Unit load device

thumb|Unloading LD3 containers from a [[Boeing 747]]

A unit load device (ULD) is a container used to load luggage, freight, and mail on wide-body aircraft and specific narrow-body aircraft. It allows preloading of cargo, provided the containerised load fits in the aircraft, enabling efficient planning of aircraft weight and balance and reduced labour and time in loading aircraft holds compared with 'bulk-loading' single items of cargo or luggage by hand. Each ULD has its own packing list or manifest so that its contents can be tracked. A loaded aircraft cargo pallet secured with a cargo net also forms a ULD, but its load must be gauged for size in addition to being weighed to ensure aircraft door and hold clearances.

The IATA publishes ULD regulations and notes there are 900,000 in service worth more than US$1 billion, averaging $ each.

Types

ULDs come in two forms: pallets and containers. ULD pallets are rugged sheets of aluminium with rims designed to lock onto cargo net lugs. ULD containers, also known as cans and pods, are closed containers often made of aluminium or a combination of aluminium (frame) and Lexan (walls) but there are examples of containers made of GRP with an insulating foam core. Depending on the nature of the goods to be transported, ULDs may have built-in refrigeration units. Examples of common ULDs and their specifics are listed below.

{| class="wikitable sortable"

|+ Lower hold containers volume in m3 (cu.ft), dimensions in mm (inches)

! rowspan=2 | Type

! rowspan=2 | Internal volume

! rowspan=2 | Height

! rowspan=2 | Depth

! colspan=3 | Width

! rowspan=2 | Contour

! rowspan=2 | IATA

! rowspan=2 | Suitability

! Base

! Overall

! Nominal

| LD3-45

| rowspan=9 |

| Full

| Double

| AKH

| Airbus A319/A320/A321

| LD2

| rowspan=15 |

| rowspan=3 | Half

| rowspan=3 | Single

| APE

| Boeing widebodies

| LD3

| rowspan=2 |

| AKE

| Airbus and Boeing widebodies, DC-10/MD-11, L-1011

| LD1

| AKC

| Boeing widebodies, MD-11

| LD4

| rowspan=2 |

| rowspan=12 | Full

| None

| AQP

| Boeing 767/777/787

| LD8 (2×LD2)

| rowspan= 3|

| Double

| AQF

| Boeing 767/787

| LD11

| rowspan=10 |

| rowspan=2 | None

| ALP

| Boeing 747, 777, 787, DC-10/MD-11

| PLA pallet

| PLA

| 747, 777, 787

| LD6 (2×LD3)

| rowspan=3 |

| rowspan=3 | Double

| ALF

| 747/777/787, DC-10/MD-11

| LD26 (P1P base)

| rowspan=5 |

| AAF

| Airbus A330, A340, A350, and Boeing 747/777/787, DC-10/MD-11

| LD7 winged pallet

| P1P

| 747, 777, 787, DC-10/MD-11

| LD7/P1P pallet

| rowspan=2 |

| rowspan=2 | None

| P1P

| All widebodies

| LD9 (P1P base)

| AAP

| Boeing widebodies, DC-10/MD-11

| LD29 (P1P base)

| rowspan=2 |

| rowspan=2 | Double

| AAU

| 747

| LD39 (P6P base)

| rowspan= 2 |

| AMU

| 747

| P6P pallet

| None

| P6P

| 747, 767, 777, 787, DC-10, MD-11

; Notes

center|Unit load device sizes|frame

Aircraft compatibility

thumb|Cross-section of an Airbus A300 showing LD3 containers

LD3s, LD6s, and LD11s will fit 787s, 777s, 747s, MD-11s, Il-86s, Il-96s, L-1011s and all Airbus wide-bodies. The 767 uses the smaller LD2s and LD8s because of its narrower fuselage. The less common LD1 is designed specifically for the 747, but LD3s are more commonly used in its place because of ubiquity (they have the same floor dimensions such that one LD3 takes the place of one LD1). LD3s with reduced height ( instead of ) can also be loaded on the Airbus A320 family. LD7 pallets will fit 787s, 777s, 747s, late model 767s (with larger doors), and Airbus wide-bodies.

Interchangeability of certain ULDs between LD3/6/11 aircraft and LD2/8 aircraft is possible when cargo needs to be quickly transferred to a connecting flight. Both LD2s and LD8s can be loaded in LD3/6/11 aircraft, but at the cost of using internal volume inefficiently (33 ft3 wasted per LD2). Only the LD3 of the LD3/6/11 family of ULDs can be loaded in a 767; it will occupy an entire row where two LD2s or one LD8 would otherwise have fit (90 ft3 wasted per LD3). Policies vary from airline to airline as to whether such transfers are allowed.

The 787, intended to replace the 767, was designed to use the LD3/6/11 family of ULDs to solve the wasted volume issue.

ULD capacity

{| class="wikitable sortable" style="text-align: center;"

|+ Widebodies

! rowspan=2 | Model !! colspan=3 | Lower deck !! colspan=3 | Main deck

! data-sort-type="number" | Containers !! data-sort-type="number" | 88×125″ !! data-sort-type="number" | 96×125″

! data-sort-type="number" | 96×125″ !! data-sort-type="number" | 88×125″ !! data-sort-type="number" | 88x108″

