[{"data":1,"prerenderedAt":534},["ShallowReactive",2],{"learn-\u002Flearn\u002Frunway-visual-range-rvr":3,"learn-nav-\u002Flearn\u002Frunway-visual-range-rvr":495},{"id":4,"title":5,"body":6,"date":427,"dateModified":428,"description":429,"draft":430,"extension":431,"faqs":432,"howTo":428,"keyTakeaways":442,"meta":448,"metaDescription":449,"navigation":450,"path":451,"quiz":452,"seo":478,"series":479,"seriesOrder":480,"sources":481,"stem":492,"topic":493,"__hash__":494},"learn\u002Flearn\u002Frunway-visual-range-rvr.md","Runway visual range (RVR)",{"type":7,"value":8,"toc":414},"minimark",[9,13,19,24,50,54,67,99,106,110,123,145,156,160,188,237,260,264,276,280,295,314,318,347,368,372,404,408],[10,11,12],"p",{},"When the visibility drops low enough that landing becomes marginal, a single general figure for visibility is not precise enough. Pilots and controllers switch to a measured, runway-specific value: the runway visual range. It is one of the most safety-critical numbers in poor weather, and it is measured and reported in a particular way that is worth understanding.",[14,15,16],"blockquote",{},[10,17,18],{},"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.",[20,21,23],"h2",{"id":22},"what-rvr-actually-is","What RVR actually is",[10,25,26,29,30,33,34,37,38,41,42,49],{},[27,28,5],"strong",{}," is the distance over which the pilot of an aircraft ",[27,31,32],{},"on the centreline of a runway"," can see the ",[27,35,36],{},"runway surface markings",", or the ",[27,39,40],{},"lights"," delineating the runway or marking its centreline. The definition, set in ",[43,44,48],"a",{"href":45,"rel":46},"https:\u002F\u002Fstore.icao.int\u002Fen\u002Fannex-3-meteorological-service-for-international-air-navigation-1",[47],"nofollow","ICAO Annex 3",", ties it to a very specific viewpoint and target: not the general view across the aerodrome, but how far you can see down the runway you are about to land on. That makes it the right number for the moment that matters, the final stage of an approach in low visibility, when what counts is whether you will see the runway in time.",[20,51,53],{"id":52},"how-it-is-measured","How it is measured",[10,55,56,57,60,61,66],{},"RVR is not judged by eye; it is ",[27,58,59],{},"measured by instruments"," placed beside the runway, and there are two main types, described in ",[43,62,65],{"href":63,"rel":64},"https:\u002F\u002Fstore.icao.int\u002Fen\u002Fmanual-of-runway-visual-range-observing-and-reporting-practices-doc-9328",[47],"ICAO Doc 9328",":",[68,69,70,86],"ul",{},[71,72,73,74,77,78,81,82,85],"li",{},"a ",[27,75,76],{},"transmissometer"," measures how much light is ",[27,79,80],{},"lost"," travelling along a fixed ",[27,83,84],{},"baseline"," between a transmitter and a receiver, a direct measure of how the air is absorbing and scattering light;",[71,87,73,88,77,91,94,95,98],{},[27,89,90],{},"forward-scatter meter",[27,92,93],{},"scattered"," by particles in a small ",[27,96,97],{},"sample volume"," of air, and infers the visibility from that.",[10,100,101,102,105],{},"Most modern installations use forward-scatter meters, which are compact and need only a small sampled volume. Crucially, the system then converts the measured atmospheric clarity into an RVR by also accounting for the ",[27,103,104],{},"runway light intensity"," in use and the pilot's eye height, because a brighter light is visible further through the same murk.",[20,107,109],{"id":108},"rvr-versus-reported-visibility","RVR versus reported visibility",[10,111,112,113,122],{},"The distinction that trips people up is ",[27,114,115,116],{},"RVR versus the visibility in a ",[43,117,121],{"href":118,"className":119},"\u002Flearn\u002Fglossary#gt-metar",[120],"glossary-link","METAR",", and they are genuinely different things:",[68,124,125,135],{},[71,126,127,130,131,134],{},[27,128,129],{},"Reported (meteorological) visibility"," is the general visibility across the aerodrome, judged against ordinary unlit objects, and reported in the ",[43,132,121],{"href":133},"\u002Flearn\u002Fhow-to-read-a-metar"," visibility group;",[71,136,137,140,141,144],{},[27,138,139],{},"RVR"," is the runway-specific distance you can see the ",[27,142,143],{},"runway markings or lights"," from the centreline, measured by instrument and reported separately.",[10,146,147,148,151,152,155],{},"Because RVR accounts for the ",[27,149,150],{},"runway lighting",", it can read ",[27,153,154],{},"higher"," than the reported visibility, since high-intensity runway lights are visible further than unlit features in the same fog, especially at night. So a runway can have an RVR of several hundred metres while the general visibility is lower. They are measuring related but different things, and you do not substitute one for the