The terms behind what's flying above
Plain-English explanations of the concepts you'll bump into on the radar — how high jets fly, how fast they go, and how to read the codes.
The Basics
What Is Cruising Altitude?
Cruising altitude is the steady height an aircraft holds during the main part of a flight — typically 9,000 to…
SpeedWhat Is Cruising Speed?
Cruising speed is the steady speed an airliner holds at altitude — typically Mach 0.78–0.85, or around 830–900…
ContrailWhat Is a Contrail?
A contrail is the thin white line a plane leaves behind at cruising altitude — condensed water vapour from the…
WingletsWhy Do Planes Have Winglets?
Winglets are the upturned tips at the ends of an aircraft's wings. They tame the swirling vortices that form t…
Identifying Aircraft
What Do Aircraft Registration Codes Mean?
Every aircraft wears a registration — a unique tail code like N123AA or G-EUOB. The first part tells you the c…
CallsignCallsigns vs Flight Numbers
A flight number is what your ticket shows; a callsign is what the pilot says on the radio. They often differ. …
CodesWhat Is an ICAO Aircraft Type Code?
An ICAO type code is a short 2–4 character designator that identifies an aircraft model — like B738 for a Boei…
SquawkWhat Is a Squawk Code?
A squawk code is a four-digit number entered into an aircraft's transponder so air traffic control can identif…