Was the IFF M4 on the ZG710 an UOR derived STF fit that was in the process of being fully integrated by the DA?
It is implied above that a UOR course of action may have been taken to avoid regs and save money (i.e. dubious reasons) - this view is perhaps a bit simplistic as the main reason is surely to save TIME (which can be shown to be a good reason). If you are offered a choice between UOR IFF in 6 months, or fully integrated by the DA in 3 years - it is surely obvious that both courses of action potentially have merit (albeit the early option carries greater risk to be balanced against the operational benefit). Even if you took such a decision to the MAA as implied above, they would not necessarily disagree, though ultimately they would just pass the buck to the relevant duty holder (who is of course the right person to make such a decision, if he has the right supporting facts, and is the right thing for the MAA to do).
It also seems from a quick skim that the Patriot battery and its actions were in effect 99% responsible - it is even dubious, given what actions the battery took, whether the crew being aware that the IFF was on the blink would have made any difference at all. Nearly all the (huge IMO) holes in the swiss cheese lie with the Patriot end of this sad event.
I'm not convinced at all that the IFF warning is the smoking gun some are implying - infact to do so is to distort true events which is a big no-no IMO when it comes to proper analysis of events leading to an incident.
The more and more the IFF warning is discussed as an issue, the more pressure you take off the surely more burning issue with the configuration and operation of the Patriot system - which should have us all far more worried from what I've read so far!