Solutions for improving ground operations efﬁciency

33 I AIRLINE & AIRCRAFT OPERATIONS

ISSUE NO. 112 • JUNE/JULY 2017 AIRCRAFT COMMERCE

Airlines are constantly striving toimprove operationalefficiencies, often by focusingon methods for reducing in-

flight fuel burn and related costs. Anotherarea that can optimise operations is onthe ground, between flight sectors.

Typical ground operations andturnaround processes are discussed here.Some of the solutions and strategiesavailable for optimising groundoperations processes, thereby improvingrates of aircraft utilisation, are identified.

Aircraft turnaround process WheelTug defines the time an aircraft

spends on the ground between an arrivaland its next departure, in terms of twosub-categories: total ground time (TGT)and turnaround time (TAT). TGT coversthe entire period from touchdown to thenext take-off, including the time requiredto taxi-in and out. TAT covers the on-block, off-block period, or the time takenbetween parking on the stand andstarting pushback for the next departure.

“There are five main categories oftasks in the turnaround process,” saysMartin Harrison, global managingdirector, airlines, aerospace and MRO atICF. “These are: disembarkation;servicing; security checks; boarding; andpushback/air traffic control (ATC)clearance. Each category features multiplesub-tasks. For example, servicing includescleaning, catering and refuelling.”

easyJet lists its main turnaroundfunctions as: customer disembarkation;baggage unloading; cabin tidy andsecurity check; customer boarding;baggage loading; refuelling; water andwaste servicing; baggage and customerreconciliation; and flightcrewpreparation. It says that these task groupsare broken down into 360 different sub-tasks. According to easyJet’s procedures,the turnaround period finishes once alldoors and holds are closed, the parkingbrake is off and the aircraft is moving at

more than three kilometres per hour(kmph), either under its own power, or bybeing pushed back by a tug. In commonwith some operators, easyJet does notconsider the pushback process as part ofthe turnaround, but efficiency gains inthis area can still bring benefits since theycould reduce TGT. WheelTug suggeststhat airlines have not previously focusedon improving pushback efficiencies due toa reliance on ground-handlers.

Influencing factors A number of factors can influence an

airline’s turnaround processes and TATs,including the airline business model, on-board service, aircraft size, and theairports and routes being served.

Delta Air Lines says variables such asaircraft size, hub versus spoke airports,and international versus domestic routesall influence the length of a turnaround.

Low-cost carriers (LCCs) and thoseoperating mainly point-to-point networksare likely to have shorter average TATsthan full-service airlines operating hub-and-spoke systems. Short TATs are aprincipal strategy of the low-cost businessmodel and are designed to maximiseaircraft utilisation. Full-service operatorsmay have longer TATs, since theirschedules are often designed aroundproviding connections at a hub airport.The turnaround process may therefore begoverned more by schedule requirements,than by a desire to minimise TAT.

Harrison points out that full-serviceairlines are more likely to need a heaviercatering service than LCCs, which couldadd to their TATs.

A widebody’s extra capacity meansthat it will require a longer TAT than anarrowbody. For example, many of thestandard turnaround processes, such asdisembarkation and loading tasks, andservicing functions, like cleaning andcatering, will take longer on a widebody,while its longer range and fuel capacitymean that refuelling will also take longer.

“Widebody ground times for full-service carriers are often driven bycommercial scheduling requirements,rather than the turnaround process,” saysHarrison. “Widebodies operating long-haul sectors can be on the ground for sixto eight hours, simply because of anairline’s preferred departure time. Thegrowing number of low-cost, long-haulcarriers may choose instead to minimiseground time and maximise utilisation.”

Turnaround procedures and TAT canalso be influenced by an airport’sinfrastructure, operating procedures andhow busy it is in terms of commercialaircraft movements and passengers.

“Airport infrastructure and curfewscan affect time on the ground,” saysMichael Muzik, senior product managerof the weight and balance solutionNetLine/Load, at Lufthansa Systems.“Turnarounds take longer at major hubsthan at smaller regional airports, due tothe higher complexity of hub airports. Atypical LCC TAT might be 20-25 minutesat a provincial regional airport, but couldtake 40-45 minutes at a major hub.”

“Large airports operating nearcapacity might request standardised TATsfrom operators for gate allocation andplanning purposes,” says Harrison. “Atbusy airports, TATs can be defined by slotavailability.”

easyJet says its TATs vary by airportaccording to the stand infrastructure.“Our standard TAT for an A319 or A320is 25 minutes when both the forward andaft doors can be used for disembarkationand loading,” says Philip Harbidge,operations performance manager ateasyJet. “We use two doors when theparking stand allows passengers to walkto and from the aircraft; be bussed to andfrom the aircraft; or when a jet bridge isused for the forward door, but steps canalso be used for the aft door. On standswhere only one door can be used, thestandard TAT increases to 30 minutes.More time is also scheduled when anairport does not allow passengers to be

Ground operations can be a major contributor to flight delays, which canlead to dissatisfied passengers and additional costs for airlines. A numberof technological solutions have been developed to improve the efficiencyof ground operations and minimise delays. Some of these solutions aresummarised here. Nick Preston investigates.

