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Low-Altitude Wind Shear and Its Hazard to Aviation (1983) / Chapter Skim
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Appendix B: Example of a Modern Wind-Shear Penetration System
Pages 93-96

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From page 93...
... Some of the features employed to achieve these ob ject Ives are as follows: o Tight airspeed control using true airspeed and inertial acceleration along the f light path as the primary feedback variables . The second derivative of wind speed between wind shears and turbulence.
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From page 94...
... plus the airspeed error and is therefore responsive to wind shear conditions. The FCC controls airspeed with elevator much the same as the takeoff flight director, except that the initial rotation (until 100-feet altitude and sufficiently positive vertical speed are attained)
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From page 95...
... The control law uses filtered airspeed, inertial acceleration along the flight path, and vertical speed as active feedbacks, plus, when under minspeed control, angle of attack derived from a vane with the high-frequency vertical wind component filtered. Additionally, minspeed control employs inertial data and control/ configuration information to remove angle-of-attack variations not associated with speed changes.
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From page 96...
... When any automatic speed control mode is engaged, the fast/slow indicator reflects the difference between airspeed ~ less high- frequency wind component ~ and the greater of the MCP speed or minspeed, and therefore acts as a clean signal for monitoring airspeed control. If the MCP selected speed is less than minspeed and airspeed is less than 3 knots above minspeed, the mode annunciated changes to ALPHA to advise the pilot why the automatic system is no longer clos ing on the selected speed.
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Key Terms

  • flight director
  • flight path
  • inertial acceleration
  • level flight
  • inertial data

  • wind shear
  • airspeed control
  • maintain level
  • wind component
  • vertical wind

  • minspeed control
  • insufficient energy
  • positive vertical
  • initial rotation
  • air data

  • airspeed error
  • speed control
  • predictive term
  • automatic landing
  • inertial vertical

  • reference unit
  • inertial reference
  • automatic speed
  • true airspeed
  • speed increases

  • shear conditions
  • target set
  • fcc mode
  • spl ays
  • wind variations


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