A comparative study of air carrier and business jet TCAS RA experiences

The Traffic Alert and Collision Avoidance System (TCAS II), a critical aviation safety system, uses onboard surveillance to automatically detect potential airborne threats and issue vertical maneuvering guidance, or Resolution Advisories (RAs), to help pilots resolve conflicts. These RAs and relevant encounter details are recorded by the Federal Aviation Administration´s TCAS Operational Performance Assessment (TOPA) program to facilitate characterization and assessment of TCAS performance in U.S. airspace. This paper summarizes a comparison of TCAS experiences among major air carriers, regional air carriers, and business jets. It found that RA rates for business jets were 4.5 times higher than major air carriers and 2.5 times higher than regional air carriers. Most significantly, business jets were 14 times more likely to be involved in low-separation encounters. The differences in operating environments was identified as a key factor: air carriers typically operate at commercial airports within strictly controlled airspace, whereas business jets more often operate at low altitudes in airspace where air traffic control separation is not mandatory between all aircraft, and the use of visual separation procedures is prevalent, often in proximity to small, non-commercial airports. Another noteworthy finding revealed non-compliance with TCAS RAs was a common factor in many low separation encounters. These results suggest current TCAS training and the design of future collision avoidance systems should explicitly consider the different environments in which TCAS-equipped aircraft may operate.