Solutions for improvingground operations efficiency

AIRCRAFT COMMERCE ISSUE NO. 112 • JUNE/JULY 2017


on the aircraft while it is being refuelled.” Certain route types can also influence

turnaround times. There may bedifferences between domestic andinternational services, for example,related to different fuel, catering orbaggage demands. “We adjust scheduledTATs according to the quantity of cabinbaggage that is typically brought to thegate,” says Harbidge. “We allow moretime for turnarounds on domestic Italianroutes, for example, because this markettends to see high cabin bag numbers andfew bags checked into the hold. A highnumber of cabin bags increases the timetaken for boarding.”

Why efficiency matters Ground-handling and turnaround

operations can be responsible for flightdelays, which result in additional costsfor an airline.

“An efficient turnaround is crucial toour operation because punctuality isimportant to our customers,” saysHarbidge at easyJet. “It also allows us tomaximise aircraft utilisation which keepscosts and fares low.”

Delta says that operational reliabilityis a key focus across the business and asmooth, safe turnaround is at the heart ofthat. It adds that many aircraft flymultiple sectors in a given day, so a delaycould have a compounding effect onsubsequent flights. Delta claims to havedemonstrated a much improved flightcompletion factor and delay performancein recent years, and says this has helpedto drive its strong revenue performance.

“An efficient turnaround is veryimportant for maintaining networkschedules,” says Stephan Ellenberger,head of ground operations, Switzerland,

at SWISS. “Flight delays are a serious

challenge,” says Altay Fellah, vicepresident, business development, AviationDivision at INFORM. “According to theUS Bureau of Transportation (BTS),external factors such as severe weatherconditions have been the main cause oflate arrivals since it started collecting datain 2003, but weather delays are nowbeing surpassed by other factors. In morethan 50% of cases, the leading reason fora delayed flight can now be traced tocircumstances within the airline’s control,such as refuelling, cleaning, maintenanceand crew scheduling.

“From 2005 to 2015, 28-45 milliondelay minutes per year were attributed tofactors that were under the direct controlof US airlines,” continues Fellah. “Thisresults in billions of dollars of delay costs.In 2016 the average cost of block time forUS airlines was $62.55 per minute. Asmall setback in one of the turnaroundprocesses can result in delays that arealmost impossible to make up, if theproblem is not identified, rectified, or atleast limited early enough. The knock-oneffect can lead to delays on other flightsoperated by the airline.”

If an aircraft is scheduled to operatemultiple sectors in a single day, but isdelayed on one of its first flights, theremaining flight sectors could also beaffected, and the extent of the delay couldget worse throughout the day, if air trafficslots are missed. Delays to one aircraftcan also affect other parts of an airline’snetwork, especially in a hub model wherean aircraft may be forced to wait for largenumbers of delayed connectingpassengers. “If one aircraft is delayed onthe stand, the next arriving flight may beunable to enter the gate at the allocated

time,” says Jan Willem Kappes, businessdevelopment manager at INFORM. “Itmay also have to wait for ground serviceproviders which have been delayed due toprevious flights.”

Airlines incur costs as a result of flightdelays, including the provision of foodand refreshments, hotel accommodationor alternative flights on other carriers fordelayed passengers or those that havemissed connections. Airlines may also beobliged to pay compensation to delayedpassengers. European Union (EU)regulation EC 261/2004 dictates thelevels of compensation that should bepaid to delayed passengers travelling toor from an EU member state, dependingon the extent of the delay.

It is difficult to determine a globalaverage for the delay-related costsincurred by airlines, due to the manypotential variables and scenarios. “Anumber of studies have tried to identifythe costs associated with delays, but theresults have been varied,” says Harbidge.

“Airlines also need to considercustomer dissatisfaction levels whenevaluating the impact of delays,” saysHarrison. “Customer satisfaction is oneelement that can influence loyalty levelsand the potential for repeat business.”

Technology solutions forimproving efficiency

Some of the technology solutionsavailable for improving efficiencies inground operations, and reducing thepotential for delays, are identified here:turnaround management software, whichis designed to optimise TATs; and E-Taxisolutions, which can increase efficiency inthe period from off-blocks to take-off.

This summary is not intended as acomprehensive survey of suppliers, andother solutions may be available.

