8
$\begingroup$

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?

$\endgroup$
8
$\begingroup$

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).

$\endgroup$
  • 2
    $\begingroup$ don't forget that the downdraft of the microburst itself also affects the airplane to compound the problem $\endgroup$ – falstro May 13 '14 at 11:05
  • $\begingroup$ While this answer addresses microbursts, which are certainly the most dangerous, it doesn't address the more common types of windshear which pilots encounter on a regular basis. $\endgroup$ – Bret Copeland May 13 '14 at 18:00
  • $\begingroup$ The reactive windshear algorithm uses both air data and inertial data to identify the presence of windshear. $\endgroup$ – Gerry Jul 6 '17 at 22:33
4
$\begingroup$

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.

$\endgroup$
0
$\begingroup$

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

$\endgroup$
  • $\begingroup$ would you happen to have a source for that? it seems to be quoted from somewhere. $\endgroup$ – Federico Feb 18 at 12:43
  • $\begingroup$ No..from my own experience and reading of various aircraft flight manuals which I was was qualified to fly. $\endgroup$ – M BA Feb 18 at 12:47
  • 3
    $\begingroup$ In that case, it would probably be best to write this answer in ordinary English instead of writing it in the style of a flight manual. As your answer is written, people who see your answer are going to think it's a quote from one particular aircraft's manual. $\endgroup$ – Tanner Swett Feb 18 at 14:37

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.