Pat- I've seen this before too, but the important thing to look for is the arrival time in NRT. There is a lot of extra time built into these schedules.
Also remember that the flight from NRT to MNL will be on the same plane as from DTW to NRT or JFK to NRT. The other plane goes to BKK, so if the plane is late from JFK, you still have a 50-50 chance you will be on the same plane to MNL and won't miss your connection.
Checking nwa.com, I see in this case the JFK-NRT plane went on to BKK, so you would have missed your connection.
[This message has been edited by Paul3456 (edited 09-29-2001).]