If you are over 30 years of age your next ECG due date will remain the same as on your UK Class 1 ATCO medical certificate. The validity period for an ECG if under 30 years of age at the time of the investigation under the European Class 3 requirements is 4 years, rather than 6 years as in the UK requirements. Therefore, if you are under 30 years of age at your next revalidation/renewal examination the date of your last ECG must not be more than 4 years ago.