Preliminary investigation of the Indian Air Force Lockheed C-130J-30 Super Hercules that crashed on Friday March 28, 2014, killing five, indicates that the accident may have been the result of wake turbulence.
The Hercules that crashed 72 miles from Gwalior in Madhya Pradesh was in a twoship formation on a training mission when it flew into the wake turbulence of the lead aircraft. Because of the low altitude (300 feet), the crew could not establish control in order to avert the crash.
The mission was flying from Agra-Kheria Air Force Station to Gwalior Airport, India.
Although the findings reportedly rule out “technical error,” incidents resulting from wake turbulence (i.e. composed of wingtip vortices and jet wash) are generally considered pilot error. Jet wash gases from engines dissipate quickly, but vortices from the wings can last three minutes.
Although most incidents resulting from a plane flying in another’s wake turbulence are reported in takeoff and landing situations at airstrips, it is also a hazard in formation flying, so that planes in the far position must concentrate on staying on or above leader’s glide path. Vortices sink at a rate of 90 to 150 meters/minute
The ICAO has separation minima standards for take-off and landing.