Turnaround managementsoftware

“Managing an aircraft turnaround iscomplex,” says Harrison. “There aremany functions in the turnaroundprocess, some of which may be carriedout internally by the airline, while othersare outsourced to third-party ground-handling or ramp-service agents. A largenumber of stakeholders are involved,such as pilots, cabin crew, customerservice personnel, cleaners, security

Turnaround time (TAT) is the time taken betweenparking on a stand and commencing pushbackfor the next departure. The turnaround processcan involve hundreds of sub-tasks performed byinternal staff or external service providers. Co-ordinating the various stakeholders is one ofthe main challenges faced by airlines.



agents and ramp personnel. Coordinatingthese functions and stakeholders is one ofthe main challenges of a turnaround.”

“Ideally, every turnaround needsproactive management and monitoringand I.T. solutions can be used to achievethis,” says Muzik. In a Lufthansa Systemswhite paper called ‘Airline TurnaroundManagement’, Muzik argues that manyairlines are still not actively controllingtheir ground processes. He suggests thatby implementing a turnaroundmanagement strategy, airlines couldimprove on-time performance andpassenger satisfaction, and reduce delaycosts.

Muzik recommends setting up areference model to plan and define themain turnaround processes and processpoints for measuring the performance ofthe turnaround. Some of the centralturnaround processes are defined as: de-boarding, de-loading, cleaning, catering,fuelling, boarding and loading. Eachsingle turnaround process can be brokendown into process points. For example,process points for disembarkation mightinclude identifying the time when doorsare opened and when the first and lastpassengers leave the aircraft. For fuellingthey might include identifying when therefuelling truck arrives, when fuellingcommences and when it is complete.Target times need to be defined for wheneach process point should begin, anddependencies between the differentturnaround processes need to beidentified. For instance, catering andcleaning can only start after de-boardinghas finished. It is recommended thattarget times be clearly allocated amongstakeholders for each turnaround task.Muzik also suggests that airlines shouldapply rules to allow for differencesbetween individual turnaround scenarios.This might include different TAT and

process assumptions depending on theaircraft type, route and airport.

“The key to coordinating aturnaround is to identify the criticalpath,” says Harrison. “This involvesdefining the desired processes and sub-tasks, when they should start and stop,and how long each stakeholder has toperform a task. Dependencies betweentasks should also be identified, whichmeans processes that cannot be starteduntil another has been completed.”

Muzik suggests airlines shouldestablish service level agreements (SLAs)with third-party ground-serviceproviders, once turnaround processes,any related rules and target completiontimes have been defined. The SLA mightinclude a requirement for serviceproviders to complete turnaround taskswithin a specific time frame. “Airlinesshould monitor the performance of theirproviders, but also implement an SLAwhich includes financial rewards orpenalties depending on whether theservice provider meets their agreedperformance targets,” says Muzik.

“Visible key performance indicators(KPIs) can be a useful tool for internaland third-party staff involved in theturnaround process,” says Harrison. “Forthird-party providers these may be basedon SLAs.”

There are software solutions on themarket that help airlines and ground-handling companies coordinate theturnaround process and reduce thepotential for ground-handling-relateddelays. These solutions permit users toestablish and measure bespoketurnaround processes, executed by third-party ground-handlers or airlinepersonnel. They provide users with a real-time picture of turnaround status and theability to compare this against set targettimes and SLAs. This can allow users to

intervene proactively and reallocateresources where available, to try andprevent certain tasks falling behindschedule, which, in turn could lead todelays. An example of an interventionmight be to request a quick cleaning fromthe relevant supplier. In addition tomonitoring real-time operations,turnaround management software mightalso include tools for identifying longerterms trends in turnaround performance.

“ICF has worked with airlines to helpredesign their turnaround processes. Thiscan also be part of a turnaroundmanagement software implementationproject,” says Harrison.

INFORM – GroundStar INFORM offers its GroundStar

software solution for coordinatingaircraft turnarounds. “The GroundStarsuite is designed to be used by airlines,airports and ground-handlingcompanies,” says Kappes. “It is the mostcomprehensive I.T. solution for optimisedairline and ground-handling processesand resource management. GroundStarsupports the planning, day-to-day andadministrative functions of all sectors ofairport ground handling, includingindividual and fully integratedturnaround processes, both in theterminal, and on the ramp. The software’ssophisticated algorithms help ground-handlers and airlines to optimise theiroperations.”

