SAS
More often than not it has become the primary navigation tool. #
I think the biggest problem here is not making a distinction between a GPS being used for PRIMARY navigation (which is absolutely fine, and is the best way because a GPS is far more reliable, accurate, less prone to gross errors) and it being used for SOLE navigation (which is stupid, because any single device can fail).
In VMC, one can perfectly well use a GPS for primary navigation. It works especially well if you load the route into it. And you SHOULD concurrently read the chart;
I know some people don't read the chart but there will always be people who do silly things, and it would be an interesting question whether a careless person with a GPS is less likely to be lost than a careless person without one; I am sure the answer is that having a GPS is better. Of course there is no data to work on because only those who get hopelessly lost and call D&D or somebody are known about, and it is very hard to get hopelessly lost with a moving-map GPS.
In IMC, one uses the GPS as primary and VOR/DME concurrently. This is also by far the best way to navigate in VMC; the two methods tend to eliminate each other's gross errors.
But this debate can go on for ever, because any navigation method other than visual navigation is bound to detract from one's visual skills! A bit like any speed limit above zero will result in deaths.
The CAA presentations are aimed at the basics, in fact the presenter at the last one I went to told me so; they appear to tailor the material to the statistics which is fair enough. They go over and over what is basically PPL revision. I don't knock it and read every word on every page, but I think there is only so many times you can tell somebody to not get distracted and stall after takeoff.
TPR
At 4,000 feet across the channel, in a PA28… If one of the fuel caps on the wing were to come off - what would be likely to happen? Nothing? The fuel in that wing would be pulled out? A disaster in the making, or nothing too serious?
Whatever happens, you should have enough fuel in the other tank to get across the English Channel, anywhere
I would be extremely worried if it was raining though!! That (leaks past filler caps on planes parked outside) I have found is the biggest reason for water in the system. Once I drained out five full-size fuel testers, completely full of water, out of a PA28. When it's 100% water it is easy to think it is just fuel.