A-034-4-17

Altitude scale of the A-034-4-17 indicator

The A-034-4-17 has a measuring range from 0 to 300 meters. The scale is not divided evenly across the full range, because low heights require more precise visual reading. From 0 to 20 meters, the scale division is 1 meter. From 20 to 50 meters, the division changes to 2 meters. From 50 to 300 meters, the scale uses 10-meter divisions. This layout makes the instrument easier to read in the most critical low-altitude zone while still giving the pilot a full 300-meter radio-height indication.

Control sector and TEST function on A-034-4-17

The A-034-4-17 includes a marked control sector on the scale. This sector is used during functional checking of the system. When the TEST button is pressed and the radio altimeter system is operating correctly, the pointer should move to the control value. This gives the crew or maintenance personnel a quick way to confirm that the indicator and the related radio altimeter circuit respond properly. If the pointer does not move to the expected value, the system should be checked according to the A-037 technical documentation.

A-034-4-17 in the A-037 radio altimeter system

The A-034-4-17 works as part of the A-037 radio altimeter system. The complete system includes the radio altimeter equipment that generates height data, antennas for transmitting and receiving radio signals, power supply circuits, protection devices and cockpit indication. The indicator is only one element of this chain. If altitude indication becomes unstable or incorrect, the fault may be in the indicator, antenna circuits, transmitter-receiver unit, power supply, wiring or protection equipment. For that reason, troubleshooting should be done at the system level.

Low-altitude indication role of A-034-4-17

The main value of the A-034-4-17 is clear visual indication at low altitude. Radio altitude is important because it shows the actual height above the surface below the aircraft, not the altitude relative to sea level. This is useful when flying close to terrain, during landing, over flat ground, over water or in conditions where the crew needs direct awareness of clearance beneath the aircraft. The pointer format is simple and quick to read, especially when the pilot needs to notice changes in height rather than focus on a digital number.

Installation and service notes for A-034-4-17

The A-034-4-17 is installed on the left instrument panel of the flight crew cockpit according to the provided installation data. During maintenance, the indicator should be checked for scale readability, smooth pointer movement, correct TEST response, connector condition, secure mounting and absence of mechanical damage. Since the instrument belongs to the A-037 radio altimeter system, replacement should be made by exact designation and compatibility with the aircraft configuration. Similar A-034 indicators may have different ranges, scales or system variants, so they should not be treated as automatically interchangeable.

Supply and documentation of A-034-4-17

When ordering the A-034-4-17, the full designation should be used together with the required condition: new, from storage, repaired, overhauled or serviceable with documents. It is also useful to specify that the indicator is required for the A-037 radio altimeter system with a 0–300 m scale. Before installation, the unit should be checked for documentation, testability, storage condition, connector integrity and compatibility with the aircraft’s flight and navigation equipment. Technical and operational documentation should be requested with the item when needed for installation or acceptance.

Related instruments: A-034-4-17AN, A-037 Version 4, A-034-4-12. These links are grouped by function and system context and do not indicate interchangeability.