What does MRA stand for in terms of IFR altitudes?

MRA stands for Minimum Reception Altitude, which is a crucial term in aviation that refers to the lowest altitude at which a particular navigation signal can be reliably received. This altitude ensures that an aircraft maintains proper communication and navigation capabilities while flying at lower levels. It is particularly important for ensuring safety and navigation accuracy, as pilots need to be aware of the minimum altitude necessary to receive navigational aids, especially in areas where terrain may obstruct signals.

In operational terms, when flying with instruments, if a pilot is below this altitude, the reception of navigation signals may be inadequate, which could lead to navigation errors. Given its purpose, understanding MRA helps pilots plan their routes and altitudes appropriately to ensure they are always above this threshold when using radio navigation aids.