If ambient temperature exceeds 45 C, within how many minutes should conditioned air be started?

If ambient temperature exceeds 45 C, within how many minutes should conditioned air be started?

• A. 60 minutes
• B. 30 minutes
• C. 15 minutes
• D. 90 minutes

Answer: (B)

When outside air is very hot, the cabin needs time to be cooled and brought to a comfortable setpoint before boarding. The conditioned air system has to overcome a high heat load from the outside temperature and sun exposure, so it needs a dedicated preconditioning window. Starting conditioned air within 30 minutes of planned departure gives the environmental control system enough time to cool the cabin and stabilize the environment. Starting earlier (60 or 90 minutes) wastes time, and starting too late (15 minutes) may not achieve the desired temperature by boarding. Therefore, 30 minutes is the appropriate preconditioning interval.

When outside air is very hot, the cabin needs time to be cooled and brought to a comfortable setpoint before boarding. The conditioned air system has to overcome a high heat load from the outside temperature and sun exposure, so it needs a dedicated preconditioning window.

Starting conditioned air within 30 minutes of planned departure gives the environmental control system enough time to cool the cabin and stabilize the environment. Starting earlier (60 or 90 minutes) wastes time, and starting too late (15 minutes) may not achieve the desired temperature by boarding. Therefore, 30 minutes is the appropriate preconditioning interval.