Airport Services Manual (Part 6) - Control of Obstacles 1983

Index Doc 9t37-AN/898 Part 6 AIRPORT SERVICES MANUAL PART 6 CONTROI, OF OBSTACXAE$ INTERN ATIONAII, CIVIL A V...

Index Doc 9t37-AN/898 Part 6 AIRPORT SERVICES MANUAL PART 6 CONTROI, OF OBSTACXAE$ INTERN ATIONAII, CIVIL A V %ATION ORGAWIXATIB%% Index  Index Airport Services Manual Part 6 Control of Obstacles Second Edition -- 1983  Index Amendments are announced in the supplements to the Cabalogue of ICAO Publicarbas; the Catalogue and its supplements are available on the ICAO website at www.icao.int. The space below is provided to keep a record of such amendments. RECORD OF AMENDMENTS AND CORRIGENDA (ii)  Index Foreword This part of the Airport Services Manual includes relationship between the Annex 14 and FANSLOPS guidance on the control of obstacles in the vicinity of surfaces (Chapter 1); and airports. Much of the material included herein is closely b) guidance an controlling obstacles at an airpart assr~ciatedwith the specifications contained in Annex 14 (Chapter 2 and Appendix 2). - Aerodromes. The main purpow of this rnanuai is to encourage the uniform application of those specifications Chapter 4 and Appendix 3 of this manual, which deal and to pravide information and guidance to States. The with obstacle surveys and shielding, respectively, arc significant additions to h e manual during the current largely based on updated material provided by States and revision are: are, therefore, klieved to be current. Should a State, at any time, consider that any portion of this material is out a) information on obstacle limitation surfaces for of date, it should inform the Secretary General of this precision approach runways category I and on the and, if possible, pravide revised materid. Index Index Index  Index Chapter 1 Surfaces 1.1 GENERAL as part of a national planning consuitation scheme. The surfaces established should allow not only for existing 1.1.1 The effective utilization of an eerdrome may operations but also for the ultimate development be considerably influenced by natural features md man- envisaged for each aerodrome. There may a h be a need made mnstructions inside and outside its boundary. to restrict obstacles in areas other than those covered by These may result in limitations on the disiances availabie Annex i 4 if operational minima calculated using the for take-off and landing and on the range of PANS-OPS criteria are not, to be increa%d, thereby meteorological conditions in which take-off and Landing limiting aerodrome utitiza tion. can be undertaken. For these reasons certain areas sf the local airspace must k regarded as integral par& of the aerodrome. environment. The degree of freedom from 1.1 ANNEX 14 - OBSTACLE obstacles in these areas is as imporeant to the safe and LIMITATION SURFACES efficient use ot' the aerodrome as ate the more obvicus pliysical ieqriirementi of the rcnways and :heir associated 1.2.1 Funcriun of the surtaces s:.-ix !. 2 i. l The following pnrag:aphs rlelbcribe the I. 1.2 The significance uf any existing or p x ~ p o ~ e d functir,t! or the vzrious s ~ r f a e defined s in Chapter 4, and nb,ject within the aeiodrorne b o ~ n ~ or t yin the vicinity of ifl certain instances incl?ldc addi tiondj i9formtic~n ihc aerodrome is assessed by ihc use cf two separate sets concerning their charr;aeri?tics. For r he benffir, of rhc of crireria defining sirspace rcquirerneats. The first of i-carier,se-feraiiiius!rations orot,s~cleiimiuirotl surbces these mmprixs the obstacle limiktion surfaces partic~lar are inc!uded in Appendix 1 to a runway and its nntended use detailed In Chapter 4 sf Annex 14 - Aerodromes. The broad purpose of these surfaces is to define the volume of airspace !hat should idealty be kept free from obstacles in order to minimize 1.2.2.1 In the experiencz of some States, significant the dangers presented by obstacles to an aircraft, either operational problems csn cnrise from the erection of tall during an entirely visual approach or iinnng the visual structuies i r ~the vicinity of airports beyond th9 areas segment of an instrilmeni approach. The wcond s e e of ;urr~,ntly recogr~izcd in Annex 14 as areas in which criteria comprises the qurfaces described in the Procediires iestriction of new construction may be necessary. The f ~ rAir Navigation Srrvices- AircraJr Operations PANS- operations; implications fall broadly under the beadiilgs QPS) (Doc 8\68], Volume II - Constnrc~ionof Visual and of safely anci efficiency Insirumenr Flrght Proceclures. The PANS-OPS surfaces are intended for use by procedure designers for the 1.2.2.2 Sdj@vimplications. I t is particularly desire ble mnstruction of instrument flight procedures and for to review carefully any proposal to erect high mas& or specifying minimum safe altitudes/heights for each oiher skeietal structures in sreas which would otherwise segment of the procedure. The procedure and/or be suitable for use by aircrafi on wide visual circuits, on minimum hetghts ma, vary with aeroplane speed, the arrival routes towards the airport or circuit, or on navigational aid being used, and in sone cases the departure or missed approach climb-paths. Avoidance by equipment fitted to the aeroplane. marking or lighting cannot be relied upon in view of the relatively inconspicuous character of these structures, 1.1.3 The surfaces of Annex 14 are intended to be af especially in conditions of reduced visibility, and a permanent nature. To be effsctive, they should notification of their existence will similarly not always therefore be enacted in local zoning laws cr ordinances or guarantee avoidance.  