On a recent hitch, the dreaded Formidable Rule of Unanticipated Consequences crashed the Digital Selective Calling party in a major way.
The very same feature that makes DSC-enabled radios so foolproof, automatically receiving a distress call on channel 70 and switching over to channel 16 for voice traffic, has turned out to be its Achilles' heel. There's no way to tell when or where it might be activated and no way to disable the feature. So if either a prankster or malfunction causes it to go off at a critical time (such as right in the middle of landing or sailing a barge or navigating through congested waters), you may find yourself without the ability to communicate.
In the course of a month in New York Harbor, we got a bellyful of this. The alarm, which cannot be ignored, went off continuously for days on end. You never knew when you might be blasted by a very loud and piercing alarm, and the radios would switch off your working channel unexpectedly.
Picture this scenario. Your loaded barge is down to 10 feet and closing on a dock, the assist tug is working on you and you're about to tell them to take their engines out of gear. Then it happens. The alarm blasts and you're now on channel 16. By the time you switch back to the working channel and tell them what you want, it is too late to avert the sickening crunch of timbers or the squeal of twisting metal.
Apparently, there is no way to disable the DSC capabilities of these radios, even temporarily. It is also next to impossible to find a suitable, commercial-grade radio without DSC. The only answer I could come up with is to bring a handheld radio to the upper pilothouse and turn all the others off when I line up for final approach or began taking in lines. Technically, this is illegal. We're required to monitor channels 13 and 16 at all times, or one of the VTS channels instead of 16. This is impossible, however, without the alarms becoming a dangerous distraction. The loss of communications could be catastrophic if it occurred at the wrong time. I now keep a handheld in the upper house at all times, sitting in the charger.
This proves that it is unwise to always blindly place your trust in new technology, and employing some of the disappearing old-school skills is a good idea.