Oakland to Chicago, July 2008.
 
Like nearly every morning before a flight, I check the weather data for my series of flights that day. This day, I see a band of moisture up near Minneapolis, but that is two states away from my leg into Chicago. Things should be fine. We should handily beat the weather into Chicago.
 
On the second leg of the day, we arrive in Oakland, and I again check the weather. The mass of moisture has moved a little but, based on my hourly summary, it still looks like we will beat the weather into Chicago by a few hours.
 
Then, just prior to pushback for Chicago Midway, we notice the fuel gauges winding up as more fuel is pumped onboard. The Operation Agent brings us the final weight and balance paperwork along with a new flight release to account for the extra gas Dispatch has added to our flight. We push back with 2,000 pounds more gas than originally planned, “just in case.”
 
The flight is smooth as we cross the Sierras and cross the barren northern Nevada ranges. Crossing just south of the Great Salt Lake, we head into the western Rockies, crossing the Front Range just north of Denver. All the way it is clear and smooth.
 
Passing Omaha, we start to see clouds approaching from over the horizon. We now begin to see the weather is moving much faster than expected. Over Iowa, we inquire as to what is going on with Chicago arrivals and the Controller replies, “Stand by for holding instructions.” Hokey-dokey.
 
We are still up high (33,000 feet) where holding is the most efficient. Holding at lower altitudes consumes more gas, and we pass on to Air Traffic Control (ATC) our desire to stay high, “as long as possible.” In flight, fuel is time and time offers options. I fire off a message to the SWA Dispatcher watching our flight informing him of our fuel remaining and Expected Further Clearance (EFC) time. (This is the time ATC expects to clear us into our destination.) Our Dispatcher has already seen us circling and sees those in front of us holding at holding fixes closer to Chicago.
 
Because of the possibility of weather at our destination, we designated a good-weather alternate of Milwaukee, about 70 miles north of Chicago. If you have looked at a SWA cocktail napkin lately, you will notice Milwaukee is not on the SWA route system. I confirm with the new Dispatcher who has taken over for our original Dispatcher, whether or not they want us to possibly proceed to an “off-line alternate.” It’s safe, but once you land, you are on your own. There are no Company resources there to help you get airborne again to your destination.

Our new Dispatcher agrees that Indianapolis would make more sense so we change our alternate and work up a new “bingo fuel.” This “bingo” number is how much gas we need to depart the holding area with to be able to fly to our alternate and land and still have 45 minutes of reserve fuel left. In other words, it is an absolute minimum amount we want to depart from holding with. 
 
In holding, the Boeing 737 uses about 4,000 lbs of fuel per hour. (About 1,000 lbs of fuel every 15 minutes.) In holding, we advise ATC that we are now about 15 minutes from diverting to Indy. Almost immediately, he informs us Chicago Approach is now taking planes into Midway. We coordinate with our Dispatcher, and he confirms the worst of the weather is now past Chicago so we depart holding and head to a closer holding location for a few turns. Just in case, I tell Dispatch via typed message: “MKE hip-pocket alternate.” Dispatch responds “Roger.” If something goes goofy getting into Chicago, we will still bolt for Milwaukee (MKE) with enough gas to land with our required 45 minutes of reserve fuel.
 
We are finally descending in to Chicago, and on the radar, we can see vast bands of rain moving to the east. By the time we reach Joliette, we can see the skyline of Chicago and laying before it, the Midway Airport. Out both sides, the passengers only see darkening skies. Running the latest weather information through our landing performance computer, we realize we will have to ask for a runway different than what the controller wanted us to use.  The controller grants us the runway we need.

We fly an approach to the advertised runway, and then circle to use the runway that affords us the best performance margins based on the runway surface conditions and wind direction. As we cross the runway threshold I duck under glideslope a tad and firmly plant the tires at the start of the touchdown zone to ensure spin-up on the wet surface to allow the brakes to work. Deploying the reversers right at touchdown, I beat the auto-brakes and slow the plane to near taxi speed about halfway down the runway. No hydroplaning or traction problems today, and we exit the runway with over 1,000 feet to spare.  About 45 minutes late, we pull into our gate in Chicago. To the Passengers, it seemed an unnecessary delay. A few deplaning Passengers look back in surprise as I tell the oncoming Captain, “We almost went to Milwaukee, then Indy, and then Milwaukee again.” To the Passengers, it was just another airline delay.