[rflrob]

Seeing other comments fault the Southwest pilot for not starting faster, but it’s not obvious to me that there was any significant delay—a few seconds at most between lining up and starting the roll down the runway. The diagram isn’t to scale, so it’s hard to tell. I wonder how much faster an expedited departure could have been.

[awiesenhofer]

From TFA: "Time 1:54, Tower: “Southwest 708, confirm on the roll?” Note that this comes 34 seconds after the previous transmission, and nearly a minute after the tower cleared Southwest for takeoff. In that minute, the FedEx plane has covered most of the distance to the airport. Presumably the visibility is so bad that the tower can’t even see the Southwest plane sitting on the runway. So the tower controller is asking: Hey, are you moving? Southwest immediately replies, “rolling now.” Investigators will also want to find out what the Southwest crew was doing through this time, in the minute after saying “we’re ready” and while knowing that another plane was about to land."

[vezuchyy]

They have their checklists and everything, it's not an unusual case when the plane goes to a runway and stops for a few seconds. Again, as an ATC, if you need a passenger plane to get out as fast as possible - be clear about it or don't clear them to the runway. It was also a Fedex pilot who figured what's about to happen by themselves.

[cameldrv]

Yes. The controller should have said "no delay" along with the takeoff clearance, but also given the extremely poor visibility (they couldn't even see 1/4 of the way down the runway), it shouldn't be surprising when a plane takes a few seconds longer on the runway to get situated and double check a few things.

[jnsaff2]

Southwest had clearance. So they are clear, you can't rush take-off or anything. They could have been more mindful of what is around them and refused to line up if 3 miles felt like too rushed.

Why are overlapping clearances allowed (and used) by rules, regulations and local operating procedures DURING CAT III operations, is beyond me.

I don't like overlapping clearances in normal times but during CAT III operations this is insane.