Crab,
You said
My point about the rig takeoffs is the legal operation of the aircraft on instruments (because you have no visual references) below VminI (50 kts in the case of the 139) despite that being in contravention of the RFM - how is that circle squared or is it given a stiff ignoring?
This is an interesting one, however that is not quite what the book says.
The 139 RFM says; "Minimum airspeed for flight under IFR (Vmini) ............. 50 KIAS."
So, It does not say you can't fly with sole reference to instruments below 50 KIAS.
It says you will not fly under Instrument Flight Rules with less than 50 KIAS.
We all know we can fly VMC under IFR. But one can't be VFR and IFR, it is one or the other. Therefore it must be VFR below 50 KIAS then VFR or IFR beyond.
Now I'll pull the pin and lob...
Prior to Sept 2012 there was no VFR at night in the UK.
So how did a 139 legally reach the magic 50 KIAS - to continue IFR, the only option then available at night, in winds less that 50 kts?
A bit of a disconnect there!
Now, post Sept 2012, we do have VFR at night. For a helicopter one needs COCISoS & 3km in class G airspace (the typical offshore rig airspace and Gillingham) to conform with VFR.
So now, with less than
3km, how can a AW139 depart at night, in Class G? You need the VMC conditions (3Km +) to be VFR, remember the RFM says no IFR until you reach the magic 50 KIAS (Vmini) not no IMC.
Back to the 50 kts hoolie
See my dichotomy?
I can't believe it is a slip up in the RFM, then again...
Edited to add for clarity, the definition in the AW139 RFM for Vmini is 'Minimum airspeed for flight under IFR'