At a hub and in context of a 35 minute MCT, it is. Yes, I know what the contract of carriage says: domestic flights doors can close at T-15. But that is incompatible with a 30 or 35 minute MCT in a fleet increasingly comprised of large narrowbody aircraft. This is my point of contention.



So you believe the misconnect rate for tickets booked at MCT is less than 5%? Despite the fact that A14 performance was only 84%? Obviously there are instances where the connecting flight is delayed as well and the passenger makes it onto the flight, but a 5% misconnect rate at MCT is absolutely laughable. It would be relatively rare that someone makes a connecting flight at MCT when their inbound was even just 15 minutes late (the earliest possible arrival time for the 16% of delayed flights).

It would mean some combination of at least three of following has to be true: 1) ground ops was fast at getting the boarding door open [arrival time is when the parking brake it set]; 2) the passenger is at or near the front of the plane; 3) the boarding door on an on-time connecting flight was not closed until T-5 or later; 4) the inbound/outbound flight gates were in the same concourse; 5) the outbound flight was delayed

Delta's A0 performance is around 60-65%. So long as passengers are in the front half of the plane, I would expect the majority of those passengers to make their connections unless Delta closed the gate of the next flight right at T-15 (which is still rare, at least at Atlanta). But if you're in the back half of the plane, it gets riskier even for flights that achieve A0. The approximately 20% of flights that are A1-A14 will probably lead to misconnects more often than not for passengers in the back half of the plane unless Delta leaves the gate open for the outbound flight until at least T-5.

Delta's Atlanta MCT has been 35 minutes since E opened, and I believe that it was Delta's MCT back in 1990 even before E opened (but I can't find an explicit source for that)*. While domestic flights into/out of F are somewhat rare, it is common in E. During that same time, the average seats on a mainline Delta plane has gone up by 30-40% while average load factors have gone up from about 75% to around 90% (meaning longer deplaning times). And while I don't have access to Delta's internal data, it does appear there is a recent trend to push gate agents to close the boarding door earlier than they used to whenever possible.

Someone is paying a price for that, and most of it is being paid by consumers buying tickets that can reasonably be expected to lead to misconnects.

* best I could find was old flight tables from the early 90s where a quick skim didn't show any valid connections less than 35 minutes but I did not find an authoritative MCT document