With the
development of airborne collision avoidance systems (ACAS) and
their fitment in aircraft since the mid-nineties it has become
possible for pilots to know if their aircraft is on a collision
course with another.
When an ACAS warning is received the pilot or crew has time to
take avoiding action. Some of the systems fitted in aircraft today
will advise what to do - climb or descend away from a conflicting
aircraft. Future developments will also give turn advice.
The effectiveness of ACAS is totally dependent on the presence
of an operating Mode C or Mode S (altitude encoding)…