Appedix F Aircraft Maufacturers Maufacturers of aircraft must meet specific miimum criteria whe it comes to certifyig aircraft for use by the aircraft operators. It is recogised by the maufacturers that the iformatio for certificatio does ot cover all aspects of the aeroplae operatios ad as such they provide additioal documets ad iformatio such as Flight Crew Operatig Mauals, Flight Crew Traiig Mauals, Flight Crew Iformatio Bulletis, Flight Operatio Techical Bulletis, ad material durig symposiums, cofereces, performace egieer traiig classes, flight crew traiig. May of these publicatios cotai procedures ad iformatio that address issues that have bee idetified as causal factors i ruway excursios. However ot all maufacturers provide the same amout or type of iformatio. Below are recommedatios for what maufacturers should provide to help address issues associated with ruway excursios. It is recogised that much of the iformatio i the list below has bee supplied by may but ot ecessarily all the maufacturers of the aeroplaes. Takeoff ad Ladig Performace Presetatio Recommedatio 3.5.1 Aircraft maufacturers should preset takeoff ad ladig performace iformatio i similar (commo ad shared) termiology ad to agreed stadards. Sigificat progress ad agreemet as to termiology ad stadards was accomplished durig the work of the Uited States FAA Takeoff ad Ladig Performace Assessmet (TALPA) Aviatio Rulemakig Committee (ARC) activity that occurred i 2008 ad 2009. I this activity six of the major maufacturers worked with the FAA, aircraft operators, busiess jet operators, airport operators, ad other idustry iterest groups to recommed a stadard termiology for reportig ad evaluatig ruways coditios whe the ruway is ot dry ad criteria for maufacturers to use whe computig the aeroplaes performace iformatio. The curret status of the recommedatios from this activity is that the TALPA ARC recommedatios have bee issued by the FAA usig advisory material. Some aircraft maufacturers have implemeted the recommedatios ad so they are i use by some aircraft operators. Airbus has chaged the way it provides data i their operatig documets for the bulk of the fleet to use termiology ad stadards cosistet with the TALPA ARC recommedatios. Boeig has used the recommedatios i creatig the certificatio ad operatioal data for their ew aeroplae programs (787 ad 747-8) ad provides aircraft operators o a as requested basis the iformatio ecessary to adjust their ladig performace iformatio to meet the recommedatios. It is recommeded that other certificatio agecies cosider the work doe durig the FAA TALPA ARC if/ whe they chage reportig termiology ad methods or chage stadards for computig the performace iformatio. Ruway Coditios ad Aeroplae Performace Recommedatio 3.5.2 Traiig material promulgated by aircraft maufacturers should emphasize the ecessity of makig best use of ruway legth available whe coditios are ucertai or whe ruways are wet or cotamiated by applyig full brakig devices, icludig reverse thrust, util a safe stop is assured. This type of iformatio is ofte icluded i the maufacturer s FCOM or FCTM with supplemetal iformatio possibly i bulletis or magazie articles. A example of a maufacturer s guidace o operatig o wet or cotamiated ruways is provided later i this appedix. Real Time Performace Moitorig ad Warig Systems Recommedatio 3.5.3 O-board real time performace moitorig ad warig systems that will assist the flight crew with the lad/go-aroud decisio ad war whe more deceleratio force is eeded should be made widely available. Part of the tools for excursio prevetio is improved techology to help the pilot with the followig decisios: to proceed to destiatio or divert, to lad or go-aroud, or to apply all deceleratio devices to their maximum Europea Actio Pla for the Prevetio of Ruway Excursios - Released Editio 1.0 - Jauary 2013 75
