Newer fleet

The claim that an airline's newer airplanes make it the most green is often touted. European charter airline TUI (pronounced Tooey) highlighted its new fleet as being the greenest in the industry. But the choices for many low fare airlines are the A320 and next generation 737, both fuel efficient airplanes have seen limited changes in the past decade.

Easyjet tried to counter TUI's green claim of having the greenest fleet by making the equally suspect statement that their company was in fact more green because they flew shorter flights.

Since aircraft have a life expectancy of at least twenty years, any recent airline, or even a company that has seen significant growth, will have a younger fleet by definition. It doesn't make sense to retire an airplane sooner than 20 years just to save between 5 percent and 20 percent in fuel costs.

So when an upstart airline claims to be 25% more efficient than its competitors, you can suspect you're being greenwashed. Even on this blog we're not immune to the airline hype machine. We promoted one airline's claims just hours ago here on Gadling:

The airline operates a brand new fleet of aircraft that operate up to 25% more efficiently than other domestic fleets. During ground taxiing, their aircraft use a single engine.

Single-engine taxi

This technique is often mentioned in reports like the one above on a specific airline's efforts to save fuel as if it were a new idea. Most airlines have been taxiing on one engine whenever conditions allowed it since the late '80s. It's hardly a new effort.

There are times, however, when it isn't possible to operate on one engine, because of a heavier than usual takeoff weight, airports with a slope on the way to the end of the runway or if baggage carts and personnel are working behind the airplane after the tug is released, since the 'breakaway' force on one engine requires higher thrust which could blow people and equipment away.

Still, when possible, it's an effective way to save up to a few hundred pounds of fuel per fight.

Reduced speeds

A typical 757 long-haul flight can only shave around 4 minutes of time if flown at Mach .82. Flying a more reasonable Mach .79 or .80 can result in close to 400 pounds less fuel burned every hour. Airlines have realized this and are adjusting flight plans accordingly.

Winglets

A company called Aviation Partners formed as a joint venture with Boeing to retrofit 737, 757 and 767 aircraft with composite 'blended winglets' that have resulted in significant savings (between 3.5 percent and 5 percent lower fuel burn and emissions) for airlines.

Constant Descent Arrivals

Airplanes are much more efficient at higher altitudes, so any descents that begin early, and then level off at a lower altitude during the approach burns more fuel. The typical 'stair-step' arrivals in the New York area, for example are designed by ATC to keep traffic in specific corridors.

With GPS equipped airplanes that can be programmed to fly a constant descent approach accurately and consistently, the FAA is looking into designing arrivals that take advantage of this new technology.

Converting just one of the lessor used arrivals into Seattle will save an estimated 175,000 gallons of fuel a month.

An added benefit is that these approaches are much quieter for the surrounding communities, which is a big reason that London has required a similar type of arrival for years.

NextGen

Using the same GPS capabilities, the FAA is working on a new air traffic control plan called NextGen, which will evolve ATC from a ground-based operation to a satellite based system of management.

In addition to improving safety and increasing capacity, this plan will allow for more direct routing for airplanes, less holding at the destination and better planning for constant descent arrivals mentioned above, resulting in less carbon emissions, fuel consumption, and noise.

It's the little things that add up

Airlines have changed the technique for pushing back from the gate. Rather than a straight back push, Delta estimated if an airplane is turned up to 70 degrees in the direction of taxi before being released by the tug, 7.6 million pounds (just over a million gallons) of fuel can be saved.

Increased use of ground electrical power at the gate instead of the onboard Auxiliary Power Unit can save a similar amount and for every pound of water in the sinks and coffee makers that is reduced on a flight, American Airlines estimates it saves 14,000 gallons of fuel.

And Boeing has made changes in the next generation 737 engines this year that are said to save an extra 1% of fuel, which will benefit all future purchasers of their most popular airliner.

So when you read about fuel efficiency claims, remember that no airline can call themselves the green champion, although Nature Air in Costa Rica may deserve a gold metal at least. Every airline has been focused on saving fuel and reducing emissions because, frankly, it's in their best interest to do so.

Their efforts have resulted in some significant savings over the past four decades, in fact.

Historically, airlines are outperforming the auto industry in fuel economy improvements. In 1972 U.S. airlines traveled 15 passenger miles per gallon. That number increased to 25 mpg in 1982 and 30 mpg in 1992. Today the number is exceeding 45 passenger miles flown per gallon.

The Boeing 787 and Airbus A350 are promising up to 20% improvements in fuel efficiency emissions, so that trend will likely improve.





Do you have a question about something related to the pointy end of an airplane? Ask Kent and maybe he'll use it for next Monday's Plane Answers. Check out his other blog, Cockpit Chronicles and travel along with him at work.