[{"data":1,"prerenderedAt":440},["ShallowReactive",2],{"learn-\u002Flearn\u002Fwind-shear-explained":3,"learn-nav-\u002Flearn\u002Fwind-shear-explained":406},{"id":4,"title":5,"body":6,"date":349,"description":350,"draft":351,"extension":352,"faqs":353,"howTo":363,"keyTakeaways":363,"meta":364,"navigation":365,"path":366,"quiz":367,"seo":394,"series":363,"seriesOrder":363,"sources":395,"stem":403,"topic":404,"__hash__":405},"learn\u002Flearn\u002Fwind-shear-explained.md","Wind shear and low-level wind shear",{"type":7,"value":8,"toc":337},"minimark",[9,20,26,31,66,70,73,113,117,120,131,135,138,214,217,221,228,234,245,252,255,259,262,275,282,294,298,330,334],[10,11,12,19],"p",{},[13,14,18],"a",{"href":15,"className":16},"\u002Flearn\u002Fglossary#gt-wind-shear",[17],"glossary-link","Wind shear"," is a change in the wind over a short distance, and near the ground it is one of the few weather hazards that can overwhelm an aircraft faster than the crew can react. Understanding where it comes from is the first step to staying out of its way.",[21,22,23],"blockquote",{},[10,24,25],{},"This is general educational information, not operational, legal, or regulatory advice. Rules differ by authority and change over time. Always verify against current official sources and follow your operator's approved procedures.",[27,28,30],"h2",{"id":29},"what-wind-shear-is","What wind shear is",[10,32,33,34,38,39,42,43,46,47,53,54,59,60,65],{},"Wind shear is a change in wind speed, wind direction, or both, over a short distance. It can be ",[35,36,37],"strong",{},"vertical",", between one height and another, or ",[35,40,41],{},"horizontal",", across a boundary such as a front. It exists at all levels, including the clear-air turbulence near a jet stream, but the dangerous kind for most flying is ",[35,44,45],{},"low-level wind shear",": shear close to the ground, where take-off and approach leave no height and little time to recover. The ",[13,48,52],{"href":49,"rel":50},"https:\u002F\u002Fwww.faa.gov\u002Fregulationspolicies\u002Fhandbooksmanuals\u002Faviation\u002Ffaa-h-8083-28b-aviation-weather-handbook",[51],"nofollow","FAA Aviation Weather Handbook (FAA-H-8083-28)"," and the long-standing ",[13,55,58],{"href":56,"rel":57},"https:\u002F\u002Fwww.faa.gov\u002Fregulations_policies\u002Fadvisory_circulars",[51],"FAA Pilot Wind Shear Guide, AC 00-54",", set out the hazard, and the international reference is ",[13,61,64],{"href":62,"rel":63},"https:\u002F\u002Fskybrary.aero\u002Farticles\u002Flow-level-wind-shear",[51],"ICAO Doc 9817, the Manual on Low-level Wind Shear",".",[27,67,69],{"id":68},"where-it-comes-from","Where it comes from",[10,71,72],{},"Low-level wind shear has several sources, and knowing them tells you when to expect it:",[74,75,76,83,89,95,101,107],"ul",{},[77,78,79,82],"li",{},[35,80,81],{},"Thunderstorms."," The downdraft, gust front, and microburst of a thunderstorm are the most violent source of shear. A thunderstorm anywhere near the airfield is a shear warning.",[77,84,85,88],{},[35,86,87],{},"Microbursts and downbursts."," A concentrated downdraft, often less than a couple of miles across, that hits the ground and fans out. It is the classic killer on approach.",[77,90,91,94],{},[35,92,93],{},"Frontal surfaces."," A sharp front, especially a fast-moving cold front, separates two different wind regimes, and crossing it brings a change of wind.",[77,96,97,100],{},[35,98,99],{},"Temperature inversions."," On a clear, calm night the air near the ground cools and decouples from a faster flow just above it, the low-level jet, producing marked shear at the top of the inversion that can persist into the morning.",[77,102,103,106],{},[35,104,105],{},"Terrain and obstacles."," Hills, buildings, and tree lines disturb the wind and create mechanical shear and turbulence near the surface.",[77,108,109,112],{},[35,110,111],{},"Sea breezes."," The boundary between cool sea air and warm land air is another shear line.",[27,114,116],{"id":115},"what-it-does-to-the-aircraft","What it does to the aircraft",[10,118,119],{},"The reason shear is dangerous is that an aircraft flies on its airspeed, not its ground speed, and shear changes airspeed suddenly.",[10,121,122,123,126,127,130],{},"Picture an approach into a microburst. On the way in, the aircraft meets an ",[35,124,125],{},"increasing headwind",". Airspeed rises, the aircraft tends to balloon above the glidepath, and the natural reaction is to reduce power and push down. Moments later the aircraft passes through the core and out the far side into the ",[35,128,129],{},"downdraft and a tailwind",". Now the airspeed falls away, lift is lost, and the aircraft sinks, exactly when it is low, slow, and configured to land, and possibly with the power already reduced from the