Controllers at 100 Airports Can Now See the Ground in Fog

Transportation Secretary Sean P. Duffy announced on 2 September that the Federal Aviation Administration has installed the Surface Awareness Initiative at its 100th airport, reaching nearly half of the 220 airports slated to receive the system. SAI gives air traffic controllers a live surveillance picture of aircraft and equipped ground vehicles moving on the airport surface, drawn from Automatic Dependent Surveillance-Broadcast data. Crucially, it works when the tower cannot see: in fog, in heavy rain, at night, and in the blind corners that exist at almost every airfield. Another 44 airports are scheduled for installation by the end of 2026.

The gap this fills is larger than most passengers realise. Only 44 of the busiest US airports had ground surveillance before this programme, using the older ASDE-X and Airport Surface Surveillance Capability systems. At every other towered airport in the country, controllers separated aircraft on taxiways and runways by looking out of the window and listening to radio calls. That works well in clear conditions and less well when a fuel truck is hidden behind a hangar or a regional jet is holding short in low visibility. Runway incursions, where an aircraft or vehicle enters a runway without clearance, have been on the National Transportation Safety Board’s most-wanted list for years.

SAI was designed as a deliberately cheap and fast answer to that gap. Rather than installing ground radar, it takes ADS-B position data that aircraft already broadcast and presents it on a display in the tower cab, which makes deployment a matter of months rather than years per site. The FAA began installations in 2024. The trade-off is coverage: ADS-B only shows what is transmitting, so unequipped ground vehicles and aircraft with the transponder off remain invisible, which is why the agency describes SAI as awareness rather than full surveillance.

Passengers will not see any of this from the cabin, and that is the point. The measurable effect shows up as fewer runway incursions and, at the margin, fewer low-visibility ground delays, because controllers who can see taxiing traffic can move it more confidently when the weather closes in. With deployment continuing through 2028, the FAA expects eventual surface surveillance at every airport with an FAA-operated control tower, which would close a visibility gap that has existed since the first towers were built.

Sources: Federal Aviation Administration, AVweb