When does the blower for the cabin heater operate?

The operation of the cabin heater blower is specifically designed to function only when the landing gear is deployed. This design choice is primarily related to safety and efficiency. When the landing gear is down, it indicates that the aircraft is either preparing for landing or is in a slower speed configuration, which may necessitate heating the cabin for comfort and passenger safety.

In contrast, the blower does not operate during all flight operations or only while in the air. The main reason is that during cruise flight, particularly at higher altitudes, the engine and airframe may provide sufficient cabin heat, making the blower less necessary. Additionally, the heating needs of the cabin are typically minimal during taxiing since the engines are running at low power and airflow may suffice without additional heating.

Therefore, activating the cabin heater blower exclusively when the gear is down optimally provides heat to the cabin when it is needed most, enhancing the passenger experience without unnecessary operation during other flight phases.