Military

CHAPTER 5

BASICS OF AIRCRAFT LOAD PLANNING

INTRODUCTION

This chapter shows how to carefully plan an air movement to ensure efficient use of the aircraft before loading. It concentrates on the manual air load planning method but also discusses automation. Air load planners must be proficient in manual air load planning techniques before using automated methods.

The following basic principles of load planning apply to any type of aircraft. Load planning--

  • Identifies the type of aircraft needed to carry a load.
  • Identifies the exact number of aircraft needed to accomplish a particular mission.
  • Identifies in advance any additional required loading aids to ensure availability at load time. Aircraft ground time is minimized when the unit is prepared to load.
  • Helps the unit prioritize the movement of cargo and personnel.

Many factors are considered in the load planning process. Primarily, the load planner must ensure the safe and efficient use of the aircraft. The load planner must comply with aircraft safety, weight and balance, and floor load restrictions. The load must be within an acceptable center of balance condition for takeoff, flight, and landing. The load planner must also consider the ease of loading and unloading. Improper planning can result in excessive loading or unloading time or structural failure in flight or on landing. A load properly planned and coordinated will go on the aircraft quickly, safely, and with minimum difficulty.

LOAD PLANNING CONSIDERATIONS

Some basic considerations affect the aircraft and aircraft stability. The following must be known before any load planning can begin:

  • The aircraft critical leg allowable cabin load.
  • The center of gravity range of the aircraft.
  • *The placement of the cargo in the aircraft so that the weight and balance check will not require rearranging of the cargo. Usually the heaviest items of cargo are placed in the aircraft CG area, with the lighter items forward and aft. See Table 2-1 for CB windows.
  • The location of the emergency exits. Cargo should not block any passenger or emergency door.
  • The location of the safety aisle. Cargo should never obstruct the required safety aisle that lets the crew move freely from the front to the rear of the aircraft.
  • The cargo loading order. The cargo scheduled to be unloaded first is usually loaded last.
  • The requirement for hazardous cargo marking, documentation, and placement within the aircraft. Each unit is responsible for certification of hazardous material and specific packaging requirements according to TM 38-250.

Other load planning considerations relate directly to the deploying unit: its mission and the expected scheme of operation upon arrival at destination. FM 55-12 details planning considerations and responsibilities.

TYPES OF LOADS

Aircraft loading is generally categorized into two types: concentrated loading and palletized loading.

Concentrated Loading

Concentrated loads are very large or heavy items, such as vehicles, tanks, or construction equipment. The precise station location on which the cargo is to be placed inside the aircraft must be computed. To properly place the cargo on a specified station, the cargo item must be marked with the correct center of balance. Since station computations enter into this method of loading, it is also called station loading.

Palletized Loading

The entire aircraft load generally consists of preloaded 463L pallets, properly secured and ready for flight. The center of each pallet is its center of balance unless the pallet is marked otherwise. The 463L restraint rail system positions and secures the pallets in the aircraft. See Appendix D for more information on the 463L cargo system.

AIRCRAFT LOADING DATA

The unit load planner must be familiar with the loading rules and limitations for each aircraft. General rules that apply to all aircraft follow:

  • Plan to move general bulk cargo, such as boxes or crates, on the back of cargo-carrying trucks or trailers. Stacked bulk cargo should not exceed the reduced configuration height of the cargo-carrying vehicle according to TB 55-46-1. Ensure vehicle weights used for load planning include the weight of the cargo.
  • Secure all general bulk cargo with a minimum of 1/2-inch diameter rope. Hemp rope is recommended; nylon is not authorized.
  • Use only forklifts rated at a lifting capacity equal to or greater than the cargo being loaded. Normally, 10K forklifts, all terrain/rough terrain (AT/RT), are used.
  • Use forklifts with a minimum tine length of 72 inches to avoid dropping or damaging the 463L pallet.
  • Use a minimum of 3/4-inch shoring when loading tracked vehicles with metal cleats, studs, or other gripping devices that will damage the aircraft floor. See Chapter 6 for more information on shoring.
  • Do not deflate vehicle tires to achieve vehicle height clearance to fit within the aircraft loading envelope.
  • Treat tires with over 100 psi as hard rubber tires; consider floor limitations.
  • Do not use the book weight or item data cards for weight and balance purposes during actual airlift. Use the actual scale weight.