first part. That headwind-to-tailwind reversal, over a few seconds, is what makes the microburst so lethal. The trained response is to recognise it early and go around with maximum available thrust, not to chase the airspeed.",[27,132,134],{"id":133},"how-it-is-warned-about-and-forecast","How it is warned about and forecast",[10,136,137],{},"Several systems and products flag wind shear:",[74,139,140,152,164,191],{},[77,141,142,145,146,151],{},[35,143,144],{},"Ground-based detection."," Larger airports use a Low Level Wind Shear Alert System (LLWAS) and Terminal Doppler Weather Radar (TDWR), and controllers pass the alerts to you, often through the ",[13,147,150],{"href":148,"className":149},"\u002Flearn\u002Fglossary#gt-atis",[17],"ATIS"," or directly.",[77,153,154,157,158,163],{},[35,155,156],{},"Pilot reports."," A crew that meets shear should and often does report it, and a ",[13,159,162],{"href":160,"className":161},"\u002Flearn\u002Fglossary#gt-pirep",[17],"PIREP"," of a gain or loss of airspeed on final is a direct warning to those behind.",[77,165,166,169,170,175,176,181,182,186,187,190],{},[35,167,168],{},"The wind shear group in a forecast."," A ",[13,171,174],{"href":172,"className":173},"\u002Flearn\u002Fglossary#gt-taf",[17],"TAF"," or ",[13,177,180],{"href":178,"className":179},"\u002Flearn\u002Fglossary#gt-metar",[17],"METAR"," can carry a ",[183,184,185],"code",{},"WS"," group, for example ",[183,188,189],{},"WS R24"," for shear reported on the approach to runway 24, or a non-convective low-level wind shear line in a TAF.",[77,192,193,201,202,207,208,213],{},[35,194,195,200],{},[13,196,199],{"href":197,"className":198},"\u002Flearn\u002Fglossary#gt-airmet",[17],"AIRMET"," Tango"," and convective warnings. Non-convective low-level wind shear can be forecast in an AIRMET, while any convective ",[13,203,206],{"href":204,"className":205},"\u002Flearn\u002Fglossary#gt-sigmet",[17],"SIGMET"," implies a shear risk too. The ",[13,209,212],{"href":210,"rel":211},"https:\u002F\u002Fwww.faa.gov\u002Fair_traffic\u002Fpublications\u002Fatpubs\u002Faim_html\u002Fchap7_section_1.html",[51],"FAA Aeronautical Information Manual"," describes these products.",[10,215,216],{},"A worked cue: if the ATIS reports a thunderstorm in the vicinity, or the surface wind is strong and gusty while a different wind is forecast just above, or a preceding aircraft reports a loss of airspeed on short final, treat all three as shear until proven otherwise.",[27,218,220],{"id":219},"the-microburst-on-approach-step-by-step","The microburst on approach, step by step",[10,222,223,224,227],{},"It is worth walking through a microburst encounter on approach, because the sequence is counter-intuitive and the right response runs against the instinct of the moment. The ",[13,225,58],{"href":56,"rel":226},[51],", describes the pattern.",[10,229,230,231,233],{},"An aircraft on a stable approach enters the outflow of a microburst and meets, first, an ",[35,232,125],{},". The airspeed rises, the aircraft tends to climb above the glidepath, and the natural reaction is to reduce power and lower the nose to get back down. This is the trap, because the headwind is the leading edge of the event, not the whole of it.",[10,235,236,237,240,241,244],{},"Moments later the aircraft reaches the ",[35,238,239],{},"downdraft"," in the core, which pushes it down regardless of pitch, and then passes out the far side into a ",[35,242,243],{},"decreasing headwind that becomes a tailwind",". Now the airspeed falls away, the wing loses lift, and the aircraft sinks, often with the power already reduced from the first phase and the aircraft low, slow, and configured to land. The same wind that helped a few seconds ago is now taking energy away at the worst possible time.",[10,246,247,248,251],{},"The trained response is to recognise the situation early, from the airspeed excursions, the sink rate, and the deviation below the glidepath, and to ",[35,249,250],{},"go around with maximum available thrust",", following the pitch guidance for a wind shear escape and not changing the aircraft configuration until safely clear. The priority is energy and climb performance, not chasing the airspeed needle. The deeper lesson is that the only reliably safe way through a microburst is not to be in one: if the cues point to shear on the approach, the decision is to break it off and wait, because once you are in the core your margins are already small.",[10,253,254],{},"A second point follows. Because the headwind-then-tailwind reversal depends on flying through the outflow, the hazard is greatest close to the ground on take-off and landing, where there is least height to trade for airspeed. The same microburst at altitude is uncomfortable; on short final it is an