Pallets and containers in the previous posts exist mainly on the surface, sea or land. In the air, ISO containers represent a 4 tonne weight overhead and conventional pallets cause all sorts of problems because it is rather difficult to get a fork lift truck through the skin of an aircraft!.
So for air transport, where different constraints and rules apply, pallets and containers have developed on their own path, pretty much unconnected with intermodal container and the familiar wood NATO/Euro pallet.
Moving stores with aircraft is expensive, of course, but where speed is needed or alternative means are hazardous or compromised in some way, there is no other option.
And so, specialist devices and techniques are used.
The two main systems in use are the 463L pallet and Unit Load Device or ULD.
The first is military and the second, civilian. Of course, there are always crossovers and grey areas but in general, the 463L pallet system is mostly used in a military context. Unlike the pallets and containers in the previous parts of the series, where military and civilian systems have converged, in the air transport world, the two are still very much apart.
To provide some scale for the number of pallet movements this parliamentary question does provide some useful context. It was tabled by Angus Robertson of the SNP, enquiring about moving supplies to Afghanistan by air and the difference between the RAF and chartered civilian aircraft.
Angus Robertson (Moray, Scottish National Party)
To ask the Secretary of State for Defence what estimate he has made of the (a) number of pallets, (b) tonnage of supplies and (c) number of flights to Afghanistan taken by (i) RAF transport and (ii) leased transport aircraft in each of the last six years.
Peter Luff (Parliamentary Under Secretary of State (Defence Equipment, Support and Technology), Defence; Mid Worcestershire, Conservative)
The Ministry of Defence (MOD) does not lease aircraft, ie rent them to be flown by MOD pilots, but rather charters with private companies to fly on the MOD’s behalf. The number of pallets, weight of supplies (in tonnes) and number of flights taken by RAF and civilian chartered aircraft to Afghanistan over the last six calendar years are as follows:
|RAF Aircraft||Civilian Leased Aircraft|
|Number of pallets||Weight of supplies (in tonnes)||Number of flights||Number of pallets||Weight of supplies (in tonnes)||Number of flights|
Digging those figures a little more deeply
- In the 5 years shown, the RAF averaged just under 14 tonnes and 6 pallets per flight with civilian charters, 30 and 13 respectively.
- The split between the RAF and civilian charters was roughly 50:50
- Both the number of pallets per flight and tonnes per flight have on average declined year on year for both
It is very difficult to draw any meaningful conclusions, the RAF has a more people focussed mission as only aircraft fitted with DAS can carry personnel, outsize cargo might not weigh much and not be palletised or the RAF is concentrating on tactical delivery in a hub and spoke arrangement in theatre.
Despite this, the pallet count is interesting in the scope of this series of posts, although the answer did not specify what a ‘pallet’ actually was!
The 463L Materials Handling Support System
The 463L is a military load carriage system that comprises pallets, netting, bags and material handling equipment specifically for the carriage of stores on tactical transport aircraft. It came into service with the United States Air Force (USAF) in April 1963.
The 463L pallet (also known as the HCU-6/E) is the main component of the 463L Materials Handling Support System.
The pallet and handling systems are designed with rolling in mind, a Euro pallet is lifted and shifted, a 463L is rolled. Constructed balsa wood with an aluminium skin the 463L is 88″ by 108″ and 2.25″ thick, inches not metres. An empty pallet weighs 290 lbs (131kg) or 355 lbs (161kg) with the net fitted which also needs a couple of inches space around the pallet edges to secure.
Each pallet can carry up to 10,000 lbs or about 4.5 tonnes.
Using the 463L system can reduce loading and unloading times by in excess of 75%, it was a significant improvement on previous methods.
Both top and bottom surfaces of the pallet are smooth in order to facilitate rolling and loading.
Cargo nets and slings are used to secure the material to the pallet.
To carry loads that exceed the dimensions of a single pallet multiple pallets can be ‘married’ together using spacers.
Modern 463L pallets no longer use the balsa wood core and instead use a series of aluminium extrusions bonded together but they still use a smooth aluminium sheets to form the top and bottom surfaces, the result is longer life and increased rigidity.
In February 2014, the MoD let an £8.3 million 4 year contract to AAR for the supply of 463L 4.5 tonne capacity Air Cargo Pallets, like I said, they are not cheap, about £2,000 each. The MoD has also used 463L pallets from Airborne Systems
The A400M can carry 9 463L pallets, 7 on the main cargo deck and two on the ramp, all whilst keeping 54 seats available for personnel. Recognising the problems with the C130J cargo area winch and Dash 4a Cargo Handling System the RAF, and others, formed the Cargo and Aerial Delivery Working Group (CADWG) to make sure that expert advice was incorporated into the design from the very start. This approach has reportedly been very successful with a number of critical design issues corrected before production, the floor tie down grid for example. Other reports are less complementary about the A400M cargo floor, especially in comparison with the C17, which is apparently the gold standard. Hopefully, the A400M will provide a big improvement over current aircraft. As regular TD readers will know, I am very enthusiastic about the A400M but recognise any new system will always have teething troubles to be resolved.
