A-034-4-8

1000-meter scale of the A-034-4-8

The A-034-4-8 belongs to the standardized A-034-4 family of radio-altimeter indicators. The main difference between the versions is the scale and display range. This version is designed for indication from 0 to 1000 meters, which gives the crew a wider radio-altitude picture than narrow low-range indicators. It is useful for aircraft that need height awareness not only near the ground, but also in extended low-altitude and medium-height profiles. The general construction remains similar to other A-034-4 indicators, but the dial layout is specific to this range.

Scale graduation on the A-034-4-8 indicator

The A-034-4-8 scale uses different graduation zones to keep the instrument readable across the full range. From 0 to 20 meters, the scale division is 5 meters. From 20 to 100 meters, the division changes to 10 meters. From 100 to 1000 meters, the scale uses 100-meter divisions. This layout gives more detail in the lower part of the range, where small height changes matter more, while keeping the upper part of the dial simple and easy to read. It is a practical cockpit scale, not a uniformly divided measuring ruler.

Danger altitude warning on A-034-4-8

The indicator includes a danger altitude setting sector with a selector and an integrated warning lamp. The crew can set the required warning threshold according to the flight task or operating procedure. When the aircraft descends to the selected value, the warning circuit activates the lamp and draws attention to the dangerous height condition. This function reduces the need to constantly compare the pointer with the scale during a busy phase of flight. It is especially useful during descent, approach, night flight, poor visibility or operation over featureless terrain or water.

TEST button and blinker flag of A-034-4-8

The A-034-4-8 has a front-panel TEST push button for checking the radio-altimeter indication channel. When the system is operating correctly, pressing TEST moves the pointer to the control reference. If the pointer does not respond, or if the radio altimeter becomes inoperative, the drop-out blinker flag appears. The blinker also indicates loss of usable altitude information, including loss of ground reflection in the system channel. For the crew, this is a clear sign that the displayed indication should not be trusted until the radio altimeter set is checked.

A-034-4-8 with A-037 transceivers and antennas

The A-034-4-8 operates with A-037 radio altimeter equipment, including A-037-1 series transceivers and the system antennas. Compatible transceiver versions may include A-037-1A, A-037-1B, A-037-1V and A-037-1G, depending on the aircraft configuration and documentation. At system level, the radio altimeter operates in the 4200–4400 MHz frequency band. The indicator is only the cockpit display element, so troubleshooting should include the transmitter-receiver unit, antennas, wiring, power supply and protection circuits, not just the front instrument.

Identification and supply of A-034-4-8

When ordering or replacing the A-034-4-8, the full designation should be used together with the required scale range. A-034-4 indicators may look similar externally, but they can differ by range, dial graduation, markings, warning settings and compatibility with a specific A-037 configuration. Before installation, the indicator should be checked for pointer movement, scale readability, TEST response, blinker operation, warning lamp function, connector condition and documentation. If supplied from storage or repair stock, service status and passport availability should be clarified before acceptance.