! Airbus A300-600

| LD3

| data-sort-value="4.10" | 4 + 10 LD3

| data-sort-value="4.10" | 4 + 10 LD3 || 20 || 21

| LD3

| data-sort-value="3.07" | 3 + 7 LD3

| data-sort-value="3.07" | 3 + 7 LD3 || 15 || 16 ||

! Airbus A330-2/800

| LD3 || || || || ||

! Airbus A330-3/900 ||

! Airbus A340-200

| LD3 || || || || ||

! Airbus A340-300

| LD3 || || || || ||

! Airbus A340-600

| LD3 || || || || ||

! Airbus A350F

| 40 LD3 || || 12 || 30 || ||

! Airbus A350-1000

| LD3 || || || || ||

! Boeing 747 classic

| data-sort-value="33" | || || || 28 || 28 || 36

! Boeing 747SP

| data-sort-value="35.2" |

| data-sort-value="9.044" | 9 + 4 LD1

| data-sort-value="9.022" | 9 + 2 LD1 || 30 || 30 ||

! Boeing 747-8/8F

| data-sort-value="44" | ||

| data-sort-value="12.022" | 12 + 2 LD1 || || ||

! Boeing 767-200

| data-sort-value="17.2" |

| data-sort-value="3.078" | 3 + 10 LD2

| data-sort-value="3.078" | 3 + 10 LD2 || || ||

! Boeing 767-300

| LD3

| data-sort-value="10.02" | + 2 LD3 || || 27 || ||

! Boeing 777-300 || ||

! Boeing 777-8F

| 40 LD3

| || 13

| 31 || ||

! Boeing 777-9

| LD3 ||

| data-sort-value="14.04" | + 4 LD3 || || ||

! Boeing 787-8

| LD3 ||

| data-sort-value="8.02" | + 2 LD3 || || ||

! Boeing 787-9

| LD3

| data-sort-value="5.08" | 5 + 8 LD3 || || || 22 || 30

! McDonnell Douglas MD-11

| LD3 ||

| data-sort-value="6.14" | 6 + 14 LD3 || 26 || 26 || 34

! Lockheed L-1011

| LD3

| data-sort-value="4.07" | 4 + 7 LD3 || || || ||

! Ilyushin Il-86/Il-96-300

| 16 LD3 || || || || ||

! Ilyushin Il-96M/T

| 32 LD3 || || || || ||

{| class="wikitable sortable" style="text-align: center;"

|+ Narrowbodies

! Model

! data-sort-type="number" | Containers !! data-sort-type="number" | 96×125″ !! data-sort-type="number" | 88×125″ !! data-sort-type="number" | 88x108″

! Airbus A319

| LD3-45 || || ||

! Airbus A320

| LD3-45 || || 11 ||

! Airbus A321

| LD3-45 || || 14

| no lower ULD || || 13 || 13

! Boeing 727-100C

| no lower ULD || || 8 || 8

! Boeing 737-200C

| no lower ULD || || 7 || 7

! Boeing 737-300SF

| no lower ULD || || 9 ||

! Boeing 737-400SF

| no lower ULD ||

| data-sort-value="10.5" | 10 ½ ||

! Boeing 737-700C

| no lower ULD ||

| data-sort-value="11.5" | 11 ½ ||

! Boeing 757-200F

| no lower ULD || || 15 ||

!Comac C919

| LD3-46

! Douglas DC-8-55F

| no lower ULD || || 13 ||

! Douglas DC-8-62/72F

| no lower ULD || || || 6

! Douglas DC-9-32F

| no lower ULD || 8 || 8 || 12

thumb|LD3 containers being loaded onto a [[Boeing 777-300ER.]]

Aircraft loads can consist of containers, pallets, or a mix of ULD types, depending on requirements. In some aircraft the two types must be mixed as some compartments take only specific ULDs.

Container capacity of an aircraft is measured in positions. Each half-width container (LD1/LD2/LD3) in the aircraft it was designed for occupies one position. Typically, each row in a cargo compartment consists of two positions. Therefore, a full-width container (LD6/LD8/LD11) will take two positions. An LD6 or an LD11 can occupy the space of two LD3s. An LD8 takes the space of two LD2s.

Aircraft pallet capacity is measured by how many PMC-type LD7s can be stored. These pallets occupy approximately three LD3 positions (two positions of one row and half of the two positions of the following row) or four LD2 positions. PMCs can only be loaded in cargo compartments with large doors designed to accept them (small door compartments are container-only).

thumb|An [[ATR 72 with its cargo door open]]

{| class="wikitable sortable" style="text-align: center;"

|+ Regional airliners

! Model

! LD3 !! 46×66” !! 88×54” !! 88×62” !! 88×108” !! 96×125”

| Fokker 100

| 11 || || || || ||

| CRJ200

| || || || 8 || ||

| BAe 146-200

| 9 || || || || 6 || 4

| ATR 72

| 7 || || || 9 || 5 ||

| ATR 42

| || 9 || || || ||

| Xian MA600

| 5 || || 5 || || ||

| Short 360

| 5 || || || || ||

| Cessna SkyCourier

| 3 || || || || ||

Identification

thumb|ULDs with their prefixes and serial numbers visible await loading at [[Melbourne Airport]]

All ULDs are identified by their ULD number. A three-letter prefix identifies its type and key characteristics, followed by a 4 or 5 digit serial number (4 if prior to October 1, 1993; either 4 or 5 if after October 1, 1993) to uniquely identify it from others of the same type, and ending with a two character (alpha-numerical) suffix identifying the ULD's owner (if an airline, often the same as IATA designator codes). For example, AKN 12345 DL means that the ULD is a forkliftable LD3 with the unique number 12345 and its owner is Delta Air Lines.

{| class="wikitable" style="text-align:left; font-size:85%;"

|+ IATA ULD prefix (overall width × height)

|- style="vertical-align:top;"

; Notes

Common prefixes

thumb|A string of LD3 containers with AKE prefix

thumb|An LD3-45 container with AKH prefix. An AKE prefix ULD is visible to the right.

AAA: LD7 container (), tall, contoured for maindeck narrow-body
AAD: LD7 container (), tall, contoured for maindeck wide-body (aka A1)
AAF: LD26 container
AAP: