MWAA is fully against increasing exceptions to perimeter rule and is lobbying hard against. Operations-wise, the airfield can certainly handle an increase in flights - there is plenty of slack time outside the rush hours to accommodate more flights. However, although the Project Journey renovations which revamped security screening and added the new pier for AA greatly increased "in-terminal" throughput, it did not actually do much for increasing the designed capacity of the buildings. The building is already 50% over its designed capacity which is taking a toll on the infrastructure.

But there is a bigger issue. The perimeter rule really exists to push much more traffic to Dulles. Increasing flights works directly against those aims.

Although the rule is officially based on "safety" - its aim is to increase safety by managing, reducing and preventing air traffic congestion - the real, and more important reason is the economics of IAD. MWAA has done a pretty good job in recent years to reduce its enplanement fees and be more economical. The land boondoggles underway will help also. But to get IAD where it needs to be it needs major increases in enplanements. IAD is still millions of enplanements below pre-pandemic levels and really, the goal is to be above 30 million as soon as it can.

And, in general, revenue from DCA cannot be used for IAD. Congress has allowed some relatively small amounts of transfer, but it has been in the very low 7 figures. and IAD needs revenue increases in mid 8 figures for decades to make a real dent. Chipping away, and chipping away, and chipping away at the limitations on DCA does not help.