Index 2 Aivporr Services Munuul Inner horizontal surface Figure 1-1, Inner horizontal surface for a single runway (where the runway code number is 4) Ru- No. 1 - 4000rn 2000m 4000m Inner horizontal surface RP = Reference Point Figure 1-2. Composite inner horizontal surface for two parallel runways (where the runway code number is 4)  Index 1.a. 2.3 mciency implications. If taH structures are provided to ensure that defined approach and miwed erected in m near areas oahwwise suibMe for instrument h will k foJowed. a p p ~ ~ a cpaihs approach procedures, increasd procedure heights m y need to be adopted, with consequent adverse effects on 1.2.3.3 Whibt visual circling protection for slower regularity and on the duration of the apprwach procedure, aircrah using shorter runways may l x achieved by a such as the denial of useful altitude aloeaaions m aircraft single circular inner horizontal surf=, with an increase in associated holding patterns. Such structures may in speed it kcoms essential to adopt a race-track pattern Gimilar t~ PANS-BPSI and u s cbcuhr arcs centred on furthermore limit desirable flexibility far radar v ~ b r e d runway en& joined tangentially by straight lines. To initial approaches and the facility to turn en route during protect two or more widely spaced runways, a mote the departure climb or missed approach. complex pattern could become neceswy, invoking four 1.2.2.4 In view of these potentially imprunt or more circular arcs. These situations are illustrated rt Figures 1-1 and 1-2 respectively. operational considerations, authorities my consider it desirable to adopt measures to ensure that they have 1.2.3.4 In fief horizoo~alsu$ace - elewlio~ datum. To advance notice of any proposals to erect bll structures. satisfy the intention of the inner horizontal surf= This will tnabk h e m to study the aeronautical &scri$ed a b v e , it is desirable that authorities mlect a implications and take such action as may be at their datum elevation from which the top elevation of the disposal to prowct aviation interests. In assessing the surface is determined. Selection d the datum shouid take operational effect of proposed new constauction, tall a m u n t of: structures would not be of immediate significance if they a) the elevations of the most frequently used altimeter are proposed to be located in: setting datum points; a) an area already substantially obstructed by terrain or b) minimum circling altitudes in use or required; and c) the nature of operations at the a k p r t. existing structures of equivalent height; and b) an area which would be safely avoided by prescribed For relatively level runways the choice of datum is not procedures associated with navigational guidanm critical, but when the thresholds differ by more than 6 m, when appropriate. the datum selected should have particular-regardto the factors above. For complex inner horizortal surfaces 1.2.2.5 As a broad specification for the outer (Figure 1-2) a common elevation is not essential, but horizontal surface, tall structures a n be considered to be where surfaces overfap the Iower suriace should be of possible signrficance if they are both higher than 30 m regarded as dominant. above local ground level, and higher than 150 m a b v e aerodrome elevation within a radius of 15 008 m of the 1.2.4 Apprwcls and transitfunol surfaces centre of the airport where the runway code number is 3 or 4. The area of concern may need to be extended to 1.2.4.1 These surfaces define the volume of aifspace coincide with the obstacle-accountable areas ~f PANS- that shouM k kept free from obstacles to promt an OPS for the individual approach procedures at the ai~port aeroplane in the final phase of the approach-to-land under consideration. manoeuvre. Their slopes and dimensions will vary with the aerodrome reference code and whether the runway is 1.2.3 Inner horizontal surS~sceand conical surface used for visual, non-precision or precision approaches. 1.2.3.1 The purpose of the inner horizontal surface is to protect airspace for visual circling prior to landing, possibly after a descent through cloud aligned with a 1.2.5.1 This surface provides protection for an runway other than that in use for landing. aircraft on take-off by indicating which obstacles should be removed if possible, and marked or %igheedif removal 1.2.3.2 In some instances, certain sectors of the is impossible. The dimensions and slopes also vary with visual circling areas wilt not be essentiaI to aircraft the aerodrome reference code. operations and, provided procedures are esublished to ensure that aircraft do not fly in these sectors, the 1.2.6 The inner approach, inner trur~sifionaland protection afforded by the inner horizontal surface need balked landing surfaces not extend into those sectors. Similar discretion can be exe~ciwdby t t h ap?ropriate author:ties when procedures 1.2.6.1 Tagether, these surfaces (see Figure. 1-31 have been es&b!ished and navigatiunai guidance define a v o i u m of airspace in the immediate vicinity of a  Index Figure 1-3. precision apgruach runway which is known as the cent. The splay of 10 per cent is based upon recorded obstacle-free mne (OFZ). This zone shall be kept free dia~rsiondata in progrdmmes conducted by two States. from fixed objects, other than lightweight frangibly mounted aids to air navigation which must be near the 1.2.6.3 The OFT {or a precisiorl approach runway runway to perform their function, and from transient category I where the code number is 1 or 2 is designed to objects such as aircraft and vehicles when the runway is prctect an aeroplane with a wing span 06 30 m to cIirntl a1 being used for category I1 or IIJ ILS approaches. When an a grdienr of 4 per reil! anC diverge from the runway OEZ is established for a precision approach runway centre line at a splay no greater than 10 per cent. The category I, it shall be clear of.such objects when the gradient of 4 per cent is that of the normal take-off climb runwny is used for category 1 11,s approaches. stirface for these azrop~anes.When allied to a 10 per cent splay, it resulrs in a siope Tor the inner transitional surfaces of 40 per cent. The balked landing surfacc 1.2.6.2 The OF2 provided on a precision approach orleinates at 60 m beyond the far end of the runway from I mway where the code number is 3 or 4 is designed to 1hrcshoiJ 2nd IS coinc~der.~ with the uke-off climb protect an aeroplane with a wingspan of 60 rn on a surface !'OFthe runway precision approach M o w a height of 30 rn having heert correctly aligned with the runway at that heighi, to climb 6.3 PASS-OPS SURFACES a t a gradien~of 3.33 per cent and diverge from the runway centre !ine at a splay no greater rhan 10 per cent. The gradient of 3.33 per ccnt is tile lawest permitled for an 1.3. I.1 'The PANb-LlPS surfaces ai'e ifitended fb! ust: all-englne-operating, barked landing. A horizorlul by proct.:di:re des;gner s piirrdr i!) in the cclns.truL.sionc f distance of 1 800 rn from threshold to the start of the instrr1n3en: Tlib;:: prrtc't.d~rr~5bvl:~t-!