Simulator Upset Training with Extended Envelopes

By Paul BJ Ransbury, CEO at Aviation Performance Solutions (APS)

In this discussion, APS addresses the capabilities of today’s advanced Flight Simulation Training Devices (FSTDs) to deliver effective, industry-compliant Upset Prevention & Recovery Training (UPRT) in comparison to forthcoming extended envelope simulator enhancements.

Flight Simulation Training Devices (FSTDs) are qualified for use in a number of ways which involve technical standards and objective evaluation. The certification process is based on qualifying FSTDs for their intended tasks in training pilots. Until recently, this training centered almost exclusively on how airplanes fly in the normal region of the flight envelope.

With Loss of Control In-flight (LOC-I) identified by ICAO, the NTSB, and the Commercial Aviation Safety Team (CAST) as the number one cause of fatalities in all categories of aviation, the FAA, EASA, IATA, and others are calling for changes to mitigate this threat. Changes have been made to the training tasks required in FSTDs for Part 121 air carriers in the United States which will require simulators that have “extended envelopes” or broader capabilities in the delivery of training for pilots, including Upset Prevention and Recovery Training (UPRT).

Understandably, there are questions about the training benefit these extended envelope capabilities will provide. It’s generally agreed that validated simulator fidelity enhancements should be embraced by the aviation training industry. However, can today’s advanced FSTDs, such as Level D full flight simulators, deliver comprehensive and effective UPRT? In short, yes they certainly can and do in the hands expert simulator UPRT instructors. However, an essential qualifying consideration to this claim is that the delivery of UPRT occurs within the specific simulator’s Valid Training Envelope (VTE), a claim that equally applies to extended envelope simulators. 

This article will discuss the anticipated changes being made to extend FSTD training envelopes, and the impact that extended envelopes can have in delivering training to reduce the LOC-I accident rate. The term “extended envelope training tasks” (such as full stall and aircraft upset recovery) refers to maneuvers and procedures conducted in a FSTD that may extend beyond current limits. Those limits where typical FSTD performance and handling qualities have been validated with heavy reliance on flight data to represent the actual aircraft.

There are six areas being addressed in Part 60 changes to Qualification Performance Standards in 2016 concerning FSTD to extend simulator fidelity envelopes: full stall training, upset prevention and recovery training, airborne icing, microburst and windshear, takeoff and landing in gusting crosswinds, and bounced landing recovery. Here, we will concentrate on the areas that impact simulator training focused on curbing the LOC-I fatality rate. From a terminology perspective per FAA Advisory Circular 120-111 on UPRT, a stall by definition is an airplane upset. In the discussion that follows, stalls are sometimes referenced separately to improve message clarity. Where UPRT is used, it includes stalls by definition.

Two of the most important areas addressed by the extension of simulator training envelopes involve training to full stalls (as opposed to an approach to stall) and upset prevention and recovery training (UPRT). The additional training value ‘potentially added’ by these particular capability improvements, in comparison to today’s advanced Level D simulators, is valuable yet fairly small in comparison to the full spectrum of training tasks to be accomplished in simulators as identified by ICAO (more below). The use of the phrase ‘potentially added’ is to acknowledge that the effective and comprehensive delivery of stall and UPRT training in any simulator primarily hinges on the quality and accuracy of the instruction delivered within the simulator’s VTE.

A primary industry accepted reference used for guidance by both the FAA in their Advisory Circular (AC) 120-111 on UPRT, and by ICAO in their Manual on Aeroplane Upset Prevention and Recovery Training (ICAO UPRT Manual) is the Airplane Upset Prevention Training Aid (AURTA). Written originally over 15 years ago and most recently revised in 2008, the authors of the AURTA were, and are, well aware of the aerodynamic, motion, and data limits of flight simulation and devised carefully structured training exercises that would remain within the VTE for existing simulators. Delivered correctly, the AURTA UPRT exercises do not call for training beyond the fidelity limitations of the simulator, typically the approach to stall warning, or in other edge-of-the-envelope regions involving high values of alpha (angle of attack) and beta (sideslip) or both. It is a common misconception that UPRT requires or teaches pilots how to attain and/or remain in these low fidelity regions of simulator’s envelope. On the contrary, simulator UPRT is centered on teaching pilots the safest, lowest risk and most direct path back to the heart of the aircraft’s normal operating region while remaining within the VTE. Furthermore, with the recent stall training standardization efforts by leading OEMs, safety organizations and training providers, encapsulated by the 2012 FAA AC 120-109 Stall and Stick Pusher Training, pilots are directed to treat the approach to stall and full stall the same.

