I'm intrigued by this fantasy world DFC inhabits. I find myself wondering, if I wanted to follow his advice, how it should work in reality. DFC paints a picture of an experienced aviator, who presumably has put this into practice a few times, so hopefully he'll be able to let me know how it works out in the real world. I personally think he's a troll, but no doubt one day he'll prove me wrong. In the meantime, taking DFC at face value:
For the sake of example, let's say I want to fly VFR from Elstree to Le Touquet to visit the market and have a spot of lunch. As is often the case, the weather in the UK is pleasant VFR, but Meteo France are forecasting lower level cloud cover forecast for the French mainland. However, as many people have experienced, it's quite common for the weather over the sea to be CAVOK with the significant cloud cover starting a few miles inland from the French coast, while Le Touquet itself basks in glorious sunshine.
So according to DFC, to remain legal our plan A is to take off from Elstree, head off towards Le Touquet, with the intention of turning round and coming back to Elstree. Plan B is to divert into Le Touquet if the weather turns out to be good enough to land there despite the adverse forecast for the region.
So, thinking about how this actually works in the real world:
1) What do I put on the flight plan?
Presumably it's got to be departure EGTR, destination EGTR with a route something like DCT LAM DCT DVR DCT LT DCT DVR DCT LAM DCT with an alternate of LFAT. I'll need to put in EETs for the FIR boundary, so do I put in two - one for the outbound leg and one for the inbound one?
2) What happens if the cloud cover is forecast to start before the FIR boundary?
The route I know I can complete is now DCT LAM DCT DVR DCT LAM DCT. I guess I now don't need to bother with the EETs to the FIR boundary. But in the real world, how does this flight plan get addressed to LFFF and LFAT? Does somebody spot that I've got LFAT listed as an alternate and add them as addressees on the offchance, or do I have to manually specify that myself? What do you do DFC?
3) Where exactly do I put LFAT on the flight plan?
In filling in the flight plan, I'm not sure I should really put LFAT in as the alternate. The flight plan forms have 2 spaces for "alternate" aerodromes, but according to the definitions in ICAO Annex 11:
Alternate aerodrome.
An aerodrome to which an aircraft may proceed when it becomes either impossible or inadvisable to proceed to or to land at the aerodrome of intended landing.
That doesn't really apply in this case. Once I get to Le Touquet, it is neither impossible nor inadvisable to return to Elstree - I just don't want to. So Le Touquet isn't really the alternate. Do you put it in the "alternate" field anyway, DFC, or do you put it somewhere else - as a RMK in field 18 perhaps?
4) In the real world, do you ever get given a hard time by ATC at the surprise destination?
I can imagine when I rock up at Le Touquet the controller being a little confused. To use one of DFC's imaginary conversations:
G-ABCD: Le Touquet Tower, G-ABCD is a Cessna from Elstree to Elstree, we wish to divert in to you.
LFAT: Roger G-CD, do you have a problem?
G-ABCD: Negative. The weather is better than forecast and we now wish to divert in to you. We did make sure you got a copy of the flight plan.
LFAT: Roger G-CD. I have a copy of your flight plan. Your flight plan shows you returning to Elstree without landing. Is there something now preventing you returning to Elstree in accordance with your flight plan?
G-ABCD: Negative. The weather is better than forecast and we now wish to divert in to you.
LFAT: G-CD standby.
Le Touquet are unfailingly helpful (if sometimes a little overworked). However, there are many other destinations where I could imagine a prolonged conversation and the real possibility of being refused permission to land. Is this ever a problem in the real world, DFC?
5) What do you do about SAR?
Obviously the route you actually fly may be very different to the one on the flight plan, which could cause problems for SAR.
Taking another example for a moment - let's say we want to fly from Elstree to Berlin and the weather across Europe is fine, but there's a band of weather approaching from the north. The forecast for Essex and north Kent is for a cloud base around 1,500' which isn't high enough to be above MSA for the early legs. If the bases actually turns out to be above 2,500' then that's plenty to safely make it out to Kent and the better weather.
Now because our plan A is to take off from Elstree and land back at Elstree if the weather is as forecast, the flight plan we must submit in DFC-world is from EGTR to EGTR with a route of something like DCT LAM DCT, a flight time of 30 mins and an alternate of EDDI.
So what happens if you get as far a Dover and the better weather? We're now on our way to Berlin, but if anything untoward happens nobody knows our intended route or our estimated ETA. If the radio goes dead, they won't have the faintest idea where to start looking. Do you put the alternate route in as a RMK? Or ask a "responsible person" to alert everyone if you don't turn up.
As an experience aviator, no doubt you've encountered all these problems with your unusual method before and found a good practical solution to them. Personally, I think anybody trying to do things the DFC way in the real world would soon see that it's ivory tower rubbish.