Use of Towbarless Tractors at Airports—Best Practices

THE NATIONAL ACADEMIES PRESS

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Copyright © National Academy of Sciences. All rights reserved. Use of Towbarless Tractors at Airports—Best Practices March 2012 airport Cooperative Research Program Sponsored by the Federal Aviation Administration

Responsible Senior Program Officer: Michael R. Salamone Research Results Digest 15 Use of Towbarless Tractors at Airports—Best Practices This digest presents the results of ACRP Project 04-07A, “Best Practices for Managing the Use of Towbarless Tractors at Airports.” The study was conducted by a research team under the leadership of Ricondo & Associ- ates, Inc., with Colleen Quinn acting as the Principal Investigator.

1 Introduction to-gate towing, and maintenance towing can be carried out faster than with conven- 1.1 Background tional towbar tractors, minimizing impacts Towbarless tractors (TBLTs), also to airport operations. known as towbarless tow vehicles (TLTVs), While some airports, airlines, and ser- are used to tow aircraft on the airport. TBLTs, vice providers have developed standards as the name implies, do not use a towbar but specific to their operation of TBLTs, no instead use a pick-up device located in the industry-wide guidance exists for this type center of the vehicle to cradle the nose gear of operation. Several incidents involving tires in order to provide direct maneuver- TBLTs have raised awareness of the need ing of the aircraft. TBLT operations have to establish “Best Practices” guidelines for increased in recent years due to the superior TBLT operations. maneuverability provided by these vehicles and a renewed focus on energy and environ- 1.2 Development of Best Practices mental conservation. The absence of tow- Contents bars and the higher operating speeds mean The use of TBLTs varies from airport to 1 Introduction, 1 that aircraft movements, pushbacks, gate- airport but is generally increasing. Although 2 Definition of Terms, 2 a TBLT represents a large up-front capital cost, it has several benefits over traditional 3 t BLT Operator Requirements, 4 towbar tractors, including the following:

4 t BLT—Vehicle Requirements, 5 • More secure control of the aircraft and greater responsiveness; 5 Aircraft-Under-Tow Requirements, 6 • Simplicity of use and reduced opera-

6 t owbarless Tractor tor training; Procedures, 7 • Allowance for operation in the entire 7 Communication, 10 airport environ, including movement

8 operator Responsibilities, 11 areas, without impacting airport

9 Weather, 12 operations; • Elimination of the need to maintain 10 e mergency/Abnormal Procedures, 12 multiple towbars (for each aircraft

11 Future Towbarless Tractor type); and Operations, 13 Towbarless tractor after disengaging from an • Energy and environmental conser- 12 Reference Material, 13 aircraft nosewheel. vation.

The development of TBLT operations best prac- States Department of Transportation (DOT)/Federal tices started with identifying industry groups in- Aviation Administration (FAA) rules and regulations, volved with TBLT operations. Once identified, the FAA advisory circulars (ACs), FAA orders, existing following groups were contacted to collect data and airport operating procedures, aircraft manufactur- discuss TBLT considerations: ers’ recommended practices, TBLT manufacturers’ recommended practices, and equipment-specific train- • Airlines that use TBLTs, ing. Where appropriate, this document may, however, • Airports at which TBLTs are in use, be used to supplement existing documentation, guid- • Aircraft manufacturers, ance, and information. • Aviation industry organizations, and Each airport presents a unique combination of • Airport safety working groups involved with physical, operational, meteorological, and regula- TBLT operations. tory characteristics that must be evaluated as a whole The information gathered from these groups when an effective TBLT operational and training was consolidated and common practices were program is being developed. This document is in- identified as were unique practices that had appli- tended to serve as a starting point for airports and/ cation on a broader scale. Regulatory requirements or operators who are considering development of pertinent to TBLT operations were also identified; their own guidance on TBLT best practices. Com- these requirements generally apply to ground vehi- munication and coordination within the local airport cles, which include TBLTs and their operators. The community is critical to ensure that the best prac- information was organized and presented as best tices ultimately implemented are clearly understood practices aimed at providing broad guidance to air- and agreed upon. It is important to recognize that ports and airlines for the enhancement of safety in the technical and operational landscapes surround- TBLT operations. ing aircraft towing are evolving, which may neces- sitate that this document be updated periodically to remain current and within existing and future regu- 1.3 Purpose latory requirements and guidelines. The purpose of this document is to provide practical planning guidance describing best practices for 2 Definition of Terms operating TBLTs at airports. This document intro- duces best practices to airports and operators that Air Traffic Control (ATC)—Personnel authorized do not currently have guidelines and can be incor- to control aircraft and vehicles operating on porated into or supplement existing documents and the airport movement area and in the airspace. handbooks. The following objectives guided the de- ATC issues specific instructions that approve or velopment of this document: disapprove the movement of aircraft, vehicles, equipment, or personnel. For purposes of this • Develop the document as a reference that is document, ATC encompasses tower, ground, useful to airports and aircraft operators, and ramp control. • Provide practical guidance to assist airports Airport Traffic Control Tower (ATCT)—A ter- and aircraft operators in developing training minal facility that uses air/ground communica- programs for the safe use of TBLTs, and tions, visual signaling, and other devices to pro- • Provide practical guidance to assist airports vide ATC services to aircraft operating on and and aircraft operators in developing and im- in the vicinity of the airport. plementing a standard set of guidelines for Airport Markings—Markings used on the runway safe operation of TBLTs. and taxiway surfaces to identify a specific run- The purpose of this guidance is to assist airports way, a runway threshold, a centerline, a hold and aircraft operators in gaining a basic understand- line, and the like. ing of the training and operational issues associated Airport Operations Area (AOA)—The areas on with TBLT operations. The guidance and informa- the airport (generally inside airport fencing) that tion in this document is not intended to be a substi- include aprons, ramps, aircraft parking areas, tute for, nor in any case supersede, existing United taxiways, and runways.