Specifically, both approach to stall and full stall events must give top priority to the reduction of angle of attack, not minimizing altitude loss. With the approach to stall and stall recovery philosophies and techniques in direct alignment with each other, the training value of pilots of transport category airplanes being taken through stall warning cues and protections to specifically experience some degree of pitch break, roll off, or deterrent buffet unique to an airplane’s full stall characteristics is notable but again, relatively small in comparison to the overall stall training awareness, prevention and recovery learning objectives. Section 208 of Public Law 111-216 – The Airline Safety and Federal Aviation Administration Extension Act of 2010 – calls for full stall training in the United States for Part 121 air carriers by 2019. Some experts express concern that the extended envelope itself may unintentionally facilitate the inappropriate use of that region thereby inadvertently enabling negative training. Negative training in the extended envelope full stall region could possibly result due to misguided prolonged stalled flight or overemphasis on subtle full stall characteristics instead of the immediate and correct application of correct stall recovery technique to exit the stalled flight region. Moreover, the necessity for pilots to intentionally fly through, and note but temporarily ignore stall protections to witness full stall characteristics runs the risk of imparting negative transfer of skills from the simulator to the real airplane despite the very best intentions of the instructor to impart valuable training. These concerns are being mitigated by requiring instructor-guided hands on experience of recovery from full stall and stick pusher activation. Once again, whether training in extended envelope simulators or not, the instructor’s role in correct and effective stall training is critically important.

The most common question concerning the forthcoming capabilities of extended envelope simulators is usually, “How much training value does an extended envelope simulator give pilots beyond the capabilities of today’s advanced simulators”? To get an idea of how effective these improvements in simulator aeromodels will be in potentially improving pilot performance, we can look to a milestone study published by the American Institute of Astronautics and Aeronautics (AIAA) titled “An Evaluation of Several Stall Models for Commercial Transport Training”. In this important research, three different simulator aeromodels ranging from the capabilities found in existing simulators to those called for by future extended envelope regulations were evaluated for their effectiveness in training recovery from unexpected stall scenarios. One of the conclusions states: “During the surprise scenario, less than one-quarter of the airline pilots strictly followed the correct stall recovery procedure. Less than half applied nose-down pitch control until the stall warning was eliminated.” The conclusions go on to state, “The airline pilots were able to train to proficiency with any of the models; some valuable training is likely with any of them, as long as instructors are aware of the deficiencies.”

Another possible approach to take to gain perspective on what the extended envelope can offer, is to look to the spectrum of training elements specified for simulator UPRT (that includes stall training) in the ICAO UPRT Manual. In reference to Section 2 of the ICAO UPRT Manual, for example, of the 68 overall training elements under simulator UPRT, a total of six training elements (9%) may be improved by the use of an extended envelope. Keep in mind, that this 9% improvement does not necessarily mean that today’s simulators can’t train in those areas and impart effective training when facilitated by an expert instructor. From this anecdotal perspective, the 9% improvement due to increased simulator fidelity in some regions of the simulator VTE represents an absolute maximum improvement. In reality, it is likely substantially less than 9% where today’s simulators can still facilitate effective instruction by an expert instructor in the same regions. Do those regions of enhanced fidelity represent a breakthrough in the effective, valuable, comprehensive and industry-compliant stall and UPRT training? The response to that question varies widely depending on who is asked – the general consensus at this point in time tends to be “No, it does not”. Most importantly though, there is no reason to wait for extended envelope simulators to provide simulator UPRT. Effective, valuable and positively transferable UPRT can be conducted right now using existing simulators within the simulator’s VTE under the guidance of an expert UPRT instructor.

Today’s advanced simulators, including future extended envelope simulators, are powerful tools for UPRT and wholeheartedly embraced by APS. We firmly believe effective and industry-compliant simulator UPRT can have tremendous training value when combined with high quality instruction. From our perspective, ideal UPRT comprehensively integrates all of the recommended tools by ICAO; academic, on-aircraft, non-type-specific simulation and type-specific simulation as provided by APS in its Jet Pilot Integrated Upset Training and Simulator Instructor Upset Delivery Training programs. The stance that effective UPRT cannot be accomplished in today’s simulators is a myth. A myth often perpetuated by an agenda which favors exclusive training in other platforms such as real jets or piston airplanes, or the fact that simulation cannot provide some of essential human factors elements. There is no single solution to effective UPRT nor the comprehensive mitigation of the LOC-I threat. A diversity of tools and a resources are necessary and will surely expand in the future.

While it is true that having an extended envelope makes improvements to the training platform, there is a much larger factor to mention just one last time as it demands attention; a far more accurate determinant of the effectiveness of training for UPRT in a simulator is the experience and capability of the instructor delivering the training. There is currently no requirement for an UPRT simulator instructor to have on-aircraft UPRT experience where the response of the aircraft along with the startle, surprise and reality factors are completely accurate. From our perspective at APS based on years of experience teaching the Simulator Instructor Upset Delivery Training program, there is no better way than real world, first-hand UPRT experience for an UPRT instructor to become fully aware of the human factors limitations associated with the delivery of UPRT exclusively in an flight simulator. It is not only the technical limitations of the simulation which must be understood, but an understanding of the psychological differences between UPRT in a flight simulator, and what pilots will truly encounter in the real world. For simulator UPRT instructors to gain that perspective, only real world experience itself is the teacher.