emergency.",[27,256,258],{"id":257},"the-night-inversion-and-frontal-shear","The night inversion and frontal shear",[10,260,261],{},"Not all dangerous shear comes from thunderstorms. Two non-convective sources catch pilots out precisely because the weather looks benign.",[10,263,264,265,268,269,274],{},"The first is the ",[35,266,267],{},"nocturnal inversion and low-level jet",". On a clear, calm night the air near the ground cools and stops mixing with the faster-moving air a few hundred to a couple of thousand feet above it. The two layers decouple, and a marked shear sits at the top of the inversion, where a near-calm surface wind can sit beneath a 30 or 40 ",[13,270,273],{"href":271,"className":272},"\u002Flearn\u002Fglossary#gt-knot",[17],"knot"," flow aloft. A worked cue: a still, clear dawn with fog or mist forming, and a forecast wind well above the surface wind, is a classic setup for shear on an early climb-out or approach, even though nothing looks threatening.",[10,276,277,278,281],{},"The second is ",[35,279,280],{},"frontal shear",". A front is the boundary between two air masses with different winds, so crossing it, especially a sharp, fast-moving cold front, brings a change of wind direction and speed. The shear is strongest close to the frontal surface and is worth anticipating when a front is near the airfield around your arrival or departure.",[10,283,284,285,288,289,293],{},"In both cases the ",[13,286,58],{"href":56,"rel":287},[51],", and the ",[13,290,292],{"href":49,"rel":291},[51],"Aviation Weather Handbook"," make the same point: the absence of a thunderstorm does not mean the absence of shear. The clues are in the difference between the surface wind and the wind just above it, and in the presence of a front or a strong inversion.",[27,295,297],{"id":296},"common-pitfalls","Common pitfalls",[74,299,300,306,312,318,324],{},[77,301,302,305],{},[35,303,304],{},"Chasing airspeed in shear."," Reacting to the first increase by reducing power can leave you short of energy when the loss arrives. The answer is usually a go-around.",[77,307,308,311],{},[35,309,310],{},"Trusting a gap near a storm."," The gust front and outflow extend well beyond the visible cloud and rain.",[77,313,314,317],{},[35,315,316],{},"Forgetting the morning inversion."," A calm, clear night can leave marked shear at the top of the inversion well after sunrise.",[77,319,320,323],{},[35,321,322],{},"Ignoring a single PIREP."," One report of shear on final is enough to change your plan.",[77,325,326,329],{},[35,327,328],{},"Discounting terrain."," A strong wind across nearby hills or buildings produces shear and turbulence on short final.",[27,331,333],{"id":332},"in-pilot-efb","In Pilot EFB",[10,335,336],{},"Pilot EFB decodes the METAR and TAF for your airfields and keeps the raw text, so a wind shear group or a gusty surface wind that hints at shear is there in front of you, and it shows SIGMETs and AIRMETs, including the convective warnings that carry a shear risk. What it does not do is detect wind shear in real time: that comes from the airport's ground systems, from ATC, and from pilot reports, none of which a planning app receives. Use Pilot EFB to spot the risk while you plan, and rely on the live warnings and your own training in the air. Pilot EFB is offline-first and is not a certified Electronic Flight Bag; briefings you have pulled stay readable offline, while fetching fresh data needs a connection.",{"title":338,"searchDepth":339,"depth":339,"links":340},"",2,[341,342,343,344,345,346,347,348],{"id":29,"depth":339,"text":30},{"id":68,"depth":339,"text":69},{"id":115,"depth":339,"text":116},{"id":133,"depth":339,"text":134},{"id":219,"depth":339,"text":220},{"id":257,"depth":339,"text":258},{"id":296,"depth":339,"text":297},{"id":332,"depth":339,"text":333},"2026-05-07","What wind shear is, why microbursts and gust fronts are so dangerous near the ground, how it changes an aircraft's performance, and the warnings and forecasts that flag it.",false,"md",[354,357,360],{"q":355,"a":356},"What is wind shear?","Wind shear is a change in wind speed or direction over a short distance, either horizontally or vertically. It matters most close to the ground, on take-off and approach, where there is little height to recover if the aircraft's airspeed and lift change suddenly. It can come from thunderstorms, fronts, temperature inversions, or terrain.",{"q":358,"a":359},"Why is a microburst so dangerous?","A microburst is a small, intense downdraft that hits the ground and spreads out. An aircraft flying through it first meets an increasing headwind, which lifts it and adds airspeed, then passes into the downdraft and the tailwind on the far side, which strips that airspeed and lift away at the worst possible moment near the runway. The