> ;Ire de?:::nc!' :., ba!ited landing surface assl;mes thar the latest point for a sareguard an aerupianc from cil:;~slcn w ~ r nobstarics p i l c ~ to initisw A b~rkedlaxding is the end of t h e when [lying on ~ns:ruments.In designi~lgrrocedure?. :r.e touchdown zone iiyhiing, and h a t changes to aircr:iP designer will de~err!i;neareas ( : i c r i z o n ~ l l y ! needed 1;;: configuration to echreve a positive climb gradien! will \.,crrcus: seg~?;lrnisof the procedare. l'hen he w1l1 U I ~ ~ I : > L ' normally r t q iire a further distan-e of YOU m which IS rile obs1acie.i u!rh:n the de~errn~ned areas, and i!,:>cci r ~ r rq:sivalent to a maximum rime ul abou! I! s A :iitj('r oc ibis anathi:\ h~ I spi;cify rnlnlrn~r? 9 , j ! s L 3 3. 3 3 per cent for the inner trdnsic~onalsurfaces resrrili.jl!ii?ldc\!irzigh;5 far e a i : ~seg:ntn: oi he prnce J u i ; f;~' from d 3.33 per cent climb gradient with a splay of' I0 ner I!sc try plLlts  Index Purr 6.- Control of Oha;acles. Chapter I. - SUB faces 1.3.1.2 The minimum a f e altitude/heighl specified performance category, reference datum height, lmlizer for the final approach phase of's flight IS wiled 'bbstacle course width and the distance be tween the threshold and clearance aiiitude/height (OCA/I,I)". A missed approach Iocalizer a n k n n a j. The airspace ran ?xhunded by plane procedure initiated by the pilot at or above this or curved surfaces which have resulted in "basic ILS altitude/height wliI ensure that, even if the pilot has no surfaces", "obstacle assessrncnt surfaces (QAS).' and outside visual reference to the ground at any wint, the the Collision Risk Modei (CRM) (see further, 1.3.2 w aeroplane will pass safely above all potentially dangerous 1.3.4 MOW). obstacles. The pilot may desmnd beIow the QCAPH only if he has visually confirmed that the aeroplane is correctly 1.3.2 Basic ILS suflaces. The "basic IES surfaoes" aligned with the runway and that there are sufficient defined in PANS-OPS represent the simplest form of visual cues to continue the approach. The pilot is protection for HLS o ~ r a t i o n s. These surfaces ire permitted to disc~ntirluethe approach at any point k 1 o w extensions of certain Annex 14 surfaces, referenmd bo the OCA/H. e.g, if the required visuai reference ceases to threshold bvel throughout and modified after threshold be available. Suck a late missed approach is called balked to protect the instrument missed approach. The airspace landing. h u s e the initiation point of the balked landing bounded by the basic ILS surfaces is however usually t m procedure is known more accurately than the initiation. conservative and therefore another set of surfaces, point sf the missed approach procedure, a smaller "obstacle assessment surfaces", is specified in PANS- airspace needs to be protected, OPS. - Note. Not all of the above is applicable to cafegow 111 1.3.3 Ohfacie assessment suflaees. The obstacle operations carried out with no deckion keigh~ assessment surfaces (OAS) establish a volume of airspace, inside which it is assumed the flight paths of 1.3.1.3 The size and dimensions of the obstacle-free aeroplanes making ILS approaches and subsequent airspace needed for the approach, for the missed missed upproaches will t x contained with sufliciently high approach initiated as or above the W A / H and for the probability. Accordingly, aeroplanes need normlly only visual manoeuvring (circling) procedure are specified in be protected from tho= obstacles that wnetrate this PANS-OPS.AeropIanes continuing their descent b l o w airspace; objects that do not penelrate it wually present the specified OCA/H, and therefore having visual no danger to ILS operations. However, if th? density of confirmation that they are correctly aligned, are protected obstacles below the OAS is very high, these ubsmles will from obstactes by the Annex 14 obstacle Iirnitation add to the total risk and may need to k. evaluated (see surfaces and related obstacle limitation and 1.5.2 belowb. The aMve airspace (funnel) is iHustrated in rnarkingilighting requirements. Similarly, the Annex $4 Figure 1-7. I t is formed by a set of plane surfaas; an surfaces provide protection for the balked landing. In approach surface (W), a grour-rri or "footprint" surface other than low visibilities, it may be necessary for the (A) and a missed approach suriace (2); a11 bounded by pilot to avoid some obstacles visually. side surfaces (X and Y i. The dimensions of the surfaces. are tabulated in PANS-OPS,Volume 11. The lateral 1.3.1.4 The airspace required for an approach boundaries of the funnel represent estimates of the (including missed approach and visual circling) is maximum divergence of an aeropiane from the runway bounded by surfaces which do not usually coincide with centre line during the approach and missed approach so the obstacie limitation surfaces specified in Annex 14. I n that the probability of an aeroplane touching the funnel at the case of a non-precision approach, missed approach any one point is 1 :lo-' or less. The probable fight paths. and visual mnaeuvring, the surfaces have a rather both vertical and lateral, for aeroplanes trackirig the ILS simpie rorrn. Typicaf cross-sections of such obstacle-free beams during an approach. have k e n based on a airspace are shown in Figures 1-4 and 1-5. The plan view consideration of possible tolerances in both the ground of such an obstacle-free area depends on ahe and airborne navigational equipment and the extent rn characteristics of the navigational facitity used for the which the pilot m y atiow the aeroplane to deviate from approach but not on the characteristics of the aeroplafie. the beam whilst attempting to follow the ILS guidance. A typical plan view is shown in Figure 1-6. (pilotage). The probable flight paths in the missed approach are based on arbitrary assumptions of minimrani 1.3.1.5 In the case of a precision approach, the form climb performance and mah-murn splay zngle of the of the obstacle-free airspace becomes more complica red aeroplane in a missed approach manoeuvre. Note that, as because it depends on several vsriabies, such as mentioned in 1 3. 