Is it worthwhile to carry a single radio - low powered at that; with the understanding that a search party would be listening on your preferred channel?

FRMS are so light and cheap nowadays...

FRS/unlicensed low-power UHF radio is OK for short range comms and even the inexpensive stuff sold nowadays is relatively good at what it does. But its main purpose is two-way communication at a prearranged frequency/channel, e.g. between two groups of hikers at short distances.

Other than limited range, the main problem with FRS radio is that you're limited to a small number of channels within the unlicensed band. Do your local SAR teams routinely check those channels? I don't know but it's not standard procedure where I live simply because FRS radio is not used by hikers and outdoorsmen on a very wide scale. Then again, some local SAR services do use FRS radio for backup at least, so in that case you might be in luck.

A decent FRS handheld can be a useful asset, but a lone individual counting on radio to call in SAR services or outside support would be far better equipped with a "serious" VHF/UHF handheld transceiver. Obviously, that requires a proper ham license (Technician class or higher), but that's pretty easy to get nowadays.

If you go that way, there are many good, inexpensive compact VHF/UHF handhelds available today. Such as the Kenwood TH-F6A: http://www.kenwoodusa.com/communications/amateur_radio/portables/th-f6a

A compact VHF/UHF transceiver weighs little more than a cheap FRS radio, but you get many, many more options, better antenna, lots more output power (5W), you can tune to a wide frequency range and the effective range is much better.

In areas with lots of people, It can work. Around Lake Tahoe where there are dozens and dozens of ski runs and golf courses, many carry the radios for communication with family and friends. As such, several lost people have been rescued by SAR using the radios. Either the SAR radios pick up the transmission or another recreationalist does and calls in to the Sheriff.

I have noticed while hunting in remote places, there is usually at least one other group on the radio in each area, but need for line of sight to communicate clearly is very limiting in mountainous places. I can hear them, but they can't hear me.

If SAR knows you have a radio, they will monitor for it. Otherwise, it would be a roll of the dice.

If you are in a high, exposed location, radios are great. If you are in a canyon or deep valley, fugedaboutit. My opinion - don't screw around- get a good PLB. If you need help, you want a reliable way to communicate that need. PLBs cost more, of course, but what is your life worth?

If you are in a relatively crowded area,there is also an excellent chance that traditional methods of signalling - . smoke,whistle, mirror flashes-will work quite well. A really good whistle only costs about $5, if you want to save money.

I notice that many rescues are now initiated by the victim calling or texting on their cellphones, which almost automatically give some location data. SAR folks really like location data.

Either get a whistle, a PLB, or carry your cell phone. Don't waste your valuable time with toy radios.

With radios, you have to have someone listening with a radio on the other end, on the same frequency as you. I would just go with a whistle. Probably about the same range as an FRS radio in canyons/valleys, and nothing is required on the receiving end for them to be able to hear you (except ears).

That being said, I do sometimes use FRS radios on camping trips, when our family is separated (possibly fishing in different areas, etc.) But we are relatively close to each other and are all on the same prearranged frequency. We're not transmitting in the dark hoping to reach some unknown person by chance.

I don't know if SAR personnel scan those frequencies as part of SOP. Kind of agree with others, I'd invest in a PLB if that's what you're using it for since at least it will be a more reliable means of signalling help, whereas an FRS/GMRS/HAM will only raise someone if all the conditions happen to be right.

HAM radio would certainly be better than FRS/GMRS in most cases. You can find them for $30-40 and at popular destinations you'll likely find a repeater. Technically you don't need a license to broadcast if you're in an emergency, but it doesn't really make any sense to carry the weight if that's all you'd be using it for. It's super easy to get licensed, a day of studying and a day to take the test and you're done.

You'll learn a lot too.

Agreed 100%.

The fact that I have FRS radio capability built into my GPS and what channel I would use in event of a problem is part of the travel plan info I leave with my wife when I go hiking.

If SAR knows you have it and will use it then they will too.
But it's not very likely they'll be listening without a tipoff to do so.

I always carry one when I go solo hiking. The one I take with me has a scan function that searches all of the channels for people talking. If you get into a jam, you can scan for others talking and then fix on that channel to communicate with them. You may have to determine which subchannel they are using, but it gives you options.

And like you said, if you left your predetermined channel with for family or friend whom you told "where you were going and when you would be back", that information could prove valuable to SAR.