In the recent years many problems are emerging due to the aircraft noise on the airport surrounding areas. The solution to this problem is not easy considering that the neighbourhood asks for the reduction of the number of aircraft operations and the airlines ask for a growing demand in the number of operations in the major airports. So the airport and regulatory authorities try to get a solution imposing a fine to the aircraft which its actual trajectory differs from the nominal one more than a lateral deviation. But, which is the value of this deviation?. The current situation is that many operators have to pay a lot of money for exceeding a deviation which has been established without operational criteria. This paper presents the results of a research program which is being carried out by the authors which aims to determine the "delta" deviation to be used for this purpose. In addition it is proposed a customized method per SID and per airport to be used for determining the maximum allowed lateral deviation by which if the aircraft is within it, then none fine will be imposed
