I looked at the NTSB's preliminary report in detail, and one thing I noticed is that Fedex was basically directly above Southwest, at less than 100 feet AGL, at the time that they advised Southwest to abort. The "abort" radio call was at 0640:34, whereas the ground position tracks show Fedex directly on top of Southwest from 06:40:29 to 06:40:49 (and even another 10+ seconds after that, albeit gaining vertical separation).
I think the human factors analysis for this incident should be interesting. Fedex was clearly concerned that ATCs plan wouldn't work from the moment they heard Southwest get the clearance. However, Fedex was polite about it and basically asked ATC to reconsider their plan when they asked to confirm their own landing clearance only to have ATC double-down on a bad plan. There's a power dynamic at play between ATC and PIC. Even though the PIC has the ultimate say to take whatever action is necessary in the name of safety, you generally don't do that unless you know for sure that there's a problem. This kind of falls into a gray zone with "maybe this'll work". Does FedEx know whether the tower in Austin has ground radar and is actively monitoring Southwest? Does Southwest think that the tower is using ground radar and can see them?
I'd be shocked if at least one of the Southwest pilots wasn't at least a little concerned with the controller's plan when they heard that there was heavy traffic on a three mile final but they still accepted the takeoff clearance. Was it a case of get-there-itis? Did Southwest's FO think it would have been better to wait but didn't want to contradict the PIC accepting the takeoff clearance? Also, I don't doubt that Southwest was in fact ready-to-go, and that they got into position on the runway and started their engine run-up without delay. So ATC gave them a clearance that they were able to comply with, and they complied. There's a difference between being "able" to comply and whether they "should" comply. So it seems like nobody involved actually had the full picture of what's going on since ATC probably didn't know about the engine run-up required, and everybody else was deferring to ATC's position of authority or assuming that they knew things that they didn't.
Of course, the flip side is that pilots never have the full picture that ATC has, and you can't have pilots questioning every little ATC decision or the system would collapse -- ATC might have a very good reason for wanting to do things a certain way and shouldn't have to explain itself, especially during a time crunch. I hope that the final NTSB report dives into this and explores where that balance of questioning decisions made by people in authority should be.
It seems concerning to me that this incident involved four pilots and one ATC, and none of them changed the plan until after it was glaringly obvious that the plan wouldn't work. By that point, it was sheer luck that fatalities were avoided. The chain of events needed to be broken earlier one way or another, the question is how.
My other thoughts:
1) Even if an airport doesn't have a full blown ground radar system, would a camera on the end of the runway be helpful so that ATC can see whether a departing aircraft has started its roll during low visibility operations?
2) What this controller did needs to be specifically prohibited by some procedure, not just protecting the critical ILS zone. It was impossible to guarantee separation under those conditions. Somebody may have thought that it was obvious you shouldn't try to squeeze in a departure when you've got a 767 three miles final on a Cat III ILS approach and no ground radar, but it appears that this needs to be written down somewhere.
3) Why wasn't the parallel runway, which was fully servicable, not being used for departures instead of using 18L in mixed mode operations? I don't think that 18R had centerline lights so maybe that's why 18L was being requested for departures. So put centerline lights on 18R if needed and use it instead.
Last edited by notam232; 9th Mar 2023 at 21:15.