A Hazard Analysis-based Approach to Improve the Landing Safety of a BWB Remotely Piloted Vehicle

The BUAA-BWB remotely piloted vehicle （RPV） designed by our research team encountered an unexpected landing safety problem in flight tests. It has obviously affected further research project for blended-wing-body （BWB） aircraft configuration characteristics. Searching for a safety improvement is an urgent requirement in the development work of the RPV. In view of the vehicle characteristics, a new systemic method called system-theoretic process analysis （STPA） has been tentatively applied to the hazardous factor analysis of the RPV flight test. An uncontrolled system behavior ＂path sagging phenomenon＂ is identified by implementing a three degrees of freedom simulation based on wind tunnel test data and establishing landing safety system dynamics archetype. To obtain higher safety design effectiveness and considering safety design precedence, a longitudinal ＂belly-flap＂ control surface is innovatively introduced and designed to eliminate hazards in landing. Finally, flight tests show that the unsafe factor has been correctly identified and the landing safety has been efficiently improved.

Determining the approach speed envelope of carrier aircraft

Many factors,such as deck motion and air wave,influence the determination of the approach speed which has an important effect on landing safety. Until recently,there are no design criteria about approach speed of carrier aircraft in the current standards and available publications. Therefore,the requirements of stall margin, longitudinal acceleration ability,altitude correction and field-of-view on approach speed were researched. Based on the flight dynamics model,the flight simulations were conducted to study the effect of the response time of engine,wave off requirements,elevator efficiency and deflection rate on the approach speed. The results presented that the approach longitudinal acceleration and altitude correction ability had crucial influence on the approach speed envelope of the aircraft. The limitations of the control requirements,field- of- view requirements and gear were also given through the simulation and analysis. Based on the above results,the approach speed envelope were determined.

Assessment of piloting behavior impact on landing risk of transport aircraft

The human factors and their interaction with other factors play an important role in the flight safety of transport aircraft.In this paper,a paradigm of risk assessment for transport aircraft interacting with piloting behaviors is proposed,with focus on landing which is the most accident-prone flight stage in aviation safety statistics.Model-based flight simulation serves as our data source for landing risk analysis under uncertainties.A digital pilot in the loop that reflects the human piloting behaviors is employed to facilitate simulation efficiency.Eight types of unsafe events in landing are identified from statistics.On this basis,the landing safety boundary is extracted via stochastic simulation to divide safety and hazardous flight status domains,which con-tributes to flight status management and risk warning.The simulation results indicate that appro-priate piloting behavior,which is active response and fast target acquisition with minimum overshoot and fluctuation,shows benefit to landing safety.The subset simulation technique is employed to further refine the boundary with less computational workload.Furthermore,the effect of airspeed,windspeed,and other factors on landing risk is also discussed.The proposed risk assess-ment method would help optimize operation procedure and develop targeted pilot training program.