Appedix F Aircraft Maufacturers utilisatio. Differet systems are curretly available or i developmet by some maufacturers ad 3rd party vedors to use existig techology to provide the flight crew iformatio to assist with these decisios. Ladig Distace Calculatios Recommedatio 3.5.4 The aviatio idustry should develop systems ad flight crew mauals to help flight crews calculate ladig distaces reliably. The aviatio idustry has chaged greatly i the past decade as to how the calculatio of performace i geeral ad ladig distaces i particular is doe. I the late 90s ACARS systems ad laptops started showig up i the cockpit. The iformatio the flight crew obtais from these systems is computed based o crew iput iformatio such as airport/ruway, weather coditios, wid, ruway coditios, approach type etc. These systems replace the eed for crew to do multiple had calculatios, flippig through paper charts ad addig/subtractig/iterpolatig i cumbersome tables ad charts. Ofte because of the umber of computatios required flight crew relied o quick checks of the umbers or did t do the appropriate performace checks at all. With the aforemetioed ACARS systems ad o-board performace programs it is much easier for the flight crew to get a appropriate aswer with less exposure to error. It is also easier for the crew to look at multiple scearios so they ca have a pla i the evet they obtai additioal iformatio late i the approach that the ruway has deteriorated. Maufacturers of these devices ad methods are cotiually searchig for better ways to do this ad i this very competitive busiess there is o doubt that cotiuous improvemet will cotiue. The availability of such iteractive systems however does ot discharge aircraft maufacturers ad operators from presetig the performace iformatio i a ituitive format that is foolproof to use. This becomes eve more importat whe the performace tables are oly used very occasioally as a backup meas to a electroic system. Data Checks Recommedatio 3.5.5 Electroic Flight Bag maufacturers ad providers (class 1/2/3) should eable the flight crew to perform idepedet determiatio of takeoff data ad to implemet where possible a automatic crosscheck to esure correct isertio of the takeoff data i the avioics. Stadard Operatig procedures should be developed to support this crosscheck. Maufacturers of EFBs are ecouraged to ivestigate to what degree they ca create simple crosschecks betwee various data sources to esure the correct iformatio is beig used i the calculatio of the takeoff data. A typical error that has caused safety problems i the past has bee the use of icorrect weights i computig takeoff speeds. Ay meas of miimisig the sources of such error has to cosider huma factors aspects of the cocered iterfaces ad how they itegrate ito the specific cockpit eviromet i which they are meat to be used. A example for a huma factor drive solutio is to require ZFW oly as the iput to the FMC istead of givig the optio of iputtig either ZFW or TOW. Aother example is removig the weight used i the previous calculatio, which requires the flight crew to iput the weight for the curret flight each time. Aother approach to reducig mistakes are gross-error checks, which must rely o totally idepedet data sources to validate cosistecy. A example of a gross-error check is the compariso of the maeuverig speeds calculated idepedetly ad from differet sources by a EFB ad the FMC. Example guidace material may be foud i the FAA AC 120-76A, Guidelies for the Certificatio, Airworthiess, ad Operatioal Approval of Electroic Flight Bag Computig Devices ad EASA AMC 20-25, Approval of Electroic Flight Bags. 76 Europea Actio Pla for the Prevetio of Ruway Excursios - Released Editio 1.0 - Jauary 2013
Flight Crew Procedures Recommedatio 3.5.6 Maufacturers should have clear flight crew procedures required to attai the published takeoff ad ladig performace. The maufacturer s performace preseted to flight crew should clearly iclude the basis for the calculatios. This would iclude items like the followig: what level of reverse thrust was assumed, what is the assumptio of the wheel brakig, is the data factored or ot, what is the air distace allowace i the data. FCOM procedures ad flight crew traiig maual recommedatios should also be cosistet with the assumptios i the data. If the data assumes prompt iitiatio of reverse thrust, the the procedures should require this, etc. Maximum Crosswid Recommedatio 3.5.7 Maximum crosswid data published by aircraft maufacturers should be based upo oe cosistet ad declared method of calculatio. The maximum acceptable crosswid depeds o the aircraft capabilities ad the ruway coditios, but also i the persoal limits of the flight crew depedig o their experiece. A cosistetly determied maximum crosswid recommedatio by aircraft maufacturers would be a good basis for a pilot to determie his persoal limit from. At this time however, maufacturers supply recommeded crosswid maximums based o the assumptios they cosider appropriate. The assumptios iclude thigs like: This is because curret methods for determiig recommeded or limitatios o crosswid are ot part of the certificatio basis for the