What it is

CAVS is an ADS-B In application that supports the flight-crew in maintaining visual contact with a lead aircraft (traffic) during a visual approach.

Benefits

• Supports higher runway throughput
• Improves pilot situational awareness due to visual display of traffic
• Reduces go-arounds (due to getting too close to another aircraft on final approach)

The FAA partnered with American Airlines and ACSS to install ADS-B In avionics, including CAVS functionality, on American Airlines' entire fleet of Airbus A321 aircraft. CAVS operations were approved by the FAA in May 2021 for American Airlines flight crews to use in equipped aircraft wherever appropriate conditions exist. The FAA approval had no expiration date, so CAVS operations are ongoing and expected to continue indefinitely.

When pilots in a terminal area use CAVS functionality, on average they achieve more consistent and smaller interarrival distances at the runway threshold, which can increase runway throughput. Operational data obtained during the benefits evaluation with American Airlines demonstrated average reductions of 11-13 seconds in Inter-Arrival Time (IAT) per runway; if such an IAT reduction could be sustained for an hour, arrival throughput could be increased by 4-5 aircraft per hour for each arrival runway. For more details, see the AIRS CAVS/CAS-A Operational Evaluation Final Report.

Availability

CAVS standards are complete and ready for manufacturers to produce the necessary avionics (see FAA Technical Standard Order - C195b and later versions). FAA guidance regarding CAVS operations exists in Advisory Circular 90-114C. At least one avionics company currently offers a product which includes CAVS functionality.

How it Works

Arrival throughput is highest when visual arrival/approach operations are in use. When visibility conditions degrade, arrival throughput can decrease, because ATC must maintain increased distances between arriving aircraft.

The CAVS application provides precise ADS-B location and velocity data to allow flight crews to better maintain visual contact and manage their relative distance behind an aircraft on the approach to an airport. Pilots must acquire the preceding aircraft "out the window" first, then the pilot can rely on the traffic display as they conduct a visual approach. The CAVS operation requires no new procedures or phraseology for air traffic controllers.

Additional Use

The FAA worked with American Airlines to evaluate an additional use of CAVS equipment to expand the meteorological conditions during which CAVS functionality can be used. The goal of CDTI-Assisted Separation on Approach (CAS-A) was to achieve visual arrival rates more often. An operational evaluation occurred from March 2023 to February 2025 for arrivals to Dallas Fort Worth (DFW) airport. The FAA worked with American Airlines and ACSS to gather data and analyze results.

When the CAS-A procedure was used by flight crews in appropriately equipped aircraft, flight time and distance savings were achieved for all arrivals. At DFW, aircraft conducting a CAS-A operation and flying a downwind segment to landing had an average reduced distance flown of 0.9 NM and an average flight time reduction of 40 seconds, when compared to other traffic. Other aircraft benefited from CAS-A operations, as well; distance and time flown were reduced for any aircraft arriving within 15 minutes after a CAS-A operation, compared to aircraft arriving without a CAS-A operation in a 15-minute timeframe. For more information, see the AIRS CAVS/CAS-A Operational Evaluation Final Report.