Accident at Flager, Colorado, 15 Sept 1951

Accident narrative

On September 15, 1951, at about 1440 Mountain Standard Time, an experimental Timm N2T-1 aircraft crashed into a crowd of spectators during an air show at the Flagler Airport in Flagler, Colorado. The pilot, who was the sole occupant, and 19 spectators were killed. Ten other persons were seriously injured. The aircraft was demolished, and several parked vehicles were extensively damaged.

### Background and the Waiver

The air show was organized for a local festival. The airport manager, Nelson W. Stake, contracted W. D. Madsen, president of Rocky Mountain Air Shows, Inc., to stage the event. Madsen arranged the acts and prepared an application for a Civil Aeronautics Administration (CAA) Certificate of Waiver, which Stake completed and submitted.

The CAA issued the waiver on September 11, waiving Civil Air Regulations pertaining to minimum safe altitudes and acrobatic flight. The waiver included special provisions requiring that no aircraft fly toward, over, or within 500 feet horizontally of spectators; that all acrobatic maneuvers be completed at least 500 feet above the surface; and that all participating pilots be thoroughly briefed prior to the meet.

On September 13, Madsen asked the CAA to add First Lieutenant Norman L. Jones, a United States Air Force pilot based at Lowry Air Base, to the waiver as an acrobatic pilot. The CAA agent complied and informed Madsen that during the pre-show pilot briefing at Flagler, he would request the horizontal distance from spectators be increased to one-half mile.

### The Flight

On the day of the show, CAA agents arrived at Flagler at 1035 and ascertained that ground safety measures, including a roped-off spectator area, had been met. The participating aircraft were delayed leaving Denver due to oil leaks.

At about 1420, a towplane and a sailplane arrived at Flagler. The sailplane pilot released at an altitude of about 2,000 feet, performed acrobatics, dove downwind, pulled up at an altitude of about 50 feet to make a "split S," and landed.

At about 1440, the Timm aircraft, piloted by Lt. Jones, arrived south of the field at an elevation of approximately 500 feet. The aircraft flew north toward the runway, laying a smoke trail at an estimated altitude of 150 feet. Opposite the south end of the hangar, while directly over the runway, the aircraft started a slow roll to the right. Its horizontal distance from the spectators' roped-off area was about 100 feet.

Upon reaching the inverted position, the nose of the aircraft dropped, and the flight path altered approximately 30 degrees to the right, toward parked automobiles and spectators. The pilot was completing his roll when the left wing struck the ground. The aircraft crashed into automobiles parked three deep and disintegrated along a 125-foot path.

### What the Investigation Found

Witnesses, including the two CAA agents, confirmed that the slow roll was started at about 150 feet and was improperly executed, as the aircraft lost altitude while inverted and slipped into the ground.

Examination of the wreckage disclosed no evidence of any failure of the aircraft's structure, controls, or powerplant prior to impact. The engine and propeller had separated from the fuselage, but propeller blade distortion indicated that power was being developed at impact. The rudder trim tab was set about 10 degrees left, and the right elevator trim tab was found in the 30-degree "up" position. The pilot's safety belt was fastened and had pulled both of its anchors from the fuselage structure. Investigators minutely examined the fuselage glue bonds; while some deterioration was noted, there was no indication this caused any malfunctioning.

The aircraft was built in 1942 as a Navy trainer. It had overturned in a windstorm in June 1950 and was subsequently repaired and fitted with a 300-horsepower Lycoming engine, replacing its original 225-horsepower engine. It was certificated in the experimental category for exhibition flights two days before the accident. The new engine was not carbureted for inverted flight. Test flights by other pilots indicated satisfactory performance, though the aircraft required slight "up" elevator trim to offset nose heaviness.

Lt. Jones held a commercial pilot certificate with the appropriate rating for the Timm. His total piloting time was approximately 2,500 hours. However, Air Force records showed his recent military flying had been in bombers, and there was no record of him having flown small aircraft acrobatically for a considerable time. His experience in the Timm consisted of about 30 minutes the day before the accident, during which ground witnesses saw him "fall out of a loop," and about one hour while en route to Flagler. Furthermore, he had not obtained the required military permission to fly civil aircraft.

The Board noted a conflict regarding pre-show instructions. Madsen testified he had admonished Lt. Jones to adhere to the 500-foot minimums and to land at Flagler for a briefing before the show. However, the sailplane pilot stated Madsen had instructed him to go into his act immediately if he arrived late. Because both pilots started acrobatics immediately upon arrival without landing, the Board concluded that Madsen gave direct or implied instructions to both pilots to do so, in direct conflict with the terms of the waiver. The Board noted that had the pilot first landed as required, the accident might have been averted.

The Board concluded the accident could only be charged to pilot error. The precise control of altitude during a slow roll requires piloting skill, current acrobatic experience, and familiarity with the aircraft, which the pilot lacked.

Following the accident, the Administrator of Civil Aeronautics announced a new policy on September 21, 1951, banning certificates of waiver for air shows that include thrill-type acts such as acrobatics not under direct radio control, intentional aircraft crashes, and similar hazardous operations.

### Probable Cause

The Board determines that the probable cause of the accident was "the pilot's loss of control of the aircraft during an attempted slow roll closer horizontally to the spectators and at an altitude lower than specified in the waiver in utter disregard of the safety of persons and property on the ground."