Although not all of the UK’s A400M’s will be fitted with the 5 tonne crane to enable off loading at locations without suitable air cargo handling equipment all of them will have a reinforced floor (just over 9 tonnes per linear meter) to enable carriage of heavy vehicles, specifically the Terrier armoured engineering vehicle.
The floor system will also have pop up rails and electrically operated pallet locks.
The nets used with 463L pallets might look slightly overkill but they are rated at 9G and have to ensure loads are secured at a range of aircraft attitudes, the consequences of load shift during flight can be catastrophic.
Aircraft like the A400M and C17 are actually volumetrically inefficient when it comes to pallet carriage, look at any image of a C17, Hercules or similar military aircraft carrying pallets and you will see a massive amount of free space, fresh air, or indeed, wasted space.
As can be seen from the images above, the 463L can be ‘floor stacked’ or loaded with other conventional pallets and containers. Putting a pallet on top of another pallet might not seem particularly efficient but it does work.
VRR also make a VIP comfort shelter based on the 463L footprint
There are also a number of specialist containers based on the 463L dimensions, everything from dog kennels to all terrain vehicle containers.
It must also be noted that the 463L pallet is not used beyond the aircraft domain, it is not an intermodal system. 463L pallets are not transferred from aircraft to trucks because mechanical handling equipment used in the land domain, ISO containers and vehicle load beds are fundamentally ill suited to the 463L.
I also like this neat solution from FLS;
Although technically they can be used beyond the airhead or Air Port of Disembarkation (APOD) they rarely are due to cost and convenience, in service land mechanical handling equipment like the JCB Telehandlers cannot lift 463L pallets because roller fork attachments are not issued as standard.
This brings me on to the subject of pallet handling for 463L’s.
463L Pallet Handling and Storage
The 463L is designed for ease of handling but only with the correct equipment.
For locations with no mechanical handling equipment many aircraft are fitted with integral cranes and winches that can be used to manipulate pallets but this is slow. Lifting equipment like cranes and hydraulic jibs can also be used although again, this is slow and inefficient.
Other than this there are two equipment types, roller forklift extensions and specialist loaders.
Forklift Roller Tine Extensions
This simple device slides over a a fork lift which provides a powered or unpowered roller bearing onto which pallets can be moved
They are lifted from their racks or staging and moved to the aircraft. After lining up with the aircraft cargo bed the pallet is slid off the rollers and on pushed onto the aircraft.
Using a set of these the in service JCB Telehandler 4,000kg could quite easily place a 463L pallet onto or off the cargo deck of an A400, c130 or C17 although it might struggle at maximum outreach. The RAF purchased 27 Telehandler 525-50’s in 2002.
Also in service is the 7.2 tonne lift Dan Truck 9680D Counterbalance Fork Lift Truck, 22 of.
A few videos to illustrate the loading and unloading process using fork lift trucks
As can be seen from the videos, forklift rollers are not absolutely necessary for handling 463L pallets but they make it much easier.
The forklift tines fit between the rollers on the aircrafts ramp.
This method means that ramp loading capacity needs to be taken into consideration because not all cargo aircraft ramps can take the same loads as the main cargo deck (C130 ramp limit is about 2 tonnes), although supports can be used in some cases to alleviate this problem, like axle stands.
Because the pallets are on rollers the objective is to ensure that the aircraft and pallet remain aligned and flat.
The Dyneema Lightweight Pallet Net saves weight, and fuel.
For higher speed loading and unloading there are specialist items of equipment available that can deal with multiple pallets, vehicles and outsize items in addition to 463L or civilian pallets and containers.
The Atlas K Loader for example can lift up to 20 tonnes and they can operate inline if more than one is available. The only problem with these very useful devices is they need a firm, flat and stable surface. They are also designed to be air portable, weighing in at about 11 tonnes.
The RAF purchased two new Atlas K loaders a few years ago and modified the existing ones for use in Afghanistan.
Also in service with the RAF at Brize Norton are four Trepel Champ aircraft loaders.
The final piece of specialist equipment for handling aircraft pallets is how they are stored and organised at an air head.
The Air Portable Cargo Handling Dock (caled the Anthony Allen dock), also from AMSS, is in service with the RAF
A complete system of 5 sections and 3 walkways weighs 2.47 tonnes and disassembles to fit on a standard 463L pallet.
The UK company Ban-Air provides many organisations with its 463L pallet storage and organisation system called the Air Pallet Rack
Unit Load Device
The term Unit Load Device is a catch all for a collection of pallets and containers used in the civilian air freight business. There is a great deal more variety in dimensions and configurations than with the 463L system as they are often designed to be aircraft specific in order to absolutely maximise volume efficiency.
Lower deck, main deck containers and pallets will also have different characteristics.
The most common ones are below;
Boeing have a good guide to ULD’s, click here
The RAF’s Voyager and BAE 146 aircraft are able to utilise ULD type containers and pallets;
The RAF’s A400M’s will not be configured for civilian pallets, this option was deleted to save money some time ago and the Voyager, without the main deck cargo door and floor will be unable to be used in the mixed or cargo role as other A330 MRTT users are able to.
ULD’s are loaded and unloaded using much the same equipment as above.
The rest of the series…