Japan Airlines and All Nippon Airways are introducing an advanced version of the computer-controlled Traffic Alert and Collision Avoidance System in the wake of last month's near miss involving two JAL aircraft, officials of the airline companies said.
TCAS, which is installed in most aircraft in Japan and currently mandated for use in the United States on all commercial aircraft with more than 10 seats, issues collision-avoidance instructions to pilots aboard aircraft facing a threat of collision.
The advanced version of the system provides safer operations for planes in close proximity. The advanced version will be mandated for use on aircraft in Europe from April, the officials said.
TCAS transmits radio signals to other aircraft nearby to determine their distance and altitude. If the system believes that a collision is imminent, it issues a warning 40 seconds before the estimated time of collision followed by an instruction to either ascend or descend 25 seconds before impact.
However, some pilots have voiced concern that TCAS is outdated and unfit for aircraft powered by the latest jet engines as it issues unnecessary warnings even when there is enough space between aircraft to avoid a collision.
The JAL planes avoided a midair collision on Jan. 31 as a result of decisions by both captains of the two aircraft to ignore the instructions of their TCAS units.
In addition to providing the data supplied by the current TCAS, the more sophisticated system is able to avoid issuing such unnecessary warnings by shortening the benchmark for dangerous differences in altitude between two aircraft to 260 meters from the current 360 meters or less, when the planes are leveling off at 9,100 meters or higher.
It also enables aircraft to take effective evasion operations even if the planes are close to each other by precisely analyzing altitude difference and approach rate.