Sometimes it may be necessary for you as a pilot to check how clearly the controller can hear you. In ATC we use a readability scale from 1 (least clear) to 5 (most clear).

The scale is as follows:

• 1= Unreadable
• 2= Barely readable, occasional word distinguishable
• 3= Readable with considerable difficulty
• 4= Readable with practically no difficulty
• 5= Perfectly readable

TOM4575: Gatwick Ground, TOM4575 request radio check

KK GND: TOM4575, Gatwick Ground, readability 5