thanks for all the information you provided.
Yes, the MEF already include a factor to the either highest obstacles or the highest terrain elevation in the grid.
I use MSA, as it is easy to remember. other instructors go with MORA. Which is also an IFR altitude. But we explained to the student the difference between VFR min et IFR minimum. those guys have just about 30hours and we just want to teach them minimum safe altitude for what they do? visual flight.
my issue is, you let the guy go. you check is nav planning and he has written that is minimum altitude is the MEF + 500'.
Great I'm happy. However during the day, the weather goes down and the ceiling is getting crap.
What would we briefing him. For us it is easy : common sense, we know what we have to do. However those student pilots with 30 hours have not yet " a common sense".
let's take an example, wx is enough but goes down. Ceiling decrease to the minimum altitude he has specified. vis is still good. So either he fly at the minimum altitude but just below the clouds (with the risk of it). or we tell him you can go down lower as long as you can see and avoid and return to the departure or diversion field. But to what altitude. the AIP will specify 500' within 150m of the highest obstacle but that is often well below the MEF in a grid.
yes it is safe to go below the MEF as the MEF is within a grid and your flight could me miles away from the highest obstacle.
so my question to the FI is what do you brief to your student when they go on their solo navigation. to which altitude could they go down if the weather was going down and they need to divert.
thx