Definition
A defined segment of flight that connects one phase, route, altitude, or procedure to another. In published instrument procedures, a transition is a specific routing that links an en route fix to the start of an approach, departure, or arrival procedure. The term is also used more broadly for any change between flight phases or airspace segments.
Plain English
A connecting piece of a flight — the bit that takes you from one part of a route or procedure to the next.
Context Anchor
Seen in NOTAMs and other FAA abbreviated text where space is limited and the word transition is shortened.
Derivation
From the Latin transire, meaning 'to go across.' A transition is literally a 'going across' from one thing to the next — in aviation, from one route segment, altitude, or procedure to another.
Why Pilots Care
Picking the correct transition determines the exact route you'll fly into or out of a procedure. ATC will often clear you via a named transition (e.g., 'cleared via the LINDEN transition'), and flying the wrong one can put you off course or into conflicting traffic.
Intuition Check
Do not assume transition names one specific maneuver or procedure. Here it simply means a changeover; the surrounding text tells what is changing.
Example Sentence 1
ATC cleared us via the BOACH transition to the ILS approach at Las Vegas.
Example Sentence 2
Clear the TRSN altitude before changing the altimeter to standard setting.