Pushing back from the terminal and making your way to the runway with engines running as soon as possible seems like the obvious procedure for a time-sensitive delivery organisation. But in a bold experiment, FedEx found a new way of saving on fuel and emissions whilst not compromising customer service.

To avoid burning fuel whilst waiting for aircraft departure, this project keeps aircraft at the gate with engines off until a runway slot becomes available for immediate take-off. It sounds simple, but in a culture built around reducing delays for customer service reasons, it was initially a counter-intuitive move.

Airlines in the United States compete for departure slots around the clock; traditionally the first to call in for departure gets the first slot. Pushing out as early as possible from the gate reduces the risk of causing a delay – the top priority in a time-sensitive business model. The team at FedEx was willing to challenge this thinking and worked with the Federal Aviation Administration, NASA and Northwest Airlines (prior to its merger with Delta) to explore whether there was such a thing as a “good delay”.

After a multi-year research project, FedEx added new departure metering standards in 2011. The effort has since saved a total of 3.8 million litres of fuel (around $2.8 million worth) and avoided almost 10,000 tonnes of CO2 emissions. Departure metering was implemented at both Memphis and Indianapolis airports with no impact to customer service quality.

Through a series of operational trials and algorithm development, the FedEx ramp tower controllers were equipped with the tools to decide the optimal time for departure. While FedEx now uses volunteer metering at its two largest domestic operations, Memphis and Indianapolis, the project has gone on to inspire other metering initiatives in the United States, including at New York’s JFK and Charlotte.