GUY NORRIS / LOS ANGLES
Two of pilots' worst enemies - darkness and poor visibility - could be defeated if rulemakers can agree on certification and development issues for EVS technology
Enhanced vision systems (EVS) grabbed most of the headlines at last year's National Business Aviation Association (NBAA) show, and for at least two good reasons. Several positive developments for the technology provided bright spots at the event and a contrast with the gathering gloom settling on the industry. Secondly, it seemed that after several false dawns, EVS was finally taking off.
EVS allows pilots to see the outside world in darkness and poor visibility. Commonly based on head-up or head-down displayed (HDD/HUD) images from infrared (IR) sensors, EVS was originally intended as a landing aid. Certification and development issues, however, have pushed it primarily towards a safety role in which its improved situation awareness capability - on the ground and in the air - is recognised as a key operational enhancement. EVS is therefore seen as directly addressing three major industry concerns: controlled flight into terrain (CFIT), accidents during approach and landing, and the issue of runway incursions.
More recently, however, the push to gain landing benefits with EVS has resumed. Two factors are widely believed to be behind this: the service entry in May 2002 of the first EVS system on a Gulfstream V (a US Navy-operated C-37A); and the inclusion of EVS among a suite of advanced technology features on Boeing's 737-900 technology demonstrator aircraft, also in 2002.
The trend took solid form in February this year when EVS unexpectedly became the focus for a US Federal Aviation Administration notice of proposed rulemaking (NPRM). In its proposal, the FAA says it is considering revising "its regulations for take-off and landing under instrument flight rules [IFR] to allow for the use of FAA-certified enhanced flight vision systems [EFVS]." In other words, the potential new ruling opens the door to landing benefits in the form of lower decision height minima to EVS-equipped aircraft, and is aimed at all categories of aircraft operating under FAR Parts 91, 121, 125, 129 and 135.
Industry responses were filed by late March and, not surprisingly, included mixed reactions. These ranged from objections to the inclusion of the word "flight" in the newly coined acronym EFVS, to comments from Boeing saying "this particular NPRM has serious conceptual flaws and its proposed requirement could potentially lead to adverse technology evolution and safety effects".
Speaking for the Part 91 (business aviation) community in particular, NBAA president Jack Olcott welcomes the FAA move, but notes that restrictions cited in the proposed rule (such as altitude limits) are "artificial and do not represent the equipment's potential; operational limitations should be based on equipment certification". The NBAA also says that, while all operators should be able to use EFVS, the new ruling should be restricted initially to Part 91 if development of a broader rule for all operators faces any sort of delay.
Given the widely differing reactions, the FAA is expected to put its proposal to an established aviation rule-making committee such as TOARAC, which advises on terminal area operations, or the All-Weather Operations Harmonization working group. The one thing all parties appear to agree on is that the FAA's action has done more than any recent event to raise awareness of EVS, both as a fast-maturing technological capability and as a situation awareness enhancement with massive operational and safety potential.
Lack of consistency
Gary Ball, the acknowledged founding father of EVS, believes the FAA action has "the potential" to accelerate the concept's acceptance, but cautions that the current technology lacks consistency and may still lag behind the level of fidelity that some airworthiness authorities require. Ball, who patented the EVS invention in 1994 after applied thermal imaging research work at Hughes Aircraft in the late 1980s, says the current situation is analogous to the early years of the video industry, when different standards emerged simultaneously. "At some time in the future, it will be in everybody's benefit to standardise. However, I am concerned that there are some excessive claims being made by competitors, and that every time someone makes a claim that can't be supported, the credibility of EVS is damaged and everyone suffers."
Setting the standard is difficult, Ball acknowledges. "You cannot make a blanket statement that all the systems will perform the same. It's not a question that system A is better than B. It depends on the micro-physics of the fog and a bunch of other physical parameters, along with how the sensors are being used and the strategy by which they are being employed. You cannot have a simple metric for EVS performance."
As with so many avionics and flightdeck advances, business aviation has been at the forefront of EVS progress. Nowhere is this more true than Gulfstream's pioneering EVS development with Kollsman Avionics and its HUD partners BAE Systems and Honeywell. Even competing EVS suppliers CMC Electronics of Canada and Portland-based Max-Viz acknowledge the industry-wide benefits of the Gulfstream-led team's work and the public-relations value of their widely seen video of night approaches to Aspen, Colorado, using the EVS.
The Kollsman EVS system, now installed or ordered for around 100 G500/G550s (GV/GV-SPs), can be traced to the original development and licensing agreement Kollsman signed with Infrared Systems International (ISI) in 1997. ISI was set up by Ball after leaving Hughes to develop and market EVS for aviation, and is now part of California-based Advanced Technologies.
Since obtaining US certification for the first EVS on the GV in October 2001, Gulfstream received approval by early 2003 for retrofit of EVS on the GIV-SP. EVS also forms part of the PlaneView advanced flightdeck in Gulfstream's new G550 long-range aircraft, which received provisional US certification in December 2002. EVS is offered as an option on the GV-based G500, which uses the same Honeywell Epic-based cockpit. Acknowledging growing owner demand for the safety enhancement, Gulfstream is also making it available on the GIV-based G300 and G400, both of which use Honeywell's SPZ-8400 avionics.
Broadband cooled camera
Kollsman's EVS, which is compatible with any raster-capable HUD, uses a broadband cooled camera that operates in near and mid-wave IR (1-5µm) and can detect runway lights and ground features, theoretically allowing lower approach minima. However, a proposed night window system, using an uncooled long-wave IR system, is being studied to provide awareness of surrounding terrain during clear night operations and would not, it is thought, provide lower approach minima.
