Originally Posted by
Stripe
I agree but I'd recommend a longer layover in ORD. MCT from AA to AY is 1:15, so you're in theory OK but a bit of weather on the east coast or in ORD will make that seem very short. In addition, you'll need to make the transfer from terminal 3 to terminal 5, which you can do via an airside bus now. DCA-ORD flights are fairly frequent so you should be able to find something with more breathing room but well under the 8 hours you're looking at in JFK.
May is probably one of the months least likely to experience major weather disruption -- no snow and before T-storm season. If there is a misconnect, OP can still probably get to TYO on time by going direct from ORD, they'd just miss the HEL stopover (they could maybe schedule that on the return instead). And if for some reason there's bad weather in ORD, they could always try for DCA-LGA/JFK-HEL-ORD as a backup. Or maybe even day-of IRROPs would let them do DCA-JFK on DL.