very surprised to hear (bbc1 news) that it was in discussions with manufactures of the engines that the new policy was reached. I would be very amazed if any of the manufactures have put the signitures on this new policy. It would take months of validation work to come up with a level that was safe- not 5 days- I have worked in validation of experiments (all be it not in aviation) for 20 years- this is just not possible. I would love someone during a tv interview to press for the new ppm 'safe levels'. I have no idea if the skys are safe to return to, I have no idea if they were ever unsafe- but I DO KNOW THAT a new policy based on a diff safe limit found by experimentation cannot be set in 5 days.