Before we go further on what is TCAS, I would like to refresh on few accidents involving aircraft in mid-air collision.
Nov 1996 – Mid-air collision between Saudi Airlines Flt 763 and Kazakhstan Airlines Flt 1907 which killed 349 passengers onboard.
Sep 1976 – Mid-air collision between British Airways Flt 476 and Inex-Adria Aviopromet Flt 550 which killed 176 people onboard.
Dec 1992 – Air crash between Libyan Arab Airlines Flt 1103 and Libyan Air Force Mig-23 Flogger on the way to Tripoli International Airport which brings fatality of 159 people including air crew.
Based on the tragedies occurred together with some other mid-air collision, a new kind of technology invented to avoid such this things from happening in the future. It’s called Traffic Collision Avoidance System (TCAS) to be used in every commercial aircraft nowdays. It is a mandatory requirement as said International Civil Aviation Organisation (ICAO) who is the global aviation authority. Now let’s dig what is TCAS and why it is too important to implement this technology on aircraft?
TCAS is a transponder which capable to inform pilot of the other aircraft surround with the same altitude. Some of you may didn’t notice that actually we do have ‘airway’ on sky what acting like a road. So, when two different aircraft is using the same route, the only thing that could help them from collision is via altitude. In this case, TCAS will give instruction to pilot to reassign into new altitude if the aircraft have potential to hit with each other.
From the figure above, we can tell that a potential of aircraft accident between FL 260 and FL 270. In this situation, TCAS will inform the pilot of FL260 to level down whilst TCAS on FL270 will ask the pilot to level up. This aircraft safety equipment is really important to keep us safe and more reliable to fly.
However, there is one mid-air collision even the aircraft already equipped with TCAS responder. It is because of the clash between TCAS instruction and Air Traffic Controller (ATC) command. When this happen, pilot will get confused and didn’t know which one that actually he needs to follow either TCAS or ATC. After the tragedy, the ICAO together with the few National Aviation Authority (NAA) mandates that if this kind of confusion happen again, pilot should stick to TCAS instruction and totally ignore the ATC.
Even the technology keep expanding, still sometimes we can’t figure what kind of accident can happen. But we didn’t simply take easy on the accident but motivate ourselves to find the best to prevent the accident from happen again.
