The dimensions discussed in this Annex are based on consideration of single-main-rotor helicopters. For
tandem-rotor helicopters the heliport design will be based on a case-by-case review of the specific models using the basic requirement for a safety area and protection areas specified in this Annex.
The interpretation of some of the specifications in the Annex expressly requires the exercising of discretion, the
taking of a decision or the performance of a function by the appropriate authority. In other specifications, the expression appropriate authority does not actually appear although its inclusion is implied. In both cases, the responsibility for whatever determination or action is necessary shall rest with the State having jurisdiction over the heliport.