According to air traffic control (ATC) audio recordings, a tower controller cleared the Diamond DA20 for takeoff from the airport in Fort Carson, Colo., 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 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 plane 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 plane hit 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 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.
The NTSB determined the probable cause as 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 FAA wake turbulence separation criteria for a small airplane following a helicopter.
NTSB Identification: CEN14TA126
This January 2014 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
In Japan in the late 70’s, I was on final to Atsugi NAF in a Cessna 150. I was cleared to land, and I saw a jolly green giant about 100 meters to my left turning up. That was normal because that pad was used for testing re-worked aircraft. Just before I was in my landing flair, they generated lift. My right wing went down at a severe angle, and I was pointed at the tower. The wing tip missed the apron by inches, and fortunately I was able to recover and go around while having a few choice words with the tower. It turns out that they had a Japanese trainee on, and he had not been in that circumstance before.
If there is no criteria for separation between a small plane and a helicopter, the CFIs ‘”misidentification of the helicopter type” has no
place in the report as a contributing factor. The
fault, if any, lies 100% with the feds for not having established separation criteria.
Sad event but a good lesson. There is considerable heavy turbine helicopter traffic at my home field. They land and depart from several locations on the airport and depart and arrive through the standard patterns. I’ve learned from experience that it is my responsibility to keep a safe distance- neither the tower staff nor the helicopter pilots seem to know or care about the wake turbulence danger to light GA aircraft. “Unable for reasons of safety” is a good phrase to use if you are not certain that you will avoid the wake. ATC staff will understand if a phone conversation takes place. Helicopter pilots on he other hand seem to be unsympathetic and uneducatable.
“helicopter pilots, on the other hand seem to be
unsympathetic and uneducatable”. almoat spit my coffee I laughed so hard.