Definition
Instrument approaches conducted at the same time to parallel runways whose centerlines are spaced less than 4,300 feet apart (and not less than 3,000 feet), where each approach is flown independently of the other. Because the runways are closer together than standard, a No Transgression Zone (NTZ) is established between the final approach courses and is monitored by dedicated controllers using high-update-rate surveillance. Both aircraft may be cleared for the approach at the same time without lateral or vertical staggering between them.
Plain English
Two aircraft are landing at the same time on two runways that sit close beside each other. Each crew flies their own approach without waiting for the other, but controllers watch a protected strip of airspace between them very carefully to make sure neither aircraft drifts toward the other.
Context Anchor
Seen in instrument approach procedures, airport briefings, and ATC operations at airports with closely spaced parallel runways.
Derivation
Simultaneous means at the same time. Independent means each approach is flown on its own without coordination between the two aircraft. Close refers to runway centerline spacing tighter than the standard simultaneous-approach minimum, which is why extra monitoring is required. Parallel describes runways aligned in the same direction.
Why Pilots Care
Increases arrival capacity at busy airports while preserving safety through defined spacing and monitoring.
Grounding Statement
Picture two aircraft lined up with two nearby parallel runways at the same time, with controllers watching the space between them very closely.
Intuition Check
“Independent” does not mean the pilot is operating without ATC control; it means ATC is not relying on normal staggered spacing between the two aircraft. “Close” has a specific runway-spacing meaning here, not just a casual sense of “nearby.”
Example Sentence 1
During simultaneous independent close parallel approaches, the crew briefed the breakout procedure in case ATC issued a turn away from the adjacent final.
Example Sentence 2
ATC implemented simultaneous independent close parallel approaches to raise the arrival rate during instrument conditions.