Abstract: This invention provides a static vent unit e.g. for use on the side of an aircraft and which in operation is subjected to airflow from any direction within a wide airflow incidence range comprises a generally flat plate having an outer surface for fitment generally to flush to an outer surface of the aircraft, a vent port through the plate for connection during operation to a static vent line in the aircraft, and a bulge on the plate outer surface surrounding at least part of a circumference of the vent port and having in cross section a convex curved upper surface extending radially inwardly from an outer edge on the plate to an inner edger on the plate adjacent the circumference of the vent port and adapted during operation to promote attachment of an airflow from within at least part of the airflow incidence range to its surface and direct the airflow into the vicinity of the vent port to provide a compensating increase in ambient pressure at the vent port.