Not long ago Gulfstream greatly increased the size of the cabin on its G100 to create the true midsize G150. With more than 50 of the new airplanes in service, the company is now busy adding the advanced capability of its larger airplanes to the high-performing midsize.
The most recent addition is Gulfstream's Enhanced Vision System II (EVS II) that uses an infrared camera mounted on the nose to peer through darkness, precipitation and murk to show pilots an image of the real world ahead of the airplane. The system has been flying on the big Gulfstreams for several years, and the "II" version, introduced earlier in 2008, improves performance while saving weight and space.
The EVS II camera is mounted in a small blister on top of the nose cone of the G150. On the larger airplanes the camera blister is on the underside of the nose. The top mounting gives a very true image of objects on the surface for taxi and runway operations without the parallax of having the camera below your feet. The camera is mounted behind a heated lens that prevents fogging or ice formation.
The infrared camera actually detects temperature differences rather than light. Runway lights, obviously, are warmer than the area around them so they show up clearly. But pavement is warmer than grass, so you can see the actual runway in the EVS image. And when you get closer, the paint of the runway centerline and numbers is a slightly different temperature than the pavement so they, too, are clearly visible.
So far the EVS image in the G150 is displayed only on the Collins PlaneView avionics displays in the cockpit. The ideal way to show EVS to the pilot flying is through a head-up display (HUD) so he can see the visible picture merged with the infrared image, plus all primary flight display and flight path guidance. That's how its done on the large cabin Gulfstreams, and with that system, crews are qualified to descend to 100 feet above the runway based on the EVS image on the HUD. At that altitude the pilot must see the actual runway lights to continue to land. But that's not an issue because the real lights and the EVS view of them on the HUD are one and the same. I, and other pilots, have landed a Gulfstream with the windshield blocked using only the EVS image and it is perfectly natural.
To see the EVS in action in the G150 we waited until well after sundown to go flying. The image can be selected on either of the two center multifunction displays (MFD) using either the top or bottom window. The top is so much better there is no point in messing around with EVS on the lower window of the display.
On taxi I could clearly see the taxi center stripe with the lights off and could easily make out the reflectors located along the stripe. With one pilot monitoring the EVS image it would be a snap to see a vehicle, other airplane or even animals ahead of the airplane. It is a definite safety advantage at night or in low visibility, particularly at uncontrolled airports.
In flight the EVS image can be adjusted for gain or brightness manually, or left in auto mode. The manual adjustment is useful when flying over brightly lighted urban areas, but otherwise, the auto mode works well. Hills, towers or other terrain features are clearly visible in the darkness, or through reduced visibility. Also, EVS shows clouds so if there are building cumulus that don't have enough precip yet to show on radar, you can see them in the dark and go around their bumpy ride as you would in daylight.
On approach to a long, well-marked runway the EVS image showed excellent detail of the airport environment from miles out. It was even more impressive going into a shorter runway that had only low intensity runway lights and no VASI or other aids. I glanced down as I neared the threshold and could easily read the runway number on EVS, but not with unaided vision. The camera is aimed down slightly from the airplane waterline so the runway threshold stays in view until you are nearly on top of it.
EVS II can be installed in any existing G150 for a cost of $340,000 and a weight of about 40 pounds. A new compact HUD from Collins will be along later and the EVS image can be projected on that. And Gulfstream will soon offer full authority autothrottles from Safe Flight and, again, the system can be installed in new and existing G150s.
Gulfstream has measured a dispatch reliability greater than 99.6 percent for the G150, matching the reliability of the large-cabin models. The airplane is the smallest Gulfstream, but it is showing very good breeding.
