Making sure new airspace plans have room for all

 - May 8, 2008, 10:31 AM

While the FAA moves forward with its operational evolution plan (OEP) to increase National Airspace System capacity by the end of this decade, a major consideration will be how many aircraft are equipped to take advantage of the resulting improvements in efficiency.

“Our biggest challenge in deriving benefits from airspace redesign is the mixed equipage and non-equipped users,” admitted FAA Air Traffic Services director Bill Peacock at the 47th annual Air Traffic Controllers Association (ATCA) meeting early last month. “They are the limiting factor in our delivery and implementation of significant airspace changes and benefits.”

The FAA has set up a separate program office to deal with that disparity, and its first order of business is to inventory current equipage to determine the capabilities of aircraft in the system today. From there, the agency and the industry will develop a “road map” to identify site-specific locations where the technology can be used.

Another challenge, according to Peacock, is flight management systems, of which Boeing and Airbus have more than 40 different versions. Because memory capacity varies, there are database limitations, and not all procedures can be loaded into a given system.

Urging air traffic controllers and pilots to “establish clear and concise” phraseology, he cited Las Vegas as an example of confusion between pilots and ATC after Rnav/RNP technology was put in place. “It requires different phrases and different communications from controllers to pilots,” he said, “and we’re in the process of creating the phraseology we need there.”

But the real challenge, said Peacock, is for the U.S. to initiate national standards and coordinate international standards for FMS/RNP, promote pilot and crew training and ensure a consistently high level of equipage from airport to airport and country to country.

Warning that the FAA’s Air Traffic Services branch is concerned “that we may end up with a high level of both conventional and Rnav procedures” that would inhibit full implementation, he said, “We need to determine the critical mass for mixed equipment. You need a high percentage of equipage and trained crews to use the technology.”

Peacock also brought up the impending domestic reduced vertical separation minimums (DRVSM), scheduled to be implemented in early 2005 in the U.S., Mexico and southern Canada. While he maintained there will be “a lot of benefits” to the user and the air traffic system, “a possible challenge for us is the new-generation jets that will be using the system and actually could be taking up some of the altitudes that we think are going to be used by some of the jets that we have today.”

Peacock cited the increase in regional jets in the system, as well as the “smaller, corporate-type aircraft,” which he said fly at jet altitudes but “much slower” and with performance characteristics that are for the most part “much different from those of the jet fleet we have today. So we are going to have to work those airplanes into the system.”  

That creates issues not only in the en route environment, he said, but also with runways that were designed for props and turboprops. “As those turboprops are replaced by jets, and those runways are underutilized, longer runways are required to accommodate the additional traffic,” said Peacock. “It’s going to increase the traffic and increase the complexities of the ATC system.”

GPS Issues

With much of the OEP’s long-term planning relying on GPS, Col. Rick Reiser of the U.S. Air Force joint program office took the occasion to counter some earlier media reports that the present GPS satellite constellation is eroding. Rather than deteriorating to the status of a “train wreck” that was “falling out of the sky,” he countered that there are currently 27 satellites operating, three more than the 24 required under an agreement between the Defense Department and the FAA.     

“We have 27 good satellites up there performing just like they are supposed to,” said Reiser. “The fact that some have lost redundancy...really is sort of irrelevant.” He explained that some have three or four boxes that are redundant, so losing one piece of redundancy is not an issue. While many are older-style Block I satellites, there are a number of block IIRs in orbit. Meanwhile, several of the new block II satellites awaiting launch are being modernized, and the Air Force is continuously assessing launch needs.

Reiser said the satellites are lasting much longer than anticipated and the Air Force is actually stretching out its launch program. The original Block II satellites were designed for a lifespan of six years, but are lasting closer to 10 years.

Responding to customer feedback, the Air Force is making the system usable for RNP and a lot more robust than it is today, including more civil signals. A second civil signal will come on line in about a year and a third civil signal around the 2004 to 2006 timeframe.

Reiser claimed that the Air Force is still on track to deliver all that was promised in terms of modernized signals, although the first launches will be delayed a couple of months. “As we improve GPS,” he said, “we are going to get a lot more accuracy out of the system.” With a second civil signal, accuracy will be 7.4 meters. “We know that accuracy is not the only issue, but that is the thing we can address most handily and readily in the current design,” he said, “and the rest will be taken care of in GPS III.”  

