Planes Are Finally Making Logical Descents Into American Runways

Planes flying into Houston are burning less fuel and making less noise than before, thanks to an FAA project implemented this month. Instead of the conventional descent—leveling out between drops in altitude—pilots will follow a steady path to the ground with the engine throttle near idle.

The shift, along with changes that will ease air congestion around Houston, is part of NextGen, the FAA’s $37 billion program to modernize how American airspace is managed by 2030.

Usually, planes approaching an airport drop altitude in steps, cranking up the engines to level out in between. That makes it easier for pilots to control descents and for air traffic controllers to keep track of everyone and manage spacing between planes. Crews check in with the ground at each interval, making sure they’re clear to drop a few thousand more feet. It’s a safe but inefficient way to get lots of planes on the ground.

Now, planes flying into George Bush Intercontinental and William P. Hobby airports in Houston will follow “optimized profile descents.” Instead of descending in stages, they will steadily drop, keeping the throttle near idle for nearly 100 miles. It’s like sliding down the bannister instead of using the stairs. Less throttle means less wasted fuel and less noise for airport neighbors. Reducing check-ins with ground control reduces opportunities for miscommunication.

The new landing procedure and other changes in Houston, FAA chief Michael Huerta said, will “turn some of the most complex airspace in the country into some of the most efficient.”

Comparing a standard step-down approach (left) with an optimized profile descent. FAA

New tools, better routes

The shift to optimized profile descents is happening now because better technology has made inefficient step-by-step process unnecessary, says Jim Davis, a national airspace rep for the National Air Traffic Controllers Association, which worked on the project.

Flight management systems, the primary navigation tools on commercial jets, have gotten more sophisticated. New Basic Area Navigation systems can better determine the aircraft’s ideal angle and rate of descent, so pilots don’t have to do the tricky calculations themselves. In August 2013, the FAA started deploying a new time-based flow management system nationwide, so air traffic controllers can track and manage aircraft from farther out, making the arrival process more efficient.

Optimized profile descents were trialled in Anchorage in 2009 and introduced at Ronald Reagan Washington National Airport in August 2012. FAA data shows that at Reagan, the average distance flown between cruise altitude and the arrival airport dropped from 51.9 nautical miles in 2012 to 50.1 nautical miles in 2013. Over a year’s worth of flights, that added up to over half a million nautical miles saved.

New descent routes must be specially calculated for every metroplex. These major metropolitan areas each have specific runway configurations and different relationships between local airports, so you can’t just tell the pilot to take the gradual path down. New routes must be carefully created and vetted by the FAA. With each completed project, the process gets easier. “We’ve developed a playbook that we started with in D.C.,” Davis says, and it’s grown since then.

Making the change national

Plans are underway to use optimized profile descents in metroplexes where a high percentage of aircraft have the necessary equipment, Davis says. Next up is north Texas, where work begins in September. Projects in Atlanta, North and South California, and Charlotte are underway or planned. Each metroplex project will cost $5-$9 million, the FAA says.

The $8 million Houston overhaul also created more efficient routes for departures and flights in bad weather, and added two entry points into the area to reduce congestion. Together, Hobby and Bush airports handle over 750,000 takeoffs and landings annually, so those changes will cut distances flown by nearly 650,000 nautical miles (748,007 miles) annually, and save three million gallons of fuel. At current prices, that adds up to $8.81 million. In an industry with tiny profit margins, that’s a big deal. Airlines will quickly see the benefits, especially Southwest, which used Houston as one of its hub cities.

As better routes are set up around the country, other airlines will reap the rewards, too. Maybe some of that will even trickle down to passengers.

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