Final answer:
The navigation source for the ILS on the Integrated Standby Instrument System is provided by ground-based transmitters, called Localizer for lateral control and Glide Slope for vertical guidance. This allows pilots to land the aircraft safely by following radio signals that align them with the runway.
Step-by-step explanation:
The navigation source for the ILS on the Integrated Standby Instrument System (ISIS) in an aircraft is usually provided by ground-based transmitters. An Instrument Landing System (ILS) facilitates a guided landing approach for aircraft by providing lateral and vertical guidance. Typically, the ILS comprises two separate systems: one for lateral control, known as the Localizer (LOC), and one for vertical control, known as the Glide Slope (GS). The onboard avionics tune into the specific frequencies transmitted by these systems to assist pilots in alignment with the runway and descent path during the landing phase.
In the case of an Integrated Standby Instrument, it functions by displaying information from the ILS when the primary navigation systems are compromised or unavailable. This redundancy is critical for maintaining safety and ensuring that pilots have access to crucial navigation data at all times, particularly during the critical phases of flight such as landing.