other.",[20,157,159],{"id":158},"how-rvr-is-reported","How RVR is reported",[10,161,162,163,166,167,170,171,175,176,179,180,183,184,187],{},"RVR is reported when the visibility or the RVR itself falls below a threshold, around ",[27,164,165],{},"1,500 m"," under ICAO practice, and it appears in the METAR as an ",[27,168,169],{},"R-group",": the letter ",[172,173,174],"code",{},"R",", the runway, and the value in metres. So ",[172,177,178],{},"R27\u002F0550"," is runway 27 with an RVR of ",[27,181,182],{},"550 m",". The figure is given in ",[27,185,186],{},"steps"," rather than to the metre, finer steps at lower values and coarser steps higher up, and it can carry:",[68,189,190,212],{},[71,191,73,192,195,196,199,200,203,204,207,208,211],{},[27,193,194],{},"tendency"," letter, ",[172,197,198],{},"U"," for upward (improving), ",[172,201,202],{},"D"," for downward (deteriorating), ",[172,205,206],{},"N"," for no change, as in ",[172,209,210],{},"R27\u002F0550U",";",[71,213,73,214,217,218,221,222,217,225,228,229,232,233,236],{},[172,215,216],{},"P"," for ",[27,219,220],{},"more than"," or ",[172,223,224],{},"M",[27,226,227],{},"less than"," a value the system can measure, as in ",[172,230,231],{},"R27\u002FP2000"," (more than 2,000 m, the maximum the system reports) or ",[172,234,235],{},"R27\u002FM0050"," (less than 50 m, the minimum).",[10,238,239,240,243,244,247,248,251,252,255,256,259],{},"For a precision approach, RVR may be reported at the ",[27,241,242],{},"touchdown",", ",[27,245,246],{},"midpoint"," and ",[27,249,250],{},"stop-end"," of the runway, because the fog is rarely uniform and the touchdown value is the one that governs the approach. US reports give the value in ",[27,253,254],{},"feet"," with an ",[172,257,258],{},"FT"," suffix instead of metres.",[20,261,263],{"id":262},"when-rvr-matters","When RVR matters",[10,265,266,267,270,271,275],{},"RVR is the currency of ",[27,268,269],{},"low-visibility operations",". The categories of ",[43,272,274],{"href":273},"\u002Flearn\u002Fthe-ils-explained","ILS approach"," are defined partly in terms of the minimum RVR, and an approach's minima specify the RVR required to begin or continue it. In poor weather the touchdown RVR can be the single value that decides whether the approach is legal to fly, which is why it is measured so carefully and reported so promptly. It is the precise, runway-specific number that the coarser reported visibility cannot provide when every hundred metres counts.",[20,277,279],{"id":278},"what-rvr-does-not-tell-you","What RVR does not tell you",[10,281,282,283,286,287,290,291,294],{},"For all its precision, RVR has limits worth understanding. It is a ",[27,284,285],{},"horizontal"," measure, taken at instrument height beside the runway, and it is not the same as the ",[27,288,289],{},"slant visual range"," down the approach, the distance you can actually see along your descending line of sight. In a shallow fog or a thin layer, you can be looking ",[27,292,293],{},"down"," through it on the approach and see the lights at a slant, even while the horizontal RVR is low, or conversely lose the runway in a bank of fog the touchdown sensor has not yet caught. The RVR is the best standardised number available, but it describes the air at a point, not the whole approach.",[10,296,297,298,301,302,305,306,309,310,313],{},"It is also a ",[27,299,300],{},"point measurement"," that can ",[27,303,304],{},"vary along the runway",", which is exactly why a precision-approach runway reports ",[27,307,308],{},"touchdown, midpoint and stop-end"," values: fog is patchy, and one end can be far worse than the other. The touchdown value governs the approach, but the others tell you what to expect on the landing roll. Reading RVR well, then, means treating it as a precise but ",[27,311,312],{},"local and horizontal"," snapshot, and combining it with the cloud base, the trend and your own eyes rather than leaning on a single figure.",[20,315,317],{"id":316},"a-worked-example","A worked example",[10,319,320,321,323,324,327,328,330,331,334,335,338,339,342,343,346],{},"A METAR for a foggy morning includes the group ",[172,322,210],{},". Decoding it: runway ",[27,325,326],{},"27",", RVR ",[27,329,182],{},", with an ",[27,332,333],{},"upward"," tendency, so the visibility down the runway is ",[27,336,337],{},"550 m and improving",". The same report's general visibility group shows ",[172,340,341],{},"0400",", a meteorological visibility of ",[27,344,345],{},"400 m",".",[10,348,349,350,352,353,355,356,359,360,363,364,367],{},"The two numbers differ, and now you know why: the ",[27,351,345],{}," is the general visibility judged against unlit objects, while the ",[27,354,182],{}," RVR is how far the runway's high-intensity lights are visible from the centreline, which in fog is further