Stage 4: definition & analysis of aircraft compliance, Issue 20 Dec 2001/Jan 2002
The new Stage 4 ruling is lenient compared to Stage 3 noise rules. Besides
a requirement for a reduction of 10 EPNdB, only aircraft certified from 2006
are required to comply and there is no phase-out of Stage 3 aircraft. Stage
3 aircraft will be allowed to continue in operation, unaffected.