1. 5 , the precise dirnerisions of a funnel aeroplane characteriseics (dimensions, equipment, do vary with a !lumber of factors. I-laving defined this performance) and ILS facility characteristics (facility volume of airspace, simple calculations atlow an OCA/H  Index (Minimum Obstacle CIearance) Figure 1-4. Figure 1-5.  Index VOR or M DB facility Nominal flight path- - - -- Figure 1-6. to ix calculated whish would protect the aesophm from PANS-BPS, is a viami exknsian af an instrument ail obstscles. The difference between the basic IES approach procedure. The size of the area for a visual surfaces and the OAS is that the dimensions of the latter manoeuvring (circling) varies with the flight speed. I1 is are based uplln a mtlection of data on aircraft ILS permissible to eliminate from consideration a particular precision approach performance during actual instrument sector where a prominent obstacle exists by- establishing meteo:ological conditions, rather than existing Annex 14 appropriate: operatiwaf procedures. ln many ca.ses, the SUT~~C~S. size of the area will be considerably larger than ahat covered by the Annex 14 mner horizontal surface. 1.3.4 ILXCollisiisiilnRiskM(Kde1 rCRMl.Theapproach Therefore circting a1titudes/heig h & calsulated according funnel of the OAS was designed against an over-all risk t.o PANS-BPS for artval operations may k +igher than budget of one accident in 10 mitiion approaches 6.e. !hose based only on ob:,tades -renetrdling :he inner a tErget level of safety of 1 x lo-' per approach). One F.orizontal surfact area consequence was that an owrational judgem,~ n was t required to assess the acsc,ptablc: de,nsity of obstacles in I 3.6 0pra:iolad rtrnlrvu, In concluston, it m ~ ; tk the vicinity of the QAS, although they might be below the stressed that ;I rJnway proteclec only hy the obstacie surface i ~ l fIn. addition, the OAS were overprotective rn Iirn~iationsurfaces of Annex 14 will not necesmriIy alloa certain areas, &cause they were relatively simple plane the achievement of the lowest possible operational surfaces designed to enclose a cornpiex shape and to allow minima if ~t docs not, at rhe same time, satisfy the easy mar?ufil application. As a consequence of these provisions of the PANS-OPS Constquentlh , factors, a more sophisticated method of relating obstacle considerai!on needs to be glvcn to objects which heights and iocations lo total risk and W A I H was penetrate the PANS-OPS surfaces, reglrrdless of whetkr developed. This method was embodied in a computer or not they penetraie dn Annex 14 o b s t 2. 1 ~irrnii~icr~ pi-cgramrne called the Collision Risk Model ICRM). I t sllrface, and such cbstacles may result irr a n operatiozal enabks a f a r more realistic assessment of the effects of wnallf, obstacles, b t h individually and collectively. The actual construction of the approach funnel fiilustrated in Fig- ure 1-81 involves some fairly detailed mathematics and cannot 1Pe done manually. However, its application is 1.4 I S H E R TRANSITIONAL AND easy, because all cakulations wilt be done by a computer. BALKED 1,AIZDINQ; SURFACES The CoIlision Risk Model is widely available. IICAO VERSUS Y SURFACES.%NIP offers the grvrce and ihe programme is availab!e for M1SSEIP h f PWQPACH SURFACE purchase 10 interested users. For Further details see 1.5 below.) 1.4.1 Wher. establishing the c?bsecle-f;,ae zone for precisian apprrlnc I I category 11 c~perations, ihe Obstacle / win# {t'ircling p~uredurrj.Visttal 2.3.5 V i s u ~rndno~u Clearance Pane: (13CI') creared ii:e inner transibional and manoeuvring !circ!ing procedure). desciibed in the balked landing surfaces. When deveioping the new ap-  Index The funnel is formed by the at of 7 surf-: - Ths W and two X am& surf-. - The "footprim" A. - The m i d am- surface P. - The w Y tramitional surfaces. Figure 1-7. The approach funnel (OAS)  Index \ ri Glide path OAS tanganziaf to the probability curve at certain kcations I x 10-7 Probability curve ~f aircraft displacemen1 Figure 1-8.The approach funnel (CRM)  Index p r w h p r w d u m coauined in PANS-OPS, V o l m 31, 1.5 ]BLACKGROUND OF ?SHE First Edition, instead of using these surfaces far COLLISION RISR MODEL obstacle assessment,the OCP used the Y surface and a new surface referred lo as the missed approach surface 1.5.1 The ColIision Risk Model (CRM) is a (see Figure 1-7). Both sets of surfam are required. In computer programme that calculates the probability of determining the need for the two sets of surfaces, the coHisioa with obstacIes by an aerophna an an ILS difference between the objectives of Annex 14 and approach and subsequent missed approach. The CRM PANS-OPS has to be taken into account. The surfaces was developed by the Obstacle Clearance Panel as a result in PANS-OPS are intended fw assessing the impact of of an extensive data mibcaion programme followed by olqects on the determination o f the obstacle clearance detailed mathematical analysis. The CRM is an important height, which in turn is used in determining approach part of the criteria for 1LS operations desrrikl in Pa11 I minima and ensuring that the minimum acceptable safety of the PANS+OPS, Volume 11. level is achkvsd (i.e. probabiliiy of mllision with objects is not more than 1 :10-'1. Annex I4 surfaces are intended 1.5.2 Obstacle assessment and obstacle clearance to define the limits around airpora to which objects can calculations can be carried out by using obstacle e x a d. - A further difference, and one s~cificrllly assessment surfaces (see 1.3.3 above). However, this associated with these surfaces, L that PANS-OPS manna] method, although simple in concept, involves provides obstacle assessment for operations down to the tedious numerical calculations and is ahus time- obstacle clearance height and, for most aeroplanes, for a consuming, particularly if the n u m b of obstacles is missed approach with one engine inoperative execuied high. Furthermore, it suffers from woomain drawbacks: above or at this height. The Annex I4 surfaces are intended to protect a hnding from the o b s k b clearan= a) Firstly, the