than the unlit view. Neither is wrong; they measure different things. For deciding whether the approach to runway 27 may be flown, it is the ",[27,357,358],{},"touchdown RVR",", the 550 m, that is compared against the approach minima, not the general 400 m. A little later the report reads ",[172,361,362],{},"R27\u002F0800N",": the RVR is now ",[27,365,366],{},"800 m and steady",", the fog thinning down the runway. The single letter on the end told you which way the weather was going each time.",[20,369,371],{"id":370},"common-pitfalls","Common pitfalls",[68,373,374,380,386,392,398],{},[71,375,376,379],{},[27,377,378],{},"Treating RVR and reported visibility as the same."," RVR is runway-specific, instrument-measured and lighting-dependent; the METAR visibility is the general view.",[71,381,382,385],{},[27,383,384],{},"Ignoring the tendency letter."," U, D and N tell you whether the RVR is improving, worsening or steady, which matters as much as the value.",[71,387,388,391],{},[27,389,390],{},"Forgetting the units."," RVR is metres in the ICAO form and feet with FT in the US form; read the suffix.",[71,393,394,397],{},[27,395,396],{},"Using the wrong runway position."," Touchdown, midpoint and stop-end values can differ; the touchdown value usually governs the approach.",[71,399,400,403],{},[27,401,402],{},"Reading P and M as digits."," P means more than and M means less than the measurable limit, not a value to use directly.",[20,405,407],{"id":406},"in-pilot-efb","In Pilot EFB",[10,409,410,411,413],{},"Pilot EFB shows the decoded weather alongside the raw report, so the RVR group is explained in plain language while the original text is always kept, the same way it handles the rest of a ",[43,412,121],{"href":133},". A briefing you have already pulled stays readable away from a signal, and pulling a fresh observation needs a connection. Pilot EFB does not measure RVR or set your minima, and it is not a certified Electronic Flight Bag, so treat it as a study and planning aid and brief from your official source of record.",{"title":415,"searchDepth":416,"depth":416,"links":417},"",2,[418,419,420,421,422,423,424,425,426],{"id":22,"depth":416,"text":23},{"id":52,"depth":416,"text":53},{"id":108,"depth":416,"text":109},{"id":158,"depth":416,"text":159},{"id":262,"depth":416,"text":263},{"id":278,"depth":416,"text":279},{"id":316,"depth":416,"text":317},{"id":370,"depth":416,"text":371},{"id":406,"depth":416,"text":407},"2026-04-04",null,"What RVR is, how a transmissometer or forward-scatter meter measures it, why it differs from reported visibility, and how to decode the RVR group.",false,"md",[433,436,439],{"q":434,"a":435},"What is runway visual range?","Runway visual range, or RVR, is the distance over which the pilot of an aircraft on the runway centreline can see the runway surface markings, or the lights marking the runway or its centreline. It is a measured value specific to a runway, used for low-visibility approach and landing, and it is different from the general meteorological visibility reported in a METAR.",{"q":437,"a":438},"How is RVR measured?","By instruments beside the runway, not by eye. A transmissometer measures how much light is lost travelling along a fixed baseline between a transmitter and a receiver, while a forward-scatter meter measures how much light is scattered by particles in a small sample of air. Both derive the RVR, and most modern installations use forward-scatter meters. The reading also accounts for the runway light intensity, because brighter lights are visible further.",{"q":440,"a":441},"Why can RVR be greater than the reported visibility?","Because RVR accounts for the runway lighting, which can be seen further than unlit features in the same conditions. Reported visibility is the general meteorological visibility, judged against ordinary objects, while RVR is how far you can see the runway lights or markings from the centreline. With high-intensity runway lights, especially at night, the RVR can exceed the prevailing visibility.",[443,444,445,446,447],"RVR is the distance a pilot on the runway centreline can see the runway markings or lights, a runway-specific value for low visibility.","It is measured by a transmissometer or a forward-scatter meter, and accounts for the runway light intensity.","Because it includes the runway lights, RVR can read higher than the general reported visibility, especially at night.","In a METAR it appears as an R-group, such as R27\u002F0550, in metres (or feet with FT in the US), with U, D or N for the tendency.","It is a horizontal, point measurement that can vary along the runway, with the touchdown value governing the approach.",{},"What RVR is, how a transmissometer or forward-scatter meter measures it, why it differs from reported