EXECUTIVE SUMMARY:
In the past, several research projects have dealt with the wake vortex hazard. ATC-WAKE proposed a ground-based solution to be installed at airports in support of reduced separation distances. The I-WAKE project dealt with on-board instrumentation and focused on overall system definition, flight simulator tests and flight-testing.

Within the frame of FLYSAFE, WP231 introduces the concept of Wake Encounter Prevention System (WEPS). This on-board system shall prevent severe wake vortex encounters during all phases of flight.

Essentially this system is intended to create an additional safety layer with respect to severe wake encounters. It is assumed that WEPS will be used in conjunction with (strategic) wake separation schemes, which on their own assure a high level of safety. WEPS shall cater for those rare circumstances in which severe wake encounters could still occur. Such circumstances may result from involuntary loss of (wake turbulence) separation, operations under visual separation rules or a component malfunction of the wake separation system. In these cases WEPS shall reliably and timely recognise imminent severe wake encounters such that safe avoidance or mitigation becomes possible. In contrast to strategic ATC wake separation schemes WEPS is of tactical nature in that its prediction horizon is unlikely to exceed a few minutes.

WEPS may rely on dedicated data received from nearby aircraft as well as from ground stations (for wake prediction), be self-sufficient by using on-board sensor information only (for wake detection) or make use of both types of information (for wake detection enhanced by prediction). WEPS shall make use of flight plan intent data of its own and, if available, nearby aircraft.

The WEPS is based on two fundamental methods to identify perilous wake vortices in the vicinity of the aircraft’s flight path:

• Wake detection by remote sensor measurement of characteristic wake quantities,
• Wake prediction by application of analytical models in conjunction with weather measurements, weather forecasts and wake-generating aircraft properties.

It is possible to combine both methods to overcome their individual weaknesses, which yields a third method:
-Wake detection enhanced by prediction
Within the frame of WP231, an application called “On-Board Wake Prediction & Alert” and abbreviated OBWPA has been developed in order to perform a Part Task Evaluation (PTE) of the WEPS wake prediction concept. The functional break down of OBWPA is depicted hereunder.

 

Based on this architecture, the following functions have been developed:

• Wake predictors (based on existing P-VFS and P2P models, extended to cruise flight altitudes)
• Conflict detection
• Severity estimation
• Alerting logic, HMI & avoidance orders

The alerting logic (shown below) defines alerts based on the expected wake encounter severity level and the time to conflict.
 
Finally, the OBWPA application was integrated into the AIRBUS THOR flight simulator and evaluated by test pilots .
All pilots have been very positive about the prospect of having a Wake Encounter Prevention System onboard future aircraft. The WEPS development and OBWPA prototype have been regarded as quite mature and well suited to demonstrate and discuss design goals and concepts.

Overall, WP231 has shown the feasibility of airborne wake encounter prevention up to cruise flight altitudes and based on wake prediction alone. Further development of the WEPS prototype to seamlessly cater for all flight phases and to include coupling of wake detection and prediction is suggested.
 
For further information please contact:
Mr. Herve Barny: herve.barny@fr.thalesgroup.com