land back on the site if an enginefails before CDP.Although an air or groundinspection is needed for all this, it'sOperational Procedures 59not always possible, so the charterershould be asked to supply a largescale map of the landing site andapproaches. If, on arrival, you decidethat the area is not suitable, youshouldn't use it (which is easier saidthan done), so it's most importantthat the customer is fully aware ofyour Company's requirements andthat he will be charged for anabortive flight should the landingsite not meet the required standards.How do you tell how suitable a siteis from the air? Difficult, that. Theeasy answer is to suck it and see, butconfined or congested areas don'tmeet Performance requirements forCommercial Air Transport, and youmay be contravening the famousRule 5 as well (low flying). Yourcustomer wants to land. You, on theother hand, have a licence to protect.If you're at all unsure, do a couple offlypasts and feel your way down –confined areas are further discussedunder Mountain Flying.The following criteria should applyto all unlicensed sites, which aretechnical requirements that do notnecessarily allow for low flying rules.A congested area is one"substantially used for recreationaland residential purposes", etc., whichofficially makes a golf course one,though you would be forgiven forthinking otherwise. A rule of thumbis 60% buildings and trees, butspecifics haven't been tested in courtyet, at least not in the UK.There should be at least oneapproach and departure lanecontaining either no or only isolatedobstacles—a downwind componentis not acceptable. The lanes andlanding areas should be big enoughto ensure you can land, take off andreach a safe height so you can touchdown into wind following an enginefailure, while avoiding obstacles by asafe margin.Try not to have marshlandunderneath the lanes because, whileit may be soft, skids or wheels maysink in during an emergency landing,which is the last place you wantdynamic rollover. In other words,the ground beneath the lanes mustbe suitable for emergency landingswith respect to slope, softness,frangible obstructions, etc. Water isOK, provided the performancegroup is suitable or you've got theusual lifejackets, floats, etc.The landing pad itself should belevel, drained, with a grass or solidsurface that does not blow up dust atthe slightest provocation (you shouldbe able to drive the average car overit). Its diameter should be at leasttwice the length of the largesthelicopter to use it, including rotors,as you will need to turn round yourtail. Watch out for anything that maysnag the skids, particularly ontakeoff. Some people like thetouchdown area marked with an H,but provided the grid reference is
accurate enough, it shouldn't be toohard to find it.If you're wanting to land wherethere's a gathering of 1000 or morepeople at an organised event,remember that no landings atunlicensed sites should beundertaken within 3000' of thatassembly without written permissionfrom the CAA and the eventorganisers (as per Rule 5 (1) d (i)).On an oil rig, the helideck frequentlywill be sloped away from the centre,to help with drainage. The slope is60 Operational Flyingnot severe, but if you land with yournose up the hill, so to speak, you runthe risk of hitting the tail rotoragainst the perimeter fences.Landing “downhill” will artificiallyraise the tailboom away from them,as will a slight forward movementwhen you touch down.Finally, a couple of points to watchif you’re ever tempted to land acrossor near railway lines, as you might ifthey’re the only firm place around.The first is that your skids moreoften than not will complete anelectrical connection used forsignalling, and you may cause someconfusion in the local signal box.The other is that trains do use thetrack outside of published schedules,so don’t be surprised to see ahumungous diesel bearing down onyou unexpectedly.Airways ManualsYou need a route guide so you canget around the airway systemwithout messing things up foranybody else.The ultimate Airways Manual is theAir Pilot, being the source fromwhich others get their information.If you ever end up in court, this willbe the one introduced in evidence,but that's not to say that others areno good. They're all potted