421C,
You have totally missed the simple fact that in order to determine that a flight can be made safely in terms of weather, fuel and everything else, at the planning stage there must be a point at which based on the information available you know you will safely terminate the flight (the destination)..............otherwise, the flight has no defined end and thus actual fuel requirements and weather requirements can not be determined.
An alternative course of action will often be planned and one may even find that during the flight that it is required.
You said;
Clealry a flight may not depart if it can't be completed safely
Horray. At last someone who agrees.
Thus, my intention is to fly from A to B along my intended route if the weather turns out to be better than forecast,
This ignores two very important aspects;
1. You must make your decision based on actual and forecast weather; and
2. You as pilot in command have to not simply use the met forecaster as the person who decides if it is safe but you alone must interpret the information provided and decide that based on the information available that it is safe to proceed on the intended route..........which you clearly can't do VFR if the intended route is IMC.
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So you depart from Exeter to Blackpool eventhough Blackpool is IMC, and will be so for longer than your endurance. Your alternate is Barton. As you are within 20nm of Barton, you find that the airfield is closed due to an accident. Your alternative plan of action now that the flight can not be copmpleted as planned is?
In this case, you departed on the alternative course of action i.e. you were diverting from the moment you departed. You planned to do this and consequently, you departed without havign an alternative course of action to what you planned to actually do.
Can a flight from A to B with forecast IMC enroute or at B be "safely made" if VMC is forecast to allow VFR back to A or to land at C or D and sufficient fuel is carried?
The answer is clearly No you can not depart intending to fly from A to B. Because you have determined that there is IMC enroute.
You have made that decision. You have decided that the flight can not be made VFR. The fact that everywhere else in the world is VMC has no bearing on that very important decision.
Perhaps we have people who can not make decisions that the weather is unsuitable and that the flight can not be made. They simply rely on having a look see, taking far more fuel than is necessary and hoping that all the airfields in the country are available.
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Leaving the legal aside, I would hate to be a passenger on one of your flights from Exeter to Blackpool.
"Now here we are at 3000ft on our way to Blackpool, the weather says that we can't get there and I knew that before we departed, I know you want to go to Blackpool, I do also. I will push it as much as I can but never mind we will probably end up in the North of England somewhere or perhaps even back where we started."
Passenger response - "Take me back to Exeter you idiot".
Passenger thinks - 'I'm never going to fly with this idiot again'
421C,
Everthing in your posts says to me that you are unwilling or unable to make a go/no-go decision - the very go/no-go decision that the law requires. You are simply surviving because ther are a multitude of fields in the country and your luck so far has not left you stranded.
Regards,
DFC