Flight Mechanics, Flight Control and Aeroelasticity

VERA-C (Vortex Encounter Risk Assessment for curved Vortices)

VERA-C is a research project that investigates vortex encounters with curved vortices. It is funded by the German Research Foundation. 


In the 1970s, the ICAO introduced vortex related separation minima to prevent severe vortex encounters. These separation requirements have proven to be safe, buth are also considered conservative. They limit airport capacities and are becoming a limiting factor for future air traffic growth. The impact of a separtion minima revision are assess via risk analysis that is based on fast-time Monte Carlo simulations.

Existing simulation models for risk assessment model vortex wakes as straight lines. In reality, vortex wakes deform quickly, break up and form to so called vortex rings. Vortex deformation is mainly triggered by atmospheric turbulence and by a phenomenon referred to as Crow-instability.

Objectives and Methods

The objective of VERA-C is to analyze the impact of vortex distortion on vortex encounter severity by means of risk analysis. The strength of a vortex encounter, specifically vortex induced upsets of aircraft attitude and flight path, is mainly influenced by vortex circulation and encounter geometry. Initial studies show that vortex deformation also has some affect on the induced disturbance. Depending on the level of distortion, the encountering aircraft upset may degrade compared to an encounter with straight vortices.

As part of VERA-C, analytical models of curved vortices will be set up and implemeted in the departments research flight simulator SEPHIR. Simulator test with airline pilots will provide a data base for the development of vortex encounter pilot control models and for models that describe the pilots severity assessment. These models will then be integrated in a fast-time simulation environment to perform risk analysis based on large numbers (~100.000) of simulated encounters. Sensitivity studies and worst-case analysis will be used to assess the impact of vortex distortion on encounter severity.

Project Program

AP1Simulator PreparationDevelopment and implemetation of analytical, parametric models of curved vortices for real and fast-time simulation.
AP2Simulator TestsPiloted vortex encounter simulations during approach with airline pilots in the SEPHIR research flight simulator.
AP3Data Analysis and Model DevelopmentAnalysis of the simulator test data and develpment of models forthe pilot's control behaviour and severity assessment.
AP4Risk AnalysisDevelopment of Monte-Carlo fast-time simulation models and sensitivity studies and risk analysis for encounters with curved vortices.
AP5DocumentationDocumentation of vortex models, simulator test campaign, Monte-Carlo simulations and overall project results.

Previous Projects

  • Assessment of Wake Vortex Safety (S-WAKE), funded by the European Commission as part of the 5. FrameWork Program (FP5)
  • CREDOS (Cross Wind Reduced Separation for Departure Operations), funded by the European Commission as part of the 6. FrameWork Program (FP6)
  • WakeNet3-Europe, funded by the European Commission as part of the 7. FrameWork Program (FP7)