Many pilots and controllers are taught to have three aims when using the RT: be clear, be concise and be correct. Naturally, good pronunciation, reasonable speed, and the use of standard phraseologies contribute to clear, concise and correct. But the use of human language to communicate is an art and not a science. There are some built-in problems in human language that contribute to potential problems in aviation communications. A few are mentioned below. 1. Readback Error – If ATC says, Cleared to land, Runway two six left, and the pilot reads back, Cleared to land, Runway two six right, the pilot has committed a Readback Error. With distractions, multi-tasking and a busy ATC frequency, this error can happen and can be difficult to catch. 2. Hearback Error – In the previous example, if the controller fails to hear the mistake in the Readback, the controller has committed Hearback Error. He failed to listen carefully to the pilot’s Readback. Since the vast majority of readbacks are correct, it takes great discipline to listen carefully to each readback. 3. Expectation Bias – Human beings have a tendency to hear what they expect to hear. If you are lined up on the runway waiting for a take-off clearance, you may believe that the next take-off clearance is for you, even though it may be for another aircraft on a parallel or intersecting runway. You heard what you expected to hear, and committed the error of Expectation Bias. 4. Assumption – If you always get a landing clearance just as you turn base, it is easy to assume as you turn base that you are cleared to land. The way to fight assumption error is to seek confirmation, I’m cleared to land, please confirm? Assumption has been a factor in many aviation accidents. 5. Ambiguity – an ambiguous statement is one that could have two or more different meanings. Ambiguity is difficult to completely avoid in human language in a complex situation. If you are doing touch and go and ATC says You’re number three to follow the twin, the statement may be very clear. But if there are two twins in front of you in the circuit, there is a risk you may mistake one twin for the other. The situation makes the instruction ambiguous – the meaning is not clear, and you may need to seek clarification. Naturally, all of these potential language problems could become more likely or more hazardous if one or both of the communicating parties has low English proficiency.5.What is the best way to prevent assumption?