squawk

Squawk is a verb meaning to utter a loud, harsh cry or squall, typically produced by a bird such as a parrot, or to protest or complain loudly. As a noun, squawk can refer to that cry or the sound itself. The term is commonly used to describe animal vocalizations and, in informal speech, to describe objections or protests.

In aviation, squawk denotes the assignment of a transponder code by air traffic control. Pilots are instructed to “squawk” a four-digit octal code on their transponder, which then appears on radar to identify the aircraft. The code is entered into the transponder’s modes (A, and often C or S) to enable radar beacon replies. The system allows ATC to correlate radar returns with a specific aircraft and flight plan. In the United States, 1200 is the standard code for visual flight rules (VFR) operations, while discrete codes such as 7500, 7600, and 7700 indicate hijacking, radio communication failure, and emergencies, respectively. The use of “squawk” in phraseology helps ensure unambiguous identification and coordination.

Etymology and usage: The general sense of squawk derives from the onomatopoeic imitation of a loud bird cry. In aviation, the term was adopted as a metaphor for the transponder’s electronic reply to radar interrogations, a signal that enables identification, tracking, and separation of aircraft within airspace.