drauk
please don't feel that I was having a go at you or the question!!
I kind-of agree with what you are syaing - how do you know if you can glide clear!? It's a toughie for sure. One thing is for certain, the CAA would look at EVERY aspect of an incident - esp if lives are lost in these litigious times.
The glide clear argument is so subjective. Hard to prove either way!
I think that by inference that you are EXPECTED to use the Thames on Helicopter Route 4 (From Battersea along the Thames to the Isle of Dogs if ditching means it would be acceptable to use if needed. As I said in the other thread, Rule 5 does mention.....person, vehicle or VESSEL! So hitting a vessel would probably be unacceptable and not within the remit of gliding clear!!!! (on a serious note - events such as the Thames Power boat racing would be hard to avoid.)
As you are probably aware, we have a "local rule book" called the Manual of Air Traffic Services Part 2 at all ATC units. Written internally, it is endorsed completely by the CAA SRG. However, it doesn't include EVERY possibilty in ATC of course. ATCO's are paid to use their judgement and apply a set of rules.
I bought the Book published by GetMapping with photos of the whole of the UK - interestingly the Lea Valley shows some fairly green expanses - but I have never been there so don't know what it actually is like! If you go to
www.multimap.com - zoom in to the Lea Valley area and then you can overlay a low quality image of the map - have a look up the Lea Valley and see what you think!
As you say - how do you know you what it is like until you have seen it!? In a court of law your map - which probably shows a solid built up area around LCY - it would be argued that you knew the area was built up and no landing sites available!!!