“Most of the delays to turnaroundtasks are only detected after they haveoccurred, leading to frustration in thedeparture lounge, and significantexpenses,” says Kappes. The GroundStarplatform can resolve this by providing areal-time overview of every turnaround.“The GroundStar platform’s coreoperational functionality is the creation

INFORM’s GroundStar softwaresuite helps airlines improve theirturnaround efficiencies. TheGroundStar has various modules.This includes GS HubControl,which has screens that enable anoverview the entire real-timeground operation at a singleairport. The user can drill downinto an individual turnaround tomonitor the status of individualtasks.

of turnaround tasks according toconstantly changing flight schedules, andthe allocation of resources to carry themout,” says Kappes. “The systemintegrates with multiple sources ofinformation to ensure that full details ofthe operation are available. Itsoptimisation algorithms provide the mostefficient deployment of resources andguarantee that contractual commitmentsare met and completed services recorded.

The GroundStar Suite featuresdifferent software modules to supportairlines, ground handlers and airports, intheir strategic, tactical and operationalplanning and management.

GS HubControl provides the defaultvisual displays and overviews for anairline operations control manager. “GSHubControl provides business rules anddedicated screens to enable a hub oroperations controller to easily view theentire ground operation at one airport,”says Kappes. The Hub View screen givesa general overview of all turnaroundstaking place at a single airport. The userdrills down into more detail by clickingon one of the flights to open a newdisplay, which lists the status of eachindividual turnaround task. It includes aGantt chart, showing the planned andactual durations of each task. The statusof each task is indicated by a colour code,which can be defined by the user. Mostusers feature ‘planned’, ‘started’ and‘finished’ as their task status options.

“GS HubControl constantlycompares the actual task duration to apre-defined target time,” says Kappes.“Customers decide how many sub-tasksthey want to define and which businessrules they want to apply. Together withGS RealTime, which provides the real-time allocation of staff and equipment toturnaround tasks, GS HubControl canautomatically move certain tasks along apre-defined timeline, following a criticalpath. Real-time, mobile interactionbetween GS HubControl and staff in thefield is made possible by mobilityfunctions, which allow staff toautomatically receive allocated tasks ontheir mobile devices and to update thestatus of the current tasks they areperforming. “This real-timecommunication means that the GSHubControl user is always up to date andcan react immediately if a task is notevolving as planned,” says Kappes.Another source of live data is provided byGS GroundFleet, which feeds automated

timestamps and location data fromground support equipment (GSE) into GSHubControl, by tracking GPS signals.

GS BIS provides business intelligencetools for a more in-depth analysis ofturnaround trends to help airlines identifyand amend any tasks that are causingregular delays. Key functions of GS BISinclude collecting and analysingoperational data and presenting KPI datain real time to dedicated target groups.

“The GroundStar suite is 100%customisable and scalable,” says Kappes.“New customers often start with onlyone part of the suite and add additionalmodules later.” The GroundStar suite isinstalled on a user’s server and can beaccessed via a desktop application. Thereare also apps available and a web portalfor staff to use on their mobile devices.

Several airlines are using theGroundStar HubControl product. Theseinclude operators in the US, Netherlands,Portugal and Scandinavia. According toINFORM, one airline reduced its ground-handling-related delay costs at aEuropean airport by 42% within fouryears of implementing the GroundStarsoftware, while a major US carrier usingit improved punctuality by 9%.

Lufthansa Systems Lufthansa Systems also offers a

software solution for the real-timemonitoring of aircraft turnarounds. Thiscapability is provided by its NetLine/HubTurnaroundManager solution, which isone module of the NetLine/Hub suite.NetLine/Hub is a tool for managing andoptimising passenger connections. In thefuture, Lufthansa Systems plans to offerthe TurnaroundManager solution as amodule in its Operations Control System,

NetLine/Ops ++. Lufthansa Systems’

TurnaroundManager module allows usersto monitor tasks in real-time andcompare performance to targetsestablished in SLAs. Users are alerted ifdelays occur, allowing a proactiveresponse if they see that a task is takinglonger than it should, or that is has notstarted on time.

“The Station Control View is thecentral display in TurnaroundManager,”explains Muzik. “It provides a graphicaloverview of all the turnarounds takingplace at a particular station or hub in theform of a Gantt chart. Every aircraft isrepresented by a single bar with threedifferent segments to show the inbound,ground and outbound events.

“Users can drill down into anindividual turnaround by clicking on theground event segment in the StationControl View,” continues Muzik “Thisopens the Workbench which providesdetailed information about each of themain turnaround tasks. The Workbenchcomprises different tabs, each of which isdedicated to a specific topic, includingpassenger connection information, crewconnection information, ATC/de-icing,and ground services. Users can monitorthe processes in text or graphical form.The Graphical display is a Gantt chart,which can be colour-coded to visuallyemphasise whether processes are on time.

