Which mode is prohibited during approach?

During an approach, the use of IAS (Indicated Airspeed) mode is prohibited due to its potential to lead to loss of control if the aircraft encounters an unexpected situation, such as turbulence or a go-around. The IAS mode would maintain a constant airspeed, which can be problematic as it does not take into account the changing dynamics of the aircraft’s descent profile, resulting in challenges during the final stages of landing.

In contrast, other modes, such as FMS (Flight Management System) Mode, VOR (VHF Omnidirectional Range) Mode, and APPR (Approach) Mode, are designed to optimize navigation and descent management during an approach, ensuring that the aircraft is guided accurately along the designated flight path to the runway. These modes incorporate essential features to assist in maintaining proper glide slope and lateral guidance, which are crucial for a safe landing.