The airspace is busy, and after receiving your clearance you read it back to the controller. However, you didn't write the clearance down, and read back what you thought the controller/clearance told you. Unfortunately, you remembered the clearance incorrectly, read back the incorrect clearance and proceed. The controller does not correct the clearance and, as you heard nothing back from the controller, you assume everything is OK. As a result you find yourself following the incorrect clearance only to find yourself involved in a near miss incident and soon find yourself the subject of an FAA investigation. The conflict is resolved, everyone breathes a sigh of relief, and you go merrily on your way.
The Letter of Investigation ArrivesSome time later you receive a letter from the FAA - a Letter of Investigation. Now what do you do? You received the clearance, read it back, no one said it was wrong and you followed the clearance only to discover that you were involved in a near miss incident. After a sleepless night you decide to answer the letter and give a full account of the incident from your point of view.
Big MistakeThe first thing you need to know is that there is no legal requirement to respond to a Letter of Investigation. In fact, if you do respond anything you say can - and will - be used against you. You do not know how much information the FAA has, so you do not want to provide them with additional information they may not have, or can not discover on their own.
The FAA Interpretive RuleDid you know that you could face an enforcement action even if you read back a misunderstood clearance to the controller and he doesn't correct you? It's the brave new world of the FAA's interpretive rule on read back errors?
Because the only data the FAA has is a recording of the controllers transmission from his mike (the ATC tape) and the pilot's testimony. There is no record of what the pilot read back to the controller, so the burden of proof now falls squarely on the pilot's shoulders.