"Mooselips Approach, Cessna 12345, 3000 feet, request practice ILS 30 at Bison, published missed, information tango."
"Cessna 12345, Mooselips Approach, Bison altimeter 3002, unable ILS 30, runway 12 in use at Bison, did you have another approach request?"
If you haven't yet had an exchange like the one, it's likely that you soon will because the FAA has decided that opposite direction approaches into towered airports are no longer allowed. To the uninitiated, practice approaches to a runway when there's opposite direction traffic may seem inherently dangerous, but it is something that's been done safely at many airports for as long as anyone can remember. One example in Northern California is Sacramento Executive where all the instrument approaches are to runway 2 and 90% of the time runway 20 is in use.
At KSAC, the procedure for handling opposite direction approaches is simple and has worked well (and without incident, to my knowledge): The tower instructs the aircraft inbound on the approach to start their missed approach (usually a climbing left turn) prior to the runway threshold and any traffic departing the opposite direct turns in the other direction.
For areas like the California Central Coast, the restriction on opposite direction instrument approaches has been in place since I arrived in June and it has serious implications for instrument flight training since the ILS approaches for San Luis Obispo, Santa Maria, and Santa Barbara are likely to be opposite direction 90% of the time. For a student to train to fly an ILS in a real aircraft, you need to fly quite a distance. Same goes for instrument rating practical tests that require an ILS because the aircraft is not equipped with WAAS GPS and/or there's no RNAV approach available with LPV minima to a DA of 250 feet or lower.
There currently is no formal FAA Order (to my knowledge) that describes this restriction, though one hopes that will change: Everyone from students to instructors to controllers would like to see this rule codified. As it stands, this restriction seems to have been passed down from on high to TRACONs in the US. Some exceptions may be allowed when there's an "operational need" such as for FAA flight checks of instrument procedures. You may be able to call your local TRACON on the phone and make prior arrangements if you need to do an ILS for an instrument rating check ride or for practice. And waivers may be issued for some airports with a high volume of training. Then again, your request might still be refused. Your tax dollars at work.