（In case of a CAO labeled shipment, a Division 6.1 primary hazard with a Class 3 subrisk may or may not be visible and accessible.?）
When overpacking a substance having a Div 6.1 primary risk with a Class 3 subrisk, as per the 2nd bullet point of DGR 188.8.131.52.3 (c) this can be in the overpack and do not require to be visible or accessible. Furthermore, for cargo aircraft loading, as per the 2nd bullet point of DGR 184.108.40.206, the same substance do not need to be visible or accessible. Both 220.127.116.11.3 (c) and 18.104.22.168 state that Div. 6.1 with no subrisk, and Div. 6.1 with Class 3 subrisk need not to be visible or accessible.Despite these ICAO/IATA interpretation, USG-13 states, Div. 6.1 with a Class 3 subrisk must be visible and accessible which is completely different from ICAO/IATA. Please clarify which is correct? (30 Nov 13)
The US interpretation is in error. Currently, a revision process is going on, and shortly the US DOT PHMSA will be issuing a final rule to correct the error. IATA is waiting for the final rule, and will be issuing an Addendum to DGR 55 Edition. Div. 6.1 with no subrisk and Div. 6.1 with Class 3 subrisk are exempted from loading restrictions and do not require to be visible or accessible. Div. 6.1 with other subrisks must be visible and accessible.