Hi, Uplinker. I am not a pilot or ATCO, so my opinion is just that, an opinion, and it is entirely possible that I am talking nonsense.
However, I work in aviation, and also know some people who work in other sectors where accuracy of information is vital. In my opinion, the design of procedures for operations with a critical need of accuracy (be it landing an aircraft or performing neurosurgery) is more inclined to reiteration of known rules than to omission of them due to assumption. In other words, it is considered safer to communicate the procedures even if they are standard than having the rule of assuming standard procedures if nothing is communicated.
When I studied linguistics (some time ago
), I remember doing theory of communication and discourse analysis, and remember that having the assumption of a standard content to be inferred from an omission of an alternative content is more likely to cause inaccuracy than having the standard content included in the act of communication. Leaving you to assume that if not told otherwise you must expect an ILS approach has a bigger probability of inaccuracy or error than telling you the obvious. If the rule was to assume that if not told otherwise you should expect an ILS approach, there are two kinds of possible communication inaccuracy: one would be to tell you the wrong information (ie expect ILS approach when it is not available) and the other kind of possible error would be not to communicate at all the desired information (ie there is no ILS available and not telling you anything, which would not happen if lack of information was NOT an option), as that would make you assume by default that the standard rule is being followed. The procedure of assuming something if not told otherwise means that in certain circumstances, the lack of information IS the message, so lack of information is an approved operational method. By not having lack of information as an operational option, we eliminate one of the possible two errors.
A "real world" example
: You and I are college students and share a room in a flat. As we are both so good looking, every other night we have company and wish to have the room for ourselves for a while. We design a code: if there is a red sock hanging from the doorknob, that means we have company and the other one is not supposed to enter the room, if there is a green sock hanging from the doorknob, that means you can come in, as nothing is happening. Now, if the rule is that "if you don't see a red sock you can enter", I can make two kinds of mistake: placing the wrong colour sock or, out of excitement, forgetting to place a sock at all. In this case, as you don't see a red sock, you assume I am all alone and enter the room, disturbing my privacy
. If the rule is "there ALWAYS has to be a sock in the door, at all times, and the colour will tell us if we can enter or not", that reduces my possible mistakes to 1: placing the wrong colour, because if I forget to put the sock, that doesn't give you specific information. You would call me on my phone and ask before entering, as we agreed that lack of info doesn't mean anything. If there are two or more options, safety is improved by not making omission one of the options, especially in accuracy-critical operations like flying an aircraft.
So basically, I believe that whoever designs operational safety policies, picks the option more likely to reduce the amount of actions leading to error. And that would be giving information EVEN if it is standard rule.
Sometimes it borders on the ridiculous, but it is universally agreed that whatever eliminates ambiguity in communication makes communication more reliable. lack of information creates ambiguity, so if there is more than one option (ILS/no ILS), supplying that info is safer than assuming one from the omission of the other, and I guess that's why it's done.
But then again, it is only my opinion, and probably just a load of nonsense, but hey, that's why I think it happens. Have a good night.
P.S. I know I could have chosen another "real life" situation, but hey, I have a right to dream!!