Airport Surface Detection Equipment (ASDE)— white, green, or red light as selected by the tower Surveillance equipment specifically designed to controller. The color and type of light transmit- detect aircraft, vehicular traffic, and other ob- ted can be used when radio communication is jects on the surface of an airport, and to present not available for controlling traffic on the airport the detected images on a tower display. ASDE movement area. is used to augment visual observation by tower Line of Sight (LOS)—An imaginary straight line personnel of aircraft and/or vehicular move- from the observer’s eye to an object. ments on runways and taxiways. Lost Communications—Loss of the ability to com- Apron (also referred to as Ramp)—A defined municate by radio. area, on a land aerodrome, intended to accom- Maintenance Towing—Towing of an airplane for modate aircraft for purposes of loading or un- maintenance/remote parking purposes (e.g., from loading passengers, mail or cargo; refueling; the gate to a maintenance hangar). The airplane and parking or maintenance. is typically unloaded (no passengers or cargo, Automatic Terminal Information Service reserve fuel only). This type of towing can in- (ATIS)—The continuous broadcast of recorded volve relatively high speeds and long distances non-control information in selected terminal with several starts, stops, and turns. areas. Its purpose is to improve controller effec- Monitor—Listen on a specific frequency [e.g., ATC tiveness and to relieve frequency congestion by ground, ATC tower] and stand by for instructions. automating the repetitive transmission of essen- Under normal circumstances do not establish tial but routine information. communications. Controller—A person authorized to provide ATC Movement Area—The airport runways, taxiways, services. and safety areas. The movement area does not Dispatch Towing—Towing of a fully loaded rev- include loading ramps or aircraft parking areas. enue airplane (passengers, cargo, fuel) from the Specific approval for entry onto the movement terminal gate/remote parking area to a location area must be obtained from ATC. near the departure runway. This type of towing Night—The hours between the end of evening civil can involve relatively high speeds and long distances with several starts, stops, and turns, and twilight and the beginning of morning civil twi- generally replaces typical pre-takeoff taxiing light or such other period between sunset and operations. (Formerly referred to as “high-speed sunrise as may be specified by the appropriate towing” or “operational towing.”) authority. Empty—A tow tug (TBLT or conventional tug) Non-movement Area—Taxi lanes, aprons/ramp that is operating without an aircraft in tow. and parking areas not under control of ATC. Escort—Airside operations vehicle leading, direct- Notices To Airmen (NOTAMs)—A notice contain- ing, and guiding a vehicle. ing information (not known sufficiently in ad- Flight Deck Observer—Personnel in the aircraft vance to publicize by other means) concerning flight deck qualified and authorized to communi- the establishment, condition, or change in any cate with the ATC, assist the TBLT operator with component (facilities, service, procedures, haz- situational awareness of taxi movements, and also ards) the timely knowledge of which is essential to apply brakes only in case of an emergency. to personnel concerned with flight operations. Foreign Object Debris (FOD)—Any item located Oversteer—Exceedance of the maximum allow- on the AOA that can be ingested or blown by an able steering angle or torsion load as defined by aircraft engine causing damage to property or the airframe manufacturer for a specific airplane personnel. model or derivative. “Hold Short”—ATC communications term used Pushback Towing—Towing of a fully loaded rev- to instruct vehicles or aircraft to hold short of a enue airplane (passengers, cargo, and fuel) from a runway, traffic, or a specific point on the airfield parked position at the gate to the taxiway. Towing such as localizer critical area, glideslope critical typically includes pushback with a turn, stop, and area, precision obstacle-free zone, and so forth. a short tow forward to align the airplane. Light Gun—A handheld directional light signal- Runway Incursion—Any occurrence at an aero- ing device that emits a brilliant narrow beam of drome involving the incorrect presence of an

