Unit load device: Difference between revisions

Revision as of 05:40, 24 July 2021

Revision as of 02:28, 18 August 2021

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{{short description|Pallet or container used to load luggage, freight, and mail on aircraft}}

[[Image:Unloading JAL 747.jpg|thumb|250px|Unloading LD3 containers from a [[Boeing 747]]]]

A '''unit load device''' ('''ULD''') is a [[Intermodal container|container]] used to load luggage, freight, and mail on [[wide-body aircraft]] and specific [[narrow-body aircraft]]. It allows preloading of cargo, confidence the containerised load will fit in the aircraft and 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 (transportation)|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&nbsp;billion, averaging ${{#expr:1000/0.9round-2}} each.<ref>{{cite web |url= https://www.iata.org/publications/store/Pages/uld-regulations.aspx |title= ULD Regulations |publisher= IATA}}</ref>

==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 made of aluminumaluminium or a combination of aluminumaluminium (frame) and [[Lexan]] (walls), which, depending on the nature of the goods to be transported, may have built-in [[refrigeration]] units. Examples of common ULDs and their specifics are listed below.

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[[Image:Airbus A300 cross section.jpg|thumb|Cross-section of an Airbus A300 showing LD3 containers]]

LD3s, LD6s, and LD11s will fit [[Boeing 787 Dreamliner|787]]s, [[Boeing 777|777]]s, [[Boeing 747|747]]s, [[McDonnell Douglas MD-11|MD-11]]s, [[Ilyushin Il-86|Il-86]]s, [[Ilyushin Il-96|Il-96]]s, [[Lockheed L-1011 TriStar|L-1011]]s and all [[Airbus]] wide-bodies. The [[Boeing 767|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 ({{convert|45|in|m|2|order=flip}} instead of {{convert|64|in|m|2|order=flip}}) can also be loaded on the [[Airbus A320 family]]. LD7 pallets will fit 787s, 777s, 747s, late model 767s (with thelarger big doordoors), 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&nbsp;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&nbsp;ft³ wasted per LD3). Policies vary from airline to airline as to whether such transfers are allowed.

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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 {{cvt|96 by 125|in|cm}} can be stored. These pallets occupy approximately three LD3 positions (it occupies 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).

[[File:FOIQRATR72.JPG|thumb|An [[ATR 72]] with its cargo door open]]