requirement that the OAS be of simple height, or a balked landing executed with all engines form (a set of plane surfam) to allow easy manual operative and initiated M o w the obstacle clearance application of the criteria, results in the surfaces being height In the missed approach eem, the PANS-OPS overprotective in certain arms, particularly in the surfaces h e 1.3.2 to 1.3.4 above), which include a vicinity of the runway. This is precisely the area where missed approach surface, are the controlling surfaces. critical obstacles &lid: path antenna, holding aircraft, The obstacle assessment surfaces IOASI fall below a etc.) are most iikely to ke sited. Hence, under the OAS priion of the Annex 14 inner approach surface and criteria, such obs~cfes m y unnecemjly prevent below that portion of the transitional surface near the aeroplanes opera ling to low minima. end of the touchdown am. In cams such as these, the b) Secondly, the use of the 0.4s implies that these Annex 14 surfaces are used to determine W H. In tke surfices muld become solid walls without any I d i n g s and b l k d landing, the inner transitional and vratiotr;il p e ~ l t yin terms of zn increase in BCAIH. balked landing surfaces are the controlling surfaces. Clearly such a situation would degrade safety. If left entirely to the operational judgement of the 1.4.2 The PANS-OPS and Annex 14 surfaces are procedures specialist to decide at what point there differen 1 for several reasons. A missed approach is to be exisrs an excessive density of obstacles around the executed at or a b v e the obstacle clearance height. At this runway, an insufficient owrational penalty muld point, tbe aircraft can not be assumed to k aligned with result. the runway as precisely as in the case of a balked tanding, as the pibt may never have had visua) reference to the 1.5.3 Therefoe, although the OAS criteria are runway. The width required for executing the missed designed to achieve a specified target level of safety, they approach is therefore wider than for a balked landing; may result in a greater Ievei of safety being imposed and thus the use of the transitional surfaces, which are wider consequently unnecessarily prevent operations to low a p r r than the innm transiljonal surfaces. Semndiy, since minima or, alternatsvtly, they may result in the safety of the missed approach may k assumed to be executed with operations k i n g degraded beiow the required standards. one engine inoperative, the climb rate will be Iess than for The CRM has k e n developled in response to these a balked landing executed with all engines operating, and problems. It will: mnsequenhy the slope d the mimed approach surface must be less than that of the balked landing surface. As a) provide risk computations (separately for ail obstacles the missed approach operation by definition has to be and for inaividual obstacles1 to a specific set of initiated at or above the obstacle clearance height, the conditions and runway envircnment; end origin of ihe missed approach surface may be clogr to the b) provide mmjnimtrm acceptable OCA/fI values for a threshold than that of the balked landiilg surfhce. s w ~ i f set i ~ of conditions and runx.va);environment.  Index Part 6. - Control of Obstucles Chapter I. - Surfaces 1.5.4 The CRM may also h used to assist: c) in deciding whether or not a particular new construction wouid result in an operatiom1 penalty a) in aerodrome planning (in evaluating possible (i.e. in an increase in OCA/H). locations for new runways in a given geographical and obstacle environment); 1.S.5 Dm 9274-AN/904, entitled Manual m the Use of the Collision Risk Model (CRA-4) for ILS Operations, b) in deciding whether or not an existing object should be provides a comprehensive description of the CRM and removed; and instructions for its use.  Index Chapter 2 Controlling Obstacles at an Airport tbse interests with rmpixt ao an existing airport where obstacles a h d y exist. Even in the i b l situation of 2.1.1 In the early days of aviation, the tights of developing a new wrkwat in an open area with no property owners were cansidered to extend from the obstacles, prevention sf future obstacles my be diff^ncult surface downward to the center of the earth and upward kcaatse Isisbricalliy airports h v e expanded bwds to infinity. Amrdingly, the owner was free to erect neighbring mmeenitis'as and, wnverxb, mmrnuaities structures on his knd to unlimited heights and any have grown towards the airport bunchries. Every effort encroachment in the airspace by others constituted a should t~ exerted by all interested parties to prevent trespass. Thb meant that aunaft could not fly over wectinn of future oktacbs and to remove or lower private pwprty at any altitude without permission of existiw obshcks. each prowrty owner. Obviously, that policy warid have prevented the development of civil avktiori and scheduled eir transportation. Graduallyw wurts and Iegislatum have naodjf~d the ownership docprim to specify that a property owner has exclusive rights to the airspace over hi land only to the greatest height which he 2.2. i National governments genesalty have the basic might reasonably l x expected to use, with a right of Tree authority and primary responsibility to eskablish criteria public transit through the air above suck height. for the Iknlitation of obstacles and to provide guidance and assistance to tho% directiy concerned with COII~TO! of 2.1.2 When buildings encroach on the airspace obstacles. These criteria should take the farm of the needed fw aircraft ~ rtioos, z a cmflkt of jnterest sries abshcle Jirniution surfaces sel irralh in Chapter 1, and between proprty owners and airwrt operators. If suck ahrruid h competibk with Ihase 1 ~ Annex. !4, Chapter 4. differences cannot tPe resolved, il may h necessary for In addition, ~ t i o n a lauthorities should make clear to the national authority charged with approving aircraft communig and airport officiais the A a t and economic operating procedures to establish restrictions limiting problems which may result from failure to maintain operations in the interest of safety. Such restrictions obstacle limitation surfaces free from obstacles. might take the form of requiring