WINDSHEAR RECOVERY

CHAPTER 04

Windshear Recovery

If windshear is encountered during take off roll or during initial climb, the following actions should be taken without delay:​

Before V1 :

The take off should be rejected if unacceptable airspeed variations occur (not exceeding the target V1) and if there is insufficient runway remaining to stop the airplane

After V1 :

• Disconnect autothrottles (A/THR), if availbale, and maintain or set the throttlr levers to maximum take off thrust;
• Rotate normallt at VR; and
• Follow the FD pitch command if the FD pitch command provides wind shear recovery guidance, or set the required pitch attitude (as recommended in the AOM/QRH)

 

Cont. . .

 

During initial Climb:

• Disconnect A/TRH (if available), and maintain or set the throttle levers to            maximum take off thrust;
• If the Autopilot (AP) is engaged and if the FD provides windshear recovery   guidance, keep the AP engaged; or follow the FD pitch command, if the FD      windshear recovery guidance; or
• Set the required pitch attitude (as recommended in the AOM/QRH);
• Level the wings to maximize the climb gradient, unless a turn is required   for obstacle clearance;
• Closely monitor the airspeed, airspeed trend and flight-path angle (as  available)
• Allow airspeed to decrease to stick shaker onset (intermittent stick shaker        activation) while monitoring airspeed trend;
• Do NOT change the flaps or landing-gear configuartions until out of the  windshear condition; and
• When out of the windshear condition, increase airspeed  when a positive  climb is confirmed, retract the landing gear, flaps and slats, then establish   a normal climb profile

Cont. . .

 

Windshear is associated usually with the following weather conditions:

• Jet streams
• Mountain waves
• Frontal surfaces
• Thunderstorms and convective clouds, and
• Microburst

Microburst present two distinct threats to aviation safety:

 

A downburst that results in strong downdrafts (reaching 40 knots vertical velocity)  A down

 

An outburst that results in strong horizontal wind shear and wind-component reversal (with horizontal winds reaching 100 knots)

 

 

SUMMARY

 

Definition of windshear, is a sudden change of wind velocity/direction.

 

Type of windshear:

• Vertical windshear (vertical variations of the horizontal wind component, resulting in turbulence and affecting aircraft speed when climbing or decending through the shear layer), and

 

• Horizontal wind shear (horizontal variations of the wind component (eg. Decreasing headwind or increasing tailwind, or shift from a headwind to a tail wind), affecting the aircraft in level flight, climb or descent)

 

Take-off Precautions

 

• Use maximum rated take-off thrust
• Use longest suitable runway
• Consider using recommended flap setting
• Consider using increased rotation airspeed
• Do NOT use speed referenced flight director 

summary.....

Approach Precautions:

 

• Stabilize approach no later than 1000 ft AGL
• Minimize thrust reductions
• Use most suitable runway
• Consider using increased approach speed
• Use autoflight systems during approach

summary.....

1. Advisory Circular, AC 00-54, Pilot Windshear Guide
2. ALAR Toolkit, FSA ALAR Briefing Note, 5.4 – Windshear
3. General Aviation Pilot's Guide to Preflight Weather Planning
4. Weather self briefing, and weather decision making, FAA

bibliography.....

End of Chapter 04