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NCSA SAFETY SEMINAR, 2/11/06 STALL/SPINS: HUMAN FACTORS IN ACCIDENT PREVENTION Monique Weil.

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Presentation on theme: "NCSA SAFETY SEMINAR, 2/11/06 STALL/SPINS: HUMAN FACTORS IN ACCIDENT PREVENTION Monique Weil."— Presentation transcript:

1 NCSA SAFETY SEMINAR, 2/11/06 STALL/SPINS: HUMAN FACTORS IN ACCIDENT PREVENTION Monique Weil

2 STALLS: SIGNS OF APPROACHING STALL: * HIGH NOSE ATTITUDE {sight} * LOW AIRSPEED {sight} * LOW AIRFLOW NOISE {hearing} * BACK PRESSURE {feel} * MUSHY CONTROLS esp ailerons {feel} * PRE-STALL BUFFET {feel}

3 STALL RECOVERIES: Forward Stall recovery: stick forward to unstall;  pause; then return to normal glide attitude; Wing drop or turning stall recovery:  opposite rudder; stick forward to unstall; pause to regain flying speed; then stick and rudder to level wings. A SPIN is an asymmetric stall that results in autorotation; the aircraft descends in a corkscrew path, rolling and yawing in a spiral path. The three stages of a spin are: (1) incipient, (2) autorotation stage, and (3) recovery.

4 Spiral dive vs. Spin EFFECT: SPIRAL DIVE: SPIN: G FORCES: Increase approx constant BANK: Tends to Increase Constant or less AIRSPEED: Increase Constant DESCENT RATE: initially not high Very high YAW STRING: Straight Points to low wing RATE OF TURN: Depends on bank; High Rotation CONTROLS: Work OK Ailerons don't work PULLING: Increases G’s Pulling has No effect

5 Spiral Dive vs. Spin  SPIRAL DIVE: Reduce bank, then increase pitch; Pulling just tightens turn and increases Gs.  SPIN: (don't use spin recovery technique in spiral dive): 1. Full opposite rudder 2. Ailerons: neutral 3. Move stick forward until rotation stops; 4. Then centralize rudders; 5. Ease out of dive.

6 STRESS REDUCTION Monitoring stress levels should be part of your scan. Know your personal signs of stress; where you hold tension; relax your breathing, sing; task shedding. Plan options for safe landouts; review plan for emergencies; stay on oxygen until you land Know your personal limits; do not dwell on little mistakes; wiggle your toes; relax your grip; drink water; open the air vent; watch for tunnel vision.

7 STRESS REDUCTION  Free your brain from harmful effects of negative stress to make it function at its best.  Concentrate on the goal rather than how nervous you are feeling, or the bad things that could happen.  Increase safety margins: A : analyze what you are trying to do C : choose from available options T : trust in the value of your perfect practice  Don't force concentration. Continually remind yourself of your goal rather than seeking ego gratification. Replace anxiety with positive imagery and positive self- talk.  Review checklists

8 STALL/SPINS: - HUMAN FACTORS in ACCIDENT PREVENTION 75% of all Fatal glider-related accidents were stall/spin in 2004 About 70% of all accidents and most stall/spin accidents occur in approach and landing phase. A sizable number of stall/spin accidents fall in the launch phase, with PT3 events being the majority. Level of flight experience and time in type varies in these accidents, from novices to highly experienced pilots The stall/spin is unexpected, resulting in serious injuries or death A stall can occur at any speed and in any attitude, when there is loss of airflow over the wing when the critical angle of attack has been exceeded. The purpose of practicing slow flight and stalls is not just to perfect the maneuvers but to really study the signs of approaching stalls in all the sailplanes you fly, in order to prevent the stall from happening.

9 STALL/SPINS: - HUMAN FACTORS in ACCIDENT PREVENTION When we practice stalls at 3,000' we hardly notice the altitude lost in recovery. At low altitude we are instinctively more reluctant to relax back pressure. A spin occurs when the aircraft stalls asymmetrically, with one wing stalling before the other and the glider rolls and banks toward the stalled wing, thus starting an incipient spin. The purpose of practicing incipient and full spins Is to recognize how a spin can happen, how the incipient spin feels and especially how to prevent a spin from developing and how to recover with minimum altitude loss.

10 Remember that there can be no spin if there is no stall. This is why it is crucial for the pilot to develop a sixth sense of what an approaching stall feels like and the ability to recover with a minimum loss of height. The most likely way that a spin can be caused accidentally is to enter a turn with too low an airspeed; The nervous pilot turning from base onto final approach is reluctant to bank the aircraft steeply enough to complete the required turn so he attempts to increase the rate of turn with the rudder. The pilot, still reluctant to bank the aircraft, tries to remove the extra bank with aileron; The pilot panics and pulls back on the stick; stall/spin is the result.

11 Train yourself to avoid these errors. Don't delay the decision to plan for the landing If it becomes impossible to reach the goal, select a new landing spot and the process begun again. Pilots can learn to prevent an error from escalating into an accident. Monitor your stress levels, use check lists and practice stress reduction techniques; loosen your grip; breathe; keep a good lookout; avoid tunnel vision. Make sure you include the letter "E" to the pre-takeoff check list - a reminder to concentrate on the emergency plan of a action for when the PT3 occurs. Be on" Orange Alert" during any low altitude flying. Maintain a high safety margin and an adequate approach speed at all times below 500'AGL. Avoid low altitude thermalling attempts; Use medium banked coordinated turns on base to final turns, as the turn rate is greater and stall in unlikely;

12 If it becomes impossible to reach the goal, select a new landing spot and the process begun again. Pilots can learn to prevent an error from escalating into an accident. Monitor your stress levels, use check lists and practice stress reduction techniques; loosen your grip; breathe; keep a good lookout; avoid tunnel vision. Make sure you include the letter "E" to the pre-takeoff check list - a reminder to concentrate on the emergency plan of action for when the PT3 occurs. Be on" Orange Alert" during any low altitude flying. Maintain a high safety margin and an adequate approach speed at all times below 500'AGL. Avoid low altitude thermalling attempts; Use medium banked coordinated turns on base to final turns, as the turn rate is greater and stall in unlikely

13 LOW AIRSPEED, SKIDDING TURNS AT LOW ALTITUDE RESULTS IN STALL/SPIN ACCIDENTS, WHICH KILL PEOPLE. You do not want to see this NTSB report of the probable cause: "FAILURE OF THE PILOT IN COMMAND TO MAINTAIN ADEQUATE AIRSPEED, RESULTING IN AN INADVERTENT STALL AND SPIN". Understand that it is a natural instinctive reaction to want to pull the stick back when the ground is approaching. Repeated training, simulated emergencies, together with practice may help the pilot use correct techniques of moving the stick forward, rather than pulling back when the unexpected happens.


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