If a commercial jet could land using a smooth, continuous descent versus the traditional stair-step approach, it could save an airline between 200 to 800 pounds of fuel each flight — something that’s now possible at Denver International Airport.

DIA has fully implemented its new arrival and departure procedures, the next phase in the Federal Aviation Administration’s mass overhaul of U.S. airspace, called NextGen. Denver is among the airports at the front end of the adoption process.

The entire program is a wide-ranging, comprehensive transformation of the navigation system for the national airspace, expected to span several decades and require participation from airports, airlines, air traffic control and other stakeholders.

NextGen essentially shifts the air traffic control system from ground-based radar to satellite-based navigation — relying on GPS. The FAA’s goal is to pack the skies with more aircraft in order to speed up system-wide traffic.

The recently completed phase at DIA trims arrival and departure fuel costs by eliminating several intermediary steps. The traditional system requires an airplane to come into and out of cruising altitude by firing its thrusters at every new altitude level, wasting hundreds of pounds of fuel.

“It may only be a difference of minutes, but minutes matter when you have 1,700 flights a day (like at DIA),” said Joseph Burns, a veteran United Airlines pilot. “I think it would take a really seasoned traveler to notice the difference.”

The FAA predicts that NextGen improvements will reduce flight delays by 38 percent and lead to a 1.4-billion-gallon total reduction of fuel burn by 2020.

The traveling public will not likely notice an immediate difference in travel time, but proponents hope that the early investment pays off in the end.

“There’s a lot of cash involved in getting these aircraft and systems ready,” Burns said. “We’ve opted to equip early because of the oceanic route benefits.”

According to Burns, the FAA looks for an airport and an airline to partner in the transition.

“As the lead carrier in Denver, we have a responsibility to come in and do this,” he said.

Southwest Airlines, Frontier Airlines, Delta Air Lines, ExpressJet, SkyWest Airlines and US Airways also worked with the team at DIA as proponents of the switch. United, with its larger global network, will benefit from its GPS-equipped aircraft on transoceanic flights where ground-based radar fails to reach.

Because of shared airspace, the metro area’s general aviation airports will also benefit from the system upgrades.

“Most of the direct cost is on the airlines side,” said Mike McKee, airport planner at DIA. “On the airport side and the FAA side, it is more time and organizing.”

The FAA will eventually require every airline to implement GPS receivers on its aircraft, but 80 percent of aircraft that fly in and out of DIA have already been equipped.

United Airlines took a team from The Denver Post into its flight simulator to test the fuel- saving approach route.

Flying the simulated descent twice, beginning above Sidney, Neb., both times, the team landed the plane first using the radar-based stair-step approach and then using the more automated, glide approach.

The team saved 200 pounds of fuel.

However, a report released last month by the U.S. Government Accountability Office found several obstacles still facing the FAA on the NextGen program reaching its expected benefits.

One of the GAO’s main concerns is that the FAA is still struggling to prioritize steps in a very complicated, multi-phase process. Additionally, it has struggled to gain full stakeholder participation.

“Even if the airport rolls out, if the (air traffic control) doesn’t implement it, it does no good,” said Greg Raiff, CEO of Private Jet Services Group and an airline analyst. “I think it is up to the FAA to really push this thing through because you really need a national coordinated effort in order to make it work.”

Raiff said that it is in the airports’ best interest to upgrade early in the process.

“It is to the airports’ benefit to get behind it and push it out faster,” Raiff said. “Airports compete for air traffic as much as the airlines do.”

DIA officials hope to gain even more airline traffic by luring them in with the promise of reduced fuel cost. Raiff said the FAA touts public safety as the ultimate purpose for the system upgrade, but the main benefit is economic.

“We all know that fuel is the single largest variable expense for airlines, and we’ve all decided to live with jet fuel costs that are $3.30 a gallon now on average,” Raiff said. “The average fuel savings is $500 a landing with this new system … that is tremendous.”

Those savings, Raiff said, should be passed on to consumers based on supply and demand.

“On a long-term basis, you have to think those savings come back to the consumer,” Raiff said.

Kristen Leigh Painter: 303-954-1638, kpainter@denverpost.com or twitter.com/kristenpainter

NextGen by the numbers (source: FAA)

Estimated yearly U.S. air passengers by 2021: 1 billion

Projected annual U.S. takeoffs and landings by 2031: 69 million

Estimated fuel saved by NextGen changes: 1.4 billion gallons by 2020

NextGen expected to cut flight delays 21% by 2018

NextGen expected to cut aircraft carbon dioxide emissions by 14 million tons

Official total cost for NextGen: $22 billion

NextGen expected to be fully implemented by 2025