aircraft, vehicle, or person on the protected area 3 tBLT Operator Requirements of a surface designated for the landing and take- This section describes the specific minimum off of aircraft. requirements for TBLT operators. These require- Ramp Control—A ground communications facil- ments include FAA guidance, airport operational ity that provides ATC services to aircraft operat- requirements, airline operating manuals, and manu- ing on the ramp area. facturers’ recommended procedures. Read Back—Upon receiving ATC instructions, a pilot repeats all, or specified parts, of the transmission. 3.1 Credentials Route—A defined path consisting of one or more courses that an aircraft can traverse on the airport. In addition to demonstrating proper training and Runway Visibility Range (RVR)—The maximum knowledge, TBLT operator licensing and badging distance along the runway at which the runway must be obtained prior to operating a TBLT. Ad- lights are visible to a pilot after touchdown. ditionally, personnel must be able to show licens- Situational Awareness—The ability to identify, ing documentation upon request. Airport opera- process, and comprehend the critical elements tors typically require that TBLT operators obtain of information about what is happening at a the following credentials prior to operating on the given point in time (i.e., knowing what is going airport: on around you). • Background checks and screening, Super Tug—See Towbarless Tractor. • Valid state-issued driver’s license (FAA AC Tail Walker—Ground personnel assigned to ac- 150/5210-20), company the aircraft to ensure sufficient clear- • Valid airport security badge/identification, and ance of aircraft tail to objects are maintained • Airport driving privileges (FAA AC 150/ during pushback and/or towing in limited spaces. 5210-20). Taxi—The movement of an airplane on the surface of an airport (ATC clearance required to taxi in 3.2 Training movement areas). Towbarless Tow Vehicle (TLTV)—See Towbar- Recommended minimum training requirements less Tractor. are listed below by training area. All areas should be Towbarless Tractor (TBLT)—An aircraft tow covered during training and airport operators should tractor that utilizes a pick-up device located in provide a means of testing of the material. the center of the vehicle used to cradle the nose Trainees should have on-the-job (OTJ) training gear tire of an aircraft. The TBLT works without prior to unescorted access and demonstrate sound a towbar, thus enabling a quick, safe and eco- situational awareness (FAA AC 150/5210-20 and nomical handling of aircraft on the ground. The FAA AC 00-65). The TBLT owner should maintain absence of towbars and the higher speeds mean training records (Federal Aviation Regulations (FAR) that aircraft movements, pushbacks, gate-to-gate 139.329.f ). towing, and maintenance towing can be carried • General: out faster than with conventional towbar tractors, –– Minimum age requirement, minimizing impact to airport operations. –– Physical qualifications, Visibility—The ability, as determined by atmospheric –– Security background check, and conditions and expressed in units of distance, to –– Appropriate level of knowledge of airport see and identify prominent unlighted objects by rules and regulations. day and prominent lighted objects by night. Vis- • Airport driver training (FAR 139.329.e): ibility is reported as statute miles, hundreds of –– An emphasis should be placed on initial and feet, or meters. annual recurrent driver training for TBLT Wing Walker—Ground personnel assigned to ac- operators, specific to each TBLT model company the aircraft to ensure sufficient clear- operated. ance of aircraft wingtips to objects is maintained –– Many runway incursion factors include a during pushback and/or towing in limited spaces. lack of driver training. See FAA AC 150/

5210-20 Appendices A and B for specific ▪▪ How adverse conditions affect TBLT driver training. braking and turning (heavy snow, strong • Airport movement area training (FAR 139. winds, etc.). 303.c): ▪▪ How exceeding the nose gear steering –– Initial training should be provided to the angle limits affects control of the TBLT. new employee or airport user that would en- –– Have a thorough knowledge of TBLT re- able the employee to demonstrate the ability quirements, towed aircraft requirements, and to operate a vehicle safely on the AOA in towing procedures as outlined in Sections 4 accordance with established procedures. through 10 of this document. –– Recurrent remedial training for personnel –– Receive training in handling emergency authorized to operate on movement areas procedures. should be provided at least yearly. • Appropriate level of knowledge of airport • Airport movement area training course rules and regulations (FAA AC 150/5210-20): curriculum: –– Proficient in communications with ATC, –– Airport familiarization, rules and regulations, –– Thoroughly familiar with airport layout, diagram, aircraft operations (FAR 139.303.c) –– Functional knowledge of the English lan- in all weather conditions; guage (FAA AC 00-65), –– Access to, and operation in, movement and –– Functional knowledge of aviation terminol- safety areas (FAR 139.303.c); ogy (FAA AC 00-65), –– Airport rules and regulations; –– Familiar with aircraft operations on the –– Movement area familiarization/situational airfield, awareness; –– Understand light gun signals, and –– Airport communications (FAR 139.303.c); –– Familiarity with airport signage –– Use of checklists (see AC 00-65 for sample checklists); 4 tBLT—Vehicle Requirements –– Physical control/maneuvering of the vehicle; –– Security on the AOA; This section describes the minimum requirements –– Airport signs/markings/lights (FAR 139. of a TBLT in order to conduct a safe and efficient 303.c); towing operation. –– Safety areas; –– Low visibility; 4.1 Access Control –– Runway incursion prevention; and –– Crew Resource Management (CRM). While operating on the movement area, TBLTs • TBLT manufacturer training specific to equip- must adhere to procedures developed by the airport ment. The TBLT operator should: operator and ATC. TBLTs operating on the move- –– Perform a pre-tow TBLT safety inspection. ment area should be limited to only these necessary –– Be thoroughly familiar with the type of tow to support operational activity. equipment and procedures to tow specific aircraft (FAA AC 00-65). 4.2 Mechanical –– Understand restrictions/limitations on tow equipment (FAA AC 00-65): A mechanically sound TBLT is required to en- –– Speed restrictions for both clear and clut- sure the safety of any towing operation. The TBLT tered ramp, and operator is responsible for ensuring the equipment –– Speed restrictions for contaminated pave- used meets safety requirements. ment conditions. • The TBLT operator should perform an in- –– Understand factors affecting the perfor- spection of the TBLT before starting a tow mance of TBLT equipment: operation. This inspection should include, as ▪▪ How speed affects control of the TBLT. a minimum, the following verifications: ▪▪ How aircraft weight affects the TBLT’s –– All equipment is serviceable and mechani- stopping distance. cally sound,