versionsof it to varying degrees, but withbetter presentation. You can evenproduce your own, which is moreeconomical if you have only one ortwo routes to cater for.The commercially available ones arereally as good as each other,whichever one you get started onprobably becoming your favourite.In addition to the best known ones,Jeppesen and Aerad, the RAF do theirown as a little sideline, which areworth a look at. All of them,however, may contain non-approvedletdowns, so inclusion of aprocedure in a Flight Guide (otherthan the UKAP) doesn't necessarilymean it can be used for CommercialAir Transport flights.The above guides are intended forIFR work—for VFR you'll need tocarry your trusty Pooley's or Flyer’sGuide or, if you're wealthy,Bottlang's, but Bottlang's doesn'tcarry helipad information.Operating MinimaThere are weather conditions underwhich you're not allowed to land,attempt to land, or take off. Aminimum cloud base and visibilitywill be laid down, based on thenavaids available, terrain, obstacles,type of aircraft, crew experience and
State legislation. You don't have todo all the hard work; the aboveAirway Manuals will have all thecalculations done for you, but howthey are derived is described belowin case you have to roll your own.These regulations aren't only forsafety, they also save your customersmoney and inconvenience. Speakingfrom experience, if you find thedeparture time creeping backbecause of weather, after about twohours, advise them to go 24 hourslater. They're still going to take thesame time at the destination—afterall, there is a job to do which is thewhole point of them going. If youdon't, you will find the day gettingunacceptably long and the Companywill still clock you on thirty minutesbefore take-off, regardless of thetime you came in. Some companiesOperational Procedures 61will pressure you into going just toget the money, knowing you won'tget anywhere. In this case, leave thechoice up to the clients. Offer noguarantees, but point out that therewill still be a charge if the wholeexercise is a waste of time. Youtherefore pass the ball into theircourt, and there's a chance you willbe appreciated for not wasting theirtime, which must be expensiveotherwise they wouldn't be flying.In any case, you are responsible forensuring that before take-off you'vegot weather minima for the relevanttimes at every destination and atleast one suitable alternative, whichmust be noted on the Nav Log ifyou intend to use them (this canmean up to 8 airfields if you includetakeoff alternates—see below). ForCommercial Air Transport, foreignairfields are also subject to UK rules,and minima which apply to you willbe the highest of:·
Those established by the Statein which you are flying.·
UK minima, as shown in theAirway Manual.·
Basic minima established byyour Company.Remember that foreign airfields tendto close down automatically whenthe weather gets too bad, whereas anairport authority in UK may onlyclose down on their own initiative inthe case of snow or a blockedrunway – however, attempts to landin marginal weather are reportedback to the Authorities.While you're not allowed to reducethe limits given, you are activelyencouraged to increase them if youthink it's necessary. As they'recalculated for fog conditions withlittle or no wind, you should makedue allowance for rain and/orcrosswinds. Naturally, minima arenot valid if anything affecting theircalculation has been changedthrough NOTAMs, or as instructedby ATC.Minima not in the Airways Manualcan be worked out with figures inthe Ops Manual. In this case, onecopy of your calculations must beretained in Ops, and another carriedon board. However, airfields used