*Another consideration when planning loads for the C-130, C-141, and C-17 is that neither has a separate troop compartment. Therefore, when planning troop movements, cargo-carrying capacity is sacrificed. The cargo load restricts the number of troops that can be carried. The following general rules apply to the use of sidewall seats when planning nonpalletized cargo on the C-130, C-141, and C-17:

  • *Cargo widths up to 76 inches for the C-130, up to 80 inches for the C-141, and up to 156 inches for the C-17 - may carry troops on both sides of the cargo. Centerline load the cargo in the aircraft.
  • *Cargo widths of 77 inches to 96 inches for the C-130, 81 inches to 96 inches for the C-141, and 157 inches to 192 inches for the C-17 - may carry troops on one side of the cargo only. Cargo will be offset to the right side of the cargo compartment.
  • *Cargo widths over 96 inches for the C-130, C-141, and over 192 inches for the C-17 - no troops will be seated beside the cargo. Centerline load the cargo in the aircraft.

PRINCIPLES OF MOMENT

To understand center of balance considerations, it is necessary to understand the principles of moment. Moment is simply the product of a force (or weight) times the distance from the reference datum line. The distance used to calculate a moment is the arm, which is expressed in inches. To calculate moment, a force (or weight) and distance must be known. The distance is measured from some known point (reference point or reference datum) to the point throughout which the force acts. Moment is meaningless unless the reference point about which the moment is calculated is specified.

There are three items used in weight and balance calculations: moment, weight, and arm. The relationship of these items can be shown by arranging them in a mathematical triangle (Figure 5-l).

Perhaps the simplest way to explain this is to look at a child's seesaw: A heavy board is placed across a fixed support about which the board balances (fulcrum). When there are two different size children riding the seesaw, they use their skill or intuition to make it operate properly. They do this by compensating with distance: the heavier child sits closer to the fulcrum and the lighter child sits farther away from the fulcrum.

EXAMPLE 1:

Look at Figure 5-2. A board is perfectly balanced with a 30-pound weight on one end and a 60-pound weight on the other. This example shows that the influence of weight depends directly on its distance from the fulcrum. For balance to exist, the weight must be distributed so the leverages or turning effects are the same on each side of the fulcrum. Note that the heavyweight near the fulcrum has the same effect as a lighter weight farther from the fulcrum.

To prove mathematically that the seesaw board is balanced, apply the formula in Figure 5-1 to determine whether or not the moments applied to each side of the fulcrum are equal.

 

LEFT SIDE

 

RIGHT SIDE

W =

30 pounds

W =

60 pounds

A =

100 inches

A =

50 inches

M =

W x A

M =

W x A

=

30 x 100

=

60 x 50

=

3,000 inch-pounds

=

3,000 inch-pounds

Substituting the values from the above example into the formula shows that each side has a moment of 3,000, and the seesaw board is perfectly balanced.

EXAMPLE 2:

If the fulcrum is unknown with the same seesaw board and the same weights as in Example 1, the problem is to determine the location of the fulcrum, or the CB. To find the fulcrum, apply the same formula described in Example 1, but first measure some distances (arm) to find the appropriate moment for each weight. To measure the distance, a specific known starting or reference point is needed. These measurements may be made from any point, but in this example, the left end of the seesaw board will be the reference point or reference datum (Figure 5-3).

Assume the distance for each of the weights on the seesaw board from the RD line measured 20 and 170 inches respectively. Note that the distances are measured from the RD to the center of mass or CB of each of the weights. Using the same formula again, compute the moment:

Weight

x

Arm  =

Moment

30

x

20  =

600 inch-pounds

60

x

170  =

10,200 inch-pounds

90

 

 

10,800 inch-pounds

Add the weights and the moments (inch-pounds) as shown above. Now, to find the distance to the center of balance (fulcrum) in this example, divide the total moment by total weight.

Total Moment
Total Weight

  =   Arm or

  10,800
      90  

  = 120 inches

Therefore, the center of balance (fulcrum) of this seesaw board is 120 inches from the RD line (Figure 5-4).

Again to prove mathematically that each side of the seesaw board is subjected to the same moment, and therefore is balanced, calculate as follows:

 

LEFT SIDE

 

RIGHT SIDE

A =

120 - 20

A =

170 - 120

=

100

=

50

M =

W x A

M =

W x A

=

30 x 100

=

60 x 50

=

3,000 inch-pounds

=

3,000 inch-pounds

Since the same moment or leverage (3,000 inch-pounds) is applied to each side, the seesaw board is balanced.

LOAD CENTER OF BALANCE

In some older publications, the term center of gravity or CG is widely used with aircraft loads (cargo). This term is the same as load or cargo center of balance. Since balance of the aircraft is mainly affected by weight variations along the longitudinal axis of the cargo inside the aircraft, the term center of balance more appropriately refers to the balance point of items of cargo or equipment that go into the aircraft.

For general cargo center of balance computation and vehicle center of balance computation, refer to Appendix G of FM 55-12.

