ARK-9

ARK-9 use with NDB and approach procedures

In aircraft equipped with ARK-9, the system can be used for en-route navigation, helicopter navigation, aircraft positioning and pre-landing maneuvers. It is especially relevant for approaches based on outer and inner non-directional beacons, where the crew must track the bearing to the selected station during the approach sequence. The unit can be preset to two frequencies, which allows fast switching between two beacons, for example the outer and inner marker stations used in older landing systems. This makes the ARK-9 useful in aircraft that still operate with classic radio-navigation procedures.

Operating modes of the ARK-9 system

The ARK-9 has several working modes. In automatic compass mode, the receiver uses both the loop antenna and the non-directional antenna, and the cockpit indicator shows the bearing to the selected station. In antenna mode, the system works through the non-directional antenna for audio reception, station search, and call-sign identification. In loop mode, the crew can use manual bearing by listening for the minimum signal level while rotating the loop antenna. This manual mode is useful when electrical interference makes automatic bearing less stable.

ARK-9 receiver and antenna equipment

The ARK-9 set includes a receiver, remote control panel, directional loop antenna unit, non-directional antenna equipment, antenna matching or amplifier elements, power supply and switching units. The receiver performs signal selection, amplification and detection. The remote control panel is placed in the cockpit and is used to select frequencies and operating modes. The directional antenna unit contains a rotating loop assembly used for bearing determination, while the non-directional antenna helps remove ambiguity and supports audio reception. Together these blocks form one complete radio compass system.

Cockpit indication with ARK-9

The bearing information from the ARK-9 is displayed on a cockpit course indicator, commonly through instruments such as UGR-4UK or compatible heading / bearing indication equipment, depending on aircraft configuration. The pilot reads the relative bearing to the tuned station and uses it for navigation decisions. Audio output to the pilot’s headset is also important, because beacon identification is done by listening to the station call sign. Without correct audio identification, the bearing may be technically displayed, but the crew cannot be sure that the receiver is tuned to the intended station.

Aircraft application of ARK-9

The ARK-9 was installed on different Soviet and post-Soviet aircraft and helicopters, including An-2, Yak-18T, Yak-40, Mi-2, Mi-8 and other aircraft depending on configuration and modernization status. On helicopters, the radio compass is especially useful for navigation to radio beacons, airfields, temporary landing sites, and route points where older radio-navigation infrastructure is still in use. Before supply or replacement, the exact aircraft type, existing wiring, antenna installation, indicator type and control-panel arrangement should be checked against the aircraft documentation.

Maintenance and supply of ARK-9

The ARK-9 is a multi-block radio-navigation system, so procurement should not be limited to the receiver alone unless the requirement is clearly for a separate replacement block. A complete set may include the receiver, loop antenna, control panel, power supply, antenna units, distribution boxes, control shafts and cabling elements. In maintenance, technicians check receiver operation, tuning, antenna rotation, remote control operation, audio output, bearing accuracy, power supply, connectors and mechanical condition of the installation. For aircraft use, documentation and completeness should be confirmed before shipment.