department records revealed no unresolved maintenance discrepancies against the airplane prior to departure.

Meteorological information

The closest official weather observation station was PRC, located 7 nautical miles (nm) west of the accident site. The elevation of the weather observation station was 5,000 feet mean sea level (msl). An aviation routine weather report (METAR) for PRC at 0853 reported calm winds; visibility 10 statute miles and clear skies; temperature 23 degrees Celsius; dew point 03 degrees Celsius; altimeter 30.20 inHg.

Wreckage and impact information

The Safety Board IIC examined both airplanes at the accident site on August 29, 2004. Both airplanes were predominantly blue and white in the ERAU paint scheme. The tops of the wings, tail, and fuselage were blue. The bottoms of the wings were white. There was a gold spiraling strip from the nose to the tail of both airplanes.

The propellers of both airplanes were made of wood and composite material. The tips of the propellers contained a chordwise red stripe.

Riddle 62 came to rest about 400 feet north of Riddle 61. The surrounding area was flat desert terrain.

Riddle 61

The main wreckage was found at 5,080 feet msl, at the approximate global positioning system (GPS) coordinates of 34 degrees 37.591 minutes north latitude and 112 degrees 14.672 minutes west longitude.

The airplane impacted the ground in a nose down attitude. The fuselage was lying adjacent to the left wing. The tail section separated from the airplane. The horizontal stabilizer, portions of the tail and tail cone, elevator trim tab, elevator, vertical stabilizer, and rudder separated from the airplane and were distributed in the debris field about 500 feet northeast of the main wreckage. One propeller blade remained attached at the propeller hub. Impact forces destroyed the other propeller blade; however, parts of it were buried beneath the propeller hub in its relative normal position. Both wings were oriented with the leading edge down in an almost vertical attitude, and exhibited extensive spanwise crush damage from the leading edge to the trai