–– All radio equipment is in working order, and • Unique identification number for each piece –– All towing connections are secure of equipment to enhance visibility, clearly dis- played as described in FAA AC 150/5210-5; 4.3 Communication • Guidance as provided in FAA AC 150/5210-5 for all airport vehicles, regardless of the TBLT A means of communication between the aircraft ownership and funding source; and flight deck and the TBLT cab is required. This is • Clear display of company logo. typically provided through the TBLT intercom system that is connected directly to the aircraft by wire. 4.7 external Elements Protection Additionally, the TBLT should be equipped with two permanently mounted, fully programmable, It is recommended that the TBLT be equipped with two-way radios, which will be the means of com- a cab to keep its operator shielded against weather, munication with ATC. external elements, and aircraft noise.

4.4 Lighting 4.8 Equipment/Accessories Adequate lighting will increase visibility of the Several pieces of equipment and accessories are TBLT, especially at night or during periods of poor recommended to be available to the TBLT operator visibility. This is especially important when the TBLT to increase the safety of the operation. It is recom- operates away from a well-lit apron area. mended the TBLT be equipped with: The following lighting equipment is strongly • ASDE-X transponder; recommended: • Dual VHF radios; Seatbelt for each TBLT occupant; • Working headlights and brake lights; • Windshield wipers and windshield defrost/ • LED light bar on top of the operator’s cab and • defogging systems; two amber strobe or beacon lights on the back; • Wheel chocks, complemented by sand bags Lights should be mounted consistent with • in snow and ice conditions (FAA AC 00-65); FAA AC 150/5210-5; • Placard with the current airfield diagram (FAA • The lights must be operational and turned on AC 150/5210-20); whenever the TBLT is in operation, whether • Placard with ATC and other essential radio or not it is in motion; and frequencies (FAA AC 150/5210-20); • Additional lighting is encouraged because of • Placard listing essential 24/7 telephone contact the TBLT’s low profile and that the TBLT numbers; may be obscured by the aircraft in tow. • Placard illustrating ATC light gun signals (FAA AC 150/5210-20); and 4.5 Painting • Placard denoting airfield signage and markings (FAA AC 150/5210-20). Adequate painting will increase visibility of the TBLT, especially at night or during periods of poor visibility. It is recommended that the TBLT be dis- 5 Aircraft-Under-Tow Requirements tinctly painted in international orange and that retro This section describes the minimum requirements reflective tape be used to outline its shape, including of an aircraft under tow in order to conduct a safe and rounded edges. Additionally, it is recommended that efficient towing operation. the TBLT be kept clean so its coloration is clearly visible. 5.1 Safety—General

4.6 Markings In anticipation of Safety Management System (SMS) requirements, all managers and supervisors Adequate markings will allow for prompt iden- should, identify, eliminate, control, and document tification of the TBLT, especially at night or during hazards within the workplace to minimize risks as- periods of poor visibility. The following markings sociated with uncertainty in the decision-making are strongly recommended: process. (FAA AC 00-65)

5.2 Mechanical Although it is recommended that all of the afore- mentioned lights be turned on, only those specified The full aircraft braking system should be avail- in FAR Part 91.209 are mandatory. Aircraft anti- able for use at all times. An aircraft under tow should be mechanically sound and able to maintain collision beacon lights should be turned on any time minimum speeds that will preclude impeding air- the aircraft engines are running. Furthermore, any port operations. Additionally, the aircraft under tow supplemental lighting not specified in FAR Part must not exceed towing speeds as determined by the 91.209 would require prior FAA approval. TBLT manufacturer, aircraft manufacturer, airport, or TBLT operator for the existing operating and air- 5.5 Equipment/Accessories field conditions. It is recommended that the following be con- spicuous inside the flight deck and TBLT cab to in- 5.3 Communication crease the safety of the operation: The flight deck observer will be the primary • A current airfield map showing all non- communicator with ATC and the TBLT operator movement and movement areas, will be the secondary communicator. The aircraft’s • All ATC and pertinent frequencies (ramp permanently mounted, fully programmable, two- control, company, etc.), and way radio will be the primary means by which the • Backup communications procedures (includ- flight deck will communicate with ATC. Communi- ing phone numbers). cation between the flight deck and the TBLT cab is also required. This is typically provided through the TBLT intercom system that is connected directly to 5.6 Personnel the aircraft by wire. The TBLT operator and flight A qualified flight deck observer is required on deck observer must monitor all radio communica- the aircraft flight deck to communicate with ATC tions and are equally responsible for adhering to all and to apply aircraft brakes, which are only to be ATC communications and instructions. applied in case of emergency and communicated as such to the TBLT operator and/or ATC. 5.4 Lighting To increase conspicuity the following aircraft 6 towbarless Tractor Procedures lights may be turned on depending on operational This section describes the recommended proce- conditions unless otherwise specified under written dures to conduct a safe and efficient towing operation. agreements and/or understandings between designated representatives of the airport, aircraft operators, and local ATC and FAA: 6.1 Before Start Procedures (Prior to Pushback and Towing) • Aircraft interior lights (night or reduced visibility operations), The following procedures are recommended be- • Navigation lights (day or night operations), fore the start of any tow operation. The TBLT op- • Anti-collision lights (per the discretion of erator and flight deck observer will be responsible operator), for adhering to these recommendations: • Upper and lower rotating beacons (aircraft • Review planned operating procedures with under tow), and flight deck observer. (An aircraft towing op- • Other supplemental lighting (requires FAA eration by TBLT requires at least two quali- approval). fied employees: one in the aircraft and one in It should be noted that under certain conditions the TBLT.) it is possible that an aircraft with lights turned on • Review current airport/airfield conditions with may incorrectly suggest to outside observers, in- the flight deck observer (NOTAMs, ATIS, cluding ATC, that the lighted aircraft is under its ATC, airport layout and geometry, pavement own power. The flight deck observer should ensure conditions, etc.). through direct communications that ATC clearly • Review planned route with the flight deck understands that the aircraft is under tow. observer.

