Last week, a friend sent me an interesting Chicago Sun-Times piece about Southwest’s December on-time performance, which, according to FlightStats, was a whopping 55% during the month. Of course, parts of the month were affected by weather, but some of Southwest’s peers had over 80% of their flights arrive on-time (within 15 minutes of scheduled arrival).
What’s very interesting thing is that there is a big difference between Southwest’s and FlightStats’ numbers. In October – the latest month for which government data is available – Southwest’s on-time percentage reported in the DOT’s Air Travel Consumer Report was 77.9%, while FlightStats reported it at 65.5%.
Minor differences between the two sources is not all to surprising, but such a wide spread is. For comparison’s sake, United’s performance as reported by the DOT was 89.9% for October, while FlightStats reported 89.1%. That’s interesting because according the DOT Air Travel Consumer Report, Southwest and United both use ACARS for their reporting.
According to the article, Southwest and FlightStats are now trying to figure out what’s going on. But even looking at government data – there is some reason to wonder about Southwest’s performance. The airline ranked ninth of the airlines that report their DOT numbers in October 2009, while Southwest came was 17th in the same month in 2010. Meanwhile, Southwest’s on-time performance for October decreased year-over-year while it improved for all airlines that report overall. Poor on-time performance is certainly is worrying for a few reasons:
- Southwest’s recent focus on business travelers. The airline has focused more on business travelers lately, adding markets like LaGuardia and re-vamping its frequent flyer program to reward passengers who pay for higher fares. Southwest has a good sales pitch for business travel, but poor on-time performance hurts that.
- The addition of the 737-800. Southwest’s announcement that it would add the larger 737-800 to its fleet was certainly exciting, but has operational and scheduling implications. Logic would dictate that a 737-800 would take more time to turn between flights, so that requires scheduling adjustments, and probably some additional ground handling procedures.
- AirTran. Adding AirTran brings another fleet type, the 717, arguably adding more complexity to Southwest’s operation. Meanwhile, if something is off with Southwest at the moment, logic would dictate that only makes an acquisition more difficult.
Now, just for fun (really!), I decided to take a closer look at some of Southwest’s numbers. The DOT on-time database is quite comprehensive, and as a bonus its free! I decided to analyze Philadelphia as its one of those busier business markets that Southwest has entered over the past few years, and US Airways’ hub provides a nice basis for comparison. (Only US Airways mainline is included.) Plus, US Airways has been focusing on on-time performance over the past few years.
Before I get going – usual disclaimer on data-laden posts. My analysis, provided on an “as-is” basis, is based on DOT data. I am relying on the fact on that data being accurate (and who knows if that’s the case with this FlightStats situation). Also, there’s always the chance that I screwed up at some point. If anyone’s interested in how I calculated these results feel free to drop me a note. Anyway…

Photo Credit: Jay Bowie. Used with permission.
First off, Southwest’s on-time performance in Philadelphia did slip a little bit from 2009 to 2010, from 74.8% to 72.2%. So there was a bit of a decrease, but nothing huge. Despite the lack of a major change (based on DOT data), there are still some interesting results to look at. It appears that Philadelphia – for lack of a better word – “amplifies” Southwest delays. As you can see below, departures are, on average, more off-schedule than arrivals. (Any diversions, which have departure delay times, are excluded.)

Those departure delays get pretty lengthy at some points during the day, so here’s a comparison to US Airways mainline:

Now, none of US Airways’ results here have regional flights, so I decided to focus on one route – Philadelphia to Boston (only in that direction) for a specific apples-to-apples comparison. US Airways has had a stranglehold on the market for awhile, and Southwest shook things up last year. There are some Republic flights mixed in so I focused on weekdays to minimize those. For on-time performance percentages, this chart excludes cancellations and diversions. (For the DOT’s monthly reports, cancellations end up hurting on-time performance. I decided to exclude them here to get what I think is a better sense of operational performance on this specific route.)

Yeah, not that pretty. It seems that the source of most delays for Southwest are on the ground. In fact, more of Southwest’s arrivals and departures to/from Philadelphia are shorter than scheduled (form gate to gate) than US Airways flights. Such a result would indicate that Southwest’s schedule, at least in terms of flight duration, could be a bit more padded than US Airways.
Meanwhile, US Airways’ better performance could indicate its turnaround times are more indicative of reality, and that the airline runs a good operation at Philadelphia (rewarding employees for on-time performance helps in that area). So let’s just go with my guess that something’s off on the ground.
Are Southwest’s legendary short turn times still realistic? The carrier appears to be carrying more connecting passengers than before (a subject of a whole other post) – and anecdotal evidence suggests Southwest is more willing to hold flights for connections. The airline’s load factors are also high – Southwest’s flights were 80.4% full in December – that’s 10.7 percentage points higher than December 2008. These situations create new challenges that the airline must address, whether it be schedule adjustments, new ground handling procedures, or perhaps extra manpower.
Anyway, here’s hoping you found this at least slightly interesting! I think this is certainly worth further examination, especially when the DOT releases the November numbers later this month. At that point I’ll probably examine a few more airports.
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