"Ramapriya" wrote in message
oups.com...
Does this get activated only when there's an aircraft in the dangerous
vicinity or will it also trigger if the aircraft is hurtling towards
some terrain such as a hill?


You are really talking about two types of systems here. One is for traffic
avoidance, which projects the path of yours and other aircraft and lets you
know if there is a conflict. Some of these systems depict all the aircraft
in the area, along with their direction and altitude, on a moving map.

Terrain avoidance systems warn you of terrain.

And does every aircraft have this system these days, regardless of
size?


No. The systems are very expensive and are typically not found on small
aircraft. However, more of the newer planes do have these systems,
especially the newer glass cockpit displays. There are even some handheld
devices that perform somewhat the same function with more or less
effectiveness. None of them substitute in small planes for a good set of
eyes looking out of the cockpit.

For one thing, traffic avoidance systems usually depend on other aircraft
having transponders, but some people don't turn their transponders on and
some aircraft have no transponders at all.