• Review contingency plans with the flight deck • At the initiation of pushback, the TBLT should observer, including: push the aircraft straight back until clear of –– Weather, all objects before proceeding with any turning –– Alternate tow routes, maneuvers. –– Lost communications, and • The aircraft may be pushed back with engines –– Emergencies. operating if permitted by airport or company • Provide a visual check of overall condition of procedures. TBLT (FAA AC 00-65). • Engines may not be started during the push- • Provide a visual check of overall condition of back operation. If required, aircraft engines aircraft (cargo doors, latches, struts, tires, etc.). should be started before the pushback. • Close entrance doors, retract or remove lad- • Prior to starting the pushback: ders, install landing gear down locks (if –– The TBLT operator should be facing in the required) (FAA AC 00-65). direction of pushback. • Test TBLT transponder (if applicable) and check –– The TBLT operator should have thorough proper working condition of minimum operating knowledge of the delineation of movement/ equipment (radios, lights, safety equipment, etc.). non-movement areas. • Verify the airport diagram (movement/non- –– ATC approval is required before entering movement) placard is available to both the the movement area. TBLT operator and flight deck observers –– TBLT operators must have a thorough un- (review Surface Movement Guidance Control derstanding of airport right-of-way rules. System (SMGCS) Plan/diagram if applicable). • Check the pre-charged aircraft brake accumu- 6.3 Aircraft Towing Procedures lator pressure before each tow, and do not use TBLT if aircraft brake pressure is below nor- The following procedures are recommended for mal operating limits. aircraft towing operations beyond the pushback. • Do not hang any equipment on the aircraft The TBLT operator will be responsible for adher- exterior (FAA AC 00-65). ing to these recommendations: • When connecting a tow vehicle, personnel • The tow team shall maintain contact with should be extremely vigilant to any sudden ATC through the proper ATC frequencies movement of the tow vehicle or aircraft (FAA (ramp, ground, or tower). AC 00-65). • Proper phraseology shall be used while in • Ensure all ground equipment and FOD is radio contact with ATC. removed from the vicinity of the aircraft and • Prior to starting the tow: pushback area. –– The TBLT operator should be facing in the • Ensure properly charged fire bottles/ direction of tow. extinguishers are accessible. –– ATC approval is required before entering • TBLT operators and flight deck observers the movement area (if applicable). must wear their seatbelts/safety belts prior to –– The TBLT operator should have thorough push back and at all times during the tow. knowledge of the delineation of movement/ non-movement areas. 6.2 Aircraft Pushback Procedures –– TBLT operators must have a thorough understanding of airport right-of-way rules. The following procedures are recommended for • TBLT operator must hold short of all manda- any aircraft pushback operation. The TBLT opera- tory instruction signs until cleared by ATC. tor will be responsible for adhering to these recom- • TBLT operator should perform smooth starts/ mendations: stops. (FAA AC 00-65); the aircraft should • Wing walkers and tail walkers are recom- not be towed with engines operating. Engines mended during pushback when other aircraft may be operating if the TBLT is only used to or objects are positioned in adjacent parking push the aircraft away from the terminal gates positions/gates. (FAA AC 00-65).