aeroplaes, ad oly a demostrated value o a dry ruway is required i the AFM. It is doubtful that maufacturers will come to a cosesus o this item without regulatory guidace as i may cases there are fudametal differeces i philosophy betwee maufacturers. A startig poit for harmoisatio would be for maufacturers to agree o usig the descriptio of the ruway ad brakig actio such as was accomplished for performace computatios for the TALPA ARC. The developmet of regulatory guidace i this field should iclude maufacturer cosultatio to esure techical ad ecoomical feasibility. Lessos Leared Recommedatio 3.5.8 Maufacturers should moitor ad aalyse all (worldwide) ruway excursios ivolvig the aeroplaes they support ad share the lessos leared. The reportig ad ivestigatio of aircraft accidets ad icidets is regulated by ICAO Aex 13. The results of such ivestigatios are sometimes shared publicly. However, due to their much higher rate of occurrece much more ca be leared from precursor evets if they are idetified as such ad acted upo. Some maufacturers review yearly or bi-yearly the sigificat accidets ad icidets as well as the causal factors ad issues highlighted by these evets. This ca be doe at meetigs ad cofereces atteded by operators, ad i maufacturer publicatios like bulletis, chages i procedures or other iformatio. modelig for differet ruway coditios, cosideratio of egie failure or ot, assumed cetre of gravity positio, flight techique (crab, sideslip), etc. Europea Actio Pla for the Prevetio of Ruway Excursios - Released Editio 1.0 - Jauary 2013 77
Appedix F Aircraft Maufacturers Iformatio o the TALPA ARC The TALPA ARC was tasked with a exhaustive review of safety issues of operatios o cotamiated ruways ad recommedig modified FAA regulatios, which would be retroactively applicable to all existig aircraft. The proposals for regulatory chages cocerig trasport category aircraft put forward to the FAA by the ARC were orieted alog three mai axes: Stadards for ruway coditio reportig (FAR139) Defiitio of operatioal ladig performace computatio (FAR25/26) Operatioal Rules (FAR121) The committee also covered FAR23/91/91K/135 operatios, which are ot further addressed here. The followig aspects were outside of the scope of the FAA TALPA ARC madate: Assessmet of ladig with i-flight failures, Overweight ladig without failures, Automatic ladig distaces, Dispatch ladig distaces. The exclusio of dispatch was made to miimise the ecoomical impact of the proposed chages. Furthermore, the itroductio of a more operatioally represetative assessmet of ladig distaces to be used for dispatch is ot cosidered to costitute a sigificat improvemet i safety levels, while accurate i-flight ladig distace assessmets are accepted as beig the major meas to reduce exposure to ruway excursios at ladig. Eve so, for the log term, the eed to review dispatch ladig distaces for cosistecy with the time of arrival requiremets was ackowledged by TALPA ARC i its submissio to the FAA. The cocepts detailed i the followig are those proposed for aircraft that will be certified uder the FAA TALPA ARC rules. The TALPA ARC rules also madate that ladig distaces i lie with the spirit of the proposal are published for all existig aircraft still supported by the maufacturer, albeit with less striget requiremets ad with a icreased grace period. For o-supported aircraft a set of fixed ad coservative factors to be applied to the AFM dispatch data are provided by the regulator. The TALPA ARC submitted its proposals to the FAA i May 2009, who will traslate them ito a Notice of Proposed Rulemakig (NPRM). I parallel, a field trial was lauched with selected airports ad operators to further validate the Ruway Coditio Assessmet Matrix. It is ot expected that the NPRM will be published before 2013 to 2015, to be followed by a madatory commet period of at least 6 moths. The proposals icluded a grace period for compliace of existig aircraft of two years. However, several maufacturers ad coutries have take o board sigificat elemets of the TALPA ARC work for their publicatios ad reportig respectively. Operatioal Rules Challeges Today, most operatioal regulatios make a very geeric statemet regardig the eed to assess ladig performace i flight ( the commader must satisfy himself/ herself that, accordig to the iformatio available to him/ her, the weather at the aerodrome ad the coditio of the ruway iteded to be used should ot prevet a safe approach [ad] ladig ), which does ot detail the criteria ad factors to be