Tragic incidents with devastating consequences
A serious accident occurred at an air show in Germany: a Robin DR400 took off just 39 seconds after an Antonov An-2, the world's largest single-engine biplane. The DR400 was caught in the massive wake vortices of the An-2, was pushed into a knife-edge attitude and crashed next to the runway. Three of the four occupants lost their lives. The investigating authority later made a video to show how the wake vortices stayed above the runway and why the DR400 took off too early.
There was also a serious incident in Switzerland in 2016: shortly after take-off, a training aircraft suddenly tilted at an angle of 70 degrees due to a wake vortex. Only the quick intervention of the flight instructor prevented a crash. This incident was later documented in the official SAND safety reports.
Physics of wake vortices
Wake vortices always occur when an aircraft generates lift. The wings or rotor blades generate counter-rotating vortices that stand behind the aircraft like invisible tornadoes in the air.
- For aeroplanes the danger begins as soon as the nose wheel lifts off and only ends when the aircraft makes contact with the ground again after landing.
- For helicopters it exists as long as the rotor blades generate lift - i.e. also during hovering or taxiing with active rotors.
The wake vortices of heavy or slower-flying aircraft are particularly dangerous. Large aircraft such as the An-2 or business jets create turbulence that can remain over the runway for a long time, depending on the weather conditions.
Proven rules of thumb for greater safety
The aviation authorities recommend clear distances:
- Time intervalWait at least two minutes before crossing the runway after a preceding aircraft or helicopter or before taking off yourself.
- Helicopter operationsKeep a distance of at least three times the rotor diameter when taxiing, taking off and landing.
- Height staggeringWhen approaching, stay above the wake turbulence track of the aircraft in front and land behind the touchdown point.
The FAA has published extensive recommendations for avoiding wake vortices in Advisory Circular AC 90-23G. The European EASA and national authorities also provide corresponding guidelines.
Technical support through digital tools
Modern apps like ForeFlight or flysto.net now offer functions such as "Wake Turbulence Alerts". With the introduction of ADS-L and the growing digital networking of air traffic, these warning systems could soon be available in real time and warn pilots specifically of dangerous wake turbulence.
Conclusion: Knowledge protects lives
Wake vortices are invisible, often unpredictable and yet remain manageable if pilots, flight schools and organisers consistently focus on safety distances and education. Training, digital aids and the consistent application of proven procedures are the key to minimising the risks. Every incident shows: Only those who recognise and respect the danger can avoid it.
Source references:
Staysafe.aero