He revealed that the Defense Department has embarked on a program to use the military signals to navigate military aircraft under IFR in civil-controlled airspace, and to get those signals certified to civil standards in cooperation with the FAA and others. When launched around 2011, GPS III will combine military and civil needs up front and will provide accuracy of half a meter horizontally and one meter vertically.

NAS ‘Imperatives’

Those attending the ATCA meeting also heard Ron Morgan, v-p of strategic planning for Lockheed Martin Air Traffic Services, spell out what he called imperatives for the future of the NAS.

“The first imperative says that separation standards must change over time from a distance-based standard to a time-based standard,” the former FAA official said. “And I’m not suggesting we move back 20 years to time-position reporting.

“But the separation between two Boeing airliners going 500 kt at 12,000 ft is five miles, while the separation between two Cessna 172s going 125 kt at 12,000 ft is also five miles. Is there better use of the airspace with the smaller aircraft with the lower speed?,” he asked. “In my mind, the answer is yes. So I think we need to do some research related to how we separate aircraft.”

Morgan said that when radar was the only tool for separation, distance-based separation was de facto. In today’s environment, he said, there is “tremendous capability” to use automation in the air traffic management system, but it hasn’t been used.

Another imperative, he added, is vertical trajectory clearances to replace altitude assignments to accommodate fuel-efficient climb and cruise configurations. Although he lauded DRVSM, he suggested that the airlines and business jet operators would like to climb on a vertical trajectory that equates to their burn rate–maybe 20 to 25 fpm, depending on aircraft type–all the way to their point of descent.

“That would be their optimal altitude,” said Morgan, although he conceded it wouldn’t be practical in all sectors of airspace because of traffic volume. “But it is possible in many locations, and it’s possible in lighter traffic conditions in the evening.”

A third imperative, he said, is to broaden the optimal range of aircraft performance to better use available airspace, and he suggested designing a broad range of commercial aircraft that could operate efficiently between 25,000- and 50,000 ft.

“Certainly not everyone could use the aircraft that flies at 25,000 ft,” he admitted, “but those that have routes of 1,000 mi or less might be served by that type of aircraft as the airspace becomes more and more congested.”

Imperative number four is to implement new technology and procedures to allow visual approaches and visual separation with less than VFR weather. With automatic dependent surveillance-broadcast (ADS-B) and avionics that allow pilots to “see” other aircraft around them, all that is needed is to change the procedures to allow pilots to execute VFR procedures in less than VFR weather.

A fifth imperative is to create runway and taxiway designs to decrease runway occupancy time and crossing traffic. “If you take a look at a runway that has high-speed taxiway turnoffs and one that doesn’t,” said Morgan, “you find that the occupancy time is decreased by about 15 seconds as a result.”

The occupancy time for a jet from crossing the threshold to point of turnoff is somewhere between 50 and 75 sec. “I’d love to tell you the answer is to build new airports,” said Morgan. “I don’t think that’s realistic; it’s not going to happen in the United States for the next 15 or 20 years.”

The use of digital data and digital voice to improve communications and safety is Morgan’s sixth imperative. Although digital datalink has been in use for such things as pre-departure clearances and ATIS, and American Airlines is testing contoller-pilot datalink communications out of Miami Center, Morgan contended that in the area of digital voice “we are not moving anywhere. And I would say that digital voice is a great opportunity for us to improve the safety of the system as the capacity increases.”

During his last five years at the FAA, about 20- to 30 percent of the operational errors that occurred were communications errors, where a missed radio call caused a misunderstanding between the pilot and the controller.

His seventh imperative is to expand the application of collaborative decision making to all stakeholders. The information is available in multiple systems, according to Morgan, but often is not accessible by those who should have it. “We are data rich and information poor,” he argued, “and we lack the communication capability to share data accurately within the system. We need to do that to be successful.”

The last imperative, Morgan said, is that whenever there is a business case to do so, elements of the NAS need to transition into space-based capability. As examples, he cited oceanic satellite communications and the move to GPS navigation.

“I’m not a proponent that every element of the NAS needs to be space based,” said Morgan. “But certainly there are elements that we need to continue to study and work on together as an industry, as a set of service users, in trying to figure out what the right elements are to transition to space based.”