This question got me wondering about the practice of tuning a navigation frequency, selecting it on the audio panel, and then identifying it by listening to the three letter Morse code signal. I know it is a sound practice, and the reason may have been explained to me years ago in a way that made sense at the time, but my understanding has been lost in the sands of time and I have gotten lazy at doing it regularly.
To clarify, I am only interested in answers that can outline a plausible scenario where a mishap could ensue as a result of not identifying an ILS/VOR station by Morse code. For example, how an aircraft might lock onto something on the same frequency that is convincingly similar enough in the cockpit indications, that undetected deviations by the pilot could drive an aircraft unto an unsafe condition and possibly result in a mishap.
So, what is the worst thing that could happen if a pilot failed to ID a Navaid? (Safety of flight, busting a checkride doesn't count!)
P.S. Bonus points if you reference a CFR part that requires it.
ADDENDUM: Thanks to those who took the time to answer. There are some good and correct answers, but a few missed the point in my asking about actual, specific risk scenarios. Because I would never argue against the practice, and I know why it's done, it just feels a bit like an inefficient anachronism when there are so many other better ways to catch an error.
I don't have near the flight hours of a seasoned part 135 or 121 pro, but I have never once uttered in the de-brief: "Gee, good thing we listened to that Morse code ID or we might have ____" (Insert scenario)
And I have debriefed plenty of mistakes, my own included. But any time I've switched navaids on an airway there is an expectation of what the next course and DME will indicate. When that needle swings reassuringly to the inbound course, and DME is plus/minus a mile, flicking that audio switch to hear a few quick beeps feels like a casual afterthought performed out of rote habit.
Because if it locks on something 90 degrees off, and many miles diferent than expected, the first thing I do is doublecheck the entry. Because my eyes can detect a mistake far quicker and more reliably that what it takes to process the audible code. (I'm not steeped in telegraphy!)
I just can't think of a plausible situation where I would be fooled or otherwise miss a mistake and be saved by the Morse code.
However, a signal from a station undergoing calibration that might be picked up but is not accurate, is a very valid concern. And that was the answer I accepted.