DCS: AH-64D | Terrain Profile Mode on MPD

Video Description

CORRECTION: I misspoke saying the range markers indicate 100 m, 1 km, and 2 km. In fact, they are 100 m (smallest arc), 1 km, 2 km, and 2.5 km. In this DCS: AH-64D video, we’ll look at the Terrain Profile Mode, or TPM, as displayed on a multipurpose display, or MPD. Later, we’ll also add TPM C-scope symbology within the helmet mounted display. Using the fire control radar, TPM is used to aid in terrain and obstacle avoidance while operating at low altitudes during low-visibility conditions. If the local visibility conditions deteriorate below 1½ statute miles (~2.5 km), TPM allows the crew to detect terrain or obstacles within their flight path before they become visible to the crew. However, TPM is only intended to augment the crew’s ability to visually see and avoid hazards by providing early warning; it cannot replace it. We’ll in a hot-start aircraft, hovering in northern Iraq. Based on earlier videos, we’ll enable the Fire Control Radar, or FCR, as our sight by pressing left on the Sight Select switch, and then pressing left on the FCR Mode switch to select TPM. As with other FCR modes, we can elect to have the FCR scan continuously or in single scanburst mode. In this example, we’ll set to continuous. On the MPD, TPM will display the terrain ahead in one of three colors, as you can see in the valley ahead: • White shading. Terrain with an elevation that is at or above the current helicopter altitude. In other words, you will collide with such terrain along your path. • Dark Gray shading. Terrain with an elevation that is below the current helicopter altitude but above the selected clearance plane. • Light Gray shading. Terrain that cannot be detected by the FCR, also referred to as “dead space”. This includes areas of radar shadow created by the terrain itself or below the lower limit of the FCR vertical scan volume. • Black shading. Non-hazardous terrain. Note that vegetation and trees are not accounted for on the TPM, and this should be factored with additional clearance when terrain is appropriate. These colors are displayed within the FCR Footprint that can vary in size between narrow and wide automatically based on your airspeed and altitude. If over 55 knots, narrow will be displayed with a 90-degreee cone and out to 2.5 km. If below 45 knots though, wide will automatically be selected, and it will have an 180-degree scan area and display out to 2.5 km. Within the footprint, we can also see range arcs at 100-meter, 1 km, and 2 km intervals and the scan wiper when the FCR is scanning. There are also four pushbutton functions. The Clearance Plane, or CLEARANCE, button determines the altitude clearance between the landing gear and the terrain. This can be set between 20, 50, 100, and 200 feet. When the FCR is not scanning, the Antenna Elevation, or ELEV, can be set between NEAR or FAR. FAR is the default setting and stabilizes the FCR scan -0.5 degrees below the horizon. This is most often used over flat terrain or high terrain is expected. The NEAR setting angles the scan -3 degrees below the horizon and is best for terrain measurements at close range or when descending a slope for better obstacle detection. The Profile, or PROF, and Profile Lines, or LINES, will come when TPM C-scope symbology is added to the HMD. We’ll come back to these in a later video.