Especially in this specific situation! It's a five-hour drive to Louisville from Chicago. United should have chartered a van for the employees and driven them there.
Can you imagine going to home depot and someone pulling drills out of your hands and giving them to employees?
What you're describing is a race condition, to use the term from real-time software. By updating faster, you reduce the timing window, but the problem can still happen - the passengers are all in the jetway, but the 4 crewmembers are in the employee lounge and just a 3 minute walk from the gate. They can still make the flight before all the passengers are out of the jetway...
In that case, I'm saying there would only be up to 66 (not 70) paying customers in the jetway. This still leaves 4 available seats for the deadheading United employees.
In other words, don't render those 4 extra United employees "invisible" to the reservation system only to later make them "visible" when they finally show up at the gate after all 70 passengers are already in their seats. United knew they needed those 4 employees in Kentucky hours before customers boarded #3411 in Chicago. The issue is that they had zero empty seats on that flight so they had to bribe/force 4 "volunteers" to give up their seats.
If United's computer system doesn't have enough sophistication to set aside plane seats for employees that have higher priority than paying customers, they deserved to have the situation escalate into a Mexican standoff between the gate agent, the seated customer, and the Chicago police.
If you're talking about a rare emergency circumstance where United's operations center doesn't know they need those 4 seats for employees until after all customers are boarded, yes that can still happen. However, that wasn't the case for flight #3411. The 4 employees were "running late" to appear at #3411's gate. This means they were not a "hot standby" crew at the airport's lounge. Instead, it meant that these employees were are either on an incoming flight or were stuck in traffic driving to the airport from home/hotel. Either way, United had plenty of time to reserve 4 seats on #3411 for their higher-priority employees but for whatever reason, they didn't do it.
All 70 passengers are in the jetway or on the plane. Say, 40 are on the plane, but 30 are still in the jetway. At that moment, United discovers that it needs 4 crewmembers on that plane. They have 4 crewmembers sitting around in a crew lounge in that terminal of the airport. They can walk to the gate in 3 minutes. 3 minutes from now, some of the passengers will still be in the jetway, waiting to board the plane. Now what?
It's not enough to just improve the computer system. The timing window still exists, even if it's smaller. What you need to fix this is some kind of business rule, like "You can't deny boarding to a passenger who's already in the jetway, no matter how badly you need their place for a crewmember".
I realize that "overbook" can mean different things but United flight #3411 wasn't oversold to statistically offset no-shows. Instead, the plane had a capacity of 70 seats[1] and United sold all 70 seats to paying customers with zero cancellations. That's a perfect economic situation for United.
What went wrong was 4 extra United employees needed a last-minute ride on that plane to Kentucky. Since this is an HN audience, I guess we could frame it as a massive failure in the "information flow" through their computer reservations system.
The very second that United knew they had 4 employees they had to acccomodate, their computer system should have immediately confirmed those 4 employees on flight #3411 first such that the plane only shows 66 available seats instead of 70. (Computers doing math for the win!) That way, either 4 of the customers get denied a boarding pass at the check-in kiosk, or they get denied at the gate that scans the barcode before they enter the jetway. Instead, United let all 70 passengers board and settle in their seats.
If United insists that their employees take precedence over paying passengers, their damn computer systems need to reflect that reality in the seating database!
All of those opportunities to have the computer system "help" were missed that would have prevented the situation from escalating to a bloody face plastered all over the news.
[1] https://www.seatguru.com/airlines/United_Airlines/United_Air...