For load center of balance computation, decide what goes on each aircraft; then compute the total load weight and balance to ensure that the load is within aircraft limits. To do this, know the--

  • Weight of each vehicle or piece of equipment.
  • Fuselage station CB of each vehicle or piece of equipment as it is located within an aircraft.
  • Total cargo center of balance limitations range of the aircraft.

The formula to find the load CB is the same as described in the previous two examples. To find the arm, the final CB of the loaded aircraft, add all the weights and moments of the cargo. Then divide the total moment by the total weight to get the final CB (Figure 5-l). If that CB is within limits (CB limitation range) for that aircraft, the load is acceptable. If the CB is not within CB limits of the aircraft, then move or resequence some of the cargo items and recalculate.

EXAMPLE:

A C-141B load with the weights and fuselage stations shown in Table 5-1 has been developed.

*The final CB of this aircraft load is 940. The cargo load center of balance limits (floating window) is in Table 2-1. The CB limits of a C-141B with a 50,000-pound cargo load is from 880 to 950. So this load is acceptable and will not endanger the aircraft.

On most aircraft loads, personnel weight and arm must be included in the aircraft load computation. Personnel should be seated all together (rarely will all available seats be filled) and their CB should be figured from the fuselage station closest to the center of the mass.

Whenever possible, seat personnel in directly opposite seats. If personnel seats are staggered on either side of the aircraft or in no particular pattern, the CB of each group must be included. The closer together personnel are seated in the aircraft, the fewer computations must be done to determine the aircraft CB.

Loaded pallets do not need a separate CB measurement and marking unless they are of unusual configuration. The loaded pallet must be part of the load CB computation, but the fuselage stations for the pallets are identified in the aircraft and along the top of the DD Form 2130-series cargo manifest forms. Pallets should not be placed on any other fuselage station except those so identified.

PLACEMENT OF AIRCRAFT LOADS

Load Planning

Boxes, crates, pallets, and other relatively small items are easy to load into an aircraft but still require a plan on how and where they should be placed inside the aircraft. Wheeled vehicles, trailers, tracked vehicles, and other large equipment require much greater planning effort.

The development of an aircraft load requires precision and a knowledge of the principles of center of gravity and balance. Once these principles are understood, aircraft loads can be easily and quickly planned without complicated mathematics.

Place the center of balance of the heaviest item at the optimum CG station of the aircraft. Place the next heaviest item forward of the first item, the third item aft of the first, and so on. This is the pyramid method of loading. It is used to quickly plan the placement of vehicles and other heavy equipment onto the aircraft. One exception to this method is trailers with prime movers. Keep the associated trailer connected to its prime mover for ease of unloading.

Verify the estimated plan after deciding the fuselage station on which to place the equipment. Using this method, together with the templates of the aircraft plans, aircraft loads can be quickly changed or reconfigured without time-consuming figuring.

Templates

The best way to plan load placement manually is to obtain templates of all the vehicles and equipment in the unit. Figure 5-5 shows some sample equipment templates and their placement on a cargo manifest. See Appendix E for more information on templates.

Loading Procedures

A large variety of cargo and equipment can be transported by aircraft. Thus, a variety of loading techniques is possible. The ultimate decision of how cargo is to be loaded and positioned aboard an aircraft is an Air Force responsibility, specifically, the aircraft loadmaster. The deploying unit normally does the loading, assisted as necessary by the Arrival/Departure Airfield Control Group (A/DACG) personnel and equipment. However, prior planning is the key. Aircraft load planning is the moving unit's responsibility.

The 55-series transportability technical bulletins provide guidance on loading specific items of equipment or systems. TB 55-45 is an authenticated source of information regarding military equipment certified for transport in Air Force and CRAF aircraft. It also helps as a reference for air movement planning and operations at all levels of command. TB 55-46-1 and -2 (microfiche) define vehicle dimensions and weights for all Army equipment in operational and reduced (shipping) configuration. All deployment planners should refer to these publications during unit deployment planning.

NOTE: In executing unit deployments, actual dimensions and weights must be used.

Follow the prescribed procedures for loading a particular item of equipment. If there are any problems, the loadmaster assigned to the aircraft is the final authority for solving them. Depending on the type of cargo or equipment to be loaded, there may be more than one single method to use. Some of the loading methods follow.

Direct Loading from Vehicles. A vehicle delivers cargo directly to the aircraft. The vehicle is positioned close to the aircraft ramp door, permitting direct transfer of the cargo from the vehicle to the aircraft cargo compartment.

Drive-in/Drive-off Method. The vehicle or prime mover is driven or backed under its own power into the aircraft cargo compartment. This method is generally the easiest for loading vehicles and is also used for vehicles with towed loads and for tractor-trailer units.

