Route Makers

Avionics technology that enables required navigational performance (RNP) approaches, optimizing of flight routes and safer landings in difficult weather conditions or very low visibility is making its way from tests and evaluation to certification and implementation in general aviation aircraft and, increasingly, to airliners.

Southwest Airlines now performs RNP approaches into 14 airports, including Chicago Midway, where it uses the technology to deconflict traffic going in and out of Chicago Midway. But the airline admits that validating the savings is a challenge. “Unfortunately, analyzing the time and fuel burn savings have presented a significant challenge,” said Southwest spokeswoman Brandy King, explaining that the process for publishing new approach paths is complex and time-consuming. “The data on total numbers of RNP approaches conducted is not as high as we had hoped for,” she said.

Along with RNP, there is a lot of attention being paid to adapting in-trail transoceanic procedures using Automatic Dependent Surveillance-Broadcast (ADS-B) over the North Atlantic. ACSS, an L-3 Communications and Thales company, is preparing for in-trail procedures (ITP) tests next year over the North Atlantic. Some Delta Boeing 767-300s, British Airways Boeing 777-200s, and US Airways Airbus A330s aircraft will be fitted with the company’s SafeRoute system - a suite of products pegged to ADS-B. SafeRoute permits pilots to more easily adjust altitude en route in airspace without radar surveillance. SafeRoute displays other aircraft in front, above and below, allowing a time- and fuel-saving track to be selected while safely maintaining separation from other aircraft. “Sometimes you get stuck at the current [level] and you’re less efficient,” said Cyro Stone, director of ACSS’s SafeRoute initiative.” While ATC allows aircraft to change altitude on request, many times those [requests] get denied. The controllers want to maintain separation. Maybe they’re not sure of the exactposition [of the aircraft].”

With SafeRoute, pilots still have to get ATC clearance. But the system makes the subsequent altitude change more efficient and creates more confidence in the people approving and executing changes.

Honeywell has a system called SmartTraffic, which similarly enables a pilot to climb, descend or perform a passing maneuver that might not be possible without this technology aid.

The ADS-B-linked system lets pilots “literally squeeze between a couple of airplanes on a flight level above them and climb through that,” said Honeywell vice president of aerospace regulatory affairs Chris Benich. “I think we’re starting to get some equity. They’re getting some significant procedures out there that are making a difference in the way airlines are able to operate their airplanes,” Benich said.

More tests

Benich said Honeywell’s in-trail tests will begin soon over the North Pacific using United Airline Boeing 747-400s. Savings should be in the range of $100,000 per year per airplane, he said.

Avionics manufacturers, however, are generally reluctant to talk return on investment, or even to discuss upfront costs. Savings depend on the specific application to which ADS-B is tasked, they point out.

Still, part of the appeal of RNP is that most aircraft are already equipped with the necessary hardware.  Aircraft already have transponders. They have TCAS. So upgrades typically require only the additional sensors and new software, which is fed information into an Electronic Flight Bag (EFB), which displays the information.  But with ADS-B capability, aircraft typically need more accurate GPS.

Still, the potential advantages are considerable. ACSS communications manager Steve Henden said ADS-B-fed, cockpit-mounted EFBs will eventually enable pilots to fly more efficiently from takeoff to touchdown.

Henden cites a pilot’s eye scenario on a transatlantic flight and how it might look using the technology. “Taxi from the gate at O’Hare on a foggy night and the captain looks down at his EFB” and sees all the aircraft taxiing around him,” he said.

Taking off across the North Atlantic Track, the pilot discovers flight level 390 is friendlier than 350. He checks the EFB display, calls ATC, receives clearance and pushes up the power levers.  The result: a safely-executed, precisely-positioned ascent between two other jets.

Descending into a congested airport like London Heathrow, meanwhile, SafeFlight’s merging and spacing application provides speed cues that tell the pilot how fast he needs to go to hit the approach point and at precisely what time.

Surface area movement management—an ADS-B application on SafeRoute—is already certified. So are merging and spacing. The next testing to be performed involves the in-trail element that connects the two and renders the re-routing relatively seamless.

Another area of technology focus is on improving the ability to safely operate in poor weather or low-visibility situations. Rockwell Collins has developed a blended Synthetic Vision/Heads-Up Display (SV/HUD). Already certified for use on the Bombardier Challenger 601 and Bombardier Global 5000 business jets with Transport Canada, “it’s working its way through the subsequent bilaterals as we speak,” said Joel Otto, Rockwell Collins’ senior director of marketing. The capabilities will be available on the Bombardier C Series, he said.

“Our ultimate goal is to achieve operational credit for lower landing minima down to 100 feet,” said Greg Irmen, Rockwell Collins vice president of business and regional systems. Achieve that, he said, and the result will be “less rerouting of flights at hundreds of airports when visibility is low.”

