Air China interline policy

[fone]

Like to check if anyone knows the official policy for Air China interlining agreements / policy with UA.

My dad has already flown the a SIN - PEK - NRT on Air China and continuing immediately on NRT - IAD on UA. Air China at SIN claims they are unable to through check the bags all the way to IAD. Resulting in him needing to clear immigration, collect the bags, then re-check and re-clear immigration at NRT, which he claims to be very tight/rushed with the huge volume of passengers.

Like to check if there is an official policy that Air China is unable to through check the bags (boarding passes can be obtained at the transfer desks) or are the counters just not well trained (or refusing to do more work).

[CarbonMan]

I've always thought that the luggage and the person are treated differently. The former can be checked through, while the latter may not. The process you described sounds crazy - it happens in the US when changing to a domestic flight on arrival, even then the bag is labelled as checked thru. But I'm sure the more experienced will give a rational answer.

[fone]

Yup, that's why I'm asking about the interlining policy and not the boarding pass, which should be obtainable at transfer desk.