“To provide real-time monitoring,TurnaroundManager collects data fromexisting automated data flows such asAircraft Crewing and Reporting System(ACARS) messages,” explains Muzik.This data is enhanced with measurementscaptured by handheld mobile devicesused on the ramp, either by the rampagent, or the ground-handler. Integration



The WheelTug solution is based on electricmotors installed in each of the aircraft’s nosewheels and powered by the APU. WheelTugclaims its solution could save between sevenand 20 minutes in total ground time betweeneach arrival and departure.

and information-gathering are the mostchallenging aspect of implementing aturnaround management project. Itrequires negotiation with ground-handlers, service providers and theairline’s own ground-handling staff.”

“It is not enough to just monitor real-time turnarounds on the day ofoperation,” says Muzik. “While this mayaddress an issue on the day, it will notidentify the cause of a recurring problem.To achieve longer-term improvements toregular delays, business intelligence toolsshould be used to identify any trends,such as the fact that a certain flight oraircraft type is suffering regularturnaround delays. Business intelligencetools can be used to identify specific fieldsof improvement to stabilise the wholeturnaround system.” Lufthansa Systemsalso offers a business intelligence tool formonitoring turnarounds.

E-Taxi solutions In this analysis, E-Taxi systems are

categorised as providing an alternativeapproach to traditional driver-operatedtractor tugs. The E-Taxi solution may becontrolled by the flight crew or from theground. Most E-Taxi solutions useelectric rather than diesel motors.

E-Taxi systems can potentially reducean aircraft’s TGT, and provide benefits byreducing fuel burn, environmental impactand maintenance costs. E-Taxi systemscan be sub-categorised into installed andnon-installed solutions.

Installed solutions There are two, installed E-Taxi

programmes in development: theWheelTug solution; and the eTaxi system,which is being marketed via acollaboration between Airbus and Safran.Both solutions involve installing electricmotors in an aircraft’s wheels or landing

gear, so that it can taxi without usingengine power, or relying on a tug vehicle.

Installed E-Taxi systems manoeuvreaircraft away from the ramp area withoutusing main engines. Operators will,however, need to leave enough time forthe engines to warm up before take-off,and to commence engine start proceduresaccordingly.

The WheelTug and Airbus/Safranprogrammes have adopted differentapproaches to installed E-Taxi solutions.

WheelTug The WheelTug E-Taxi solution is

based on two electric motors, with oneinstalled in each of the aircraft’s two nosewheels. Power for these motors issupplied from the aircraft’s auxiliarypower unit (APU). The WheelTug systemcan move an aircraft backward andforward, without using the aircraft’sengines. An aircraft with the WheelTugsolution installed will, therefore, be ableto enter a stand, push back and taxiwithout using the aircraft’s engines or atractor tug. The main aim of the system isto optimise TGT.

The complete WheelTug systemcomprises a nose wheel assemblycontaining the electric motors, severalavionics boxes and a dedicated flight deckcontrol panel. The control panel is usedto turn the system on and off, and toapply the desired forward or reversemovement. Steering is controlled usingthe aircraft’s steering tiller. There is anoptional feature called TaxiCam, whichhas a set of cameras to provide the pilotwith exterior situational awareness fortaxiing purposes, via a live feed to acockpit display or electronic flight bag(EFB).

“The on-board system can beretrofitted, and easily installed andremoved in one overnight maintenancevisit,” says Isaiah Cox, chief executive

officer at WheelTug. The WheelTug solution has been in

development for more than a decade.“We have used this time to modify andrefine the design,” continues Cox. “Onechange we have made is to reduce the sizeof the wheel assembly by reducing thewidth. In late 2016 the Federal AviationAdministration (FAA) accepted ourcertification plan for the 737NG family.Recertifying part of the landing geartakes time, but we expect the system tobe approved for operation on the 737NGfamily by 2019.” Once WheelTugreceives its first supplementary typecertificate (STC), it expects to developfurther STCs for the A320 family andpotentially regional aircraft. Widebodiesare not currently a priority, but WheelTugsays it will evaluate all options.

WheelTug identifies a number ofpotential cost benefits that its systemcould provide. “The main benefit is thepotential to reduce TGT,” says Cox.“Others include a reduction in pushbackcharges, fuel expenses, insurancepremiums and engine-relatedmaintenance costs.”

“We have analysed data fromthousands of narrowbody flights andestablished that there is a correlationbetween TGT and an airline’s operatingmargin,” claims Cox. “Airlines withshorter TGTs tend to have higheroperating margins. Reducing ground timewill increase aircraft utilisation. Ouranalysis shows that the average pushbacktime for a narrowbody is eight minutesfrom the point at which the aircraft isready to push back, to the moment itactually starts to taxi forward underengine power. For a typical nose-inparking scenario, we estimate that anaircraft with the WheelTug system couldcomplete the same manoeuvre in oneminute, providing a TGT saving of sevenminutes per flight.”

