Definition
Simultaneous instrument approaches conducted to parallel runways whose centerlines are separated by less than 2,500 feet, where aircraft on adjacent final approach courses are sequenced (staggered) by ATC so that they are never abeam each other. Because the runways are too close for independent operations, the approaches depend on a required diagonal separation between aircraft on the two finals.
Plain English
Two parallel runways that are close together, used for landings at the same time, but with controllers keeping the aircraft on each runway slightly ahead of or behind each other rather than side by side.
Context Anchor
Seen in instrument procedure and ATC discussions for airports that use nearby parallel runways during instrument arrivals.
Derivation
"Closely spaced" refers to the runway centerline distance being narrow. "Dependent" comes from Latin dependere, meaning "to hang from" — here it signals that one approach hangs on, or relies on, the other being staggered correctly to keep aircraft safely apart.
Why Pilots Care
These procedures allow higher arrival rates at busy airports but require precise heading and altitude compliance to avoid loss of separation.
Analogy
Think of two nearby lanes of traffic moving in the same direction. Cars can move side by side in separate lanes, but if the lanes are tight, traffic control may keep one car slightly ahead of the other instead of letting them line up exactly together.
Grounding Statement
Picture two aircraft lined up for two neighboring runways, with ATC keeping one slightly ahead or behind so the two flight paths remain safely separated.
Intuition Check
“Dependent” does not mean the pilot depends on the other aircraft for guidance. It means the two approaches are linked by required spacing, so ATC cannot handle each aircraft as if the other one were not there.
Example Sentence 1
Approaching the airport, the crew was told to expect closely spaced dependent approaches to runways 28L and 28R, with the traffic on the parallel runway one mile ahead.
Example Sentence 2
During the briefing the captain noted the airport was conducting closely spaced dependent approaches and reviewed the required heading tolerances.