LJ:-
Could I ask you to clarify where in UK Law it legislates military RTS? I'm just curious what deemed it illegal.
It's Military Law not to make a false written statement or certification. That applies to all that are subject to Military Law, in particular it applied to ACAS. He received a CAR from Controller Aircraft that granted "Switch on Only" clearance for the Chinook HC2. Apart from being an almost useless Controller Aircraft Release, and possibly unique, it made the aircraft effectively inoperable other than for ground training purposes only. You could switch on the comms/nav suite but not use it let alone rely on it.
Despite that, ACAS signed an RTS and the aircraft went into Sqn service, even though it was still undergoing the BD testing regime, who as we now know grounded their aircraft because it was "positively dangerous" and urged the RAF to do the same. The very next day ZD576 crashed, killing all 29 on board.
I believe that the RTS procedure is now different and under the auspices of the MAA. The above arrangement was supposed to be foolproof, as both men (CA and ACAS) had to sign together that the aircraft type was airworthy and fit for service. It would seem that the system, the men and the aircraft all failed that test. The system has been altered but is still compromised in that the operator (MOD) issues its own RTS's (via the MAA). Neither the accident nor the actions of ACAS have yet been properly investigated, despite evidence being supplied to Haddon-Cave, Lord Philip, and the Provost Marshal.