change can be tens of knots in seconds.",{"q":361,"a":362},"How am I warned about wind shear?","Through several channels: ground systems such as a low-level wind shear alert system or terminal Doppler radar that pass alerts through ATC, pilot reports of shear, the wind shear group in a TAF or METAR, and forecasts of non-convective low-level wind shear in an AIRMET. Thunderstorms always carry a shear risk, so a convective warning is also a shear warning.",null,{},true,"\u002Flearn\u002Fwind-shear-explained",[368,377,385],{"q":369,"options":370,"answer":375,"explanation":376},"What is the most dangerous kind of wind shear for most flying?",[371,372,373,374],"Clear-air turbulence near the jet stream","Low-level wind shear close to the ground","Shear between two cruise altitudes","Horizontal shear across a high-altitude front",1,"Shear exists at all levels, but the dangerous kind for most flying is low-level wind shear close to the ground, where take-off and approach leave no height and little time to recover.",{"q":378,"options":379,"answer":339,"explanation":384},"As an aircraft flies through a microburst on approach, what sequence does it meet?",[380,381,382,383],"A tailwind first, then a headwind","A steady crosswind throughout","An increasing headwind first, then a downdraft and a tailwind","A downdraft only, with no wind change","The aircraft first meets an increasing headwind that lifts it and adds airspeed, then passes into the downdraft and tailwind on the far side, which strips airspeed and lift away. That headwind-to-tailwind reversal is what makes the microburst so lethal.",{"q":386,"options":387,"answer":392,"explanation":393},"What is the trained response to a microburst encounter on approach?",[388,389,390,391],"Go around with maximum available thrust","Reduce power and chase the airspeed needle","Lower the nose to regain the glidepath","Change configuration immediately to slow down",0,"The trained response is to recognise the situation early and go around with maximum available thrust, following the pitch guidance for a wind shear escape and not changing configuration until safely clear. The priority is energy and climb performance, not chasing the airspeed.",{"title":5,"description":350},[396,397,399,401],{"label":52,"url":49},{"label":398,"url":56},"FAA Advisory Circulars (AC 00-54, Pilot Wind Shear Guide)",{"label":400,"url":210},"FAA Aeronautical Information Manual, Chapter 7 Section 1 (Meteorology)",{"label":402,"url":62},"ICAO: Doc 9817, Manual on Low-level Wind Shear","learn\u002Fwind-shear-explained","Weather","rYyeicHxuhpotQolfqzIzzbncRHkHEZtB02Ip0kwE0c",{"related":407,"newer":426,"older":434,"series":363},[408,414,418],{"path":409,"title":410,"description":411,"date":412,"topic":404,"draft":351,"minutes":413,"series":363,"seriesOrder":363},"\u002Flearn\u002Freading-a-surface-analysis-chart","How to read a surface analysis chart","Decode a surface analysis chart: isobars and the pressure gradient, highs and lows, warm, cold and occluded fronts, and what the big picture tells you before you read the METAR.","2026-06-20",3,{"path":415,"title":416,"description":417,"date":412,"topic":404,"draft":351,"minutes":413,"series":363,"seriesOrder":363},"\u002Flearn\u002Fthe-international-standard-atmosphere","The International Standard Atmosphere (ISA)","What the ICAO International Standard Atmosphere is, its sea-level values and lapse rate, and how ISA deviation underpins altimetry, performance and density altitude.",{"path":419,"title":420,"description":421,"date":422,"topic":404,"draft":351,"minutes":423,"series":424,"seriesOrder":425},"\u002Flearn\u002Fhow-to-read-a-sigmet-and-airmet","How to read a SIGMET and an AIRMET","What SIGMETs and AIRMETs warn of, the phenomena codes, how long each stays valid, and a worked SIGMET decoded field by field, with the ICAO baseline and the US differences.","2026-06-18",5,"decode-the-weather",4,{"path":427,"title":428,"description":429,"date":430,"topic":431,"draft":351,"minutes":432,"series":433,"seriesOrder":413},"\u002Flearn\u002Frest-requirements-explained","Rest requirements and minimum rest","What counts as a rest period, how EASA and the FAA set the minimum rest before a duty, the idea of a sleep opportunity, and the weekly rest that protects against cumulative fatigue.","2026-05-10","Regulations",7,"duty-rest-and-flight-time-limits",{"path":435,"title":436,"description":437,"date":438,"topic":439,"draft":351,"minutes":432,"series":363,"seriesOrder":363},"\u002Flearn\u002Fhow-aviation-data-goes-stale","How aviation data goes stale","Every weather and NOTAM product has an issue time and a validity, and once you are offline you hold a snapshot. Here is how METARs, TAFs and NOTAMs expire, and why the timestamp matters.","2026-05-04","Briefing",1781989193389]