The meteorology course built the physics: wind shear as a change of the wind vector between two points, and the low-level kind, met on the final approach or the take-off and initial climb path, as the operationally vital subset. The principles-of-flight course built the wake: the trailing vortex pair every lifting wing drags behind it. This lesson owns what the crew does about both.
Recognising low-level wind shear
Low-level wind shear announces itself on three channels, and recognition means listening to all of them. The first is the forecast and reported picture: wind-shear warnings, SIGMETs, ATIS remarks, and above all the reports of preceding aircraft, the most current data an approach ever gets. The second is the visible convective evidencethe meteorology course catalogued: the gust front running ahead of a storm, roll clouds, blowing dust rings, virga under a cell, and windsocks around the field disagreeing with each other, the classic signature of a downburst's outflow. The third channel is the aircraft itself: uncommanded excursions from the stabilised picture, airspeed jumping or falling with no power change, groundspeed and airspeed diverging, vertical speed swinging, thrust far from the usual setting for the profile, and, where fitted, the ground proximity warning system's (GPWS) windshear warning mode, whose workings the instrumentation course's alerting lessons taught.
Escaping the shear
The effects come straight from the meteorology course's inertia mechanism: crossing a shear, the aircraft keeps its speed over the ground for a moment while the air changes, so a headwind gain balloons it above the path and a headwind loss or tailwind gain drops the airspeed and lift and sinks it below, and near the ground the sink is the killer. The actions when shear is actually met are the type's windshear escape manoeuvre, flown as the manufacturer's procedure prescribes: maximum thrust, wings level, pitch flown toward the climb attitude and to the margin of the stall warning when the performance demands it, and the configuration left unchanged until clear of the shear. On approach the encounter means an immediate go-around: no attempt to recapture a glidepath the air has stolen. The same drill answers entry into a strong downdraft: the aircraft rides descending air, sinking at unchanged attitude and airspeed, and whether it can out-climb the air is a performance bet, so the escape is flown at the margin and the bet avoided in the first place wherever the choice exists.
When shear is merely suspected, the precautions are cheaper than the cure: delay the take-off or the approach and let the cell pass, since the convective shear-makers move through in minutes; choose the longest suitable runway and the one best oriented against the reported shear; use the type's recommended configuration and any speed additive the AFM provides; brief the escape manoeuvre before it is needed; and monitor the groundspeed-airspeed pair through the approach, the earliest instrument evidence there is. A current microburst alert is not a challenge; it is a reason to hold.
The microburst
The meteorology course's downbursts lesson built the machine: a microburst is an intense, small-scale downdraught from a convective cell that strikes the ground and spreads radially outward, in the dry variant driven by evaporation with no rain ever reaching the surface. Operationally it is the complete shear sequence in one crossing: entering the outflow gives a headwind gain and a tempting balloon above profile, the core gives the downdraft, and the exit gives a tailwind, airspeed and lift collapsing exactly when the aircraft is lowest and slowest. Its scale is the trap: small enough to sit inside the aerodrome boundary, brief enough to appear and die between two wind reports, violent enough to defeat the performance of anything crossing it low.
The wake behind the wing
To the aircraft flying behind, the trailing vortex pair is wake turbulence, and the principles course taught why it is feared: an aircraft entering a vortex near its core is rolled, and a strong enough vortex rolls it against full opposite aileron. The circulation is the wingtip's doing: the pressure difference escapes around each tip and rolls up into two counter-rotating columns a short way inside the wingtips. Generation begins at rotation, when the wing starts lifting, and ends at touchdown. Behind the aircraft the pair sinks, typically levelling off 500 to 1,000 ft below the flight path; near the ground it can sink no further and the vortices move apart sideways, one toward each side of the runway, while a crosswind can hold the upwind vortex stubbornly over the runway, the wind cancelling that vortex's outward drift, or carry the downwind one onto a parallel runway, the wind doubling its drift. In calm air the pair persists for minutes; strong wind and turbulence tear it up.
Strong wakes and bad winds
The severity logic reads off the vortex-strength physics, and three factors combined give the strongest wake: heavy, clean and slow. Weight is the dominant factor, more lift meaning stronger vortices, which is why the separation categories run on mass; a slow wing works at high lift coefficient and winds the vortex tighter; and a clean wing concentrates the shed circulation at the tips instead of distributing it along flaps. That is precisely a large aircraft just after rotation or on an intermediate approach: the aircraft ahead of you at exactly the moments you are lowest. The worst wind near the ground is a light crosswind, around the vortex's own sideways drift speed, because it holds one vortex in place on or near the runway while calm air lets the pair live longest; a strong wind is the friendly case, breaking the wake up.
Keeping clear
The first line of defence is the separation table the air-law course taught from the PANS-ATM, distance-based and run on the categories: behind a SUPER, a HEAVY needs 9.3 km (5.0 NM), a MEDIUM 13 km (7.0 NM) and a LIGHT 14.9 km (8.0 NM); behind a HEAVY, a HEAVY needs 7.4 km (4.0 NM), a MEDIUM 9.3 km (5.0 NM) and a LIGHT 11.1 km (6.0 NM); and a LIGHT behind a MEDIUM needs 9.3 km (5.0 NM). Where the minima are not applied, a visual arrival maintaining own separation among them, ATC issues a caution of possible wake turbulence and the pilot-in-command becomes responsible for the spacing, entitled to ask for more.
The second line is geometry, and every technique is a consequence of the facts already taught. The wake sinks below the leader's flight path, so the follower flies at or above the leader's path, displaced upwind where the wind allows. Generation begins at rotation, so a departing follower rotates before the heavy's rotation point and climbs above its path. Generation ends at touchdown, so a landing follower lands beyond the heavy's touchdown point, where no wake was ever laid. And because the ground-level vortices drift with the wind, the light-crosswind runway deserves the most suspicion, not the least.