The Future of FMS

 - April 30, 2009, 12:11 PM

Flight management systems have never been considered simple pieces of equipment, but the technology is quickly evolving beyond basic navigation and performance functionality to include a host of new capabilities that hold the promise of changing the way pilots fly for the better.

Absent from some of the latest integrated avionics systems are the bezel-mounted control display units (CDU) flight crews have known since the 1970s. Instead, many modern business jets and some of the latest airliners are integrating FMS controls with the flight displays and cursor control devices (CCD), allowing pilots to point and click their way through a variety of menus or drag and drop any portion of their flight route (a technique known as “rubber-banding”) to include or modify a waypoint. The changes are resulting in cockpits that are more intuitive than those of the past–and even those of the present, in many cases–while packing more capability than ever before.

At the same time, hardware and software upgrades available from FMS manufacturers are opening the possibilities for complex, curved RNP (required navigation performance) procedures and the latest WAAS LPV (lateral precision with vertical guidance) approaches. The changes expand the operational capabilities of properly equipped airplanes today while serving as a cornerstone for future operations in so-called NextGen airspace.

“Integration of flight management systems with the displays is absolutely the trend that will continue to evolve into the future,” said Chad Cundiff, vice president of crew interface products for Honeywell. “There are just so many more possibilities when you start presenting flight-planning data graphically.” Pilots seated downwind of the latest and greatest integrated flight decks can rubber-band a flight plan line using the CCD, interrogate a waypoint on the screen and then click on the waypoint to pull up a list of likely actions from ATC, such as go direct, hold, intercept and so on.

Honeywell has already implemented these concepts in iNav, the flight-planning interface in the Dassault EASy and Gulfstream PlaneView cockpits based on the Primus Epic avionics system. In the Dassault cockpit the CCD is a large track ball mounted on the center pedestal, while in the large-cabin Gulfstreams pilots manipulate the cursor using switches on each sidewall. In both cases the result is the same: a crew interface that is more reminiscent of a Windows or Mac operating system than the traditional hunt-and-peck sequences that are required with a stand-alone FMS.

Many pilots flying business jets with graphical flight-planning interfaces, in fact, liken the difference between old and new to the change that occurred when PC users went from DOS to Windows. Going back to an airplane with standard FMS equipment after flying with the Primus Epic-based system and the latest iterations of the Rockwell Collins Pro Line 21 avionics system requires a period of “re-education,” pilots say. The number of available menu pages in a stand-alone Collins FMS, for example, is 86 compared with just 11 using Pro Line 21’s graphical FMS interface.
Research has shown that pilots training to use traditional FMS equipment retain only about 80 percent of what they’ve been taught in the classroom. They know what they need for everyday operation of the airplane, but things get murky when it comes time to dig deeper into FMS functionality.

Honeywell polled Dassault EASy and Gulfstream PlaneView pilots as they completed their initial training to determine whether the new graphical tools are indeed as easy to master as the designers had hoped. While Gulfstream retained the CDU and flight guidance control panels in PlaneView, Dassault threw its pilots straight into the deep end of the pool by requiring them to use the EASy trackball on every flight. When asked, pilots of both cockpits overwhelmingly said the new operating tools represented a “significant improvement” to a “real breakthrough.” Honeywell went back and talked with pilots who had been flying with EASy and PlaneView for many months or even years and found that they still remembered all the techniques they’d been taught in initial and recurrent and continued to use them once they got back home.

It was another story for pilots who flew exclusively with EASy or PlaneView for an extended period of time and then had to transition back to a cockpit fitted only with traditional FMS units. “The interesting thing we found is that those who stayed with the graphical tools for a few years and then tried to go back to the traditional CDU needed a little bit of help remembering all those keyboard commands they used to use,” Cundiff said. “That confirmed for us that the future is going to continue to focus on expanding the use of these graphical tools.”  

Future capabilities that could benefit from a graphical interface include advanced traffic separation and in-trail procedures and dynamic routing around weather. Honeywell is working on software upgrades for Primus Epic, and Rockwell Collins has introduced a new cockpit called Pro Line Fusion that will take the graphical concepts to a new level, designers say. For pilots flying with Pro Line Fusion avionics in the Cessna Citation Columbus, Embraer Legacy 450 and 500, Gulfstream G250, Learjet 85 and Bombardier Global series, FMS CDUs will become far less important. “The graphical flight-planning tools we are integrating with Pro Line Fusion will greatly simplify the pilots’ job,” said Tim Rayl, senior director of advanced products at Rockwell Collins. “It’s a whole new way of flying and managing information.”