take ito accout for the determiatio of a safe ladig distace. The lack of clear directio has led to aircraft operator operatios departmets fillig the regulatory deficit with a variety of policies of their ow iitiative (or sometimes uder requiremet from their atioal Operatioal Authorities). Such variety of aircraft operator policies was observed by the FAA i the aftermath of the Chicago-Midway accidet, ad subsequetly led to the publicatio of SAFO ad AC. These documets made recommedatios applicable to US operators to perform i flight ladig performace assessmet, icludig the maer i which the Operatioal Ladig Distace should be derived, ad istigated the additioal 15% margi, except i emergecy situatios. Proposals Dispatch ladig distace assessmet The FAA TALPA ARC has recogised that the curret dispatch ladig distace, i particular o a wet smooth ruway, might, i some cases, like hot & high elevatio airports or descedig ruway slope, deliver usatisfactory margis. This is why a i-flight ladig performace assessmet will be required to be made systematically as part of the approach preparatio. 78 Europea Actio Pla for the Prevetio of Ruway Excursios - Released Editio 1.0 - Jauary 2013
I-flight ladig distace assessmet The proposed FAR 121 operatioal rules will madate a systematic i-flight ladig distace assessmet based o a Factored Operatioal Ladig Distace (FOLD) equal to 115% of the OLD published for the prevailig coditios (100% if emergecy or i-flight failure): This 15% FOLD icremet serves to provide a margi to cover variatios i parameters eterig i the OLD calculatio, like for example: The variability of ruway frictio due to evaluatio ad reportig of surface cotamiatio, chagig ruway coditio due to weather ad i the case of wet ruway surface issues such as texture loss ad precipitatio rate The variability i the flare executio or deceleratio meas applicatio by the pilot The variability i touchdow speed due to turbulece or the impact of cross-wid Use of Autobrake The proposal of operatioal rules icludes a exemptio regardig the applicatio of the 15% margi whe usig autobrake: If the FOLD for maual ladig is less tha the Ladig Distace Available (LDA) Ad if the OLD for automatic brakig is less tha the LDA The the FOLD for automatic brakig may be loger tha the LDA The ratioale for this exemptio is that the pilot ca always override autobrake whe required. Exemptio from I-Flight Assessmet It will be permitted to omit the i-flight assessmet for ladig o the ruway plaed at dispatch oly if: Dispatch was performed for DRY (or worse), ad if at time of approach preparatio a DRY ruway ad o worse coditios tha the stadard oes cosidered for dispatch are reported (e.g. o tailwid whe zero wid cosidered for dispatch, o higher VAPP tha usual) Dispatch performed for WET, ad if at time of approach preparatio a WET ruway ad o worse coditios tha the oes cosidered for dispatch are reported ad the ruway is maitaied to the stadards defiig grooved or PFC ruways i AC 150-5320. Ruway Coditio Reportig Challeges There is ot curretly a sigle worldwide stadard for ruway coditio reportig. Most frequetly, the type of cotamiat (ad its depth whe available) is reported, although the meas for measuremet, the threshold for reportig i terms of ruway coverage, as well as the format, termiology ad resolutio of the reported iformatio vary with local ATC practices. Where ruway frictio measuremets by dedicated vehicles are available, such frictio values are sometimes reported to flight crew, although maufacturers do ot provide ay correlatio of ruway frictio measured with a vehicle or a trailer with aircraft performace capabilities o the same surface. Some aircraft operators ad local regulators have developed their ow guidace. Europea Actio Pla for the Prevetio of Ruway Excursios - Released Editio 1.0 - Jauary 2013 79
Appedix F Aircraft Maufacturers I North America, after ladig, pilots usually report to ATC their assessmet of brakig actio o a scale from GOOD to POOR to ATC, ad thus to followig aircraft. This may occur spotaeously whe brakig actio is foud to be lower tha expected for the reported ruway coditio, or o request by the tower. Proposals The cetrepiece of the regulatory proposals is what became kow i the work group as the ruway coditio matrix. Its structure adheres to the existig ICAO ruway codes ad shows seve ruway coditio levels associated to codes from 0 (for il brakig actio) to 6 (for dry), where each ruway coditio code (except 0) is matched with a correspodig aircraft performace