Definition
A unit of frequency equal to one million cycles per second. Used to describe the frequency of radio waves, including those used for aviation communication and navigation.
Plain English
A way of measuring how fast a radio signal vibrates. One megahertz means the signal completes one million cycles every second.
Context Anchor
Seen when tuning or reading aircraft radio frequencies, such as tower, ground, approach, emergency, and navigation frequencies.
Derivation
From the Greek 'mega' meaning 'great' or 'large' (used in measurement to mean one million), combined with 'hertz', named after the German physicist Heinrich Hertz, who proved the existence of radio waves. So 'megahertz' literally means 'one million hertz' — one million cycles per second.
Why Pilots Care
Aviation VHF radios operate between 118 and 137 megahertz, so correct tuning is required for reliable communication and navigation signal reception.
Intuition Check
Megahertz is not the radio message itself. It is the measurement used to identify how fast the radio signal is cycling each second.
Example Sentence 1
The pilot tuned the radio to 121.5 megahertz, the international emergency frequency.
Example Sentence 2
VOR navigation stations transmit on frequencies expressed in megahertz.