visibility, and how to decode it.",true,"\u002Flearn\u002Frunway-visual-range-rvr",[453,462,470],{"q":454,"options":455,"answer":460,"explanation":461},"What does runway visual range measure?",[456,457,458,459],"The general visibility across the whole aerodrome","The distance a pilot on the runway centreline can see the runway markings or lights","The cloud base over the runway","The crosswind on the runway",1,"RVR is the distance over which a pilot on the runway centreline can see the runway surface markings or the lights marking the runway or its centreline, a runway-specific value for low-visibility operations.",{"q":463,"options":464,"answer":460,"explanation":469},"Which instruments are used to measure RVR?",[465,466,467,468],"A barometer and a thermometer","A transmissometer or a forward-scatter meter","An anemometer","A ceilometer only","RVR is derived by a transmissometer, which measures light lost along a baseline, or a forward-scatter meter, which measures light scattered by particles, with the runway light intensity taken into account.",{"q":471,"options":472,"answer":460,"explanation":477},"Why can the RVR read higher than the reported visibility?",[473,474,475,476],"Because RVR is always rounded up","Because RVR accounts for the runway lights, which are visible further than unlit features","Because the reported visibility is always wrong","Because RVR ignores fog","RVR accounts for the runway lighting, which can be seen further than ordinary unlit objects, so with high-intensity lights, especially at night, the RVR can exceed the general reported visibility.",{"title":5,"description":429},"decode-the-weather",9,[482,484,486,489],{"label":483,"url":45},"ICAO Annex 3: Meteorological Service for International Air Navigation (RVR)",{"label":485,"url":63},"ICAO Doc 9328: Manual of Runway Visual Range Observing and Reporting Practices",{"label":487,"url":488},"FAA Aviation Weather Handbook (FAA-H-8083-28)","https:\u002F\u002Fwww.faa.gov\u002Fregulationspolicies\u002Fhandbooksmanuals\u002Faviation\u002Ffaa-h-8083-28-aviation-weather-handbook",{"label":490,"url":491},"SKYbrary: Runway Visual Range (RVR)","https:\u002F\u002Fskybrary.aero\u002Farticles\u002Frunway-visual-range-rvr","learn\u002Frunway-visual-range-rvr","Weather","kKEhRCQ2zZPGDa9056GCPyRgXGMDj2xMvOw7FUTEhNk",{"related":496,"newer":513,"older":520,"series":526},[497,503,508],{"path":498,"title":499,"description":500,"date":501,"topic":493,"draft":430,"minutes":502,"series":428,"seriesOrder":428},"\u002Flearn\u002Ftemperature-inversions-and-stable-air","Temperature inversions and stable air","What a temperature inversion is, how it makes the air stable, and why that explains haze, fog, smooth rides, trapped pollution, low cloud and wind shear.","2026-06-12",4,{"path":504,"title":505,"description":506,"date":507,"topic":493,"draft":430,"minutes":502,"series":428,"seriesOrder":428},"\u002Flearn\u002Fmountain-waves-and-rotor","Mountain waves and rotor","How stable air over high ground sets up mountain waves and the violent rotor beneath, the cloud signs that reveal them, and why they deserve respect.","2026-06-09",{"path":509,"title":510,"description":511,"date":507,"topic":493,"draft":430,"minutes":512,"series":428,"seriesOrder":428},"\u002Flearn\u002Fpressure-systems-highs-and-lows","Pressure systems: highs, lows, ridges and troughs","What highs, lows, ridges and troughs are, the weather each brings, which way the wind circulates around them, and how to read them on a pressure chart.",7,{"path":514,"title":515,"description":516,"date":517,"topic":518,"draft":430,"minutes":502,"series":519,"seriesOrder":416},"\u002Flearn\u002Fvfr-weather-minima-and-cruising-levels","VFR weather minima and cruising levels","The visibility and distance-from-cloud minima for visual flight, and the semicircular cruising-level rule, with the ICAO, EASA and FAA figures attributed.","2026-04-05","Regulations","plan-a-vfr-cross-country",{"path":521,"title":522,"description":523,"date":524,"topic":525,"draft":430,"minutes":502,"series":428,"seriesOrder":428},"\u002Flearn\u002Fmass-and-balance-basics","Mass and balance basics","What datum, arm, moment and centre of gravity mean, how to work a centre-of-gravity calculation step by step, and why the envelope matters, not just mass.","2026-04-03","Operations",{"slug":479,"title":527,"part":480,"total":480,"prev":528,"next":428},"Decode the weather",{"path":529,"title":530,"description":531,"date":532,"topic":493,"draft":430,"minutes":502,"series":479,"seriesOrder":533},"\u002Flearn\u002Fvolcanic-ash-and-sigmet","Volcanic ash and the SIGMET","Why volcanic ash is so dangerous to aircraft, how Volcanic Ash Advisory Centres and SIGMETs warn you, and why an ash SIGMET runs longer and starts earlier.","2026-06-05",8,1782839406000]