See-and-Avoid at Two Hundred Knots

The U.S. air traffic control system relies heavily on the "see-and-avoid" concept and visual separation in terminal airspace — despite known human perceptual limitations that make visual detection of conflicting traffic unreliable at high closure rates, in low visibility, and in congested airspace. ADS-B Out (transponder broadcast) has been mandated since 2020, but ADS-B In (the cockpit display component that lets pilots see nearby traffic) has not been required despite NTSB recommendations dating to 2008. The January 2025 Reagan National midair collision — killing 67 — validated these failures with catastrophic consequence.

The DCA midair killed 67 people — the deadliest U.S. aviation disaster in over two decades. NTSB documented 15,000 near-misses between helicopters and airplanes near DCA over a 4-year period, indicating enormous pre-existing risk. Visual separation is used routinely at hundreds of airports nationwide, and terminal airspace operations affect every commercial airport in the country.

TCAS (Traffic Collision Avoidance System) provides resolution advisories for equipped aircraft but is designed for en-route encounters, not terminal-area operations at low altitude. ADS-B Out broadcasts aircraft position, but the complementary ADS-B In — which would display nearby traffic on cockpit displays — remains unregulated 17 years after NTSB first recommended it. The Black Hawk helicopter in the DCA collision had ADS-B Out but its crew could not see the approaching airliner on any display. Air traffic control relies on radar and controller judgment to separate traffic, supplemented by visual separation during VFR conditions. The DCA investigation found that FAA used visual separation "to promote efficient traffic flow without consideration for the limitations of the see-and-avoid concept." No automated conflict detection system exists specifically for helicopter/fixed-wing interactions in terminal airspace. The NTSB approved 50 new safety recommendations from this single investigation — the largest set from any single NTSB investigation in recent memory.

An ADS-B In mandate would give pilots direct awareness of nearby traffic — a fundamental capability gap today. Automated conflict detection algorithms designed specifically for terminal airspace (with mixed helicopter and fixed-wing traffic at low altitude and high closure rates) could supplement controller judgment. Systematic analysis of near-miss data — 15,000 incidents were documented but never acted on — could drive proactive airspace redesign rather than waiting for the next catastrophe.

A team could prototype a terminal airspace conflict detection algorithm using publicly available ADS-B data (e.g., from OpenSky Network or ADS-B Exchange) to model helicopter/fixed-wing encounter geometries near busy airports. Another approach: design a near-miss trend analysis pipeline that ingests FAA ASRS or mandatory occurrence data and surfaces emerging collision-risk hotspots. Skills in geospatial data analysis, signal processing, or human factors would be most relevant.