displaced thresholds (tesulting in a reduction in effective runway length), 2.2.2 In addition ro setting criteria, government higher weather minima for operations, reductions in agencies should, where feasible or necessary, authorize authorized ai~craf i masses and possihiy rwuiciians of local community sff~ialsto adopt zoning regulations to certain aircraft types. Any of these actions could seriously limit heights of buildings and trees to minimize future affect orderly and efficient air transportation to an airport penetrations of obstacle limitation surfaces. Also, and adversely affect the economy of the communities governments should authorize airport operators (or local served by the airport. wrnrnunitiesJ to acquire air easements or property rights (where such authority does not already exist), including 2.1.3 Control of obstacbs in the vicinity of airpotts the w w e r to condemn property in the public interest by is, therefore, a matter of interest and concern to national the exercise a l eminent domain. Governments may also governments, local mmmuni ties, property owners and adopt rules and regulations designed to ensure airport operators. There are severe legal, economic, social notification of possible future obstacles in the interest of and political limitalions to what can be achieved by any of safety of aircraft operations.  Index Part 6.-L ' o n ~ oj'Ot.xrades l Chapter 2. - Contrul/ing Obstac!cs ar a,l A tiport 2.2.3 L m I mmrnunity bodies such as municipal or easements and purchase of' property. Each of them issues county adm~nistrations, planning agencies and is dealt with in greater deiail in the following paragraphs. construction licensing authorities should, when properly authorized, adopt height mning regulations based on appropriate obstacle timitation surfaces. and limit future devefopments accordingly. They may require property owners or developers to give formal notice of any proposed structure which may penetrate an obstacle 2.3.1 Enactment of zoning regulations incorporating limitation surface. Local bdies should co-operate closely height limits related to airwrt obstacle limitation surfaces with a i r p ~ r toperators to ensure that the measures taken is a difficult and complex grcacess but a necessary one. A provide the greatest possible degree of safety and Model Zoning Ordinance to achieve this objective' is efficiency for aircraft operations, the maximum economic presented in Appendix 2. As a general rule, any benefits to neighbouring communities and the least community desiring to adopt such an ordinance will need possible interference with the rights of property owners. legal authority eo do so from a higher level d government. Even when so authorized, the effectiveness 2.2.4 Ultimate responsibility for limitation and of height zoning as a means of protecting airports may IE control of obstacles must, in practice, rest with the airport severety limited. operator. This includes the responsibility for controlling obstacles on airport property and for arranging the 2.3.2 It has become a well-established principle of removal or lowering of existing obstacles outside the law that wnrng cannot be so restrictive as ta deprive a property owner of his right to the use of his property airport bundaries. The Iatter obligation can be met by negotiations leading to purchase or candenmation (where without adequate cornpensation. Many height zoning authorized) of air easements or title to the properly. ordinances have been ruled invarid by the courts when property owners have claimed invasion of their proprty rights. 2.2.5 Each airport manager should designate a member of his staff to be responsible for the continuing 2.3.3 Such considerations limit the effectiveness of process of making sure that airport approach, departure height zoning, particularly in the mos! critic:?!areas dose and manoeuvring areas remain clear of obstacles which to runway ends, where obstacle firnitation surfaces may may jeopardize safety. The airport manager, or his require very low heights. Any height zoning must designee, should work closely with government agencies recognize lhis fact and provide for a minimum aIIowabIe at all levels, mtional and !creal, to ensure that all possible height which is reasonable in terms of existing land use in steps have been taken to prevent erection of obstacles, the vicinity. Even so, local opposition to aircraft including providing information to zoning authorities on owrations and to any form of restrictions on use of the location, length, orienurion and ekevation of runways property m y give rise to legal chatlenges leading w on which obstacle limitation surfaces are based. The possible invalidation of any but the most carefully drafted airport manager must maintain constant vigilance to zoning ordinance. prevent erection of obstacles around his airport and he should alert other agencies tn potential problems which 2.3.4 Height zoning, and indeed any form of zoning, m a y arise under their jur~sdstion.In order to fulfil these cannot k made retroactive. Existing structures and trees obligations, the airport manager should ef;tablish a which do not conform to the zoning limits arc generally programme of regular and frequent visual inspectiohs of permitted to continue as non-conforming uses. Obstacles all areas around the airport in order to l~sure that any of this nature must be dealt with by other mezhods, such construction activity or natural growth (i.e. trees) likely to as purchase of' easements or property rights. infringe any of the obstacie limitation surfaces is discovered before it may become a problem. This 2.3.5 The fact that obstacle limitation surfaces for n inspection programme should also include a dally single airport may overlie the prowr:y of several observation of all obstacte lights, both on and off the independent communities or legal jurisd~crions furlher airport, and corrective action in the case of light failure. complicates the problem of adopting effeca~vezoning. Airport operators have nn zoning p w e r s , and must rely 2.2.6 In summary, once he national government bas on the co-operation of neighbor~ngccrnrnvnities. This set forth the necessary criteria, :he principal methods of may lnvoive as xarry as !hirty or forty separate conrro!Iing obstacles availsble to community aurkorities ju:isCivtv~ns, srlrne ~f whrch may k u n c o - o ~ r a t i v eIn and airport operators are height zoning. purchase of some cases, higher governmental bodies have au thorned  Index the creation of regional planning groups with the wwer ta zoning limits are not in effect nr are inadequate to protect adopt uniform zoning standards. For example, in one obstacle limntation snrfaes. such instance, a srate governtrent has authorized establishment of jotnt alrport i.onrng boards with '%.4,3 Where negot~ationsto obrair! casements itre not membership from the airport operalor and each successful, nhen thc airport tlperator should give surroiinding municipality. The b a r d is empowered to consideration to the semrtd alterndtne, 1.e purchase of adopt land use restrictions withrn 3. 