When do you set your altimeter to 29.92 under ICAO rules during climb or departure?

Setting your altimeter to 29.92 inches of mercury is a standard procedure that reflects the transition from using local altimeter settings to a standardized pressure setting as you climb through the transition altitude (TA). Under ICAO rules, the transition altitude is the height at which aircraft switch from referencing local air pressure to the standard pressure setting of 29.92 inHg, which is used for flight levels above that altitude.

When pilots reach the transition altitude during ascent, they adjust their altimeter setting to 29.92 inches of mercury. This practice ensures consistent altitude readings among aircraft operating in the same airspace and helps prevent altitude conflicts and enhances overall safety.

The other scenarios mentioned do not correspond with the proper timing for this adjustment. Approaching cruising altitude or the transition level either occurs before the altimeter setting is changed or pertains to different altitude management procedures, and setting the altimeter at the initial approach fix is related to returning to local altimeter settings for approach rather than ascending.