Towed Loads. Certain loads, such as trailers, must be towed or backed aboard the aircraft either by a prime mover or by manhandling. If the towed load remains with the prime mover aboard the aircraft, the trailer may or may not remain hitched to the prime mover inside the aircraft. To conserve space, the trailer may be uncoupled. In that case, the tongue is normally lowered on the aircraft floor under the prime mover and placed on parking shoring.

NOTE: Take care to ensure that proper shoring is placed under the tongue to prevent damage to the aircraft floor.

Pushed Loads. Some loads may be pushed aboard the aircraft either by manhandling or by a pusher vehicle. This method is particularly helpful in pushing large trailers aboard the aircraft because the driver can more easily control the operation. A pusher vehicle must be equipped with a pintle hook that is attached to the front bumper of the vehicle. Standard Army vehicles are not equipped with such devices. A unit may have to fabricate one, using scrap iron and a salvaged pintle hook. See Appendix D for more information on pusher vehicles.

Winched Loads. It may be necessary to winch wheeled or tracked vehicles and skid-mounted or palletized cargo into the aircraft cargo compartment. The winching method is particularly useful where cargo compartment clearances and ramp inclines are critical. The winch is also used to unload cargo or vehicles; it provides necessary restraint and control when the cargo is moved down the aircraft ramp.

Airdrop and Low Altitude Parachute Extraction System (LAPES). For information on LAPES, see FM 100-27.

Loads that Require Materials-Handling Equipment. Several devices are available to ensure rapid loading and unloading of aircraft. Common loading aids provided by the Air Force are the various K loaders (25K, 25K tactical [TAC], and 40K). The 25K loader can accommodate up to three 463L cargo pallets and can carry a maximum of 25,000 pounds. With front and rear extensions installed, the 25K TAC loader can accommodate up to five 463L cargo pallets and can carry a maximum of 25,000 pounds off hard surfaces and 35,000 pounds on hard surfaces. The 40K can accommodate up to five 463L cargo pallets and can carry a maximum of 40,000 pounds. All three are air- and surface-transportable. In addition to the K loaders, 6,000- and 10,000-pound capacity forklifts supplied by the deploying unit or DACG/TALCE can be used to handle single 463L pallets. See Appendix F for more information on MHE.

AUTOMATION

There are two automated systems available to the airload planner. They are the Automated Air Load Planning System (AALPS) and the Computer-Aided Load Manifesting System (CALM).

AALPS

AALPS is an Army-fielded automated airload planning system that supports deliberate planning and execution phases of air movement as well as force design and analysis. It is currently fielded as a prototype on the Sun 3/140 microcomputer. In FY 93, AALPS software will be converted to a hardware platform based on the 80386/80486 microprocessor and the Unix operating system. In FY 94, it will interface with the Transportation Coordinator-Automated Command and Control Information System (TC-ACCIS) and become a stand-alone module of TC-ACCIS.

AALPS applies to at least three levels of functional users: the unit movement officer (UMO), the deployment planner, and the contingency planner/force designer. AALPS provides "first cut" load plans and the ability to edit/modify those loads for actual deployment. AALPS supports the deployment planner, usually the division transportation officer (DTO), with estimates of airlift requirements for deployment lists and produces output such as load reports, graphic manifests, and force closure estimates. Contingency planners/force designers can determine airlift requirements for numerous force options or packages for any delivery method and configuration.

Final fielding of AALPS as a module of TC-ACCIS is scheduled for FY 94. Software may become available as early as FY 93. Consult the supporting installation transportation office (ITO) or DTO for current status.

CALM

CALM is an Air Force-fielded automated system used to load plan C-130, C-141, C-5, and KC-10 aircraft. The system uses interactive graphics to help the load planner produce and complete cargo manifests.

CALM is a hard disk-based system requiring a minimum of 2.5 megabytes of disk memory to store the entire program. An additional 2.5 megabytes of disk storage space is recommended to adequately utilize the capabilities of the system. CALM runs on IBM-compatible computers with a minimum of 640 kilobytes (KB) of random access memory (RAM), a CGA or EGA graphics card, a hard disk, one 5 1/4-inch floppy disk drive, and a standard IBM AT keyboard with 10 function keys.

CALM software can normally be obtained through the unit's ITO or DTO. It normally consists of five 5 1/4-inch floppy disks. An additional graphics package, Graphics System Software (GSS) IBM device drivers, Volume 11, is required to run the CALM program. CALM versions newer than 5.0 should no longer require a separate GSS driver system because of different graphics software technology.

Refer to AF Manual 28-346, Volume I/II, the end user manual for CALM, for further information. The Air Force Field Assistance Branch for CALM may be contacted at DSN 596-5771 or commercial (205) 416-5771.



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