What is a common reason a pilot would need to report loss of navigation instruments?

Reporting a loss of navigation instruments is critical for maintaining safety in flight operations, particularly in instrument meteorological conditions (IMC). Unforecast weather conditions can create sudden changes in visibility and atmospheric conditions, which may render navigation instruments unreliable or unusable.

When a pilot encounters unforecast weather, such as unexpected low ceilings or visibility, it can lead to a situation where reliance on navigation instruments is heightened due to degraded visual references. If the pilot suspects or confirms that the navigation instruments are not functioning correctly in these changing conditions, they must report this to air traffic control. This alert allows for better situational awareness among traffic and may lead to necessary adjustments in flight operations, such as vectoring to alternative routing or holding patterns until conditions improve.

Relying on navigation instruments is especially crucial during phases of flight such as approach and landing, where precision is vital. Thus, a failure or perceived loss of functionality of these instruments in response to unexpected weather would warrant immediate reporting to ensure safety.