I'm staggered at the number of posts about radar operation and differing views and understanding about it - it is obviously very complex. It therefore seems all the more extraordinary that a crew select an approach type (long transit at 200ft) that relies for safety on radar, which clearly has a lot of risks associated with its use (that they probably didn't fully realise), to rely on for obstacle avoidance. The route guidance the crew followed has been criticised heavily by some - but the chart itself did not include any vertical profile so was surely obviously not an IMC let down procedure. I guess the associated notes might include minimum heights, but it seems highly unlikely. So why did the crew choose to carry out the whole route at 200ft? Was it too much automatic default to the over sea APP1 coupled approach mode, without enough thinking?
Clearly this procedure has important uses for SAR, but by using it here the crew put themselves in a position of having to rely on a complex system - radar - with considerable risks to be safe.
Safety of course is all about risk minimisation and the risks of using a simple IMC let down, minimising distance at low height, relying on GPS waypoints, seem to be far less to me. Blacksod really doesn't look a tight, tricky location to get into. With the two GPS systems accuracy would be pretty much guaranteed, and it would have been easy to verify position using other tools such as RadAlt anyway. And all the benefits of radar and FLIR could also still used, but with far less risk of hitting anything if - as seems here - radar use is flawed.
Furthermore such an approach would take far less flight crew attention - frankly it could have been flown single pilot without problem.
So why did the crew apparently choose to blend the APP1 approach mode with this VFR inter lighthouse route guidance? Or maybe they didn't choose it - could it have been specified by the operator to do this? And they didn't question it?