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Figure 17-10. The OODA Loop.
F
igure 1-8. The Observation, Orientation, Decision, Action (OODA Loop).ACTOBSERVEORIENTDECIDE
Orient, the second node of the Loop, focuses the pilot’s attention on one or more discrepancies in the flight. For example, there is a low oil pressure reading. The pilot is aware of this deviation and considers available options in view of potential hazards to continued flight.
The pilot then moves to the third node, Decide, in which he or she makes a positive determination about a specific effect. That decision is made based on experience and knowledge of potential results, and to take that particular action will produce the desired result. The pilot then Acts on that decision, making a physical input to cause the aircraft to react in the desired fashion.
Once the loop has been completed, the pilot is once again in the Observe position. The assessment of the resulting action is added to the previously perceived aspects of the flight to further define the flight’s progress. The advantage of the OODA Loop model is that it may be cumulative, as well as having the potential of allowing for multiple progressions to occur at any given point in the flight.
The DECIDE Model
Using the acronym “DECIDE,” the six-step process DECIDE Model is another continuous loop process that provides the pilot with a logical way of making decisions. [Figure 17-11] DECIDE means to Detect, Estimate, Choose a course of action, Identify solutions, Do the necessary actions, and Evaluate the effects of the actions.
First, consider a recent accident involving a Piper Apache (PA-23). The aircraft was substantially damaged during impact with terrain at a local airport in Alabama. The certificated airline transport pilot (ATP) received minor injuries and the certificated private pilot was not injured. The private pilot was receiving a checkride from the ATP (who was also a designated examiner) for a commercial pilot certificate with a multi-engine rating. After performing airwork at altitude, they returned to the airport and the private pilot performed a single-engine approach to a full stop landing. He then taxied back for takeoff, performed a short field takeoff, and then joined the traffic pattern to return for another landing. During the approach for the second landing, the ATP simulated a right engine failure by reducing power on the right engine to zero thrust. This caused the aircraft to yaw right.
The procedure to identify the failed engine is a two-step process. First, bring power to maximum controllable on both engines. Because the left engine is the only engine delivering thrust, the yaw increases to the right, which necessitates application of additional left rudder application. The failed engine is the side that requires no rudder pressure, in this case the right engine. Second, having identified the failed right engine, the procedure is to feather the right engine and adjust power to maintain descent angle to a landing.
However, in this case the pilot feathered the left engine because he assumed the engine failure was a left engine failure. During twin-engine training, the left engine out is emphasized more than the right engine because the left engine on most light twins is the critical engine. This is due to multiengine airplanes being subject to P-factor, as are single-engine airplanes. The descending propeller blade of each engine will produce greater thrust than the ascending blade when the airplane is operated under power and at positive angles of attack. The descending propeller blade of the right engine is also a greater distance from the center of gravity, and therefore has a longer moment arm than the descending propeller blade of the left engine. As a result, failure of the left engine will result in the most asymmetrical thrust (adverse yaw) because the right engine will be providing the remaining thrust. Many twins are designed with a counter-rotating right engine. With this design, the degree of asymmetrical thrust is the same with either engine inoperative. Neither engine is more critical than the other.
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1.
2.3.45.6.The DECIDE ModelAeronautical Decision-MakingA. AnalyticalB. Automatic/NaturalisticEvaluation of eventOutcome desiredWhat is best action to doEffect of decisionDetectionSituationPilotAircraftEnviromentExternal Factors• Risk or hazard• Potential outcomes• Capabilities of pilot• Aircraft capabilities• Outside factorsSolutions to get you thereSolution 1Solution 2Solution 3Solution 4Problem remainsDoneEvaluation of eventOutcome desiredTake actionDetectionPilotAircraftEnviromentExternal Factors• Risk to flight• Pilot training• Pilot experienceSuccessful
Figure 17-11. The DECIDE model has been recognized worldwide. Its application is illustrated in A while automatic/naturalistic decision-making is shown in B.
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Since the pilot never executed the first step of identifying which engine failed, he feathered the left engine and set the right engine at zero thrust. This essentially restricted the aircraft to a controlled glide. Upon realizing that he was not going to make the runway, the pilot increased power to both engines causing an enormous yaw to the left (the left propeller was feathered) whereupon the aircraft started to turn left. In desperation, the instructor closed both throttles and the aircraft hit the ground and was substantially damaged.
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Pilot's Handbook of Aeronautical Knowledge航空知识手册3(66)