level. The latter two types of report should be used oly for dowgradig of a ruway from a frictio category basically idetified via cotamiat type ad depth. Pilots will be iformed of cotamiatio o the ruway as soo as i excess of 10% of the ruway surface is cotamiated, while ruway coditio codes will be reported for each third of the ruway whe more tha 25% of the etire ruway surface is cotamiated. If a frictio measuremet or reports from precedig aircraft s pilots (PiReps) idicate that the frictio levels have dropped below those expected for the type of cotamiat o the ruway, the airport should report a lower coditio code i lie with the observed frictio or brakig actio. The iformatio to be trasmitted to the flight crew icludes: Differet criteria of ruway coditio reportig ca be used as etry poits for the determiatio of the applicable aircraft performace level. These reportig criteria are: Cotamiat type ad depth, Pilot brakig actio report (PIREP), ad Ruway frictio measuremet (Mu (μ)). The ruway coditio code for each third of the ruway The type ad depth of the cotamiat ad percetage of coverage i 25% icremets (to avoid curretly used terms such as thi ad patchy ) The PIREPs whe available. 80 Europea Actio Pla for the Prevetio of Ruway Excursios - Released Editio 1.0 - Jauary 2013
Airport Ruway Coditio Assessmet Assessmet Criteria Dowgrade Assessmet Criteria code Ruway Coditio Descriptio Mu (μ) Deceleratio ad Directioal Cotrol Observatio PIREP 6 Dry - - 5 Wet (icludes water 1/8 or Frost 1/8 or less depth of: Slush Dry Sow Wet Sow 40 or Higher Brakig deceleratio is ormal for the wheel brakig effort applied. Directioal cotrol is ormal Good 4 15 C ad Colder outside air temperature: Compacted Sow Brake deceleratio ad cotrollability is betwee Good ad Medium. Good to Medium 3 Wet ( Slippery whe wet ruway ) Dry Sow or Wet Sow (Ay Depth) over Compacted Sow Greater tha 3 mm (1/8 ) depth of : Dry Sow Wet Sow Warmer tha -15 C outside air temperature: Compacted Sow 39 to 30 Brakig deceleratio is oticeably reduced for the wheel brakig effort applied. Directioal cotrol may be oticeably reduced. Medium 2 Greater tha 1/8 depth of : Water Slush 29 to 21 Brake deceleratio ad cotrollability is betwee Medium ad Poor. Potetial for hydroplaig exists. Medium to Poor 1 Ice Brakig deceleratio is sigificatly reduced for the wheel brakig effort applied. Directioal cotrol may be sigificatly reduced. Poor 0 Wet ice Water o top of Compact Sow 2 Dry Sow or Wet Sow over Ice 2 20 or lower Brakig deceleratio is miimal to o-existet for the wheel brakig effort applied. Directioal cotrol may be ucertai. Nil Europea Actio Pla for the Prevetio of Ruway Excursios - Released Editio 1.0 - Jauary 2013 81
Appedix F Aircraft Maufacturers The TALPA ARC recommeded that frictio values should o loger be trasmitted to pilots, but restricted to use by the airport authorities i cosolidatig the ruway coditio assessmet, maily to dowgrade a ruway coditio assessmet from descriptive characteristics. The Ruway Coditio Assessmet Table as preseted hereafter, ad i particular the area show i grey, is therefore meat for airport use oly. It is otable that this matrix provides a recommedatio for the performace-wise classificatio of ruways that are reported as Slippery Whe Wet (Code 3) due to rubber cotamiatio or otherwise degraded ruway frictio. The cocept of reportig ruways as Slippery Whe Wet whe the measured frictio drops below the maiteace threshold was previously recommeded for eforcemet by the atioal authorities i ICAO Aex 14, but o associated aircraft performace was so far available to allow the flight crew to take this iformatio ito accout i their ladig performace assessmet. Actual i-service experiece has bee already acquired with the matrix i Alaska ad some airports i other orther US states, ad has bee extesively tested i real coditios durig witers 2008-2009 ad 2009-2010. The ruway coditio classificatio made i the matrix will also be the basis of the digital NOTAM system curretly beig developed i the US. The lack i stadardisatio of today s ruway coditio reportig has bee idetified as a cotributig factor to overru accidets at ladig. There are ecouragig idicatios from other iteratioal workgroups that these proposals developed i the frame of the TALPA ARC will fid their way ito various iteratioal rules ad regulatios. Operatioal Ladig Distace The TALPA proposal defies aircraft performace oly for i-flight ladig distace determiatio to reflect actual aircraft maximum performace as it ca be