Meanwhile, CMC and Max-Viz have quickly established themselves as fast-growing rivals in the business aircraft EVS arena. CMC is also positive about the NRPM and its possible effects. EVS marketing manager Mike Venables says: "It's great, it is much more than we had expected at this time. We believe EVS will be as significant as weather radar was in the 1950s." Max-Viz director of operational requirements Richard Hansen also adds that responses to the proposal show "an almost universal acknowledgement of the additional safety benefits of EVS, while the proposal shows the FAA is looking at advancing technology to improve safety levels, and wants to stick with EVS".
CMC's big move into the business jet world has been secured through Bombardier, which selected CMC's SureSight dual-band IR EVS and a Thales Avionics HUD as standard equipment on the Global Express. Flight tests of the IR system, dubbed the I-series, are expected to start on a Bombardier aircraft around July, with certification targeted for March next year. First deliveries of the fully integrated Thales-led EVS suite on the Global Express are due to begin in 2005. The work is partially supported by a C$9.9 million ($6.2 million) development grant from the Canadian government's Technology Partnership Canada (TPC) programme. The government investment will be repaid from sales royalties. The TPC funding supports development work on video processing and software integration, as well as simulation and flight testing.
The agreement with Bombardier also gives CMC two years worth of exclusivity, and provides new opportunities for later generations of SureSight sensors. These include using focal plane arrays from IR sensors aimed at military applications, with 30 times more sensitivity than the present commercially available systems. Export sensitivity surrounds some aspects of the InSb (indium antimonide) technology at the heart of the cooled sensor (which converts IR energy into electricity to generate an image), although CMC is confident that "regulations will unfold" to allow advanced versions to flow through to the commercial market.
Lower-cost applications
For lower-cost, enhanced situation awareness applications, CMC is also developing the uncooled M-series. This micro-bolometer-based system operates in the 8-14µm range, "which means it will see the whole scene, but not the approach lights", says Venables. The I-series, operating in the 1-5µm range, "will see the runway and the approach lights", he adds. The lighter M-series, which will weigh less than 3kg, will display images on an HDD. "We expect that something like a Learjet-sized aircraft would be a candidate for the M-series, as would smaller [Cessna] Citations," says Venables. Flight tests of the M-series are expected to begin next January, with certification likely to be approved as early as the following April.
Max-Viz, until recently a relatively unknown new company, has made dramatic strides in its quest for market recognition with two main uncooled IR-based EVS systems - the EVS-1000 and EVS-2000. The company's biggest coup to date is its selection by Cessna and Dassault for their respective Citation and Falcon families. In March, Max-Viz also received the first FAA certification for an EVS without a HUD, when its EVS-1000 installation was approved on a Bombardier Challenger 601-3A modified by California-based Total Aircraft Services.
"Business aviation OEMs [original equipment manufacturers] see things differently. Business aviation is expanding to many more outlying points and demands more safety. Therefore, the OEMs want EVS across their entire product line, and we have different offerings to suit different needs. The first to sign up for that was Cessna, and we're talking to them about all of the aircraft they have in production," says Max-Viz president Gregg Fawkes. The dual-sensor EVS-2000, which uses a combination of short and long-wave IR sensors in the 1.2-1.6µm) and 8-14µm ranges, respectively, is available on the Sovereign and Citation X, both of which will be certified with EVS by the end of 2003.
The lighter, single-channel EVS-1000, aimed mainly at enhanced situation awareness, is to be offered on the Citation CJ1, CJ2, CJ3, Bravo, Encore and Excel. It is also expected to be offered on the Mustang, although Fawkes adds that there are "no signed up customers for the Mustang". Initial EVS-1000 deliveries on the Citation family are also expected by year-end.
Flight tests of the EVS-1000 on the Dassault Falcon 900EX are close to completion, with certification expected as early as May. A separate FAA supplemental type certificate (STC) for US-operated Falcon 900s is also expected around mid-June, with another STC for the Falcon 50 possibly preceding it by around one month. Work is also under way to certificate the system in the Falcon 2000. As with the Challenger installation, the Falcon EVS system is housed in the fin cap, although a nose-mount in the radome is optional.
The Cessna mounting, known specifically as the EVS-2500 in the case of the Citation X and Sovereign, is protected beneath a Kevlar fairing on the upper side of the nose aft of the radome. To minimise frontal area in the Citation X system, Max-Viz has developed a beam-splitter arrangement which allows both short and long wave sensors to use a single window.
Wide field of view
Max-Viz is also developing a wide-field-of- view sensor array covering up to 150° by "ganging" three EVS-1000s together. This system is being flight tested by several US helicopter operators, and has been demonstrated to the US government, says the company. Further off, Max-Viz is also examining an advanced EVS which fuses IR imagery with data from a millimetre-wave radar. "At the moment, it's operating at around 94GHz, but we're looking at going to 140GHz to improve resolution," says Fawkes who adds that trials could begin in the company's Cessna flying testbed by the end of the year.
For possible HUD-related EVS applications, such as the Boeing Business Jet, Max-Viz is also working closely with its Portland-based neighbour Rockwell Collins Flight Dynamics. The two companies are keen to explore the joint potential of EVS in several key markets, including the Falcon family. "We have around 150 Falcons that have the HUD in them, and all have a slot-in capability for a raster-card, and can be upgraded easily," says Flight Dynamics senior manager corporate aviation, Larry Brandt. All the indications are there that the long-awaited EVS era is finally about to begin.
Source: Flight International
