Clearance Clarification

Posted by Certain-Pollution426@reddit | flying | View on Reddit | 2 comments

Please read whole thing before answering this. When are you cleared to cross a runway?

As soon as the controller has said it OR after you have responded to his clearance IN FULL. (FAR, AIM, AC, etc., reference would help)

Taxiing a 172 and told to taxi via B and hold short of 13. I arrive and hold short. 1 minute after holding short, given instruction to "CROSS 13.....(and more taxi clearance)". I start rolling while I read back the instructions. Immediately after I'm done responding, controller amends and comes back with, "HOLD SHORT of 13". I slam on breaks and not sure if the prop tip had crossed the line, but it sure looked like it. Trying to see if I need to change my response times and take it slower. I'm very familiar with my airport and taxi all the time, using common routes.