expected to be achieved by a lie pilot, realistic but without margi. This distace is called Operatioal Ladig Distace (OLD), made up of the compoets described here below. Air Distace The legth of the airbore distace is the distace covered i 7 secods at the groud speed correspodig to the approach speed (icludig temperature effect ad 150% of the tailwid or 50% of the headwid). The touchdow speed is 96% of the approach speed, which more accurately represets moder jet aircraft tha the defiitio i EASA AMC 25.1591. Activatio of Deceleratio Meas Deceleratio meas are take ito cosideratio i lie with their iteded use as prescribed i the Stadard Operatig Procedures (SOP): groud spoiler deploymet ad maximum pedal brakig at or ear mai gear touchdow, maximum reversers if their use is iteded, at or ear mai gear touchdow. There is o allowace for delayed pilot actios. Groud Roll I lie with the ruway coditio matrix above, the proposal idetifies ad defies aircraft performace levels matchig the 6 ruway frictio codes, which are equally valid whatever the origi of the ruway coditio classificatio: cotamiat type, measured ruway frictio or pilot reports o brakig actio. Each of the 6 levels is associated to a ruway code betwee 6 Dry ad 1 - Poor, ad is approximately cosistet with the frictio coefficiets described for the appropriate ruway cotamiat i the latest issue of EASA AMC 25.1591: 6 Dry 5 Good Wet 4 Good to Medium Compact Sow 3 Medium Loose Sow 2 Medium to Poor Stadig Water, Slush 1 Poor Ice No performace level is provided for Nil, sice operatios i these coditios are prohibited. Provisios of performace credit for WET Grooved or Porous Frictio Course (PFC) ruways have bee made. However o specific ruway code was assiged to such ruways: A grooved or PFC ruway is cosidered as a ehaced safety, that would be dissipated if performace credit was give systematically, Maiteace ad miimum frictio thresholds set i Aex 14 for a ruway to be declared slippery whe wet with associated aircraft performace level are uder review by ICAO, which put them outside the time frame of TALPA ARC. 82 Europea Actio Pla for the Prevetio of Ruway Excursios - Released Editio 1.0 - Jauary 2013
Ruway coditio code Brakig Actio Cotamiat Descriptio OLD computatio 1 Air Distace Groud Roll ad frictio REV credit 6 - DRY Flight Tests demostrated value reduced by 10% 5 Good Wet Uchaged FAA/EASA model with wet ati-skid efficiecy 4 Good to medium Compact Sow 3 medium Loose Sow 2 Medium to poor Stadig Water, Slush 7 sec, with 4% speed decay Cosistet i essece with EASA CS25.1591 Allowed 1 Poor ICE 1 Defied wheel brakig coefficiets are assumig a frictio limited situatio. Fial performace is adjusted appropriately to accout for autobrake deceleratio cotrols. Europea Actio Pla for the Prevetio of Ruway Excursios - Released Editio 1.0 - Jauary 2013 83
Appedix F Aircraft Maufacturers A example of a maufacturer s guidace for operatig o wet or cotamiated ruways. NOTE: The followig iformatio is a example of maufacturer s guidace for operatig o wet or cotamiated ruways. This iformatio is a example oly ad may chage. It will ot be kept up to date. Slippery Ruway Ladig Performace Whe ladig o slippery ruways cotamiated with ice, sow, slush or stadig water, the reported brakig actio must be cosidered. Advisory iformatio for reported brakig actios of good, medium ad poor is cotaied i the PI chapter of the QRH. The performace level associated with good is represetative of a wet ruway. The performace level associated with poor is represetative of a wet ice covered ruway. Also provided i the QRH are stoppig distaces for the various autobrake settigs ad for oormal cofiguratios. Pilots should use extreme cautio to esure adequate ruway legth is available whe poor brakig actio is reported. Pilots should keep i mid slippery/cotamiated ruway advisory iformatio is based o a assumptio of uiform coditios over the etire ruway. This meas a uiform depth for slush/stadig water for a cotamiated ruway or a fixed brakig coefficiet for a slippery ruway. The data caot cover all possible slippery/cotamiated ruway combiatios ad does ot cosider factors such as rubber deposits or heavily paited surfaces ear the ed of most ruways. Oe of the commoly used ruway descriptors is coefficiet of frictio. Groud frictio measurig vehicles typically measure this coefficiet of frictio. Much work has bee doe i the aviatio idustry to correlate the frictio readig from these groud frictio measurig vehicles to aeroplae performace. Use of groud