2 km of the airport Lhe property, The airport owrator muld resurt to the boundary under approach areas, and 1.6 krn elsewhere. acquisition of the property by condemnation if the The board may also enact height-restriction zoning within government has authorized such action. I n such cases, 1.6 and 2.4 km from the airport boundary. the airpart operalor must pay a seasonable compensation to the property owner, i.e. at the fair market value of the 2.3.6 As suggested by the above, land use zoning PropertY. may also be helpful in certain areas as a means of preventing erection of ~bstacles. Where feasible, 2.4.4 One major airport o r has k e n undeveloped areas may be zoned for uses which do not specifiatty authorized KDuse the power o f condemnation normally involve tall structures. Such uses m a y include for obstacle ciearane w a maximum distanm of 4. 8 km agriculture, recreational activities, parks, cemeteries, from the ends of the runways. ~orndemnarrionof property aum parking and low (one-story1 industr~albuildings. for the purpose of installing navigational aids is also authorized, but wi:hout the restriction as to distanm. 2.3.7 As outlined in Appendix 2, typical zoning ordinances generally include a statement of the purpase of or necessity for the action, a description of the obshcle 2.4.5 Purchase of property rights involves several limihtion surfaces which should conform k the surfaces obstacles. I f the property $0 i x acquired would be described in Chapter 1, and a statemenk of altowable removed from the tax rolis, as is nlien ~hr:i ; + S t when the heights which should conform to the specifications in a ~ r p ? rISt pubticiy owned, ilae commur;$ryoffic~alsand rhe Annex 14, Chapter 4. Prur isiorts are also made for a anrport neighkmi:~nta!, r;pposc \Re at~tionk c a u s t !)f the rnzrlin~urnallowable heig h ~ ,fur e r i s t i ~ ~non-conforming g added tax b~rLieri0 1 1 other proper t:e< ! i l ~ i -r ,i c ~hbours :~ uses, for marking and lighting v i ubsscles and for appeals of thc affected property may ohjec t I(>kcqirisition by Ithe l ' i the ~ ~~ ~ r o v i s i o rof~ sthe urd~r,,rnce. ?];port tor a ntlmk: of icdsljnr {lwt;c:.shrp of properiy which is not needed fhi air;?t)r? purposes :]jay be a burden to tne a ~ r p opeidL:lr ! b u ~ 3 g s enf the aitdcd experlse o f rnia!nralnlng the property. 1.4 PURCHASE OF E.4SEMENTS A N D PROPERTY RIGHTS 2 4. h The tar; ~xl?rn!rtior~prohiern ~ o u l dhe met by agreement ttr pav a sun? tn lies: :if tarer, bat this ( w i d be 2.4.1 Inthoseareas~herezoningisinddequate,such an ex:rs cxpenrc :o rhc ~ i r p o r rnpeyator for prtlpertv as locations close tir runway crlrls or where existing which i s :lor real!) netrlud, A helie- ~ o l u t ~ o nwherr. obstacles are present, the arfpcJrt operator should take feasible, would k to sell the hutk of ~ i r cp r r j p r t y to steps to pralect abe obstacle limiht~onsurfaces. These private owners sub,ject 10 protective coberla nts designed steps should include remuval o; reduction in height of to prevent creation of' future obstaulcs, Resalc cf property existing obstacles, as well as measures tc ensure that no would, of course, have tn ke consisr~ntwith ,!ppIicah!e new obstacles mav be erected in the future. zoning i n the area. Re!ond a distance of irh3~1; 300 rlr from a runway end and land needcr! for apprwsch !ightlng 2.4.2 An airport authority ccrutd achieve these systems or other navigafional air!\, the airport operator objec:ives either hy purchase of easements or properly should Re able to sell most ~. r l ~ e lant!r subject to rights. Of ihese two alternatives. the purchase of appropriate height and use re~trict~ons. Such sales would easements would r>ftcn prove t r ~ Ge more simpit. and hzip t:r rcccver a substan~izl par! of !he cost of economical. In t h ~ scase, the dirpnr i auihority srzcl;iesthe acqutsi~ion, would elirnin~t!? the cu~!i~!urnp zos! consent of h e awn.er :at i t ; psylnC suitable rnaintenal~ceand wou!d re:u:n the I;lr-rd trr the I ~ rirljs. ~ X compensation) to lower the h e r ~ h :of thc ohsricle I?, Approprratt* use restrictions ~ o u l d inc!utle !haw question. This nrav be done by c l ~ r ~neirptlattot\ ct wi!h the meni:onsd rt: Sec::r:n 2.3 s k v c , i: stiifr iiht'? ,!re prn;)rrq Owncr. b:;~h dr: 2gret'nleTit 5houltf also rncylude a au?hu~!zedby zccrng regulation$ ::rid accilystiihii. r i j iile pirj rl+,liln IO orevent eleuttr17!GI i ' d ~ u r e~bsractes,if hc!ght C0nmuni;jr.  Index h r r 6. ConRob of'0hiiurkr.s Chapter 2. - Co~~tr#Iii!ig Obs ttic.lt7s3 t utr.A :rporI 2.5 KOTIFICATION OF Articles I2 through 19 deal with a ~ n t r e i of PROPOSED COFYSTR liCTI61N conslruction in the vicinity of licensed arrpres, The paov1sion.s of these articles specify that the outhwity 2.5.1 One of the difficult aspects of obslacle control cornpetem for granttnr i.!