JAFO, everyone knows that dense ash clouds cause immediate engine failures and that at the extremity of the ash clouds, there is little or no immmediate damage and that just outside the extremity, there is no damage at all. Where would you like me to fly the Nimrod, so that my report can be of any use to NATS? Oh, and by the way, the lat and long of the line of safety is moving with the wind. The core issue is not about defining what ash can do to aircraft (we already know), but rather it is how can NATS give an IFR route clearance that is hazard free? The nub of the problem is that NATS takes legal responsibility for their clearances. Unless they know, from one minute to the next, where the line of safety is, they cannot possibly give IFR clearances that do not require the crew to see and avoid. Its a legal issue, nothing more and, IMHO, BA are onto the case.
BA is currently flying a 747 over GB with their boss on board; probably trying to establish a company policy; ie if the aircraft has remained clear of any haze or cloud, has flown in daylight and landed without any damage, it must be safe to fly (VFR) in those conditions.
Deliberately flying a Nimrod or any aircraft into haze, or worse, above N Europe at the moment is stupidity. Other than the risk to safety, it will not provide any help to resolve the problem.
Regards
Ed