GRA 55

GRA 55

Affordable Radar Altimeter Solution

  • Cost-sensitive solution for helicopter and GA aircraft based on the GRA 5500 architecture
  • The all-digital design provides a smooth, consistent readout
  • Highly accurate, rugged and reliable
  • Interfaces with the GI 205 stand-alone indicator, Garmin flight displays and 3rd party equipment

The all-digital design of the GRA 55 represents the latest and most accurate technology available in radar altimeters. It’s built to meet the needs of even the most demanding helicopter and general aviation applications.

Discover the All-Digital Advantage

The GRA 55 utilizes the same patented technology as our high-end GRA 5500. This state-of-the-art digital signal processing technology can intelligently process hundreds of altitude readings every second and filter out anomalies, smooth altitude tracking and crosscheck data and system integrity. These benefits combine to provide a smooth and consistent readout of your altitude Above Ground Level (AGL).

The GRA 55 is designed to work in a multitude of environments, allowing you to go from rough terrain to tree canopies, sand to choppy water and know exactly how much room you have to manoeuvre. Gain added peace of mind knowing that the radar altimeter is operating normally thanks to advanced, comprehensive self-testing technology that continuously monitors incoming data and system integrity to help assure that the altitude provided is accurate, even in low-visibility conditions. In most installations, this self-testing technology eliminates the need for the pilot to interact with the GRA 55 in any way.

For Part 135 helicopter operators, the GRA 55 fulfils the radar altimeter equipage requirement established by the FAA for adoption by April 24, 2017.

Choose Your Display Option

Designed to work with the stand-alone GI 205 radar altimeter indicator, as well as Garmin flight displays like the G500, G500H and G600, the GRA 55 conveniently puts your AGL readout right where you need it. Together, the GRA 55 and GI 205 can comprise a complete radar altimeter solution without the need to purchase a flight display. The system's reliability and accuracy, along with its flexible display capabilities, make it an optimal solution for operators equipping for NVIS operations. Thanks to patented technology, it also offers a simpler installation that can further provide you with weight and cost savings by eliminating the need for long lengths of antenna cabling that are traditionally required in the installation of radar altimeters.

Physical Characteristics

  • Unit Height (with mounting rack): 3.99” (101.3 mm)
  • Unit Width (with or without mounting rack): 3.02” (76.7 mm)
  • Unit Depth (with mounting rack and connector): 11.62” (295.2 mm)
  • Unit Depth (with mounting rack, connector and configuration module): 12.08” (306.9 mm)
  • Unit Weight (with mounting rack): 3.5 lbs (1.6 kg)
  • Typical Mating Circular Connector Weight: 0.13 lbs (0.06 kg)
  • Typical Mating RF Connector Weight (2X): 0.07 lbs (0.03 kg) (weight listed is for 2 connectors)

General Specifications

  • Operational Temperature Range: -55° C to +85° C
  • Altitude Range: 25,000 ft maximum
  • Software Compliance: RTCA/DO-178B Level C
  • Hardware Compliance: Not Applicable - The GRA 55 does not contain any complex or programmable logic devices
  • Environmental Conditions: RTCA/DO-160F

Performance Specifications

  • Altitude Accuracy: ± 1.5 ft (3 - 100 ft AGL); ± 2 % (> 100 - 2500 ft AGL)
  • Altitude Range: -20 - 2550 ft AGL
  • Altitude Alert Outputs Range: 0 - 2500 ft AGL
  • Altitude Output Time Constant: 0.1 second maximum
  • Transmitter Output: Frequency: 4.25 - 4.35 GHz "Gated" FMCW; Power: 1.0 W nominal
  • Horizontal Velocity: 0 - 200 knots maximum
  • Vertical Velocity: 20 ft/sec maximum (up to 100 ft AGL); 25 ft/sec maximum (above 100 ft AGL)
  • Pitch Angle: ± 20° maximum
  • Roll Angle: ± 20° maximum (with published altitude accuracy limits); ± 20° to ± 30° (with ± 20 % altitude accuracy limits throughout entire altitude range)

Power Requirements

  • Supply Voltage: 14/28 VDC. See the Environmental Qualification Form for details on surge ratings and minimum/maximum operating voltages
  • Power Consumption: 13.75 W maximum (0.5 A at 27.5 VDC, 1.0 A at 13.75 VDC)

Compatibile Devices

GI 205 Radar Altimeter Indicator

Compatible Garmin Flight Displays* (via ARINC 429):




*Requires software versions compatible with support for display of radar altimeter.

  • Views: 2055
  • Brand: Garmin
  • Product Code: GRA 55
  • SKU: 010-00946-05
  • Availability: In Stock
  • £6,688.31
  • Ex Tax: £5,573.59