The trend toward using graphical flight planning techniques began with business jets a decade ago, but since then the tools have migrated down into light general aviation airplanes equipped with Garmin’s G1000, Avidyne’s Entegra and Honeywell’s Apex glass cockpits and up market into the latest airliners, namely the Airbus A380 and Boeing 787. Even long-time makers of traditional FMS equipment such as Universal Avionics and CMC Electronics are exploring ways to enhance their products by applying graphical user tools.

At its heart the core navigational side of the flight management system is composed of three functional pieces: a database, a processor and a user interface. Designers of next-generation integrated avionics systems such as Pro Line Fusion and CMC Electronics’ FronTier cockpits are aiming to reach even higher levels of efficiency and simplicity through greater use of graphical interfaces. Both of these avionics systems aim to define a new generation of cockpit that will add more flight management tools and closer integration of onboard systems.

The goal of Pro Line Fusion designers is to develop an architecture where flight plans can be easily created and modified using an integrated control display unit featuring an entirely new FMS user interface that organizes data by phases of flight. This, they say, will further reduce the number of CDU pages with which the pilots interact and provide a more intuitive overall user interface. Through the use of interactive map symbols, for example, pilots flying with Pro Line Fusion will be able to point and click on the displays and move seamlessly from one display to the next, calling up interactive dialog boxes and text windows aimed at optimizing data presentation and flow.

The WAAS Revolution

Professional pilots of all stripes will continue flying with traditional FMS equipment for years to come, mainly because so many airplanes in operation are equipped with the stand-alone units and many more are still rolling out of the factory with the units installed. Airlines will be especially slow to adopt the new technologies, but even in business aviation graphical interfaces and CCDs will probably remain out of the mainstream for many more years to come. But big changes are coming for traditional FMS products as well.

Universal Avionics has been at the forefront of the efforts to bring WAAS capabilities to the FMS. In the last year-and-a-half the Tucson, Ariz. avionics maker has added to a steadily growing list of WAAS LPV approvals, starting with the Challenger 601 and progressing through a variety of models from King Airs to Falcon 20s to the Boeing 727. Approximately 75 operators are currently flying WAAS LPV (lateral precision with vertical guidance) approaches using the Universal FMS family. The FAA’s recent announcement that WAAS LPV approaches now outnumber ILS procedures in the U.S. has boosted the interest level in the satnav operations, leading to a rush among FMS makers to add the capability.

Two “first of type” STCs were recently issued to West Star Aviation for Universal’s UNS-1Lw FMS with LP/LPV monitor in the Cessna Citation Bravo and V series airplanes, the avionics maker said last month. Marking the first approval of Universal’s WAAS-capable FMS for these aircraft types, the certification opens the door for any other Cessna 550 and 560 operator to add WAAS capabilities to its aircraft. West Star’s STCs included approval for 3-D coupled WAAS GPS (Rnav) LPV procedures.

Interest among helicopter operators in WAAS LPV approach capabilities has picked up in recent months as well, said Jason Mason, a senior marketing engineer at Universal Avionics. Certification programs for the Sikorsky S-76, S-92 and other helicopters are under way, he said.

The new WAAS-based approach types, coded as Rnav (GPS) LPV on approach charts, are by far the fastest growing GPS approach type in the U.S. As part of its NextGen national airspace system improvement plan, the FAA is focused on reducing operators’ dependence on older ground-based navaids such as ILS and VOR, and increasing the use of WAAS GPS navigation. Because of its ability to alleviate airspace congestion, save fuel and improve safety, satellite navigation technology is being applied worldwide, with systems in Europe and Japan planned to be operational soon.

Operators of aircraft equipped with satnav-enabled avionics can take advantage of lower descent minimums at more airports and improved performance and safety in bad weather. The WAAS-capable FMSs allow pilots to fly to ILS-like minimums (as low as 200 feet) at airports without an ILS approach with RNP-like accuracy of 0.3 nm without special operational approval from the FAA, as is required for RNP SAAAR (special aircraft and aircrew authorization required) procedures.

A number of WAAS LPV equipment approvals for business jets have been completed recently or will be finished soon as avionics manufacturers, installation centers and operators get serious about gaining the needed certifications to fly the GPS-based procedures. Rockwell Collins last year secured approval for the WAAS LPV upgrade in the Challenger 604 as part of a contract with the FAA’s Aviation Systems Standard Division. The certification clears a path for all Challenger 604 operators to upgrade to a new LPV-capable FMS from Collins. Universal Avionics, meanwhile, announced certification for its UNS-1Fw WAAS LPV-compatible FMS in the Learjet 60 in a joint effort with STC holder Haggan Aviation of Englewood, Colo.

Duncan Aviation in Lincoln, Neb., has announced plans to certify LPV in a variety of business jets, including two Learjet 45s carrying the Universal UNS-1Ew FMS; two Gulfstream G100s, also with the UNS-1Ew FMS; a Cessna Citation Ultra with a single UNS-1Espw FMS; and a Falcon 900 with Honeywell’s NZ-2000 FMS upgraded with Version 6.1 software. While WAAS LPV approaches use GPS to provide landing minimums similar to those of ILS, upgrading Part 25 airplanes to the satnav capability requires an STC plus the installation of WAAS-compatible GPS receivers and in many cases additional cockpit annunciators.