~nsaridciionjirences may license is the problem of anticipating new wnstruation which the construction of bu rldings only with the consent of may penetrate obstacle limitation surfaces. Airport the aeronautics authorities when construction is within operators have no direct means of ~reveneingsuch a radius al 1.5 km kom the airwrt reference point developments. As noted above, they s bould conduct (see Section 2.6 h i o w ) or on the take-off, tanding and frequent inspections of the airport cnvit;:ns to learn of safety areas. Consent of the aeronautics authorities is any suck projects. Although there is no legal obligation also required if conslruciion is intended. to exceed for airport o ~ r a t a r s to report proposed cons~uction specified height limits within various larger radii from when they become aware of it, their own self-interest and the airport reference mint, or within specified the need to protect the airport indicate the wisdom of distances within the approach zones. bringtng such matters to the attention of the appropriate authorities. Of course. where an obslacle is to be located b) United Kingdom (GK) - CAP 168 "Limnsing of on airport property, such as electronic or visual aids, the Aerodmmes", Decemkr 1918, Chapter 4 The - airport owrator is responsible for reporting such projects. Assessment a ~ l dTreatment of Obshcics Section 1 1 specifies that. under the Town and Country 2. 5. 2 Several countries have enacted Iegislatian or Planning I~erodrames) Direction 1972, the Civil adopted regutations designed to assign reswnsibility for Aviation Authority safeguards certain important reporting new construction pro~ects.The obligatiorr to aerodrrmn~e>against future developments which might report suck construction m y rest with local agencies such prejudice their actuaI or potential use for flying as planning b d i e s or construction licensing authorities or purwsc:. A safeguarding r i p is deposited with the with the developer himself. In some cases, height Iirnits local planning authority, showing the height a b v t have been specih~cd;these are generally mnsistena with which MW mnstruction near an aerodrome may the criteria of Annex 14, Chapter 4 , below which local interfere with its use. The planning aufhoriqis required authorities may authori~ea projec: without higher review. consult the Civil Aviation Authoritv :bout any if any part of a proposed development appears to development exceeding the app~opriat~reference penetrate an obstacle Irmiration surface, then the project level. if a licensee (airport operator) becorner; aware of a should be referred to the appropriate civil aviation proposed development which in his opinion ~rtfringes authority for review. T h ~ srevlew would examine the any cr~ierionor would inhlhrt ~ntandeddeve!npment af effect of the envisaged construc;ioi; on arr navigatilrn In the aerodrome, he should request the phnaing general and on operat~onalprocedures in use in part~cular. autha-iiy tu take this into consideration in determining If the conclusion of the above study is char the proposed the application. construction can be permsited under some conditions, these should also be identified, e.g. display of sbslacle - Federal Aviation Regulations. C) C'nitpd Stotes if/S) marking and lighting, compliance with other approprwle Part 77 (Amended 4 March 1972) measures for continued safety of air navigation, etc. FinaHy, all concerned should be natiri'ied oh the new Sectrun 77.i I requires each person proposilag specified construction through charts (in accordance with Ancex 4 kinds of constructwn or alterdtior! to give "adequate - Aeronauiical Charts? dnd through Notices to Airmen notice" to the Adrninistraior of the Federal Aviation (NOTAM) or Aeronau t~ccl Informa tion Pu blicationr; Administration (FAA) together with suppIcmenml CAIP) pursuant to Annex 15. notrups 48 hours &fore the start and upon completion. Section 77,13 requires sponsors to notify the Admrn~strator of any construction or alteration nf 2.5.3 Among other States, the Federal Republic of more than 200 ft above ground level at 11s site, or of Germany, the United Kingdom and the Untted Seares greater height than an irnaginarv surface cr ;endir.g have established procedures for reporrlng proposed ourwilrrl and upward a t a slope of 100 tn I for a construclion. Highlights of such procedirres in efftci as horl~nnrald~stanceo i 20 000 ft from the nearest point of the indicated datcs) are summarized Tor i n f r ~ma!~on. r of 1 1 7 ~nearest r u n w a y a1 an) public r;irport having ar ieast (11.rcrunway more than 3 200 f t in length. Steeger a } Frdcr~lRpplubtic qf' G~rmunv!17RC;j --.4cronitutics c;bpeu are specifithst:icit. location and elevation survey. Where this wit! be done by the use uf aerial photographs and pho:ugrarnme tric prtEesses a b u t three stations a t he ends of !he: ruilways, a ?tation a? the airport 4.3.7 To establish the required airport e!evation, referer.ce point snd an outlying statisn just beyond the Including runway profile elevations and bench marks limits of the obsl;lcles in eaci! direction from ehe alrport from which obstacIe etevaticns will be determined, spirit wiIl rruftice. Where atrial photographs will not be wed, levelling of third-order or higher accuracy should :b run one iocai vontro! sration wit1 ke reqblred dt the airport to the airport. This ievelfing should bz run forward arrd rekrence j x j t m t.in:? one at the end or' each rir:,way. backward from two existing bench matks h t w e e n which Enough addrtiona! c!utlying stations alsr; wiIl he rcquircd a satisfactory check ts obtained and which are based on In permla Ike Iocai:nn, (:om thcsc rta~infis, of each mean sea level efevations. Where it is not practicable to ~ b s t n ~ l e cchan t every obstacle Obstacle rietmzion and selection that is detected in the fiela. A selection r n u t~.ie made ?a include the most impor&!;: obstacles, plus lhcse 4.3.17 The locations and the elevations of obstacles portraying obstacle naruie and distr~butior! !larr~ughahl! comprise the most important information shown on an rhe chart area. An effort shou!d be madc lo portray I?!: obstacle chart. The party personnel must be thoroughly density of ohsracIer; in each area hy selecring e few rnrlrc familiar with the imaginary surfaces that define obstacles. obstacics ili ilreas where the density is ;.,,,n :r: The validity of the published obstacle chart depends upon selected in less ilongested areas. the care and judgemenl exercised by field party ptrsnnneI in the detection and selection of obstacles, and in the subsequent work of locating thern and determining their elevations. 4.3.22 The iocatron ihorironiai pus!!:ni*.: !!:us! Ijr:..! determined for nich i,bstacle selecic:! '