Graham wrote:
But the point still holds. Unless he’s prepared to go down to LFOB <1hr (and who is, on a flight of non-trivial length?) he doesn’t get any more range using a totaliser than he can get with a rule of thumb.
I think you can. Without a totaliser I will apply larger reserves than if I have a totaliser.
The difference between 0.5hr and 1hr and 1.5hrs is huge in terms of the European airport / avgas / C+I matrix.
If you know the remaining fuel to say +/- 15 mins versus knowing it to +/- 1hr, makes a very big difference.
I don’t know. I plan for a minimum of 1hr LFOB currently, and I don’t think I’d plan for less than that even if I had a totaliser.
I plan for 20USG LFOB, less in exceptional cases (like CAVOK everywhere and lots of options, I would go down to 15) and 20 is almost 2hrs. The key is that one can do it with much more certainty.
How often have you fill up the tanks after a long flight with varying winds, unplanned climbs and descents, etc, and worked out how much was really left, versus the plan? 
Peter wrote:
I plan for 20USG LFOB, less in exceptional cases (like CAVOK everywhere and lots of options, I would go down to 15) and 20 is almost 2hrs.
With 86.2 USG useable and a planned LFOB of 20 USG, you are planning max fuel burn of 76% of capacity.
In my rule of thumb with the TB10, I am planning max fuel burn of 80% of capacity – so I don’t accept that I’m wasting range by not having a totaliser.
Peter wrote:
How often have you fill up the tanks after a long flight with varying winds, unplanned climbs and descents, etc, and worked out how much was really left, versus the plan?
Admittedly I don’t do much in the way of (very) long flights with much-changing winds and unplanned climbs and descents. We don’t refuel on return to home base (in case the next person is weight-limited) so admittedly that exact check doesn’t happen very often. But I always check what’s left with the dipstick, and it never varies from what is expected by an amount that is not well within the noise in terms of the margins of safety I wish to operate in. When the fill-up experiment does happen (usually away from home) it is always very close to what I am expecting, within 5 litres a side or so. That is in the noise for my purposes.
I agree the certainty and precision is nice, but not having it doesn’t limit my range.
I really don’t understand what the problem is about having the fuel totalizer or not.
With fuel totalizer you can switch tanks before the engine quits and use more or less the full amount of fuel onboard.
Without fuel totalizer you can just fly on a tank until the engine quits, switch tank and fly the next one until it is dry. That is how this has been done some decades ago, but the engines are still the same. This does not hurt. The engine won’t stop turning.
OK, admittedly, you should tell the passengers about your plans, because they will hate you otherwise 
I did that several times already. There is just no other way in classic equipped charter aircraft with fuel gauges that tend to lie one or the other way.
Graham wrote:
I agree the certainty and precision is nice, but not having it doesn’t limit my range.
I think for PA28-160 last time we’ve calculated it was marginal on full tanks a headwind from EGTR to EGPF and using school reserves.
If it is WITH the totaliser, then yes, it is doable.
How can one possibly trust a totaliser when measuring in USG anyway? One surely needs a totalizer for that, right? YMMV. Literally.
Peter wrote:
That’s all fine but the OP has a PA28R which has more capability, and he does do longer trips.
I am so happy my new plane provoked that much “interesting, informed and intelligent discussion” that EuroGA front page promises :)
Let me remind my original concerns about this very particular plane (and this time it’s not even close to “hijacking a thread”!): There is no problem with fuel planning in skitour-in-Sweden mode! If I fill the tanks completely, with me and my partner on board there’s still 53 kg left for our stuff. That’s more than we can carry on our backs anyway! I don’t even need to look at the totaliser in this mode. I don’t care if the actual endurance is 7h15’ or 6h15’, there is no way we are planning a leg more than 4h long (and that’s already longer than the longest we ever flew).
Things get interesting however in family-vacation-on-Corsica mode. And the family does want to do this trip again! (… on condition I take a set of spare tubes). At 120 kt, EPKM to LFKO are minimum 5h30’ apart, no routing, no wind, no approach taken into account. No way to fly it without a stop if the dog is on board. A logical stop half way would be the beloved Portorož LJPZ, which in practice I should be able to reach in 3h30’. But then, in this trip mode, I can’t take off with full tanks! If we want to take any luggage, I need to start the whole trip with 45 … 50 … 55 gal. I prefer 55, but the less fuel I take, the more stuff can fit in.
But the problem is I am relying on tabs/dipstick to make sure this amount of fuel is there – or perhaps filling the tanks before the trip and then releasing a carefully metered amount of CO2 and TEL through flying alone. The particular route I mentioned has nice options for stops and I could really push it to the limits – say, add 45’-60’ reserve to the anticipated flight time EPKM-LJPZ and be mentally ready for landing earlier, at Maribor LJMB, if winds are not favourable. If LJPZ suddenly blows up on my final approach, Pula LDPL or Rijeka LDRI are just around the corner… What limits me, however, in pushing it to the limits, is the accuracy of my way of determining how much fuel there is on board at the beginning of the trip :)
Mateusz wrote:
Turns out the GTN650 is properly connected to the EDM and I do have that lauded LFOB function available within a few clicks in the GTN menu.
The start-up / avionics check screen of the GTN (the same that says “CDI half-left half-up no flags”) also has the fuel information (fuel left and fuel flow). If it gets data from a fuel totaliser, that data is white and cannot be changed. If it doesn’t, it is green and can be changed by pressing on it.
I assume you already do check that your CDI/HSI/GS is showing the test pattern of “half-left half-up no flags”? I recommend to add to that check “fuel information white and the same as on the fuel totaliser”. In my plane, it starts green/outdated (data from last shutdown) and after several seconds it turns white and displays the numbers from the fuel totaliser. I “always” wait to see that the connection was established correctly and I will have fuel information in the GTN unit.
