Whilst realising that it is an unwise virgin that argues the legislation with JimL, I have to ask whether his definition of VminI is a genuine definition or an interpretation. The reason I ask is that I always ‘assumed’ that minimum speed on instruments was the speed below which you should not reduce to whilst flying on instruments, rather than specifically a speed to which you had to accelerate to before you could achieve safe flight on instruments.
As an example, the S61 (correct me if I’m wrong, it’s been a very long time) had a quoted minimum speed on instruments of 50 kts; however, one of the category A (in those days) take-off profiles had a TDP of 50ft and a minimum cloud base (or vertical visibility) for departure of 50ft. Allowing you to achieve TDP whilst theoretically remaining in visual contact with your rejected take-off area still in sight. This then left you to accelerate from a near vertical climb and an airspeed just registering on the ASI, into forward flight and up to something equating to VminI whilst IMC. Not a million miles from the procedures that are being talked about on this thread, the difference being that we would be carrying out this process from an airfield with a published SID or missed approach procedure to follow.
In my opinion, the important feature of such departures has nothing to do with doppler indicators or anything else that detracts from the primary task of setting an attitude and power setting appropriate to the procedure – to quote my personal guru of instrument flying, “Attitude plus Power = Performance”.
Please don’t confuse this rambling with a defence of departing from an essentially hostile environment (not in the JAR sense of the phrase) with negligible visibility. In my world, operations with an RVR below 400m require specific training and authorisation from the ‘competent authority’.
Cheers
TeeS