Same flight, different cabin availability.
 

Doing a search for RN seats for IAD-HKG flight departing on 9/18 and getting different cabin availability for the same flights (ORD-HKG); changing based on connections.

First flight got this: Available Cabins: F8, FN8, A7, ON4, O0, J9, JN8, C9, D9, Z8, ZN8, P8, PN8, R3, RN3, IN0, I0, Y9, YN9, B9, M9, E9, U9, H9, HN9, Q9, V9, W9, S9, T9, L9, K9, G0, N0, XN9, X9

Second flight got this: Available Cabins: F8, FN8, A7, ON4, O0, J9, JN9, C9, D9, Z9, ZN9, P9, PN9, R0, RN0, IN0, I0, Y9, YN9, B9, M9, E9, U9, H9, HN9, Q9, V9, W9, S9, T9, L9, K9, G0, N0, XN9, X9

Both are for the same flight UA895 ORD-HKG but with different connection from WAS, can someone explain the difference?

Thanks.

The system shows the least possible inventory across all flights for a connecting itinerary.

Yes, and there are other numerous threads on this - when searching for flights, availability for all connections will show based on the lowest amount available for all flights. So the flight from IAD on the first connection has different availability, and based on that, it looks different for 895. Once booked, it will show the segments availability seperately when looking at your itin. To see true availability for 895, you'll need to do a search for ORD-HKG.

Good suggestion. Thanks.