Synthetic vision provides pilots a database-generated image of terrain. “Based on the position of the aircraft, a synthetic view of the world’s topography is presented to the pilot,” Otto said.

Although similar to the view you get with the enhanced ground proximity warning system (EGPWS), Otto says SV’s data is “much richer because it superimposes the terrain information in a head-up form.”

 “In the daylight, if you wanted to have synthetic vision and the real world, they have to line up to each other very, very closely,” Otto said.

In tests, Bombardier and Rockwell Collins compared varying combinations of flight guidance symbology—with and without S—on both the HUD and the head-down display (HDD) during ILS approaches.

Rockwell Collins says in its data releases that preliminary results indicate that ILS tracking accuracy was improved 70% laterally and 25% vertically when SV was displayed on the HUD. Tracking on the HDD with SV also showed improvement when compared to the HDD without SV, according to Rockwell Collins.

“Combine this kind of capability with WAAS (the wide area augmentation system) and LPV (local precision vertical)-type flying and you get simulated CAT I, CAT II using GPS –WAAS, or space-based, augmentation system corrected,” Otto said.

 “As EGNOS (European Geostationary Navigation Overlay Service) and other things come on line, this will start to move across the world,” he said.

But to become useful operationally, SV/HUD must get operational credit. “That’s the thing that actually gets you lower landing minima,” Otto said.

Rockwell Collins says that to achieve those lower landing minima for WAAS/ LPV approaches it plans to use its MultiScan weather radar to cross-check the vertical solution vis-à-vis the runway.

Rockwell Collins is focused initially on regional airlines in the 70-to-100 seat range as potential customers for SV/HUD technology.  “The 50-seat [RJs] probably not as much,” he said.

Rockwell Collins is realistic about return on investment. “If you fly primarily in the middle of the United States it will be tougher to get that payback,” Otto said. “But if you fly into the northwest, up in Alaska and Canada, the scenario is different. Eighteen months to three years is kind of the typical payback period most [carriers] are looking for,” Otto said. Higher fuel prices tend to narrow the investment window. Payback expectations become compressed. Still, for an airline that’s looking at SV/HUD as a long-term strategic investment, “a five-year kind of a payback” is still feasible Otto said.

Despite the fact Rockwell Collins will have standard dual HUDs on the Boeing 787, the company said it has not had a discussion with Boeing about rendering them dual SV/HUD-capable. Rockwell Collins is waiting for operational credit to lower landing minima. “We’re highly confident we’re on the path to get there,” Otto said.

Blended View

Honeywell, meanwhile, has developed Enhanced Vision System/Synthetic Vision System (EVS/SVS) technology that combines EGPWS technology with HUD symbology to give pilots continuous situational awareness of their flight path, terrain and navigational environment using cues that are familiar and providing them a VFR view regardless of weather or visibility conditions.

SmartView is predominantly targeted at business and general aviation aircraft now, but the application to airliners is obvious.

Honeywell Aerospace staff research scientist Trish Ververs, who has led EVS/SVS development, said the idea was to improve the pilot’s ability to detect a runway and land even in difficult conditions such as very low visibility or strong crosswinds.

Layers of data are correlated in real time, including HUD symbology, conformal terrain, color-coded terrain, range rings for distance, EGPWS warnings and runway markings.

“The goal is to give pilots the information they need, when they need it, and in time to do something about it,” Ververs said.

As part of its development program, Honeywell has also given SmartView HDD capability. “In the head-down configuration you can color things and match it to the color of the surrounding environment. With HUDs, it’s sometimes not clear what you are looking at,” Ververs said.

Honeywell says that in flight tests so far performed, pilots—even though they may have been wary of HDD mode at the outset—easily adapted to it. “There are no mental gymnastics involved,” Ververs said.

Weather Detection

Rockwell Collins, meanwhile, is growing increasingly confident in the ability of its MultiScan weather radar to find, fix and interpret weather. In 2012 the company plans to roll out its MultiScan Threat Detection Radar V2, a system that in August was still undergoing flight trials. The essence of the upgrade—an algorithmic development—is to “help pilots interpret what they see,” Otto said. What’s a weather formation actually mean to an airplane? What’s the real nature of the threat?

By concentrating on individual cells, as opposed to simply doing a series of horizontal sweeps, the goal is for MultiScan V2 to vary gain, pulse width and frequency to determine what potential for damage a given cell really poses. Is there lightening and hail ahead, or simply lots of airborne moisture? Is a storm growing, or decaying? “We can penetrate behind those things and see and help pilots understand the bigger picture,” Otto said.

Karen Walker contributed to this article.