Point out what is likely to happen as a direct consequenc...

The ATC clears a locally-based aircraft to climb using the local language. The clearance creates a conflict with another flight whose pilots do not understand the local language and are thus unaware of the impending circumstance. Loss of separation results.

The pilot mishears a clearance but instead of reading the clearance back responds “Roger”. ATC does not challenge this response and a level bust results.

An ATC clearance for another aircraft is read back incorrectly but the error is not appreciated by ATC because of interference from the simultaneous initial call.

A pilot about to commence an approach to a runway is instructed to change to the parallel runway. The clearance is issued too late for the pilots to carry out a thorough re-brief; they proceed anyway having failed to assimilate the go-around procedure for this runway.

The pilot of Rushair 1234 requests descent clearance as follows: “34, request FL120”. The ATC mistakes the caller for Jetair 314 and responds: “314 descend FL120”. Rushair takes this clearance as intended for him and a level bust results.