radio altimeter

A pilot checks the radio altimeter during the final approach.

Definition

1. Noun:
   • An instrument that measures altitude using radio waves: A "radio altimeter" is a device that determines the height of an aircraft or other object above the ground by transmitting radio signals downward and measuring the time it takes for the signals to reflect back from the surface.

Usage Examples

• (The device measured the aircraft's height above the ground using radio signals.)
• (The instrument provides accurate altitude data near the ground.)

Advanced Usage

• "Radio altimeter reading": the numerical value displayed by the device.

  • The radio altimeter reading dropped rapidly as the plane descended. (The height measurement decreased quickly.)

• "Radar altimeter": a synonym for radio altimeter, often used interchangeably in aviation contexts.

  • The radar altimeter is essential for terrain avoidance systems. (A device that uses radio waves for altitude measurement.)

Variants and Related Words

• Altimeter (n): a general instrument for measuring altitude, often using barometric pressure.

  • The altimeter showed the plane was at 30,000 feet. (A device for measuring height, not necessarily using radio waves.)

• Radio (adj/n): relating to the use of electromagnetic waves for communication or detection.

  • The radio signal from the altimeter was clear. (The electromagnetic wave used for measurement.)

Synonyms

• Radar altimeter: an altimeter that uses radar (radio detection and ranging) technology.
• Electronic altimeter: an altimeter that operates using electronic signals, often including radio waves.

Related Idioms

• "On the radio altimeter": referring to altitude data provided by this specific device.
  • The aircraft was on the radio altimeter at 200 feet. (The pilot was using the radio altimeter for altitude information.)