Situational awareness is fundamental to safe flight. Cockpit instruments can provide precise indications of an airplane’s position and trajectory, but once the world outside grows too dark, cloudy or foggy to see, pilots must rely on the safety margins built into IFR procedures to maintain safe separation from the ground.

Most pilots, that is. A small but growing minority benefit from the enhanced- and synthetic-vision systems (EVS and SVS) that are becoming available even for single-engine turboprops and helicopters.

Gulfstream has led the way with enhanced vision. Since winning supplemental type certification for EVS on the Gulfstream 500 in September 2001 it has installed the system on more than 250 aircraft, and the company is on track for certification this year of both the second-generation EVS (EVSII) and the synthetic vision primary flight display (SV-PFD) that it announced at last year’s Farnborough International airshow.

Both systems were evaluated last fall aboard a G450 during two days of flight testing at Aspen, Colorado. The two pilots involved found that at night the EVSII displayed a clear image of surrounding mountains that blended into the background of the dark night sky when seen with the naked eye.

EVS enables pilots to see runway markings, taxiways, adjacent roads and surrounding areas in conditions of low light and reduced visibility, and helps them avoid runway incursions and other hazards. Since February 2004 the U.S. Federal Aviation Administration has allowed pilots using certified enhanced flight vision systems (EFVS) on a straight-in approach to descend below decision height, decision altitude or minimum descent altitude, though they must be able to see the required cues without the EFVS before descending below 100 feet.

As the FAA noted, the rule could allow for “operational benefits, reduced costs and increased safety for aircraft equipped with an EFVS.” Used with a HUD, the agency added, the system “may improve the level of safety by improving position awareness, providing visual cues to maintain a stabilized approach and minimizing missed approach situations.”

The EVSII is based on a forward-looking infrared camera (FLIR) from Kollsman (Booth No. 441), which also supplies the sensor for the first-generation system. The camera has an improved cryogenically cooled detector that is more sensitive in identifying runway lights during the approach. The imagery it generates is displayed on the Honeywell head-up display (HUD) and can be viewed on two of the four head-down displays in Gulfstream’s PlaneView cockpit.

Kollsman, which markets its EVS under the Weather Window brand, has gone on to announce additional options. Grob selected its Gavis general aviation vision system, which comes complete with aerodynamic fairing, to equip its new SPn utility jet. The Micro-ViS HUD, which does not require an overhead projection unit, can be overhead- or panel-mounted in cockpits too small to accommodate conventional units. And it has launched an ESVIS (enhanced synthetic vision system) program to develop a hybrid system combining enhanced and synthetic vision.

Gulfstream’s PlaneView, which is based on the Honeywell Primus Epic, is also the platform for the SV-PFD, which overlays a large three-dimensional color image of terrain with the PFD instrument readings. The terrain view combines data from Honeywell’s enhanced ground proximity warning system (EGPWS) with data on obstacles to depict terrain, obstacles, runways and approaches. The PFD element, meanwhile, augments the standard symbols with HUD symbology, including a flight path marker, a path-based flight director runway outline and a runway lead-in line.

Jeppesen (Booth No. 1105) has developed its own terrain database to support SVS development by avionics manufacturers as well as its own electronic chart and flight planning products. Combining data from the U.S. Space Shuttle’s radar topography mission with information from other sources, the Jeppesen database covers the latitudes between 60 north and 56 south at a resolution of 3 arc-seconds or 90 meters and the remaining areas at a minimum of 30 arc-seconds. It uses a proprietary process to create minimum safe altitude buffers based on terrain classification, source and the proximity of the terrain to an airport.

The Bombardier EVS (BEVS) that is installed as standard on the Global Express XRS and as an option on the Global 5000 is also available for retrofit on Global Expresses. Developed by Thales (Booth No. 1271) and certified in August 2005, it combines the French firm’s 40- by 26-degree head-up flight display system with a CMC Electronics SureSight infrared sensor system for a total weight of less than 100 pounds.

Field of view for the raster image produced by the FLIR is 30 degrees, and the camera is mounted in the upper nose, in line with the pilot’s normal line of sight, to give what Bombardier says is a more natural cockpit view. The imagery is also shown on a head-down display for the copilot.

CMC (Booth No. 1233) delivered its 100th SureSight EVS system last October. The I-Series sensor used for the BEVS has a cryogenically cooled infrared detector system operating in both the 1 to 3 micron and 3 to 5 micron infrared bands.

The SureSight range also includes the low-cost M-Series sensor, an uncooled, single and sealed LRU weighing just 2.2 pounds that provides enhanced situational awareness. Pilatus selected the camera plus CMC’s PilotView Class 2 electronic flight bag for displaying the imagery as a forward-fit and retrofit option for the PC-12. The sensor system is also installed on several helicopter models.

In March, Universal Avionics Systems (Booth No. 1012) added European certification of its Vision 1 SVS to the FAA approvals already secured. Vision 1 provides both an egocentric view of the terrain ahead, oriented to the aircraft’s lateral and vertical position, and an exocentric or wingman’s view.

The egocentric view maintains the standard foreground symbology with traditional flight director cues but replaces the blue-over- brown background with real-time terrain view imagery oriented to the airplane’s heading, pitch and roll attitude.

The exocentric view provides a view of the aircraft, flight profile and terrain based on the FMS flight plan and portrayed from a point of view above and behind the aircraft.

By early next year there should be a certified EVS for the Boeing Business Jet. Rockwell Collins (Booth No. 720) is working to integrate a multi-wavelength infrared sensor from Max-Viz with its own head-up guidance system (HGS) 4000 HUD, which is installed as standard on the corporate and VIP 737 derivative. The upgrade will be available as a Service Bulletin and will require an upgrade to the HGS 4000 as well as the addition of the sensor, according to Boeing.

Max-Viz makes two uncooled sensor systems, the long-wave EVS-1000 and dual-band EVS-2000. Cessna offers the EVS-1000 as a Service Bulletin retrofit for the Citation Excel and XLS.

Further down the platform size scale, L-3 Avionics Systems (Booth No. 1646) has adapted a camera used in automobile applications to produce the Iris EVS. Targeted for helicopters, high-end piston airplanes and possibly business jets, the Iris EVS uses a barium strontium titanate sensor and produces imagery that can be viewed on head-down displays.