A-034-4-18

Reading the 0–1500 m scale of A-034-4-18

The supplied product photograph shows a non-linear metric scale extending from zero to 1500 metres. The lower range is expanded around the first tens and hundreds of metres, while the upper part of the scale is compressed. Visible reference values include 20, 40, 60, 80, 100, 150, 200, 300, 400, 500, 600, 1000 and 1500 m. This arrangement gives the pilot more visual resolution close to the ground without requiring a larger instrument face.

During operation, the main pointer follows the signal received from the radio-altimeter electronics. The reading represents clearance above the reflecting surface directly beneath the aircraft, not barometric altitude above sea level. Terrain relief, bank angle, antenna installation and the valid operating envelope of the associated system can influence when a reliable indication is available. The crew must therefore interpret the pointer together with the aircraft flight manual, warning indications and other flight instruments.

Danger-height setting and visual warning functions

A yellow rotary selector on the lower right of the face is used to set a danger-height reference. The selected threshold is represented on the scale by the associated index mechanism. When the aircraft descends through the preset radio height, the connected warning circuit can provide a visual or combined warning according to the installed radio-altimeter configuration. The lower-left red element forms part of the warning and control interface visible on this execution.

A red sector or flag on the scale is used as a reliability cue when the radio-altimeter signal cannot be used, the equipment is outside its valid range or a fault condition is detected. Exact behaviour depends on the complete system and must be checked in the relevant operating documentation. A serviceability check should include smooth pointer movement, correct operation of the height selector, flag response, illumination, connector condition and the system test mode. The scale and warning elements must remain clearly visible through the glass.

Interaction with A-037-family radio-altimeter equipment

The A-034-4 indicator family is associated with radio-altimeter installations such as the A-037 family and related low-altitude equipment. In a typical signal chain, antennas transmit and receive the radar signal, the transceiver processes the reflected signal and forms altitude information, and the cockpit indicator displays the result. The indicator also provides the crew interface for choosing a warning height and receiving fault or low-height cues.

Aviamisto catalogues related system equipment such as the A-037-1 transceiver and the A-037 Version 10 set. These links explain the general radio-altimeter architecture, but they do not establish automatic interchangeability with the -18 indicator. The exact transceiver, antenna set, cable and connector combination must be confirmed for the intended aircraft configuration.

Cockpit installation, applicability and ordering checks

The instrument is intended for recessed mounting in a pilot instrument panel. Its square front flange, four mounting points, circular scale and two lower controls remain accessible to the crew, while the cylindrical body and electrical connector are located behind the panel. Published supplier references associate A-034-4 indicators with several aircraft and helicopter installations. Mi-8-family helicopters and An-26 or An-72 aircraft are reported for related configurations, but exact applicability of A-034-4-18 should be treated as unconfirmed until it is matched to the aircraft component list.

Before ordering, compare the complete designation, 0–1500 m scale, dial language, illumination supply, connector, mounting depth and warning interface with the removed unit and aircraft documentation. The offered part should also be checked for passport, preservation record and test documentation when these are required. The product is listed in the Altimeters & Indicators category. Exact mass, overall dimensions, connector pinout, operating temperature and backlight supply for the -18 execution require confirmation from its own passport or technical conditions.