regularly in this way should bepermanently in the Manual, and it'sthe Company's responsibility to selfcheck them. Such calculations will behigher than anything precalculated,because they come from blanketfigures which allow for aircraft inlower performance groups avoidingobstacles visually if an engine failson take-off, so Cloud Ceiling figureswill vary as to where you can start toconstruct your Net Flight Path data(see Performance). If that happens at300 feet (that is, your engines areassumed to be working till then),expect a 300 ft Cloud Ceiling.The same principle goes for RVRfigures, which are related to the timerequired to see and avoidobstacles—if you're going at 90knots, 1500m RVR will give youthirty seconds between seeing andmissing anything. RVR is thedistance you can see in the directionof take-off or landing, determined bya certain procedure, usually with theaid of a transmissometer, and basedon runway lights at setting 3. Thedistance given is taken as the RVRfor the time being, that is, only validfor a short time. If the reported RVRis below your expected minima,62 Operational Flyingyou're not allowed to start anapproach past the outer marker (orat least descend below 1000' aboveaerodrome elevation), even if you'veestablished visual reference abovethat height. As they say, there is anapproach ban (see Glossary). Theminimum visual approach visibility is800m (1200m in Canada), to guardagainst shallow fog. Increase thelimits if the autopilot is out.It's a good idea, in a commercialenvironment, to have something upyour sleeve, meaning what do you doif the ILS goes off halfway down anapproach? In training, you wouldprobably go around, but that'sexpensive and the commercialdepartment will love you if you keepadding 10 minutes to each flight.Many ILSs use an NDB as an outermarker, so why not be ready toconvert to an ADF approach? or aVOR (or whatever)? Mostprofessionals don’t expect to landfrom an approach, which means theydon’t get fixated and try to get inwhen they shouldn’t. Non-standardminima must be retained with flightdocumentation for 3 months.Planning RequirementsTake-Off/AlternatesIf your multi-engined aeroplanecan either stop or continue to 1500'above the aerodrome while clearingobstacles by the margins, the takeoff minima may not be less than:Facilities RVR(m)Vis (m)Cat DNil (Day Only) 500Runway Edge Ltg and/orCentreline Marking250 300Runway Edge, Centre Lights 200 250Runway Edge, Centre Lightsand Multi RVR150 200At night, at least runway edge and
end lights are required. RVR/Vis forthe initial part may be replaced byyour own assessment. If you need tore-land immediately, and thereforesee and avoid obstacles in the takeoff area, refer to the table below.The height at which your engine failsmay not be lower than that fromwhich the one-engine-inoperative net takeoff flight path can be constructed.When RVR/met vis is not availableyou cannot take-off unless the actualconditions satisfy the applicabletake-off minima.Eng FailHt'<50 51–100101–150151–200201–300>300RVRm 200 300 400 500 1000 1500Use the higher of the tablesaccording to circumstances.For Class 1 helicopters (Group A)minima may not be less than:Onshore heliports with IFR departure RVR/VisNil Facilities (Day) 250 m*Nil Facilities (Night) 800 mUnlit/unmarked defined runway/FATO 200 mRwy edge/FAT lights, centre marking 200 mRwy edge/FATO and centreline lighting,RVR info150 mOnshore heliports without IFR dep 800 m*or rejected takeoff distance, whichever is greaterWith no reported met vis or RVR,you can only commence a take-off ifthey are equal to or better thanrequired minimum (obvious, really).For Class 2 (A (Restricted) minimamust be at least 800 m RVR/Vis,remaining clear of cloud during takeoff or until reaching Class 1capabilities. For Class 3 (Group B),try at least 600 ft cloud ceiling and800m RVR/Vis.You must nominate a suitablealternate (on the Nav Log) to returnto when weather conditions at theOperational Procedures 63aerodrome you're departing from arebelow those required for landing, incase you have to return in a hurry.Favourable landing conditions at thisalternate must be reported andforecast to be at or above landingminima 1 hour either side of ETA,and it must be within a certain timeat one-engine-out speed, typically 30minutes for a twin piston and 60 fora turbine (the terrain and weatherconditions en route must permit this,that is, your single-engined climbperformance may not get you overobstacles in the way). Forhelicopters, it's an hour at normaltwin IMC Cruising Speed.If there is no suitable diversion,delay the flight until one is, or thedeparture weather improves. In fact,without an alternate, departureminima should be not less thanthose for landing at the sameaerodrome. If you have to see andavoid obstacles on departure, a cloudceiling should also be specified.Takeoff minima depend on manyfactors, including the PerformanceGroup or Class of the aircraft,
