Happy 2024 everybody! If you flew this holiday season, you probably had nothing go wrong at all. That was the case for nearly everyone… except for those who flew Southwest to and from Chicago’s Midway Airport just before Christmas. I’ve seen some reports call this a meltdown. That’s laughable. But what went wrong is actually a very interesting story.
Looking at Anuvu data for December 16 through December 26 to cover the Christmas ramp-up, no airline but Southwest canceled more than 1 percent of flights. JetBlue and Spirit hovered around having 65 percent of flights arrive within 14 minutes of schedule (pretty good for JetBlue), but no other airline was below 75 percent. The big three were all above 80 percent. It was a good time.
Southwest, however, had more cancellations, so let’s unpack that by day.
Southwest Operational Performance Late December 2023
As you can see, Southwest was running a spectacular operation up until December 23, and that’s when things got ugly for three days. The airline canceled 134 flights on the 23rd, 299 on the 24th, and 110 on the 25th.
The problem child here was Chicago. On the early evening of the 23rd, dense fog settled in over the Chicagoland area. It was so dense that visibility was below minimums for safe operations at Midway, and Southwest had no choice but to take action. It first diverted the airplanes that were on their way before the fog settled. Then it canceled the rest of the day plus the early morning departures the next day. On the 23rd, 128 of the 134 systemwide cancellations touched Midway.
The next morning, the fog was still there, but the forecast was for it to lift by mid-morning. The Terminal Area Forecast (TAF) put out by the National Weather Service (NWS) at 3am CT on the 24th said that fog would remain until 9am and then it would lift. But the weather improved more rapidly than that. A look at the reported conditions (METAR/SPECI) for Midway that day shows that at 4:53am, fog had lifted and visibility was up to 2 miles. By 5:01am it was up to 6 miles, and then just before 6am it was still at 4 miles.
As I understand it, Southwest was hesitant to believe this, but after consulting with the NWS, it decided that the forecast was good enough that it could send flights toward Midway again. Oops.
By 6:30am, the fog was back with a vengeance and visibility was less than 1/2 mile. On top of that an overcast settled in at 200 feet. That overcast didn’t get above 300 feet until the 11:16am METAR which means it went a lot longer than planned. Those airplanes that headed toward Midway ended up diverting.
That day, Southwest canceled 299 flights but only 181 touched Midway. The rest were mostly downline impacts where those airplanes were supposed to go. This did cause a jam up at Midway, however. Airplanes eventually made their way in, but there weren’t enough gates. Usually, the taxi-in time at Midway for Southwest is around 7 minutes. On the 24th, the average for the day was just over 59 minutes.
The weather ended up being fine after that, but Southwest had to play catch-up. Would it be able to fix the operation or would this end like the last holiday season where it truly melted down and fell apart for days on end? In this case, it was the former.
On Christmas Day, there were only 8 cancels at Midway. The total of 110 cancels was residual damage from the day before, but the airline rebounded to operating 77 percent of the flights that did fly on schedule that day. By the 26th, only 4 flights were canceled through the entire system, though on-time performance has lagged somewhat and didn’t climb back above 70 percent again until the 28th.
This wasn’t a meltdown by any stretch. While I’m sure some things could have been handled better with hindsight, there was a real, safety-related disruption that Southwest couldn’t avoid. Midway is a huge station for the airline, and almost nobody else flies there. But over at O’Hare, the weather was marginally better. Why wasn’t there as much of an impact there?
The problem is that while O’Hare has multiple runways set up for Cat III landings using the Instrument Landing System (ILS), Midway’s best runways have only Cat I capability. What the heck does that mean?
The ILS allows airlines to make approaches with limited visibility. How “limited” the visibility can be depends upon a variety of factors Airports, aircraft, and crews all need to be approved to use each category of ILS, or it can’t be done.
The three categories — I, II, and III (subsets A, B, and C) — have different rules based on decision height and runway visual range (RVR). The decision height is the altitude at which the decision to land has to be made based on ability to see the runway. The RVR is how far a pilot on the center line of a runway can see the runway markings. Here are the basic FAA rules on each category:
- Cat I – Decision Height >200 feet, RVR >2,400 feet
- Cat II – Decision Height >100 feet, RVR > 1,200 feet
- Cat IIIa – Decision Height n/a, RVR > 700 feet
- Cat IIIb – Decision Height n/a, RVR > 150 feet
- Cat IIIc – Decision Height n/a, RVR n/a
The thing is, as I understand it those numbers will vary by airline, aircraft, etc. It can also vary by runway depending upon equipment. Frankly, I got far down this rabbit hole and then gave up. The point being, I believe Southwest’s minimum RVR at Midway is 3,000 feet, and it was below that for much of this time.
Meanwhile at O’Hare, Southwest can go down to an RVR of 600 feet, because O’Hare has runways with Cat II/Cat III capability. So why doesn’t Midway have that?
The big issue here is that Cat II and Cat III have requirements for runway approach lighting to enable low visibility approaches. And Midway just isn’t physically able to comply. Why not? Have you seen Midway?
Midway is a very old airport that is completely hemmed in by roads and neighborhoods. They were able to realign Cicero on the east and put some of the terminal on the east side, but the runways are where they are. And there isn’t room to put all of the required lights. Or shall I say, the Federal Aviation Administration (FAA) doesn’t have the appetite to do so because of what’s involved.
Here’s how the FAA explained it to me:
Establishing CAT II / CAT III approaches requires specialized equipment and clear areas that would call for significant land acquisition deep into residential neighborhoods and commercial areas around Midway Airport.
That’s understandable. And the reality is that this kind of dense fog that requires Cat II/III landings doesn’t happen all that often. I can’t imagine it being worth the disruption to the lives of residents and the expense. So when it just happens to fall right before Christmas, we just have to deal with it.
I realize this has been a very deep dive, but the point is that Southwest was impacted by something that almost no other airline faced. As usual, weather caused trouble, but this time, Southwest recovered just fine. While I’m sure there will be learnings from this that could have helped reduce cancellations and delays, the end result wasn’t bad at all, especially compared to what happened last year.