Interstate S-1B1 N46336

Summary

On 17 August 2013 at about 17:35 local time, a Interstate S-1B1 registered N46336, operated by Commemorative Air Force - Delaware Flying Wing, was involved in an accident near Lititz, Pennsylvania, United States. One person was on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

17 August 2013 at 17:35

Classification

Accident

Location

Lititz, Pennsylvania, United States

Nearest airport

Lancaster Airport (LNS)

Coordinates

40.1203, -76.2900

Aircraft

Interstate S-1B1

Registration

N46336

Category

Airplane

Year built

1943

Engines

1

Operator

Commemorative Air Force - Delaware Flying Wing

Operating rule

Part 91: General Aviation

Purpose of flight

Air Race/Show

Phase of flight

Not recorded

Route

Lititz → Lititz

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

ERA13LA366

Nobody was injured.

The pilot’s failure to control the airplane’s pitch attitude, which resulted in an aerodynamic stall during the initial takeoff climb. Contributing to the accident was the pilot’s failure to set the trim in accordance with the pretakeoff checklist and the airplane’s encounter with wake turbulence from a preceding airplane.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The airplane departed as the fifth airplane in a formation of six airplanes during an airshow demonstration and was about 75 feet to the trailing right of the preceding airplane during the takeoff and initial climb. The pilot reported that, about 10 feet above ground level (agl), the airplane drifted right of the runway centerline and that he then realigned the airplane with the centerline. About 35 feet agl, he encountered "severe turbulence," and the airplane banked left uncontrollably. He attempted to regain control of the airplane; however, it stalled and subsequently impacted the ground in a nose-low attitude. A left crosswind of about 3 knots existed at the time of the accident. According to Advisory Circular 90-23F, "Aircraft Wake Turbulence," "a crosswind will decrease the lateral movement of the upwind vortex." Postaccident examination revealed that the pitch trim was set in an almost full nose-up position. The pilot likely did not comply with the before takeoff checklist and confirm that the trim setting was at 0 before takeoff. In addition, the airplane likely encountered wake turbulence from the preceding airplane. The pilot reported no mechanical malfunction or abnormality that would have precluded normal operation.

Quoted verbatim from the NTSB record.