How to Bring a Plane Down: FAA Greens Landings

The next time you fly, during the landing, you probably won’t think you are crashing but you may feel something a bit different.  The U.S. Federal Aviation Administration (FAA) is changing the way planes land in order to reduce fuel consumption and emissions.  The FAA is straightening the descent path instituting a process called Continuous Descent Approach (CDA).

During a conventional landing a plane descends and levels out before repeating the process.  Viewed in profile this descent path would look like a flight of stairs.  Each time a plane levels out on the descent, more fuel must be burned in order to arrest the descent and hold at the new altitude.

During a CDA landing the steps are removed and the fuel needed for the leveling off is never burned.  Never burned means a reduction in emissions and since the fuel is not needed it also increases trip efficiency by reducing the weight of fuel that must be carried.  As an extra bonus, noise pollution is also reduced on approaches that use CDA.

The FAA has been slowly rolling out the new approach procedure.  Alaska Airlines reported a CDA test flight in 2010 as resulting in a 35% reduction of emissions.  The Alaska Airlines test flight was done at Seattle-Tacoma International Airport (Sea-Tac).  “Alaska Airlines estimates the new procedures at Sea-Tac will cut fuel consumption by 2.1 million gallons annually and reduce carbon emissions by 22,000 metric tons, the equivalent of taking 4,100 cars off the road every year. They will also reduce overflight noise for an estimated 750,000 people living below the affected flight corridor.”

New technology in flight tracking allows for the change of approach.  Satellite technology and on-ground additions help complete the navigation picture.  New navigation systems also increase safety in inclement weather.

The average person dominantly navigates in only two dimensions.  Airplane pilots routinely navigate in three dimensions, a piloting skill most often shared with submariners.  The sky, versus under the sea, is comparatively crowded, making the new technology instrumental in flight tracking and allowing CDA style landings to be done safely.

In emergency situations commercial flights will dump fuel.  This is done as safety ratings allow for less weight on landing than take-off.  Emergencies are one thing but entertainment is another.  Attendees of air-shows may witness the environmental damage of what is called a dump-and-burn.  The picture above shows an RAAF F-111 igniting their dumped fuel.

Photo Credit: John O'Neill