Like any other business, airlines are hawkish about keeping costs in line. The biggest expense for an airline is fuel. Recently, oil prices have climbed, and as a result, airlines predictably have begun to re-emphasize fuel-saving strategies that often are allowed to wane. Single-engine taxi operations, minimizing APU usage, and flying a cost-efficient flight plan are all common ways to stretch the company dollar.

Balancing the pilots’ needs with those of the bean-counters to save money is a never-ending source of tension. In general aviation, it is standard procedure to fill the tanks and go, no matter how short or how long the flight is. Preventing water condensation in the fuel is a common rationale for this, especially for an airplane that doesn’t fly every day.

But in a jet, topping of the tanks is almost never an option. Most of the time, this will cause a landing weight that exceeds the limit. Further, it’s very expensive. Roughly 3 percent of the fuel on a jet is used to carry the fuel on a jet, and that is a number that adds up. Dispatchers, who actually file the flight plans, will take into account the anticipated weather and regulatory needs and fuel the flight accordingly. Each airline has a different policy when it comes to planning fuel, but most will plan to land with the legal reserve plus a small cushion.

Further, every airline keeps extensive records on fuel burn. Historical burn data is tracked for each route, flight, time of day/month/year, individual aircraft, each engine, and even for each captain—and the accuracy of the data is uncanny. Analyzing this info allows an airline to keep fuel costs in check without comprising schedule integrity or safety.

One of the most common data points used is the frequency of a diversion based on the amount of extra fuel carried. For example, an airline knows that a given flight has a normal completion percentage of X. For every so many minutes of extra fuel, the completion percentage needle may move incrementally upward. At some point, no amount of extra fuel is going to make a statistical difference, but it will harm the bottom line. And, once that point is reached, the success of other flights (the connections) comes into play, because if one airplane diverts for weather, odds are that a whole bunch will divert.

For pilots, there is almost never too much fuel, but there does need to be an acceptance that you can’t save every flight, and sometimes a diversion is the best option for all involved. Over time, the cost of carrying extra fuel begins to exceed the potential savings. As a result, it is incumbent upon us to realize that we need to think of fuel in terms of extra minutes. How many extra minutes of fuel do I need or want, based on weather, anticipated routing delays, et cetera? What amount of fuel am I comfortable landing with at the destination? There is nothing wrong with adding some extra fuel, as long as it is done with the big picture in mind. Adding extra fuel for the sake of adding it is a waste and only hurts the bottom line, and it runs the risk of driving up ticket prices and chasing away your passengers.—Chip Wright