• TBLT operator should maintain slow speeds • Inspect aircraft for damage upon completion and high turning radii during turning maneu- of the tow per manufacturer’s recommenda- vers. For example, Boeing recommends the tions and report any damage. maximum allowable steering angle be 80 per- • Prohibited operations: cent of the conventional towbar limits. The –– Passing other vehicles or aircraft, conventional towbar limits were reduced for –– Leaving a TBLT unattended with the engine towbarless towing to provide a margin of safety running, and for the absence of shear protection furnished –– Driving a TBLT under an aircraft. by the towbar/tow lug connection. • Aircraft brakes should not be used except in the case of an emergency. 6.4 towbarless Tractor Repositioning • Maximum allowable towing speed should Procedures be determined by the operator based on the TBLT repositioning consists of driving the TBLT TBLT model and aircraft under tow. Recom- without an aircraft in tow. It is sometimes referred to mendations for towing speeds in good weather as “TBLT operating empty.” During repositioning, conditions: the following is recommended: –– Towing speed in apron/ramp areas should be no faster than walking pace. • Use service roads if the service road weight –– Towing speed in close quarters, turns and bearing capability and width are adequate near gates should be restricted to less than (FAA CertAlert 08-06). When the use of ser- 2 mph. vice roads is not practical, the TBLT may use –– Towing speed limited to 6 to 8 mph on airport movement areas in accordance with long hauls, straight portions not to exceed rules, regulations, or agreements with the air- speeds as recommended by the TBLT or port. While on airport movement areas, the aircraft manufacturer. TBLT operator must be in radio contact with • Reduce towing speeds according to aircraft ATC at all times. weight and airfield conditions (snow, ice, wet • Driving under aircraft is prohibited. pavement) (FAA AC 00-65). • Driving under passenger boarding bridges is • Towing personnel should not place them- prohibited. selves in the direct path of aircraft wheels nor ride on any external portion of an aircraft or 6.5 Dispatch Towing Procedures tow vehicle (FAA AC 00-65). • The TBLT operator should have knowledge 6.5.1 Overview of aircraft nose gear operating specifications Dispatch towing is the towing of a fully loaded to ensure the nose gear maximum allowable revenue airplane (passengers, cargo, and fuel) from steering angle is not exceeded and the nose the terminal gate or remote parking position to a gear is not overstressed. location near the departure runway made possible • Upon completion of the tow operation, the by the increased towing speeds achievable with a aircraft should be positioned such that the TBLT. Dispatch towing with a TBLT has been iden- nose gear is aligned with the aircraft. tified as a strategy to reduce aircraft taxi fuel burn Wing walkers should be used in congested • and engine emissions. areas such as the gate areas or non-movement areas having short separation distances from 6.5.2 Dispatch Towing Issues fixed or moveable objects. • Tail walkers should be used during towing Dispatch towing has been used at some airports operations when the aircraft is turned in areas in the U.S. However, a number of issues related having short separation distances from fixed to dispatch towing have been identified that limit or moveable objects. widespread use. First, TBLT towing places heavy • Prior to disconnecting the TBLT from the air- stress loads on the nose gear. Tests conducted by craft, the aircraft parking brake should be set Virgin Atlantic and Boeing found that dispatch tow- and/or chocks placed on the aircraft. ing with TBLTs resulted in a reduced operational

life of aircraft nose gear because of the additional • ATC personnel should be provided familiar- stress. Additionally, the TBLT must disconnect ization of TBLT limitations. from the aircraft near the end of the runway and re- • A means of communication with the TBLT turn to the terminal. This return trip represents an operator’s company should be provided. additional vehicle on the airfield with which ATC must maintain contact until such a point that the TBLT exits the movement area or can use a vehicle 7.2 Responsibility (See Section 5.3) service road. The flight deck observer will be the primary communicator with ATC while the TBLT operator 6.5.3 Procedures will be the secondary communicator. For the reasons described above, TBLT dispatch • The flight deck observer may authorize other towing is not a recommended practice. If dispatch personnel in the flight deck to communicate to towing is requested, the operation should be re- ATC on their behalf; however, the flight deck viewed on a case-by-case basis. Airports and opera- observer is accountable to adhere to all ATC tors should apply the towing procedures outlined in instructions. Section 6.3 and monitor the operation to determine • The TBLT operator will monitor appropri- if additional regulations are necessary. ate radio frequencies, but will not, however, communicate directly with ATC unless directed by the flight deck observer who has 7 Communication communications responsibility during the Effective communication between airport users tow operation. and ATC is a key to safe airport operations. This sec- • The TBLT operator will act as an extra set of tion describes communication requirements, respon- “eyes and ears” and otherwise provide additional situational awareness to the flight deck sibilities, and procedures during TBLT operations. observer. As such, the TBLT operator will maintain direct radio contact with the flight 7.1 Requirements deck observer and communicate with him/her only as necessary. • Towing operations require continuous contact • An alternate method of communication with with ATC via an aviation band transceiver ATC (when conditions restrict aircraft battery while in the movement area, whether or not operation for instance), is through an escort in motion. vehicle in direct contact with the control tower • Proper aviation phraseology and phonetic and the TBLT operator. The escort vehicle alphabet should be used at all times. would accompany the aircraft throughout the • Satisfactory speech is required (radio commu- towing operation (FAA AC 00-65). nication should be made slowly and clearly). • Communications will only be of a profes- sional nature and necessary to ensure the safe 7.3 Procedures and secure movement of aircraft. • The flight deck observer must obtain clear- • The TBLT operator and flight deck observer ance from ATC prior to operating on any must always remain in communication with movement area (FAA AC 00-65). each other. • The flight deck observer will read back ATC • The TBLT operator and the flight deck instructions when appropriate and/or required observer must have the capability to commu- (e.g., “Hold Short of ___,” “Roger,” “WILCO”). nicate directly with ATC at all times during • The TBLT operator will acknowledge ATC towing operations. instructions through read back procedures • The tow team must be able to monitor the with the flight deck observer ATC frequency they are assigned to at all • Identify TBLT operations to ATC as “Super- times regardless of the person who is in con- Tug {Equipment #}.” TBLT operations using tact with ATC. smaller equipment (e.g., TBLTs designed to