RNP Coming to an Airport Near You

Required navigation performance will be a key element of NextGen airspace. The benefit of a so-called RNP SAAAR approach is that it can carve out a highly precise, curved path through the sky that usually results in lower landing minimums–sometimes much lower. But gaining approval is a costly and complex endeavor requiring submittal of monthly operational reports to the FAA, pilot simulator training and operations manual revisions. Considering that fewer than 100 RNP SAAAR approaches have been published so far, most operators probably won’t go to the trouble of gaining approval until their home airport has an RNP approach. But as more RNP procedures are created, operators who forego such approvals will be at a disadvantage compared with those who are SAAAR compliant.

To assist operators seeking to upgrade to RNP capability, Honeywell has launched Go Direct, a consulting service designed to help business jet operators take advantage of new RNP SAAAR procedures the FAA is adding at scores of airports around the U.S. The agency plans to publish 60 new RNP SAAAR procedures per year for the next two years. Some airports scheduled to receive an RNP approach in the next 12 months include Teterboro, N.J.; Aspen and Eagle, Colo.; Monterey, Calif.; and Scottsdale, Ariz. If your home airport or an airport you use often offers an RNP SAAAR approach, the approval can mean the difference between landing or having to execute the missed approach and consider other options.

The major advantage RNP procedures have over other types of approach is their tighter lateral boundaries, which allow the creation of curved pathways through mountain valleys or by using so-called radius-to-fix (RF) turns to avoid terrain or obstacles. The RNP SAAAR approach to Atlanta DeKalb-Peachtree Airport (PDK) is a good example of the benefits RNP can provide. The approach to PDK’s Runway 2R incorporates a continuous descending turn designed to avoid the tall towers that block the straight-in approach to the field. Due to the east-west flows at nearby Hartsfield-Jackson International, a straight-in ILS or WAAS LPV approach to this runway would be hard to implement, even if the obstacles southwest of the airport were removed.

While WAAS LPV approaches are excellent alternatives to traditional ILS procedures, they have performance limitations that prevent them from incorporating curved paths. The FAA’s RNP program is aimed more at FMS-equipped operators who can fly curved RF legs. Honeywell’s corporate flight department at Morristown Municipal Airport in New Jersey became one of the first in the country to obtain approval for RNP SAAAR operations, gaining certification for its own Gulfstream G450 and G550. Since then Honeywell has been named an RNP SAAAR designated consultant, giving the company the authority to assist other operators and providing the opportunity to create the Go Direct branded service package.

The service offering is split into three categories, the first dealing with aircraft equipage, the second with the operational approval documentation that must be submitted to the FAA and the third with database validation and ongoing RNP SAAAR recordkeeping. Installing RNP-compliant avionics and uploading the latest FMS software adds to the cost of RNP compliance, as does the database validation and monthly record-keeping program. Additional simulator training is required as well, and all of the large training providers are offering RNP-specific courses. Although the process takes around three months to complete and requires additional pilot training, many operators can upgrade to RNP simply by loading new FMS software, according to Honeywell.

“RNP takes advantage of a lot of technology that has evolved over the last 30 years, such as inertial reference systems, GPS and FMS, but it sets a new performance standard here and now,” said Honeywell’s Cundiff. “We want to help get more operators flying in the RNP environment because the capability is so amazing.”

NBAA has provided the FAA with a list of RNP SAAAR procedures that would benefit business aircraft operators. Several of those approaches are in the process of being created now. Honeywell and Jeppesen worked with the FAA to create an RNP SAAAR approach to Morristown’s Runway 5, primarily as an exercise aimed at showing what is involved in developing such procedures at an airport used predominantly by business aircraft operators. Honeywell never gained final approval for the approach, partly because the three major New York-area airports are undergoing a major traffic-flow redesign that may or may not fit with the RNP procedure as designed. After the New York airspace redesign is implemented, Honeywell might go back and amend the Morristown RNP procedure as needed to gain approval for it, Cundiff said.

Most newer business jets equipped with Honeywell flight management systems can be upgraded for RNP through a software upload to version 6.1 (for NZ-series FMS equipment) or 7.1 (for Primus Epic-equipped aircraft), both of which will be available later this year. Older airplanes might require a new FMS and perhaps other equipment such as an inertial sensor and upgraded GPS receiver. A WAAS GPS receiver is not specifically required, but having one eliminates the need to do a pre-departure RAIM (receiver autonomous integrity monitoring) check. For an FMS to meet the requirements of RNP, it needs to be able to fly a curved path. Also, when the pilot presses the go-around button, the FMS should be able to remain in the nav mode. This latter capability in Honeywell’s FMZ-2000 and Primus Epic platforms is being addressed through software updates, Cundiff said.

