AW Aviation Consultancy Services Limited
Radar data consultants.
QNH-M ; QNH monitor alert
Incorrect QNH setting may result in loss of terrain separation, where a pilot thinks they are higher than they actually are.
AWprojects are specialists in the setup, configuration and optimisation of a downlinked Mode S QNH alert. Aircraft with the correct avionic setup can downlink the QNH setting in use on the altimeter. This data may be contained in Asterix 34/48 or Asterix CAT 62 radar data. AWprojects fully understand the QNH downlink function and how different aircraft can downlink different QNH setting, even when flying on the standard pressure setting. Aircraft could approach an airfield with the QFE or field elevation pressure setting so this will need to accounted for in any safety net design.
QNH-M
Incorrect QNH setting monitoring.

In the most basic form aircraft (with the required avionics fit) downlink to the radar the currently set pressure setting on the altitmeters subscale. This may be the current QNH, the 'standard QNH' or the airfields QFE. However, some aircraft designs complicate this..
Some aircraft when on the standard pressure setting of 1013.2hPa bypass the subscale setting, leaving it as the last used QNH. This makes the downlinked QNH very difficult to interpret. However, by understanding the nature of the aircrafts behaviour AWprojects have designed a complete safety net to warn of aircraft approaching with the incorrect subscale setting on the altimeter.
We take account of aircraft behaviours (understand which aircraft bypass the subscale and which dont), QNH/QFE settings.
Warnings can then be generated and snet to the display to warn controllers that an approaching aircraft may not be using the correct pressure setting.
AWprojects can advise RDP designers how best to use the downlinked QNH and what may or may not be appropriate for their customers needs.
The AWproject visualizr includes the QNH-M monitor which displays the erroneous QNH in the aircrafts text data block.