Definition
A unit of frequency equal to one million cycles per second (1,000,000 Hz). Used to express the operating frequency of radio waves, particularly in aviation communication and navigation systems.
Plain English
A way of measuring how fast a radio wave vibrates. One MHz means the wave goes through its full cycle a million times every second. Aviation radios are tuned to specific MHz numbers so pilots can talk to the right station or controller.
Context Anchor
Seen on aircraft radios, navigation equipment, antenna specifications, and maintenance test equipment.
Derivation
From the Greek 'mega' meaning 'large' or 'great,' combined with 'hertz,' named after the German physicist Heinrich Hertz, who proved the existence of radio waves in the late 1800s. So 'megahertz' literally means 'a million Hertz,' or one million cycles per second.
Why Pilots Care
Pilots tune communication and navigation radios using frequencies expressed in MHz.
Analogy
MHz is like the address for a radio signal. If you tune to the wrong number, you are listening in the wrong place.
Intuition Check
MHz does not mean speed, distance, or signal strength. It means frequency: how many times a signal repeats each second, counted in millions.
Example Sentence 1
The tower controller instructed the pilot to contact departure on 124.35 MHz after takeoff.
Example Sentence 2
VHF communication radios operate between 118 and 137 MHz.