Analysis of potential wake vortex encounters at a major European airport

Frank Holzäpfel (Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt, Oberpfaffenhofen, Germany)

Aircraft Engineering and Aerospace Technology

ISSN: 0002-2667

Publication date: 4 September 2017



In this study, 12 potential wake vortex encounters that were reported at a major European airport have been investigated. Because almost all encounters occurred in ground proximity, most pilots conducted a go-around. The primary purpose of this study is to discriminate between incidents caused by wake vortices or rather by effects like wind shear or turbulence. Detailed knowledge of real-world encounter scenarios and identification of worst-case conditions during the final approach constitute highly relevant background information to assess the standard scenario used for the definition of revised wake turbulence separations.


Wake vortex predictions using the probabilistic two-phase wake vortex model (P2P) are used to investigate the incidents in detail by using data from the flight data recorder, meteorological instrumentation at the airport and numerical weather prediction.


In the best documented cases, the flight tracks through the vortices could be reconstructed in good agreement with wake vortex predictions and recorded aircraft reactions. Out of the eight plausible wake vortex encounters, five were characterized by weak crosswinds below 1.5 m/s combined with tailwinds. This meteorological situation appears favourable for encounters because, on the one hand, weak crosswinds may compensate the self-induced lateral propagation of the upwind vortex, such that it may hover over the runway directly in the flight path of the following aircraft. On the other hand, tailwinds limit the propagation of the so-called end effects caused by the breakdown of lift during touchdown.

Practical implications

The installation of plate lines beyond the runway tails may improve safety by reducing the number of wake vortex encounters.


The conducted investigations provide high originality and value for both science and operational application.



The support of the DLR colleagues, Carsten Schwarz and Dennis Vechtel of the Institute of Flight Systems, with the analysis of the aircraft reaction during the encounter is greatly appreciated. Henning Dorff is gratefully acknowledged for his preliminary analysis of the encounters.


Holzäpfel, F. (2017), "Analysis of potential wake vortex encounters at a major European airport", Aircraft Engineering and Aerospace Technology, Vol. 89 No. 5, pp. 634-643.

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