Up Early, Coast to Coast. Running in Chicago.

[canyonwalker]

PA Anniversary Trip Journal #1
MDW Airport - Thu, 7 Nov 2024, 3:00pm

Hawk and I got up early this morning to travel coast-to-coast, to Pennsylvania to celebrate her parents' 60th anniversary. We packed our bags last night so we could leave quickly today. Dawn was only beginning to break when we were already out of the house and walking to meet our driver outside the gate.

As we rode to the airport the day's schedule was off to a good start. We'd been able to wake up, shower and dress, and leave home promptly. There were no problems with the driver. The inbound flight for our aircraft had departed on time. There was no reason to expect delay. But then....



The delays started as we neared boarding time. Our aircraft had arrived on schedule, but our crew were arriving on a different flight and they were delayed at least 10-15 minutes. The airline asked the inbound crew to begin our boarding, which was good because our actual crew ended up more like 40 minutes late. Even so, our boarding completed 10-15 minutes late. Then we sat parked at the gate until 35 minutes late. The pilot explained that we had to wait for more fuel. Uh, why wasn't "gas up the plane" the first thing the ground crew did? Instead it was like, "Okay folks, we're ready for an on-time depar— oh, no, the gas gauge is on E!"

Being delayed— "Taking the D," as flight crews call it— in San Jose put pressure on our connection at MDW. And our delay grew even longer as the pilot routed around rough air near Denver. The 1h10m connection time we'd carefully chosen (other flight options had precariously short connections like 40 minutes) was reduced to a mere 35 minutes when we landed.

Whenever one flight is delayed I always check if my connecting flight is delayed, too. Delays tend to propagate systemwide. And 90% of the 20-ish flights I've flown with Southwest in the past year have been delayed. Well, wouldn't you know it— our connecting flight today was on time. The quick lunch on the ground I'd planned to have in Chicago disappeared as we sprinted to our next gate to make the boarding call. I guess instead of Panda Express ll be eating that half a protein bar I tucked in my bag.

Comments

[some_other_dave]

The air traffic system is pretty close to capacity much of the time. It is relatively brittle, and not too resilient to damage/delays/stoppages. This is a major reason why delays usually propagate across the whole system.

... This was a major field of study at a previous employer of mine ...

[canyonwalker]

As a frequent flyer, especially on Southwest Airlines, I'm very familiar with the reality of delay propagation as well as the real-world factors driving it. Here I simply referred to the problem rather than explaining it because I didn't wish to get into a discourse.

A few things about Southwest's operations drive greater delay propagation than with other airlines. For one, they run a more decentralized, point-to-point routing map vs. other carriers' more hub-and-spoke model. Two, they run more short routes than others, often having one aircraft fly 5 routes a day. Three, and perhaps most importantly, they build their route scheduling on "fast turns" from one flight to the next.

These fast turns made more sense when the airline's planes went out less full, but with more passengers to pack in now ("higher load factors" in industry speak), and with the addition of the 737 MAX 8 configuration that accommodates 30-ish more passengers than other models, the turn times are frequently unrealistic.

When one flight arrives late due to any of a number of factors, there's little to no slack in the downstream schedule to make up for it. And because the turn times are unrealistic for current conditions, the delays tend to snowball throughout the day as each aircraft is even more behind schedule on each of its subsequent routes.

[some_other_dave]

Exactly!

Several of those factors also exacerbated the problem they had last year when their computer system rolled over and s**t the bed.