Plain English Meaning

A way of counting how often something repeats every second. One hertz means one repeat per second; a million hertz means a million repeats per second.

Full Definition

The unit of frequency equal to one cycle per second. It measures how many times a repeating event — such as a radio wave oscillation — occurs each second. Symbol: Hz. Common multiples in aviation are kilohertz (kHz, thousands of cycles per second) and megahertz (MHz, millions of cycles per second).

Context Anchor

Pilots encounter hertz when reading about radio, navigation, and electronic signals, usually shown as kilohertz or megahertz for aviation frequencies.

Derivation

Named after Heinrich Hertz, the German physicist who first demonstrated radio waves in the late 1880s. The unit was adopted internationally in his honor, replacing the older term 'cycles per second.'

Why Pilots Care

All aircraft and operate at frequencies expressed in Hertz or its multiples; selecting the wrong frequency means no with or loss of navigation guidance.