Changing the rules for setting the altimeter below TMA

From 23. 1. 2025, a change in the rules for setting the altimeter below the TMA will apply. Until now, the altimeter was set to the QNH of the specified airport (to which the TMA belongs). The exception was parts of the TMA that have a lower boundary defined by the flight level (FL##). Below them, the regional QNH was flown to the transfer altitude.

We will now fly at the QNH of a specified airport simply everywhere below its TMA.

In an ATZ whose upper boundary or part thereof is formed by the lower boundary of the TMA, we will fly to the QNH of the designated airport. In an ATZ of airports located below a TMA but not touching the TMA, we will fly to the QNH of the relevant uncontrolled airport during the operating hours of the AFIS unit or a unit providing information to known traffic. Outside of operating hours, we will set the QNH of the designated airport.

In the event of multiple TMAs overlapping, a pilot flying below the TMA will use the QNH belonging to the airport whose TMA is the lowest.

Complete information about the changes can be found in the updated UL-1, ZL-1, BAL-1 regulations.

Jiří Krajča, Chief Inspector of ULL Operations