Five Gulfstream operators so far have tapped Honeywell’s expertise for the RNP SAAAR approval process. An operator who is interested in gaining operational approval for RNP can should contact Honeywell to determine how best to meet the FAA’s requirements. Honeywell representatives assist the operator with the RNP application as part of a “turnkey” service package costing $90,000.

RNP for Everybody Else

Avidyne founder Dan Schwinn is on a mission to bring RNP capabilities to the general aviation masses by proving that an FMS designed for piston airplanes, turboprops and light jets can do everything a system installed in a multimillion-dollar business jet can do. “Our objective is to make RNP totally mainstream,” Schwinn said. “It couldn’t be further from that now with this SAAAR business–in other words, how to avoid having anybody be able to use RNP for anything.”

Avidyne has designed a clean-sheet flight management system called the FMS 900w that incorporates a number of features and operating logic that until now had been present only at the higher end of the FMS spectrum. This includes RNP legs, route types and transitions presented graphically on the displays. The FMS 900w technically can be used to fly an RNP SAAAR procedure, but it lacks the approval to do so because of the absence of backup nav capability and other FAA-imposed limitations, Schwinn said.

“The FMS is [designed] to do what’s required,” he noted, “but there are a bunch of other things we’re going to have to do before RNP can be enabled. We’re working on those various things. I’d like to see it work out like WAAS LPV has with the adoption over time of RNP.” Allowing light GA airplanes to fly curved RNP procedures, Schwinn said, would help with obstacle avoidance and traffic separation in busy airspace.  

Besides having RNP functionality, the Avidyne FMS can host multiple redundant processes running in tandem. This provides a single apparent interface to the FMS, even though more than one central FMS computer is performing the navigational calculations. In the two-display application Avidyne is currently testing on a Cirrus SR22, two independent FMS computers provide data to a single virtual FMS. The design avoids the problem of a pilot becoming confused by having to deal with two data sources or having to interpret the data in the event one of the FMS computers fails. Because the FMS computers are always synchronized, a failure of one computer won’t be apparent to the pilot except for an alert message noting the failure.

“We’ve built an architecture that will scale up the market pretty much as far as we want to go with it,” said Schwinn. Avidyne’s FMS design team, he said, counted among its group of engineers some who had worked for Honeywell and Smiths on systems for business jets and airliners.

Everything the pilot needs to operate the Avidyne FMS is included on the large multifunction display. Access to Entegra Release 9’s capabilities involves the simple task of pressing a desired bidirectional page key. The various display options within a page are represented as tabs. Pressing the same key in a desired direction navigates through the tabs. All drop-down menus in Release 9 are context sensitive and choices are displayed in a prioritized order. Even the cursor is context-sensitive, providing an indication of whether the operation is intended to insert a leg or to modify an existing waypoint. The design avoids the use of menus and provides a method for performing basic editing functions.   

An integrated, digital WAAS navcom/ surveillance suite is managed within the FMS 900w–a design that Schwinn said re-imagines what the flight management system can be–while dual-redundant databus interconnection automatically synchronizes data among displays, the FMS keypad and a variety of safety sensors. Airplanes in the category of the single-engine Cirrus SR22 represent the low end for the FMS 900w, Schwinn said. “It’s really designed for single-pilot IFR in higher-end Part 23 airplanes, including turboprops and jets,” he said, adding that Part 25 airplanes approved for single-pilot exemptions could also be candidates for the cockpit.

The market introduction of Entegra Release 9 will finally give Avidyne a potent answer to the Garmin G1000 avionics system, which has fared better in the market for a variety of reasons, not the least of which is a perception by some that the Garmin cockpit is more capable and easier to use. With Release 9, Avidyne hopes to erase that perception.

Garmin pioneered the low-end FMS with the GNS 430/530 and later the G1000 cockpit in the Cessna Citation Mustang and a range of piston singles. The G1000 preserved the same modes and techniques used in the company’s hugely popular GNS 430/530 combined navcom units. With tens of thousands of the 430/530 units installed, the operating system has become the de facto standard in general aviation, and that’s quickly becoming the case with the G1000 system as Garmin adds to its list of OEM customers.

Cessna chose the G1000 avionics suite for the Mustang because it delivers “at-a-glance” situational awareness and all the capabilities a pilot of a business jet needs yet costs less than higher-end systems. Consolidating all primary flight, navigation, engine and sensor data onto large, flat-panel displays, the three-screen Garmin G1000 avionics system for the Mustang is similar to the avionics in Cessna piston airplanes, except for the inclusion of a dedicated FMS keypad.