A bit OT, but what's up with flight numbers for MSP-SEA on DL? They are, in order,
1653
1453
1753
2153
2253
41
1953
Except for 41 (which a 'continuation' of LHR-MSP), they are all XX53, not really in order and missing a few numbers. It's a rather interesting way of grouping them, and I also haven't noticed this on any other city pair that I've looked at.