WheelTug has produced a chartcomparing the traditional pushbackprocess with proposed operations usingits own system. The chart shows that anaircraft with the WheelTug system wouldhave no need for GSE, would requirefewer personnel and processes than thetraditional approach, and that it wouldhave fewer safety factors to consider. Anaircraft with the WheelTug system wouldnot have to wait for a tug to becomeavailable or for the coupling anduncoupling processes to take place. Itwould also not be necessary to go



WheelTug has produced a pyramid diagram todemonstrate how the use of its system couldreduce the time used for pushback. The use ofWheelTug with TaxiCam removes the need forground equipment and reduces personnelrequired during pushback.

through the engine start-up proceduresduring the pushback, with engines startedwhile the aircraft is taxiing out instead.The engine start process would still needto begin at least three to five minutesbefore take-off, since engines need thislong to warm up.

WheelTug adds that its solution couldallow aircraft to turn 90 degrees on astand and park side-on at the gate toallow front and rear doors to be used fordisembarkation and loading. This is madepossible by the lack of jet blast whilemanoeuvring, but depends on airportstand infrastructure. Cox claims that, inaddition to the seven-minute pushbacktime saving, this strategy could reduceTAT by 13 minutes, providing a TGTsaving of up to 20 minutes. This claim isbased on evidence from a trial by UnitedAirlines’ LCC subsidiary TED at Denver(DEN) in 2006. The trial involved using aY-shaped air bridge which was connectedto both the front and rear doors of theLCC’s A320s to allow two-doordisembarkation and loading.

Cox suggests that each minute ofTGT saved, could save airlines $50-200per minute depending on a variety offactors, including whether passengers areflying for business or leisure, and howcritical the flight is, in terms of the rest ofthe network. Flights that would causemore knock-on effects when delayed,would be considered more critical. TGTsavings on critical flights would thereforebe more valuable.

Using the WheelTug system fortaxiing, rather than the aircraft’s engines,could reduce costs associated with enginemaintenance, foreign object debris(FOD), and brake wear. It will alsoreduce fuel burn during taxi. WheelTugbelieves its solution will reduce a 737’s

taxi fuel burn by about 21lbs per minuteor by up to 84% per minute, comparedto a typical dual-engine taxi scenario. TheWheelTug system will add about 300lbsto an aircraft’s operating empty weight,but Cox suggests the lower fuel burnduring taxi reduces the marginal fuelrequired. “An aircraft with the WheelTugsystem installed would be weight-neutralat take-off due to the reduced marginalfuel requirement, so it would not burnany additional fuel in flight,” he claims.

WheelTug says that operators usingits systems could see first-year savings ofup to $2.00 million per aircraft, rising to$4.00 million per aircraft after five yearsas airlines become used to the system’sbenefits and begin making greaterprocedural changes.

WheelTug says it has received lettersof intent (LOIs) from 22 airlines. It plansto lease its system to airlines under anoperating lease, or a power-by-the-hour(PBH) model that includes maintenancereserves. Lease rates will be based on anairline’s expected cost savings.

Airbus/Safran Airbus and Safran announced plans

to market their proposed ‘eTaxi’ solutionin June 2017, following completion of aresearch and testing phase. A decision onwhether to proceed with an officiallaunch of the eTaxi system could be takenin the near future depending on airlinefeedback.

eTaxi uses electric motors installed ineach main landing gear leg. The motorsare powered by the APU, which allows anaircraft to push back and taxi withoutusing its engines or tractor tugs.

At this stage, the eTaxi system isdesigned for the A320 family only,

including classic engine option (ceo) andnew engine option (neo) variants. It isproposed that the solution would beavailable for line fit and retrofit. Thereare no plans to develop the eTaxi systemfor widebody aircraft.

Airbus claims the eTaxi system couldprovide time savings of up to threeminutes per pushback, since it avoidsissues associated with coupling anduncoupling tow bars. It adds that userswould be less exposed to ground-handling delays, such as the late arrival ofa tug vehicle. Airbus also claims that theeTaxi system could reduce block fuelburn on shorter sectors by up to 4%,since aircraft will not use their engines formost of the taxi-in or out. It claims thatthe equivalent annual saving could be upto several hundred thousand dollars peraircraft. The installed electric motorswould add weight to the aircraft, butAirbus says that this would be less than400kg, and that the effect on in-flight fuelburn performance would be minorcompared to the savings achieved on theground. Using electric motors for taxiing,rather than aircraft engines, is alsoexpected to reduce nitrogen oxide (NOx)and carbon monoxide (CO) emissions.Airbus adds that an additionalenvironmental benefit would be areduction in noise during taxiing. TheeTaxi system allows engines to start upaway from the ramp area, reducing therisk of engine damage from FOD.

