Radar, transponders and TCAS
9 min read
Primary and secondary radar
Primary radar sees reflections: no help needed from the aircraft, but no identity or altitude.
Secondary surveillance radar (SSR) interrogates the aircraft's transponder: Mode A sends the 4-digit code (4,096 codes), Mode C the pressure altitude in 100 ft steps, Mode S a unique 24-bit address and more data (selected level, heading, speed), interrogated selectively.
IN THIS LESSON
- Weather radar
- TCAS / ACAS
Read the whole lesson with FL340 Pro.
ATPL theory course by course: short lessons written from the EASA Learning Objectives, with questions that explain the answer. Free with an account.