availability of markings, lighting,runway surface and width, distancesavailable and your experience(inexperienced crews should add 100feet and 200m to these figures).DestinationsLanding Distance requirements mustbe satisfied on both the mostsuitable runway for landing in stillair, and any you may need because offorecast wind conditions. You mustnot descend below the en routeminimum altitude (MOCA) untilyour position has been positivelyidentified, and you must reconfirm itafterwards (well, you would,wouldn't you?). You should alsohave a copy of the let-down plateavailable, with all required groundand airborne aids being serviceable.When in IMC, you should notdescend below MSA (as on thechart) until established in theapproach or hold procedure. As thesafe altitude is based on correct entryprocedures, it will cover a certainarea of ground, so if you're givensomething non-standard, such as avery long downwind leg that takesyou off the chart, beware!The Decision Height (or MinimumDescent Height, depending on the sortof approach) is the height at whichyou must go around if you can't seeanything vaguely resembling arunway. If the Cloud Ceiling is lowerthan this, you may (unless prohibitedby national regulations) carry outone approach to check if you can seeanything (known in the trade as'assessing the visual referenceavailable'), but Missed Approachaction must be taken at DecisionHeight on a precision approach ifyou can't.A precision approach is an ILS or PAR.A non-precision approach is basicallyanything else, such as VOR or ADF,which only has azimuth guidance(that is, only left or right, without upor down). It is characterised by largesteps, that is, major descents atcertain stages requiring large powerchanges that can be a pain with anengine out. It’s often a good idea tokeep a consistent glide path as muchas possible throughout a nonprecision approach – the minimumheights at each step are just that –minimum heights. There’s nothingto stop you being above them if you64 Operational Flyingare descending under control (300feet per mile gives you 3°).On non-precision approaches, ifvisual reference has not beenestablished by Minimum DescentHeight, you may fly level at thatheight if your heading is within 15°of the runway QDM, and you maygo down further if you can seewhere you're going, if you can landat normal touchdown speed. This,unfortunately, raises the temptationof a dirty dart for the runway if yousee it, without really being in aposition to cope with the situation—you are in a high drag landingconfiguration, and have been forsome time. There are noperformance figures for go-aroundsunder those conditions.If you can't see anything by your
estimated time of reaching thethreshold, you must go around.After 2 successive overshoots you'reallowed no more attempts until asignificant improvement in theweather is reported—the meaning of'significant' is left to common sense,but you can have a third go if you'vepreviously used an autopilot, or youhave an emergency.You may abandon an instrumentapproach in favour of a visual one ifyou have the aerodromecontinuously in sight, you are belowall cloud, and conditions are equal toor better than those for circling (bearin mind, though, the minimum RVRof 800m (1200 in Canada), evenwhen visual, which is to guardagainst shallow fog reducing thevisibility in the final stages).For destinations, forecasts mustindicate that the weather will be at orabove the minima for 1 hour eitherside of ETA. For a non-precision orcircling approach, the ceiling mustalso be at or above MDH.Destination and En-Route AlternatesShould the weather deterioratebelow acceptable limits you mustconsider diversion, but if things areimproving, you can request holdingat the optimum level for up to a halfof your holding allowance beforegoing elsewhere. If you eat into this,you should have 2 alternatesavailable, with enough fuel to reachone of them (a minimum of 60 nmaway) with 45 minutes' holding fuelon arrival.You can use an Isolated Aerodromeprocedure instead of alternate fuelfor destinations with no suitablealternate, which means you mustcarry significantly more fuel thannormal, that is, about 2 hours' worthas