How does wind shear affect aircraft while landing and taking off? How do pilots detect that they are encountering wind shear and what would they have to do to prevent it from turning into a bad situation?
The most dangerous form of windshear for planes is the microburst. This is a downdraft that after it hits the ground spreads out in all directions. It is dangerous particularly for planes low to the ground (on takeoff and landing)
When a plane coming in for a landing approaches the microburst it will enter a headwind and see and increase of airspeed and lift, the inexperienced and unsuspecting pilot may then reduce engine power to slow down and keep himself aligned. After the plane passes through the burst it will enter a tailwind decreasing lift which may cause the plane to crash into the ground short of the runway.
To prevent crashing the pilot would need to keep power and possibly abort the approach to wait out the burst.
Detecting windshear from the ground is done with doppler radars (TDWR) and multiple wind sensors (LLWAS) which can detect the changes in wind which will be relayed to pilots in accordance with regulations (3-1-8).
All turbine powered airplanes used in §121 operations, except for turbopropeller powered airplanes, must have a windshear detection system installed, this is detected in one of 2 ways, using the onboard weather radar (predictive) or using the wind sensors on the aircraft like the angle of attack and airspeed (reactive).
Windshear recognition and recovery, both during takeoff and landing are regularly practiced in simulators. Recognition includes a sudden loss of airspeed or a sudden increase in airspeed (probably to be followed by a sudden loss). Recovery (at least back when I was flying) included going to max power while bringing the nose up until stick shaker activation, which condition you would fly in until through the shear.
As soon as uncommanded: speed deviation of 15-20kts. Vertical speed deviation and glide slope deviation of 1 dot and if EGPWS incorporates windshear call outs and Flight Director guidance for windshear recovery; SIMULTANEOUSLY:
DISCONNECT AUTO PILOT MAX THRUST FOLLOW FD GUIDANCE (or WINGS LEVEL MAX PITCH TO STICK SHAKER) DO NOT CHANGE CONFIG(EXCEPT SPEED BRAKES CLOSED IF THEY WERE OPEN) ADVISE ATC ADVISE CABIN