IN THE 1980s a cabin crew at American Airlines observed that its passengers would happily wolf down in-flight dinner salads, but nearly three-quarters of them would leave the customary olive. Robert Crandall, the company's boss at the time, promptly removed it. It turned out that the airline paid its caterers based on the number of ingredients in the salad: 60 cents for four items and 80 cents for five. The olive was the fifth item. This move saved more than $40,000 a year. In 1994, Southwest Airlines followed the suggestion of a flight attendant and removed the company’s logo from rubbish bags, saving the carrier $300,000 a year in printing costs. In an industry that serves fussy customers and operates on thin margins, how else do modern airlines cut costs without cutting corners? They start by mimicking doughnut-dodging supermodels who watch their weight down to the second decimal place. Airlines bin bulky in-flight magazines, lay thinner carpets and serve food in light cardboard boxes. Some airlines have jettisoned safety equipment for emergency water landings on those aircraft that do not fly above water. Seats have become lighter. In its Airbus A321 planes, Air Mediterranée, a French carrier, replaced 220 economy seats, each weighing 12kg, with skinnier ones made from lighter materials such as titanium that weigh around 4kg. GoAir, an Indian low-cost carrier, hires only female flight attendants because they are on average 10–15kg lighter than men. Such parsimony pays off. Fuel accounts for a third of an airline’s costs and every kilogram thus shed removes $100 from an aircraft’s annual fuel bill.

Small design tweaks on modern aircraft, which are not as thirsty as their predecessors, also help. Southwest Airlines estimates that it saves 54 million gallons of fuel a year after installing winglets, or upturned wingtips, on its fleet to reduce drag. EasyJet, a European budget carrier, uses special paint that eliminates microscopic bumps on the aircraft’s body to help it cut through air more easily and, the airline claims, burn less fuel. Internationally, pilots are being persuaded not to take off at full throttle and to get their aircraft to cruising altitude (where the air is thinner and there is less drag) as quickly as possible. When landing on long runways, pilots may let the aircraft slow down on its own instead of putting the engines into reverse thrust. Some low-cost carriers like India’s SpiceJet have learned to work their fleet aggressively. Pilots of its Bombardier Q400 turboprops, which serve smaller cities, fly their planes faster to shave a few minutes of flight-time off each leg, which lets the airline squeeze in an additional flight every day. The increased fuel burn at higher speeds is more than paid for by the additional revenue from the extra flight.

And yet for all the stress that airlines willingly take on, boarding delays cost them up to $1 billion a year in Europe alone. Airbus thinks it has the answer: it has been granted a patent for a portable cabin that copies the seating arrangement of an aircraft. The module, docked at a gate, is loaded with passengers and their luggage and is then slotted into an empty aircraft like a matchbox that neatly slips into its case. The plane then flies to its destination; after landing the detachable cabin is removed and replaced by another module containing a new set of passengers ready for take-off. The futuristic design seems likely to cost billions of dollars and many years to develop – and it may never get off the ground. In the meantime, airlines will continue to weed out that extra olive.

Update: This blog post has been amended to remove the news peg.