The funny thing about statistics is you can really manipulate them to say pretty much whatever you want. Airlines are certainly good at doing that when it comes to on-time performance. United says it was the best of the legacy carriers in February of this year. American says the same thing. Southwest can also lay claim to it. If you go beyond the legacies then Alaska and Hawaiian have legitimate claims as well. So who is right? It just depends on which set of numbers you think matters most.
To illustrate this, I dug into masFlight’s data, and narrowed it down to the big four airlines in the US (American, Delta, Southwest, and United). I included both mainline and regional numbers all lumped together. This makes it easy to compare, but I must apologize to Alaska. Their numbers were so good, it skewed the graphs and made it harder to illustrate my point clearly. I’ll get back to them later, but kudos to them for absolutely crushing it.
Let’s start with American’s favorite metric, D0. As far as American is concerned, the best way to run an on-time operation is to get those airplanes off the gate at or before scheduled departure time. And sure enough, American is very good at that.
You’ve probably cursed American for leaving the gate just as you ran, out of breath, from your late connecting flight. But in general, American is right. The best way to keep an airline running on time is to leave on time. But if that’s the case, then why does this next metric look so different?
This is arrivals exactly on time (or earlier), A0.
The chart has completely flipped. And if we look at the metric the Department of Transportation uses (arrivals within 14 minutes), it’s even more pronounced.
Now all of a sudden, American has the worst performance of the big four while Southwest has the best. What the heck is going on here?
Well, this illustrates the time-honored tradition of airlines padding their block times. See, airlines have to figure out how long to schedule a flight. If you say a flight from LA to San Francisco is going to take 8 hours, chances are you will always arrive before schedule, even with those horrible SFO delays. The downside for an airline is that to schedule a 1 hour flight to take 8 hours, you have to then commit an airplane to that lengthy time. You have to staff for that, and it just makes for a hugely inefficient operation.
Of course, nobody is actually scheduling flights with that extreme amount of padding, but different airlines have different strategies. If your block times are too tight, you won’t run enough flights on time. If they’re too long, you’ll run an expensive and inefficient operation.
So what’s the best way to do this? Well let’s take a look at one of my favorite metrics, B0. This shows the percentage of flights that operated within their scheduled block times in February. Let’s be very clear about what this means first.
Delta has a flight from LA to SFO that is scheduled to leave at 12p and arrive at 132p. That means its scheduled block time is 1 hour and 32 minutes. If the flight leaves at 12p and arrives at or before 132p, then it will have operated within scheduled block time. But what if it’s delayed an hour and doesn’t leave until 1p? Well then, as long as it arrives by 232p, it will have still operated within the scheduled 1 hour and 32 minute block time. Departure and arrival time doesn’t really matter. It’s just looking at the duration. Make sense?
So this chart shows the percent of flights that operated within that scheduled block time.
What does it tell us? Exactly what you’d expect. American is completing just shy of 70 percent of its flights within the scheduled block time. That means American is running a leaner operation and is trying to keep block times tight. For it to run like this and still have more than 80 percent of flights arrive within 14 minutes of schedule is impressive. Yet it still does make you wonder if American could use a little more padding in there.
At the other end, look at what Southwest is doing. It’s operating more than 80 percent of flights within scheduled block. That means the airline is likely being very conservative and is running a less efficient operation. If you’re a passenger, you might not care. But financially and operationally, it’s not where you want to be.
Now, this is a pretty basic look, but there were a lot of other observations from playing with this data. So…
- Remember I said Alaska was amazing? It had a better D0 than any of the big 4 at 77.2 percent (mainline was over 80 percent!), and a better A14 as well at 90.7 percent. It did all this with a B0 of 71.7 percent. That is THE operation to emulate.
- Last time I wrote about United, I found out that it calculates its push back times differently. For most airlines, the clock starts when the brakes are released on the airplane at the gate. But United doesn’t start the clock until the airplane actually starts moving backwards. What does that mean? If it used brake-release time like everyone else, its D0 would be higher, and its B0 would be lower. By how much, I don’t know.
- American and Delta push their mainline and express flights at roughly the same rate (within a couple points), but not United. United had a mainline D0 of only 64.5 percent yet a regional D0 of 73.2 percent. At the same time, United mainline arrived within 14 minutes of schedule 87.3 percent of the time while Express was only at 82.1 percent. You all know why. United is padding the heck out of mainline with a B0 of 86.8 percent. Express, however, has a B0 of only 71.6 percent.
- Neither Spirit nor Allegiant could get even half of their airplanes off the gate on time. Allegiant didn’t even get 60 percent of flights to the gate within 14 minutes of schedule while Spirit made it to 65 percent. They also had the tightest block performance with B0 at 49.66 and 62.95 percent respectively.
- Frontier, on the other hand, got 77 percent of flights out on time with 88.8 percent arriving within 14 minutes. The B0? An extremely high 85 percent. They’re buying on-time performance with longer blocks. That’s ok if it’s temporary while they get their house in order, but it’s probably not sustainable in the long run for an ultra low cost carrier.
- JetBlue did not do well. It had 53 percent of flights leave on time and just over 70 percent arriving within 14 minutes of schedule. But it had a B0 equal to American so it’s trying to run a more efficient operation. That’s not easy to do in the northeast.
