OCF Flashcards
Stall + Yaw =
OCF - The moment in time when unexpected results occur from normal control inputs
Static Directional Stability
Can be positive, neutral or negative tendency to return to equilibrium after disturbance in horizontal plane
The 5 phases of OCF are?
Stall Departure Post-Departure Gyrations Incipient Phase of Spin Steady-State Spin
A stall occurs when?
When an increase in AOA produces a reduction in lift and an increase in drag.
Wing stalls when boundary layer separates from upper surface of wing.
Clean Stall Indications
Warning at 21.5 units / 10kts prior
Buffet at 25 units / 1-2kts prior
Stall at 26 units / 0kts prior
Takeoff Configuration Stall Indications
Warning at 21.5 units
Buffet onset at 26-27 units
Stall at 29-30 units
Approach Stall Indications
Warning at 21.5 units / 10kts prior
Buffet at 28 units / 1kt prior
Stall at 29-30 units / 0kts prior
Emergency Flap Stall Indications (stall airspeed 9-11kts greater than approach stall)
Warning at 21.5 units
No stall warning
Stall at 23-25 units
**Very disorienting, abrupt roll-off
Departure Definition
Departure is when aircraft transitions from controlled to uncontrolled flight or the moment when normal control inputs stop working or airspeed <85kts
CNATRA definition: Any time aircraft rolls uncommanded through 90°AOB following stall
Post Departure Gyration
Random/uncontrolled motions of aircraft about any axis after departure but before incipient phase
Incipient Phase
Initial phase characterized by: Stalled AOA Rotation in direction of spin Varying roll, yaw and pitch rates Average rotation rate slower than steady state
Steady State Spin
Final phase (self-sustaining spin) characterized by: Sustained auto-rotation Stalled AOA
Symptoms of impending departure
Mushy flight controls
Unresponsiveness to control inputs
Buffeting and buffet noise
Wing walk
Signs you have departed
Excessive yaw rate
Spinning or tumbling
Decaying airspeed and uncontrollable altitude loss
4 instruments to scan
Altimeter – time available
AOA – upright or inverted, type of recovery
Airspeed – stable indicates steady state spin
Turn needle – pegged in direction of spin
Upright Spin: Aircraft rolls and yaws in the same direction
Upright spin = stalled AOA + yaw
Inverted Spin: Aircraft rolls and yaws in opposite directions
Inverted spin = negative stalled AOA + yaw
Recovery occurs in exact opposite order of OCF progression. Use anti-spin controls to bring you from steady state spin to:
Incipient spin (AOA/needle pegged, speed oscillating)
Post-stall gyrations (AOA/needle/speed oscillating)
Departure (No response to control inputs)
Stall (AOA above stall)
Recovery (Controls neutral)
2 steps to recover
Reduce yaw rate
Reduce angle of attack
Progressive Spin: Occurs when aircraft enters second spin immediately following recovery from first spin.
Direction of rotation normally opposite original spin
May result from holding in anti-spin inputs after rotation stops, holding in aft stick during recovery, or initiating recovery pullout with insufficient airspeed or excessive AOA
High Speed Spiral: Not a spin. Characterized by…
Nose low attitude High roll rates Minor yaw rates AOA not pegged Airspeed increasing Turn needle in direction of roll/yaw
Pilot factors in OCF
Time distortion: perceived to be passing 5x faster than it really is
G-force distortion: unreliable “seat of pants” cues. You must disregard perceived G forces and trust your instruments
Control inputs: You must position all controls deliberately and visually check all controls for correct position
The two most important procedures to remember are?
NEUTRALIZE – IDLE
Accelerated Stall
Stalls entered with load factor >1G
Directional Departure
Caused by excessive or abrupt rudder application at low/moderate airspeeds. Limited stall warning.
Vertical Maneuvering Departures
> 90° pitch abruptly forward
<90° nose falls slightly backward
Avoid maneuvering within 20 degrees of vertical <100kts to prevent tail slide
Three inverted spin modes
- 60° AOA: 50-120kts, 1000ft loss, 3-4s spin rate
- 40° AOA: 100-160KTS, 1000ft loss, 3-4s spin rate
- 25° AOA: 140-200, 1700ft loss, 3-4s spin rate
Two upright spin modes
30° AOA: 150kts or greater/+10kts in turn, 1250ft loss, 6s spin rate
45° AOA: 100-110kts, 1000ft loss, 4s spin rate
Recovery from inverted spin
Full opposite rudder and lateral for -40 and -60 modes
Lateral stick pro-spin for -25 mode
Failure to neutralize lateral stick with airspeed increasing past 160kts may result in entry into the -25 AOA spin mode and delay recovery
Departure Checklist
Stall/Aero Checklist – Complete Lap belts – tighten Visor – down Rudder pedals – adjust aft for full throw Harness – locked Landing gear, flaps/slats – up, Boards – in Batt switches – On Control aug – SBI Altimeter, AOA, airspeed, turn needle – check operation ICS – Hot mic Throttle friction – Set Departure checklist complete
Post-Departure Checklist
Control AUG – All
Deep Stall Characteristics
Increasingly heavier buffeting as stall deepens Yaw rate Increasing sink rate Wing drop Reduced lateral control
Low airspeed departures
Occur any time airspeed is so low that aerodynamic forces are negligible and aircraft is functionally ballistic. Can occur above 0kts and in any nose-high attitude. Any lateral stick input at zero airspeed will introduce yaw rate
You will not initiate any low-airspeed departures within 20° of pure vertical
70° Nose High Departure
300kts, >14k
15-17 unit pull to 70°, power idle below 150kts
As aircraft departs, perform OCF procedures
Airspeed 0kts, nose falling
Recover at 150 to nearest horizon
110° Nose High Departure
350kts, >14k
15-17 unit pull to 110°, power idle below 150
As aircraft departs, OCF procedures
90° Nose High Departure
Same as 110° just wait for nose to get 90° nose low
Recover at 150
Pedal Turns
Clean, >18k, CONTR AUG in ALL
Slow to 21-22 AOA
MRT, hold 21-22
30° AOB turn using rudder only then reverse
Slow to 26 units
Rudder and aileron, attempt turns in both directions until departure
Wing Walk
An unintentional maneuver during approach, waveoff or takeoff where very high AOA and pitch attitude will result in loss of horizontal stab authority. The wing is positioned in a stall condition and the aircraft is kept aloft by the thrust vector. Ailerons or elevators remain marginally effective resulting in wing walk.
