The Israeli air force is testing a cockpit upgrade for its Sikorsky CH-53 helicopters.

Arie Egozi/TEL AVIV

OPERATIONAL evaluation of Israeli air force upgraded Sikorsky CH-53s has only just begun, but the pilots are already saying that the new avionics have stretched the capability of the heavy-lift helicopter beyond anything that they have known.

The air force decided to upgrade its 42 CH-53s after almost 25 years of operating different types of the helicopter. "We decided to extend its operational life and improve its capability because there are no substitutes on any drawing board," says a senior air force official. The upgrade programme has been based on the experience of the air force in flying CH-53s under different conditions, including combat and special missions.

The idea behind the CH-53 2000 upgrade, is to lower pilot work-load and improve the capability to perform missions, requiring accurate navigation, in high-threat areas. The solution is a glass cockpit, which allows hands-on collective and stick (HOCAS) flying under all conditions. Israel Aircraft Industries (IAI) was selected as prime contractor with Elbit as avionics integrator. Airframe changes were minor, resulting mainly in a higher maximum take-off weight.

Most of the changes were made in the avionics. The two multi-function colour displays (MFCDs) are the main external features in the redesigned cockpit. A new mission computer allows the MFCDs to replace the paper maps and lists, which had been used previously.


Minor changes were made in the stick and collective to allow HOCAS selection of all the displays available on the two MFCDs. With a flip of a switch, the displays offer the pilot, or pilot and navigator, a variety of data stored on the high-capacity optical-disk system. The 150 x 150mm MFCDs can display normal maps or zoom on an area of special interest to show aerial photographs and to overlay these with threat symbols. The flight route can be planned according to the threats and other limitations. The system presents line-of-sight (LOS) from known threats such as missile batteries. When a green line connects the helicopter's position with the threat's position, the route flown is safe. When the line becomes red, the LOS imposes immediate danger and the route should therefore be changed. Simulated routeing can be used to help in planning a safe route.

The pre-planned route can be updated easily using real-time data, immediately before take-off or during the flight. This is made possible by the cockpit-interface unit located near each MFCD. "In the old cockpit, the captain could not be involved in the route changes. With the dual displays in a copy mode, the captain is a full partner in changing the route. The access of the experienced captain to the changing procedure is sometimes vital," says another senior air force officer.

The Doppler/global-positioning system (GPS) navigation of the CH-53 was also upgraded and now the satellite-based navigation system corrects the radar-based solution every second. Accuracy is absolute and, as important, the Doppler system "learns" to be more accurate by accumulating the constant data. "If at any point the GPS is blocked, the Doppler will function more accurately," says the squadron's technical officer.

The Elbit night-vision-goggle/head-up-display system is integrated into the upgraded avionics system, allowing full night capability. The human-engineering effort in the redesigning of the cockpit went far. The radio-frequencies selector was transferred from the front panel to the collective, and the captain can operate the main modes of the avionic systems from a switch on the stick.

The up-grade continues and as more modified CH-53s are deployed to air force squadrons, the software "blocks" are being added to obtain the best performance, from this unique heavy helicopter. The CH-53 2000 cockpit (left) incorporates multi-function colour displays (above). The flight technician's panel (far left)

Source: Flight International