Guidance for professional pilots on UPRT focusing on the Skidded Turn Stall scenario in a jet trainer.
Introduction
In the dynamic world of aviation, pilots must be prepared to handle a myriad of flight scenarios. One such scenario that requires particular attention is the Skidded Turn Stall, a complex situation that can occur in multi-engine aircraft with one engine inoperative. This article provides an in-depth exploration of Skidded Turn Stalls within the broader context of Upset Prevention and Recovery Training (UPRT).
Understanding Skidded Turn Stalls
Skidded Turn Stalls are a unique and challenging flight scenario. They occur when an aircraft is in a turn and the pilot applies too much rudder in the direction of the turn, causing the aircraft to skid. If this is combined with a stall, the aircraft can enter a spin. This situation is particularly dangerous in the traffic pattern, where altitude is limited.
The Role of On-Aircraft UPRT in Skidded Turn Stalls
On-aircraft UPRT is an invaluable tool in preparing pilots for real-life flight scenarios like Skidded Turn Stalls. Training in aircraft such as the SIAI Marchetti S211 allows pilots to experience the actual outcomes of these stalls and practice appropriate recovery techniques in a safe yet realistic environment. This hands-on experience is crucial as it exposes pilots to the aerodynamic conditions of a full aerodynamic stall with substantial sideslip present, conditions that cannot be effectively simulated in even the most advanced full flight simulators.
The Limitations of Flight Simulators in Skidded Turn Stalls
While flight simulators have revolutionized pilot training, they have their limitations, especially when it comes to Skidded Turn Stalls. Even the most advanced simulators lack sufficient flight test data associated with full stalls with substantial sideslip. Consequently, the airplane performance presented in a substantially uncoordinated full aerodynamic stall by advanced simulators is at best a 'best guess', based on wind tunnel and extrapolated data. This limitation underscores the importance of on-aircraft UPRT, where pilots can experience these conditions first-hand.
The Role of Angle of Attack (AOA) Indicators in Skidded Turn Stalls
AOA indicators, such as the modern Garmin AOA probe, are useful tools in the cockpit. However, they are not infallible. For instance, in a skidded stall maneuver, there may be little to no pre-stall warning due to the uncoordinated entry. This inconsistency is not a reflection of the quality of Garmin's AOA products, but rather an inherent limitation of civilian AOA systems in stalled flight conditions. Therefore, while AOA indicators can aid in stall prevention and recovery, they should not be viewed as the ultimate solution.
The Importance of Upset Awareness and Prevention in Skidded Turn Stalls
The primary purpose of practicing the Skidded Turn Stall is to emphasize Upset Awareness and Upset Prevention. As demonstrated in the video, even with an ideal recovery technique, the aircraft uses approximately 800' of altitude to recover from the situation. This highlights the fact that if an aerodynamic stall occurs during a circle to land or in the latter base/final legs of the traffic pattern, there may not be enough altitude or time available to survive. Therefore, comprehensive UPRT solutions must focus on Upset Awareness and Prevention.
The Necessity of Upset Recovery Training in Skidded Turn Stalls
Despite the emphasis on prevention, Upset Recovery Training remains a vital part of stall training. Pilots must witness the fully evolved aerodynamic stall event to gain an ingrained understanding of stall prevention. Proper stall training should include the escalation of the flight condition from slow flight, to approach to stall, to stall (coordinated and uncoordinated), followed by repetitive preventive and recovery intervention training at each phase of the escalation.
Why Not Pull More G During Recovery in Skidded Turn Stalls?
A common question arises as to why the pilot doesn't pull more G during the recovery. The answer lies in the airspeed available post-stall. To minimize altitude loss in a dive recovery post-stall, pilots must ensure the wings are level, load the airplane to a maximum AOA that falls short of the Critical AOA, and manage energy state by accelerating post-stall while maximizing lift yet keeping airspeed below Va throughout the dive portion of the recovery.
Post-Event Discipline in Skidded Turn Stalls
After any airplane upset, pilots must ensure the aircraft is stabilized in pitch, power, configuration, and trim before shifting their focus to other tasks. Only then can they safely begin to expand their situational awareness to tasks such as troubleshooting and longer-term strategies to get the airplane back on the ground safely.
Conclusion
Skidded Turn Stalls present a unique challenge to pilots. Through comprehensive UPRT, including on-aircraft training, pilots can gain the skills and knowledge necessary to safely navigate these complex situations. While tools like simulators and AOA indicators have their place, they cannot replace the value of hands-on experience and a strong focus on Upset Awareness and Prevention.
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References:
- Aviation Performance Solutions. (2021). S211 Skidded Turn Stall - Circle to Land Scenario. Retrieved from https://apstraining.com/resource/s211-skidded-turn-stall-circle-land-scenario/