tow regional jets) can be identified as “MiniTug • Participate in “Before Start” briefing with {Equipment #}.” TBLT operator and escort, if applicable. • Identify a TBLT repositioning to ATC as • Act as primary communicator with ATC. “Maintenance {Equipment #}.” • Use proper aviation phraseology and phonetic alphabet at all times. • Use satisfactory speech (slowly and clearly). 7.4 Contingencies • Apply brakes in case of an emergency and • The TBLT operator should use a headset if when directed to do so by the TBLT operator ambient noise is too loud. • Monitor aircraft brakes hydraulic pressure • A backup form of communication with ATC (FAA AC 00-65). should be provided. • A communications plan should include con- 8.3 towbarless Tractor Operator tingencies in case of lost communications. The TBLT operator has the following responsibilities: 7.5 Emergencies • Use a checklist (FAA AC 00-65). The TBLT operator and/or flight deck observer • Acknowledge ATC instructions through read may communicate directly with ATC in case of an back procedures with the flight deck observer. emergency. • Operate the TBLT in safe manner (FAA AC 00-65). • Ensure placards specified in Section 4.8 are 8 oPerator Responsibilities visible inside the cab, check for temporary This section sets forth the responsibilities of all placards (FAA AC 00-65). parties involved in TBLT operations. • Ensure equipment is serviceable and func- tioning properly before starting tow. • Provide a “Before Start” briefing to the tow 8.1 tBLT Owner team. • When the TBLT owner is an aircraft operator • Ensure compliance with aircraft lighting under Title 14 CFR Parts 91, 91K, 121, 125, requirements (FAR 91). Ensure ATC clearance is obtained prior to 129, and 135, it must establish guidance that • entering the movement area. clearly defines duties and responsibilities and • Ensure ATC clearance is clearly understood employs the use of a checklist. and acknowledged with flight deck observer. The TBLT owner should submit procedures • • Perform pre-tow circle check: to the Certificate Holder District Office –– Ensure all equipment and personnel are (CHDO), including at least (FAA AC 00-65): clear of the airplane prior to tow. –– Safety instructions, –– Check with flight deck observer that ad- –– Operating procedures (including day vs. equate hydraulic pressure has built up for night), aircraft brakes. –– Initial and recurrent training, –– Check proper positioning of torque links if –– Radio communication, and required. –– Towing procedures checklist. –– Turn on all TBLT exterior lights (FAR 91). • The TBLT owner is required to maintain train- –– Turn on position lights between sunset and ing records (FAR 139). sunrise (FAR 91). Wear communication headset (except in limited 8.2 Flight Deck Observer cases where procedures dictate that the wing walker wears it for pushback). The flight deck observer has the following re- Remain in constant contact with flight deck sponsibilities: • observer. • Check ATIS, NOTAMs, airport diagram, ATC • Stop TBLT upon losing communication with frequencies, and so forth. flight deck observer or ATC (FAA AC 00-65).

• Halt operation if direct LOS with wing walkers 9 Weather is lost. Weather conditions should be taken into consid- • Perform a final visual check for damage when operation is complete. eration before starting towing operations. Below is a • Obey emergency stop instructions given by list of weather-related recommendations: any team member (FAA AC 00-65). • Consider using an escort in poor weather • Act as communications backup in case of conditions. communication failure between the flight • Aircraft towing in low visibility (below 1200 deck observer and ATC. RVR) is discouraged. • May be delegated responsibility of communi- • If applicable, TBLT operator and flight deck cating with ATC by the flight deck observer. observer must be familiar with the SMGCS plan. • When ice, snow, slush, or water at near freez- 8.4 Escorts ing temperatures is present, the TBLT may be Escorts should be used in bad weather condi- fitted with tire chains, preferably on the axle tions, in case of an emergency, if the TBLT operator closest to the aircraft. does not have the required credentials to operate on • In poor weather conditions, speeds should be the movement area, when the flight deck observer reduced as dictated by the airport/aircraft oper- cannot fulfill the requirements of the primary com- ator. The following speeds are recommended: municator with ATC, or at the discretion of airport –– Close quarters, turns, near gates: < 1 mph. management. When an escort is used, the escort –– Straight portions when about to stop: vehicle operator is responsible for: < 3 mph. –– Long hauls, straight portions: < 6 mph. • The route to be used during the tow operation. • When lightning is present, the TBLT opera- • The speed of the tow operation. tor should not wear a headset connected to the • Continuous monitoring of communications aircraft. If the TBLT operator and flight deck between the flight deck observer and ATC with observer are no longer in communication, lost the capability to contact the ATC if necessary. communication procedures should be initiated. • In strong wind conditions, TBLT operations should be restricted based on manufacturer’s 8.5 Wing/Tail Walkers recommendations. The following applies to wing and tail walkers: 10 eMergency/Abnormal Procedures • Properly signal the TBLT operator as soon as it appears the aircraft is in danger of colliding This section provides some examples of recom- with an obstruction (FAA AC 00-65). mended actions in the event of an emergency. These • Use luminous wands at night (FAA AC 00-65). actions should be tailored to specific situations. • Use approved hand signals. • Loss or failure of the aviation band transceiver • Remain at least 10 feet from TBLT and aircraft during a reposition requires the immediate stop- nose wheel and main gear during movement. page of the operation; the tow operation cannot • Do not occupy or transit the direct path of the proceed without proper ATC clearance. aircraft wheels (FAA AC 00-65). • ATC may use light gun signals to direct the • Do not cross under aircraft during movement. TBLT, although the safest method to proceed • Do not ride on any external portion of aircraft would be to contact airport operations for an or TBLT. escort out of the movement area. • Remain in direct LOS contact with the TBLT • Aircraft under tow that become disabled may operator. request mechanics for inspection and possible • Wing and tail walkers are not required to: back-up tow to the ramp or maintenance area. –– Participate in annual proficiency checks, • All emergencies must be coordinated with air- but should attend recurrent training, or port operations for an escort to access the airfield. –– Be fully qualified in all towing procedures. No unescorted direct access will be allowed.