opposed to 45 minutes. Theamount of the reserve is related tostatistical information about localweather conditions, and is coveredmore fully later.Met reports and/or forecasts mustindicate that the weather at theaerodrome will be at or above theplanning minima below for an houreither side of ETA:Approach Planning MinimaCat II and III Cat I (RVR)Cat I Non-Precision (RVR with ceiling ator above MDH)Non-PrecisionNon-Precision (RVR with ceiling ator above MDH) plus 200 ft/1000 mCircling CirclingDH/MDHThe starting point for Decision Heightis the Obstacle Clearance Height for thelanding aid, or Circling Minima as analternative (Circling Height shouldbe regarded as MDH/DH for anyOperational Procedures 65instrument approach followed bycircling). Add 10 feet (sinkallowance) to that, plus the PressureError Correction for the type, whichwill be in the Flight Manual, so DH= OCH + PEC + 10 feet. If the ILSis offset, the DH must be at least theheight at the Middle Marker.The OCH for non-precision
approaches should include a fudgefactor for sink and PEC, so you canread OCH directly as the MinimumDescent Height (MDH for nonprecision approaches being the sameas DH for precision approaches), orMDH = OCH. If you're a newbie,that is, you have less than 50 hoursP1 on the relevant type, expect toincrease your DH or MDH by 100'.Non-Precision Approaches(Onshore)The MDH for a non-precisionapproach must be higher than theOCH/OCL for the category ofaircraft, the system minimum (seetable below), or any State minima.Approach Aid System Min(ft)ILS No Glide Path 250SRA (½ nm) 250SRA (1 nm) 300SRA (2 nm) 350VOR 300VOR/DME 250NDB 300NDB/DME 300VDF (QDM & QGH) 300Visual ReferenceYou cannot continue below MDHunless you can see (and identify) atleast one of:·
elements of the approach orrunway lights·
the threshold or touchdownzone, their markings or lights·
visual glideslope indicator(s)MDH is a height below which you mustnot descend, and not one at which youmust fly to comply with theprocedure, so you don't have to goto it immediately. For a 3°glideslope, you should be 1642 feetabove the threshold elevation at 5nm (including a 50-foot screenheight). At 10 nm, the height shouldbe 3234 feet. Put more simply, forevery nautical mile, you can descendabout 300 feet (actually 318), whichwill help with power changes.Required Runway Visual Range (RVR)You may get an RVR report with 3figures, covering the touch-down,middle and stop end of the runway,respectively. The touch-down onemust be at least equal to landingminima, but the others need merelybe enough to stop safely, providedthey are more than that required fortake-off. The RVR for landing froma visual circuit is 800m (1200 inCanada), or the lowest Cat 1 RVRfor the intended runway, whicheveris the less, regardless of approachlighting, time of day or type ofaircraft. As mentioned, this is forshallow fog, where you may see theairport from height, but lose sight ofit as you descend on the approach (avisual approach must be authorisedby ATC). The minimum RVR for anon-precision approach depends onthe MDH, approach and runwaylighting as shown below. At night, atleast runway edge, threshold andrunway end lights must be on.66 Operational FlyingNPA Minima – Full FacilitiesWith runway markings, 720m+of high or medium intensityapproach lights, runway edge,threshold and end lights, all on.
NPA Minima – IntermediateWith runway markings, 420–719m HI/MI approach andother lights.MDH(ft) Aeroplane Cat and RVR(m)A B C D250–299 1000 1100 1200 1400300–449 1200 1300 1400 1600450–649 1400 1500 1600 1800650 + 1500 1500 1800 2000NPA Minima – Basic FacilitiesWith runway markings, <420mof HI/MI approach lights,runway edge, threshold and endlights, which must be on.MDH(ft) Aeroplane Category and RVR(m)A B C D250–299 1200 1300 1400 1600300–449 1300 1400 1600 1800450–649 1500 1500 1800 2000650 + 1500 1500 2000 2000NPA Minima – Nil FacilitiesRunway markings, edge,threshold & end lights, or none.MDH(ft) Aeroplane Category and RVR(m)A B C D250–299 1500 1500 1600 1800300–449 1500 1500 1800 2000450–649 1500 1500 2000 2000650 + 1500 1500 2000 2000Tables only apply to approach slopes under 4°. Steeperones normally require VASIs or similar to be seen fromMDH. RVR is either reported RVR, or met vis