Why Comair's On-Time Performance is More Concerning Than Atlantic Southeast's

(MoneyWatch)  This isn't a new theme, but once again in July Delta's regional operators Comair and Atlantic Southeast (ASA) had horrendous operations. Let's take a look at what's going on.

In the on-time derby, ASA can be proud - they weren't as bad as Comair. Comair had the worst performance of the month with 63.6 percent of flights arriving within 15 minutes of schedule. ASA, however, shouldn't brag. They were next to last with 68.3 percent. AirTran's 69.8 percent was the only other carrier under 70 percent.

As you can imagine, seeing those three at the bottom must mean that something was going on in Atlanta. And that's true. July was an average month for precipitation, but it was a stormy month. Of the 31 days, 9 of them had thunderstorms, and that's bound to mess things up. So let's look at Atlanta specifically.

In Atlanta, ASA ran a 67.2 percent on-time number while Comair had a dreadful 49.9 percent. Pinnacle, which has a larger operation at Atlanta than Comair for Delta, had 68.2 percent of flights arriving on time while Delta itself had 76 percent. It's normal for the mainline operation to have a better on-time record than regionals since the mainline carrier will usually take priority, but Comair was just downright awful.

ASA showed it can run a good operation. Its Cincinnati flying achieved an 88.6 percent on-time performance while Comair suffered through 74.1 percent. That may have been good were it in Atlanta, but it's just terrible for Cincinnati. And at JFK, Comair came in at the rear once again with only 58.7 percent on-time. Nobody else was below 65 percent.

Of the 24 flights that were delayed more than 80 percent of the time during the month, 7 of them were operated by Comair with only one operated by ASA. And Comair's problem was really spread out. Some problems were in Atlanta, but others were at JFK, LaGuardia, and Newark. ASA's problems seemed to really be focused on Atlanta.

What caused all these delays? Well, here's a chart:

As you can see, Comair canceled a shockingly high number of flights - more than 5 percent, in fact. Comair also saw a couple percentage points more in Air Carrier Delays. To their credit, they by far had more extreme weather delays than anyone else - more than 4 percent of flights - and there's nothing they can do about that. They also had a very high 14 percent of flights delayed due to the national aviation system. (That means that it's related to the stuff you see on fly.faa.gov.) ASA, on the other hand, had a much higher percentage of delays due to late arriving aircraft. That could, of course, be related to weather delays further up the chain.

From these numbers, it looks like Comair really had a hard time running a good operation whereas ASA might have simply been a victim of the Atlanta-related delays. It looks very different for the two companies despite the similarly dismal results.