• In the event the aircraft nose gear becomes dis- 11.2 Standards connected from the TBLT during the tow and cannot be reconnected, or if the tow equipment Airports and operators that extensively use TBLTs has a mechanical problem and cannot continue may eventually be faced with new standards that the tow operation; the aircraft will need to be: will enhance operational safety. Some of these stan- –– Towed by another TBLT, or dards may address: –– Taxied clear of the movement area, and • Widening and/or strengthening of airport –– Positioned in a location that will not ob- service roads to accommodate repositioning struct airport traffic flow. TBLTs, • If oversteering occurs, perform an inspection • Additional guidance on TBLT painting and of the aircraft in accordance with the aircraft lighting, maintenance manual and report any damage. • Additional guidance on lighting of aircraft • When the tow is complete, make chocks imme- under tow, diately available to prevent the aircraft from • TBLT operating performance limitations (cre- rolling. ation of manufacturer’s operations manual), • In weather conditions that involve snow, ice • Radio equipment requirements, and frost, use sand bags and chocks as neces- • TBLT seat belt equipment requirements, sary and appropriate. • Minimum TBLT operator training, • TBLT operator simulator training, and • Reporting of TBLT incidents and accidents. 11 Future Towbarless Tractor Operations 12 Reference Material The use of TBLTs varies from airport to airport around the world, and the operational benefits indi- The following material was collected in the course of this project and is useful in understanding issues cate wider use of TBLTs in the future. Both techno- and challenges associated with ensuring safe TBLT logical improvements and new standards of use are operations at airports: to be expected in the coming years as TBLT equipment evolves. • International Air Transport Association, Air- port Handling Manual, 29th edition, January 1, 2009. 11.1 Technology • Federal Aviation Administration Airport A semi-robotic tractor is currently being tested Safety and Operations Division, CertAlert to tow aircraft from the airport gate to the takeoff 08-06, SuperTBLT Operations on Part 139 point or to the gate after landing. This type of tow- Airports (all surfaces), July 1, 2008. barless system uses a “turret” to which the aircraft • SAE Aerospace, Aerospace Recommended nose wheel is clamped and rotates as the pilot of the Practice: Towbarless Towing Vehicle Oper- aircraft steers the nose wheel, allowing the pilot to ating Procedure, May 2003. steer the aircraft via the towbarless system and using • Towbarless Tow Vehicle Industry Work Group, the aircraft’s brakes. The towbarless system leaves Meeting Report, September 9–10, 2009. the aircraft pilot in control of the taxiing and would • U.S. Code of Federal Regulations, Title 14 not require any personnel inside the TBLT. Part 91, General Operating and Flight Rules, Under this concept, the towbarless system would August, 18, 1989. be managed through a command and control com- • U.S. Code of Federal Regulations, Title 14 munication center located in the ATC tower. The Part 91.209, Aircraft Lights, February 9, 1996. eventual goal of the program is to fully automate the • U.S. Code of Federal Regulations, Title 14 taxiing process. The semi-robotic towbarless system Part 91K, Fractional Ownership Operations, has the potential to improve the air and noise qual- September 17, 2003. ity, reduce fuel and engine costs as aircraft would • U.S. Code of Federal Regulations, Title 14 not be under its own power. As such, this type of Part 121, Operating Requirements: Domestic, towbarless system has the potential to provide envi- Flag, and Supplemental Operations, Novem- ronmental and financial benefits. ber 8, 2007.

• U.S. Code of Federal Regulations, Title 14 • U.S. Code of Federal Regulations, Title 14 Part 125, Certification and Operations: Air- Part 139.303, Personnel, June 4, 2004. planes Having a Seating Capacity of 20 or • U.S. Code of Federal Regulations, Title 14 Part More Passengers or a Maximum Payload 139.329, Pedestrians and Ground Vehicles, Capacity of 6,000 Pounds or More; And Rules January 1, 2005. Governing Persons On Board Such Aircraft, • U.S. Department of Transportation, Federal November 8, 2007. Aviation Administration Advisory Circular • U.S. Code of Federal Regulations, Title 14 00-65 Change 1, Towbar and Towbarless Part 129, Operations: Foreign Air Carriers Movement of Aircraft, November 8, 2010. and Foreign Operators of U.S.-Registered • U.S. Department of Transportation, Federal Aircraft Engaged in Common Carriage, Feb- Aviation Administration Advisory Circular ruary 10, 2011. 150/5210-5, Painting, Lighting and Marking • U.S. Code of Federal Regulations, Title 14 of Vehicles Used on an Airport, April 1, 2010. Part 135, Operating Requirements: Commuter • U.S. Department of Transportation, Federal and On Demand Operations and Rules Gov- Aviation Administration Advisory Circular erning Persons On Board Such Aircraft, 150/5210-20, Ground Vehicle Operations on October 10, 1978. Airports, March 31, 2008.

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