Non-installed solutions Non-installed solutions involve some

form of ground-based pushback vehicle.They may not involve any modificationsto aircraft systems. Several differentdesigns have been developed, includingtractor tugs that can be controlled fromthe flightdeck, and wireless remote-control vehicles that are operated byramp personnel.

TaxiBot TaxiBot is a series of semi-robotic,

tractor tugs developed by IsraelAerospace Industries (IAI) in associationwith GSE manufacturer TLD. When aTaxiBot is used, the pushback operationis performed by a human operator in thecab of the tractor vehicle, although IAI isplanning to automate this process. Oncethe pushback is complete, control of theTaxiBot vehicle is passed to the pilots

IAI has developed the TaxiBot solution inassociation with TLD. There are two models ofTaxiBot; the TaxiBot NB for narrowbodies andthe TaxiBot WB for widebodies. IAI claims theTaxiBot can reduce pushback times, and provide,fuel and maintenance cost savings.



who then use the tractor vehicle, ratherthan the aircraft’s engines, to taxi out.This is referred to as pilot control mode(PCM).

“A TaxiBot can also be used fortaxiing after landing, although it is morelikely to be needed for dispatch,” saysEran Tamir, business development, IAILahav. “There are two main reasons forthis. First, the taxi-out process usuallytakes longer, so there are more savings tobe realised there. Second, it is logisticallyeasier to connect a TaxiBot at the gatethan on the taxiway after landing. Evenso, there are likely to be scenarios withlengthy taxi-in times where TaxiBots willbe used.” With a fully loaded aircraft, aTaxiBot can achieve taxiing speeds of upto 23 knots.

A TaxiBot does not have a tow bar.“The nose landing gear is clamped on arotatable turret at the centre of thetractor vehicle,” says Tamir. “Pilots thencontrol the taxiing process using theaircraft’s steering tiller and brakes. Theaircraft’s brakes are used to control thespeed of taxi. The pilot’s brakingcommand is transferred directly to theTaxiBot via sensors, thereby reducing thespeed. Acceleration is achieved byreleasing the brakes. Acceleration ratesadapt to the pilot’s braking pattern andthe location of the aircraft. There is noneed for a dedicated flightdeck interface,”

continues Tamir. “No modifications arerequired for 737 Classics or NGs. For theA320 family, a switch must be installedon the flightdeck, which mimics an‘engines-on’ status for the aircraft’shydraulic systems.”

There are two models of TaxiBot: theTaxiBot NB for narrowbodies, and theTaxiBot WB for widebodies. IAI hasalready received FAA and EuropeanAviation Safety Agency (EASA)certification for the use of its TaxiBot NBwith A320 family aircraft. It has alsoreceived EASA approval for the 737Classic and NG, and expects to receiveapproval from the FAA in the near future.IAI is considering certifying the TaxiBotNB for 757s, subject to customerdemand. “The TaxiBot NB was operatedin a trial with Lufthansa’s 737 fleet, andwe are in discussion with other airlines,airports and ground-handlers,” saysTamir. “Certification of the TaxiBot WBis expected in 2019.”

Tamir claims a TaxiBot will providereductions in turnaround time, fuel burn,noxious gas emissions and maintenancecosts. “A TaxiBot can reduce block timeand improve airport efficiency at the gatearea,” says Tamir. “With a TaxiBot, theaircraft does not need to be pushed backall the way to the pushback line. At manyairports, aircraft are pushed to adesignated ‘pushback’ line, where the

engine-start process is completed. This isto minimise disruption for other aircraftentering or leaving the ramp area.TaxiBot users can be pushed back aminimum distance, since they will notneed to wait for engine-start, with thepilots clearing the gate area immediatelyin PCM mode. This could shorten theregular apron clearance time by two tothree minutes for a twin-enginenarrowbody, thereby reducing congestionin the gate area and delays and increasingefficiency for other aircraft as well.” IAIbelieves that apron clearance time-savingswill be bigger for a four-engine widebody.

Tamir claims that using a TaxiBot canreduce taxi-out fuel burn by 85%. Headds that CO2 and other noxious gasemissions are reduced by 85% whencompared to normal taxi-out procedures,and that noise levels are reduced by 50%.“It is expected that engine and brakewear will be reduced by using a TaxiBot,and that FOD incidents will decline by50%,” adds Tamir. “A TaxiBot can alsoprovide more traction than an aircraftunder its own power on slippery or icysurfaces, since it has eight wheels incontact with the ground, rather than theaircraft’s two nose wheels.”

Although the TaxiBot will not requirepower from the aircraft, the APU will stillneed to be run to provide lights and airconditioning for the cabin.



