Diamond Aircraft Ind Inc DA20-C1 N959DA accident near Fort Carson, Colorado

Probable cause

The flight instructor's loss of control after takeoff following a wake turbulence encounter from a preceding helicopter. Contributing to the accident were the flight instructor's misidentification of the helicopter type and a lack of Federal Aviation Administration wake turbulence separation criteria for a small airplane following a helicopter.

NTSB analysis

**This report was modified on 1/22/2015. Please see the public docket for this accident to view the original report.**

According to air traffic control (ATC) audio recordings, a tower controller cleared an airplane for takeoff about 23 seconds after a UH-60 helicopter was cleared for takeoff from a midfield location. The tower controller ensured that a runway separation standard of 3,000 feet was present and did not give a wake turbulence advisory. The flight instructor reported that she was aware of the helicopter's takeoff and that she perceived adequate separation from the helicopter. The flight instructor incorrectly identified the helicopter as a Bell UH-1, which weighs less than the UH-60. Shortly after takeoff, the airplane encountered the wake vortex of the helicopter and entered a steep left bank. The flight instructor attempted to counteract the left roll with full right aileron inputs, but she was unable to maintain control. The airplane impacted terrain near midfield and came to rest inverted. A review of ATC audio recordings and airplane performance data revealed that the airplane trailed the helicopter by about 48 to 63 seconds at the midfield location and was about 150 to 200 feet above ground level when it encountered the helicopter's wake vortex.

Current Federal Aviation Administration (FAA) ATC guidance does not require specific wake turbulence separation criteria for a small airplane following a helicopter nor does it require a controller to give a wake turbulence advisory for a small airplane following a helicopter. Current FAA pilot guidance, including the Airman's Information Manual and an advisory circular on aircraft wake turbulence, also do not recommend separation criteria for a small airplane following a helicopter.

Text from the NTSB. Open the NTSB docket for CEN14TA126 for the full record.