convertedas below. The MDH above refers to its initial calculation.RVR doesn't need to be rounded up to the nearest 10feet, as when converting to MDA.Class 1 & 2 HelicoptersOnshore Non-Precision Approach Minima FacilitiesMDH(ft) Full Intermediate Basic250-299 600 800 1000300-449 800 1000 1000450 + 1000 1000 1000Refer to aeroplane tables for description of facilities.Only for approaches below 4 degrees. Normallyrequires VASIs or similar to be seen from MDH. Figuresare reported RVR or converted met visibility. WhereMAP is within ½ nm of threshold, minima for full facilitiesmay be used regardless of approach lighting, but youstill need runway edge, threshold and end lights andmarkings. At night, ground lighting must illuminateFATO and obstacles. Single pilot, min RVR is higher of800 m or Table 3.Converting Reported Met Vis to RVR*Lighting in Operation RVR = Met Visibility XDay NightHI Approach and Rwy Lighting 1.5 2.0Any lighting other than above 1.0 1.5No Lighting 1.0 N/A*Don’t use for take-off or Cat II/III , or when RVR is available.Precision Approaches (Onshore)For these, a Cat I operation usesILS, MLS or PAR with a DH above200 feet, and RVR above 550 metres(500 for helicopters). The DH is atleast the highest of:·
the OCH/OCL for the categoryof aircraft·
minimum DH in the FlightManual (AFM), if any·
the minimum height withoutvisual reference·
200 feet, or any State minimaVisual ReferenceYou cannot continue a precisionapproach below a DH determined asabove, unless you have at least oneof these visual references (for theintended runway) visible andidentifiable:·
elements of the approach or
runway lightsMDH(ft) Aeroplane Category and RVR(m )A B C D250–299 800 800 800 1200300–449 900 1000 1000 1400450–649 1000 1200 1200 1600650 + 1200 1400 1400 1800Operational Procedures 67·
the threshold or touchdownzone, their markings or lights·
visual glideslope indicator(s)Runway Visual RangeMinimum RVR is governed by theDH, approach lighting and runwaylighting/marking, shown below.At night, at least runway edge,threshold and runway end lightsmust be on.Cat 1 Approach vs Facilities & DHRefer to aeroplane tables for facilities. Nil approach light facilitiescomprise runway markings, runway edge, threshold and endlights or no lights at all. RVR values either as reported, or visconverted as above. Figures only apply to conventionalapproaches with slope below 4°.The DH refers to initialcalculation; associated RVRdoes not have to be rounded upto the nearest 10 feet, like whenconverting to DA.Class 1 & 2 helicoptersRefer to aeroplane tables for facilities. Figures are reported RVRor met vis converted using the above. Figures only apply toconventional approaches with glideslope up to and including 3.5degrees. At night at least runway edge lights must be available.The DH refers to initial calculation;associated RVR does not have to berounded up to the nearest 10 feet,e.g. when converting to DA. TheDH applied must not be less than1.25 x minimum use height for theautopilot. Single pilot, minimumRVR shall be at least 800 m, exceptwhen using a suitable autopilotcoupled to an ILS.Single-Pilot OperationMinimum RVR may not be less than800m, unless a suitable autopilot,coupled to an ILS or MLS is used, inwhich case RVR above may be used,but DH must be not less than 1.25 xthe min use height for the autopilot.Commencement and Continuation ofan ApproachAn approach may be startedirrespective of the RVR, but notcontinued past the outer marker (orequivalent—see note) unless thereported controlling RVR/vis isequal to or better than the minimumrequired. Once past the outermarker, you can continue if yourvisual reference has been establishedat the DH/MDH, and is maintained.With no outer marker, you mustmake the decision to continue orabandon before descending below1000 feet above the aerodrome onfinal approach.Note: The "equivalent position" is aDME distance, a suitably locatedNDB or VOR, SRE or PAR fix, oranything else that independentlyestablishes your position.Visual Manoeuvring (Circling)Circling is visually manoeuvring to arunway or FATO (for helicopters)after an Instrument Approach toanother one, or the same one if theapproach is not straight in (morethan 30o off, in fact). Minima for thiswill give the necessary obstacle
