Flight Level The altitude expressed in hundreds of feet indicated on an altimeter set to 29.92 in. Hg or 1013.2 mb. Related Articles: PPL Air Law in Canada: Foundational Rules & AirspaceIFR Regulations: What INRAT Students Must KnowPlanning IFR Flights: Core Concepts for the INRATWhat is the IATRA? Overview of ATC Rules & Flight Procedures for the IATRA Exam