As you would expect, every American Airlines aircraft has a maximum takeoff weight, which varies from flight to flight, and includes the total weight of passengers, cargo, and fuel. Because the interaction of these variables is not widely understood, I would like to use this month’s column to tell you about what we call weight and balance calculations.

The maximum weight at which a given airplane can take off is a function, first and foremost, of its certified structural capabil­ity. However, wind speed, runway conditions, temperature, airport altitude, and other factors can sometimes reduce the allowable takeoff weight. A good example is high-­altitude airports, where even a small increase in temperature can reduce the takeoff weight limit by thousands of pounds.

In addition to limiting the allowable weight at takeoff, weather conditions can also dictate the nature of an aircraft’s payload. For example, strong winds en route or poor weather at a flight’s destination city may require us to allocate more of the maximum allowable weight to reserve fuel for a circuitous flight plan — leaving less allowable weight for passengers and cargo.

It is also important that we maintain an airplane’s center of gravity within certain parameters. For example, the two engines on the rear of an MD80 aircraft’s fuselage make it a tail-heavy airplane. Thus, in the event we have an MD80 carrying fewer than 60 passengers and no cargo or luggage (which is obviously not very likely), we may ask passengers to take seats toward the front of the airplane to ensure proper balance.

Managing all of this is a group of professionals called load planners, who work at the “load house” at our headquarters in north Texas. Our planners — who typically handle between 40 and 50 flights from as many as 10 cities during an eight-hour shift — are all thoroughly familiar with the characteristics of each aircraft type in our fleet. They rely on state-of-the-art technology and good communication. During the flight-planning process, they are in constant contact with passenger-service and ramp personnel, acquiring passenger counts and cargo information.

Planners begin detailed work on each flight about 90 minutes prior to its scheduled departure. Flight dispatchers — using a program that factors in information on weather­, passengers, and cargo — determine the flight’s fuel requirements. The planners then assign luggage, mail, and freight to specific cargo holds and fuel to fuel tanks in order to keep the aircraft’s center of gravity in the optimal position and enhance performance. Because an aircraft’s principal fuel tanks are in the wings, as fuel is burned during a flight, the plane’s center of gravity shifts. Since aircraft operate most efficiently at a slightly “nose high” angle — in other words, with the front somewhat lighter than the rear — the fuel plan is designed to ensure this result.

When the flight plan is done, fuelers and baggage handlers are told how to load the airplane. Everything gets finalized during the 10 minutes prior to departure. As the flight is taxiing to the runway, the pilots receive the final center-of-gravity information — based on the exact passenger count and the cargo and fuel on the aircraft — from the load planners. This information enables the pilots to set proper trim settings for the aircraft’s stabilizer and wing flaps for takeoff.

Load planning is just one of the many activities our people are engaged in behind the scenes to make sure your trip with us is as safe and comfortable as possible. It’s a pleasure for me to shed a little light on this important endeavor, and it’s an honor for all of us at American Airlines to have you with us today.

Thanks, and have a great trip!

Picture of Gerard Arpey

Chairman & CEO
American Airlines