For those of you who enjoy hearing about my job, here’s a little story from Friday night:

I had two flights going from Vegas to Reno. Due to snow and low visibility, the afternoon dispatcher had planned them with some extra fuel plus Boise as an alternate, which seemed reasonable to me when I arrived on duty.

If we’re going to divert, we never plan to burn all of our extra fuel, keeping some in the tanks in case unexpected problems come up. Generally, we plan to land at our alternate with a standard amount of 5000 lbs. From there, the math is pretty simple; we add the fuel burn from the intended destination to the alternate and use that amount as our decision point for diverting.

In this case, if the fuel burn to Boise is 3800 pounds, the captain and I might agree to divert once we get down to 8800 pounds of fuel to make sure we arrive in Boise with about 5000. For my two Reno flights, they could hold for 10-15 minutes before having to leave for Boise. If the weather cooperated as forecast, that should have been no problem.

Unfortunately, about the time both flights pushed back from the gate in Vegas, Reno’s visibility dropped to 3/4 mile as the snowfall increased. For us to land in Reno, the visibility needs to be at least 1/2 mile. I immediately wished that both flights had more fuel onboard, but I didn’t want to take a delay to bring them back to the gate.

They took off. The visibility dropped to 1/2 mile. My heartrate rose a bit. The visibility could drop further, or the airport might need to close the active runway to clear the snow, either of which would stop us from landing on schedule.

Now I had to look at my options. With Boise as my alternate, the probability was much greater that both flights would divert, creating problems for all involved and costing thousands of dollars. Unfortunately, 737s don’t have in-flight refueling capability like some military jets, so I was stuck with the fuel on board.

My solution? Change the alternate to San Jose, which is about 1200 pounds closer. San Jose would allow us to hold for about 15 minutes longer, increasing the chances that the conditions would improve enough to land safely. We call this shortening up. I sent this new plan to both captains through our cockpit text messaging system, and both agreed. I also called our people in San Jose and asked them to stay late in case we needed to divert there. Normally, they go home when their last flight lands, but we can ask them to stay if necessary.

Sure enough, by the time they drew near Reno, the airport was temporarily closed while the snowplows struggled to clear off the runways. The snow was falling faster than the plows could clear it. Both flights went into holding and told me via text message. I worked out diversion plans with both of them: if we can’t get cleared in to land by 7700 pounds of fuel, we’ll divert to the new alternate of San Jose.

We waited. And waited. I watched them spin on my radar. I kept checking their fuel electronically. They sent me brief updates from the Reno control tower: “Plows can’t keep up.” “10 more minutes.” Our decision fuel approached, and I started wishing I had given one flight Oakland as an alternate instead. That way I could have split the diversions between two airports instead of overwhelming one airport as they’re trying to close. My deodorant started to kick in. I checked the latest braking action report that tell me how slippery the runway is. It had gotten more slippery since the last report, so I notified both crews. Each flight had maybe 10 minutes left and would have already diverted had we not shortened up to a closer alternate.

Finally, both flights landed safely, and I could relax. The best part of a situation like this is getting the message that the flight has touched down. By avoiding two diversions, we saved the company perhaps $4000 or more, avoided a potential problem involving a crew’s maximum time on duty, and delivered the passengers where they wanted to go on the first try. What I did wasn’t anything special; nearly all of my coworkers would have handled the situation in a similar or better fashion. But I was happy to contribute and help solve the problem.