HC - Geoffers has beaten me to it.
Basic 139 has a rad alt generated call at 150ft as pointed out by Geoff. This can be suppressed/eliminated (not suspended as with AVAD), consciously or inadvertently, by the flick of a tiny unguarded switch on the central panel. It could be easily knocked in a dark cockpit.
This little switch, in its self could lead to problems if the crew are unaware it is in the regrade position while descending low level, either IMC or on an inky black night. A warning on the CAS (Crew Alerting System) while in regrade might be a helpful improvement. I don't recall there even being an advisory, maybe Geoffers could help me out here, as I never knowingly fly with it in regrade.
While on the subject of CAS warnings, you get a warning every time you arm the floats, which seems to me a waste of a warning at a time in the flight when if something else is going on it would be good to know about it. The crews get so used to cancelling a warning as they arm the floats that they might inadvertently cancel a coincidental warning without noticing.
Maybe an advisory would be more appropriate. Just a thought.
Red