The example of Figure 7.2.A is a shipment of 10L of Acetyl Iodide UN1898 which was transported surface to the airport as Surface LTD QTY therefore it bears the surface LTD QTY mark without the letter “Y”. From London, it was to be airlifted. The DG List in the DGR states, UN1898 max for LTD QTY is only 0.5L, and to ship 10L, you need a CAO package PI 855. Therefore the shipper’s authorized agent at London Airport repacked the shipment into a UN specification CAO packaging worthy to stand all the normal conditions of air carriage, i.e., pressure differential, temperature differential and vibration. This is why Figure 7.2.A shows all the needed markings and labels for an air shipment. I would personally say that the surface LTD QTY mark without the letter “Y” should be removed from the package for clarity.
If an Air LTD QTY provision is available for air carriage, the shipper or his agent must still repack the surface LTD QTY package into an Air LTD QTY package as there are particular air requirements that must be adhered to. Refer 18.104.22.168; 1.3.2 ‘e) and 22.214.171.124 all specifying air requirements which are different from surface transport. In this case, after repacking, the letter “Y” must be added to the mark meaning that the package is now good for air transport. The letter “Y” means that the package is good for air transportation. If there is no “Y”, it means the packages is not suitable for air transportation.
Caution must be exercised as there are cases like UN 0012 Cartridges, small arms where it has a surface LTD QTY provision but for air transport, LTD QTY is forbidden.