Not long here, I made my comments with regard to post 1102, concerning the lack of TCAS on Nimrod ac. TCAS has saved many a mid-air in the civilian world and I did not have the benefit of it on my Herc back in 2002. I don't know where the Nimrod fleet is now with TCAS but the real point is, not fitting Mode S and TCAS will pile up the restrictions on where this ac can operate. And as someone has pointed out, would probably have been paid for in fuel cost savings anyway. (Different budget??) I was just making a point that these advancements in the Aviation world are provided for a reason. The cash strapped MoD always delays compliance for the last possible moment, sometimes beyond. It is informative for anyone questioning the MoD approach to Duty of Care.
Manning an eng det in Akrotiri with no spare Nimrod engineers will be a major headache. Safety aspects of not fitting Mode S probably aren't that great, but the there are fundamental operational changes that will arise because of this failure to comply.