Mototok Mototok International GmbH has

developed a series of remote, radio-controlled tug vehicles, powered byelectric motors. It offers vehicles suitablefor all aircraft sizes, including commercialairliners.

The SPACER 8600 is suitable foraircraft with a maximum taxi weight(MTW) of up to 95 tonnes. This coversall regional and most narrowbodyaircraft. It is already certified for the 737Classic and NG, and A320 families, andis approved for the latest generation 737MAX and A320neo families. “BritishAirways has ordered 28 SPACER 8600sfor its operation at London HeathrowTerminal 5,” says Marc Hemery, sales,EMEA at Mototok.

A larger vehicle, the SPACER 195,will be capable of pushback operationson larger aircraft with an MTW of up to195 tonnes. Mototok expects this variantto be certified for ramp operations in thenear future.

Mototok’s SPACER vehicles areoperated by a single ramp agent with aremote control. No wing walkers arerequired. “The operator does not requirea special licence,” says Hemery. “Anyonecan use a Mototok tug after a half-daytraining session.”

Mototok SPACER vehicles can beconnected from the front or rear of theaircraft’s nose wheel. They feature a one-click loading system, which secures ahydraulic door and clamps around thenose wheel before raising it on aplatform.

Hemery says that a Mototok vehiclecan provide a quicker and moremanoeuvrable pushback thanconventional tugs. The Mototok loading

process is quicker than connecting a towbar, taking 10-15 seconds. The SPACERvehicle’s ability to turn an aircraft’s nosewheel on the spot also allows it toperform more precise manoeuvres.

TowFLEXX TNA Aviation technologies has

developed the TowFLEXX series ofwireless, remote-controlled tug vehicles,which are powered by electric motors.

“The TowFLEXX 5-series can be usedon any Bombardier, Embraer, ATR, Saabor other regional aircraft with amaximum take-off weight (MTOW) ofup to 120,000lbs,” explains MichaelTurwitt, co-owner and managing partnerof TNA Aviation technologies. “A newTowFLEXX vehicle is being developedfor larger aircraft.”

TowFLEXX vehicles are in use with awide variety of customers includingairport authorities, fixed-base operators(FBOs) general aviation flightdepartments and hangar owners. TNAalso has five airline clients.

TowFLEXX vehicles do not use towbars. “We use quick, soft-capturecoupling technology, explains Turwitt.“After the tug has been steered into placeunder the nose gear of the aircraft, thewheel cradle is closed and the entire nosegear is lifted off the ground.”

Turwitt says a TowFLEXX vehiclewill provide pushback time-savingscompared to traditional tractor tugs.“Docking and undocking is faster andrequires less personnel, resulting in timeand labour savings.” He also emphasisesthe added flexibility: “The equipmentneeds less space and can move aircraftinto tight areas that are impossible toreach with traditional tow tugs.”

Other airline strategies Airlines have been using other

strategies to optimise their groundoperations.

“Our turnaround process is alreadyvery efficient, but we are always lookingfor ways to improve by using innovativeequipment, changing turnaroundprocesses, or removing waste,” saysHarbidge at easyJet. “Airport stand andgate infrastructure is the biggest driver ofinefficiency. We are working with airportsto ensure the necessary infrastructure is inplace to permit boarding via both frontand rear doors, since using two doorssaves about five minutes per turn.

“We have implemented a number ofprocesses to improve turnaroundefficiency in recent years,” continuesHarbidge. “These include the removal ofthe on-board headcount, unless this isrequested by the ground or air crew. Thiscan save three minutes and offsets theadditional time required by allocatedseating. We have also introduced the useof powered aircraft steps and flexiblebaggage belts which reduces the numberof ground agents required.”

Delta says it continues to look forways to improve the efficiency of theboarding process and the overallturnaround. It has recently implementedmeasures to close the boarding processfive minutes before the scheduleddeparture time, to improve overall on-time performance. Delta is also testingbiometric boarding pass technology.

It has worked with frontline teams toimplement better time managementstrategies during the turnaround processto ensure aircraft leave on time. Duringpushback at hub airports like Atlanta,Delta’s ground crews now push aircraftout of the gate at a 45-degree angle,rather than completing the full 90-degreeturn. It says this has reduced pushbacktimes and improved the taxi-out.

“SWISS conducts regular continuousimprovement workshops to maintain ahigh level of performance for turnaroundactivities,” says Ellenberger. “At ourZurich hub we have introduced aminimum ground time process withenlarged cleaning crews.”



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easyJet says that airport stand and gateinfrastructure is the biggest cause of turnaroundinefficiencies. Where infrastructure allows,easyJet performs disembarkation and boardingusing both the front and rear doors of theaircraft. It claims that using both doors canreduce TAT by five minutes.

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