Parallel Runway Traps

Monday, September 25, 2023 at 07:07 PM ET

Verified

When simultaneous instrument approaches are being conducted to parallel runways, ATC employs a no-transgression zone (NTZ) of variable dimensions to monitor and ensure proper separation, as depicted below. The FAA's Aeronautical Information Manual has lots more detail on the various ways NTZs are implemented, which aren't really relevant to VFR pattern operations at either towered or non-towered airports.

Key Takeaways:

Parallel runway configurations significantly contribute to "wrong-surface events" (WSEs), where aircraft land or depart on the incorrect runway, occurring nearly every other day.
A fatal mid-air collision at North Las Vegas Airport highlighted these risks, as a Piper aircraft, despite multiple clearances for Runway 30L, mistakenly lined up for and collided with a Cessna on the parallel Runway 30R.
Contributing factors to such incidents include the complexity of parallel and offset runway layouts, pilot distraction during maneuvers, expectation bias, and a failure to adequately see and avoid other traffic.
Effective risk management for parallel runways involves thorough pre-flight review, active listening and verification of ATC clearances, utilizing electronic guidance, and maintaining heightened situational awareness and vigilance to see and avoid other aircraft.

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Airports and their runways come in all shapes and sizes, from turf strips lacking any real markings, but with trees at both ends, to massive, busy, complicated affairs like ATL, DFW, JFK or ORD. And pilots are expected to understand and comply with all procedures for operating at them, including taxiways and hotspots, runway intersections, LAHSO (land and hold short operations), and even soft-field takeoffs and landings on unpaved surfaces. As too many close calls involving runway incursions and near-misses remind us, sometimes things don’t go as planned.

A lot of the incursions and near-misses involve single- or crossing-runway events—and pilot error right alongside ATC mistakes. The industry’s conversation about these events is ongoing, but doesn’t often consider a common airport configuration: parallel runways. That’s too bad, especially since that configuration likely was a contributing factor in a recent fatal mid-air.