At what altitude is the maximum APU bleed extraction for air conditioning?

The maximum APU bleed extraction for air conditioning typically occurs at FL250. This is crucial because it indicates the highest altitude at which the auxiliary power unit (APU) can effectively provide bleed air for the aircraft's air conditioning system. At this altitude, the bleed air pressure is sufficient to maintain the necessary cabin temperature and comfort levels without risking engine performance or safety.

Above this altitude, the efficiency of the APU in maintaining those parameters tends to decrease, limiting its effectiveness for air conditioning demands. Thus, understanding this altitude boundary is vital for flight operations to ensure adequate cabin conditions during climb and cruise phases.