frictio vehicles raises the followig cocers: the measured coefficiet of frictio depeds o the type of groud frictio measurig vehicle used. There is ot a method, accepted worldwide, for correlatig the frictio measuremets from the differet frictio measurig vehicles to each other, or to the aeroplae s brakig capability. most testig to date, which compares groud frictio vehicle performace to aeroplae performace, has bee doe at relatively low speeds (100 kots or less). The critical part of the aeroplae s deceleratio characteristics is typically at higher speeds (120 to 150 kots). groud frictio vehicles ofte provide ureliable readigs whe measuremets are take with stadig water, slush or sow o the ruway. Groud frictio vehicles might ot hydroplae (aquaplae) whe takig a measuremet while the aeroplae may hydroplae (aquaplae). I this case, the groud frictio vehicles would provide a optimistic readig of the ruway s frictio capability. The other possibility is the groud frictio vehicles might hydroplae (aquaplae) whe the aeroplae would ot, this would provide a overly pessimistic readig of the ruway s frictio capability. Accordigly, frictio readigs from the groud frictio vehicles may ot be represetative of the aeroplae s capability i aquaplaig coditios. groud frictio vehicles measure the frictio of the ruway at a specific time ad locatio. The actual ruway coefficiet of frictio may chage with chagig atmospheric coditios such as temperature variatios, precipitatio etc. Also, the ruway coditio chages as more operatios are performed. The frictio readigs from groud frictio measurig vehicles do supply a additioal piece of iformatio for the pilot to evaluate whe cosiderig ruway coditios for ladig. Crews should evaluate these readigs i cojuctio with the PIREPS (pilot reports) ad the physical descriptio of the ruway (sow, slush, ice etc.) whe plaig the ladig. Special care should be take i evaluatig all the iformatio available whe brakig actio is reported as POOR or if slush/stadig water is preset o the ruway. Wheel Brakes Brakig force is proportioal to the force of the tyres o the ruway ad the coefficiet of frictio betwee the tyres ad the ruway. The cotact area ormally chages little durig the brakig cycle. The perpedicular force comes from aeroplae weight ad ay dowward aerodyamic force such as speedbrakes. The coefficiet of frictio depeds o the tyre coditio ad ruway surface, (e.g. cocrete, asphalt, dry, wet or icy). 84 Europea Actio Pla for the Prevetio of Ruway Excursios - Released Editio 1.0 - Jauary 2013
Automatic Brakes Use of the autobrake system is recommeded wheever the ruway is limited, whe usig higher tha ormal approach speeds, ladig o slippery ruways, or ladig i a crosswid. For ormal operatio of the autobrake system select a deceleratio settig. Settigs iclude: MAX AUTO: Used whe miimum stoppig distace is required. Deceleratio rate is less tha that produced by full maual brakig 3 or 4: Should be used for wet or slippery ruways or whe ladig rollout distace is limited 1 or 2: These settigs provide a moderate deceleratio suitable for all routie operatios. Experiece with various ruway coditios ad the related aeroplae hadlig characteristics provide iitial guidace for the level of deceleratio to be selected. Criteria to be fulfilled by a effective ruway excursio prevetio system The system should work i real time ad cotiuously assess the positio of the aircraft relative to the ruway to which it performs the approach, as well as its actual eergy level. The system should work i maual ad automatic ladig ad maual ad automatic brakig. It should make a coservative but realistic assessmet of the stoppig distace required uder the prevailig coditios for that eergy level. It should compare the ecessary distace with that available. It should alert the flight crew durig the approach whe a safe stop o the ruway is ot esured. It should alert the flight crew durig the groud roll whe more deceleratio is required. No ruway overrus should occur with aircraft equipped with the system uder coditios for which it is certified without a alert beig triggered. The system should ot geerate alerts uecessarily. A system fulfillig these coditios permits the defiitio of clear procedures associated with the alerts (go-aroud, maximum brakig ad selectio of max reverse thrust) that ca, whe applied, prevet ruway excursios. Example of procedures required to obtai published performace Europea Actio Pla for the Prevetio of Ruway Excursios - Released Editio 1.0 - Jauary 2013 85