TL;DR: If I blast out a periodic SOS, what rescue action should I expect? Similar to if I activated an EPIRB, or something less?

This question is inspired by If I receive an SOS signal, what is the proper response? Also by the fact that I recently read about the survival story of Jose Alvarenga, whose fishing boat was taken out to ocean by a storm - Alvarenga had a radio and used it to call for help, but the search team called off the search in the storm and the radio battery did not last until after the storm, but I wonder if he could have gotten more out of the battery sending periodic SOS instead of voice so they could keep tracking him.

I am new to all this and am not licensed yet. My daughter knows even less about this, but she is interested, especially in Morse code. We have practiced it a little bit, and she quickly remembered the pattern for SOS.

If someone has the ability to broadcast an SOS and does so, but nothing else (for whatever reason, whether lack of knowledge or otherwise), what would be the reaction by the amateur radio community and/or the government and their rescue services?

I would like to think that it would be like in the movies, that someone would get a fix on my position and that search and rescue would start a search in that area. I am picturing in my head a few hams getting bearings on the SOS while one of them is contacting emergency services, who would likely have even better capability for triangulating. Basically, I'm envisioning that it would be treated similar to an EPIRB and that every reasonable effort would be made to mount a rescue.

But if all you do is blast out a periodic SOS in an appropriate range then what would the expected response be in reality?

For some context: I like to do a lot of outdoor activities, mostly hiking. I have been studying boating/sailing material and hope to be out on the water too within the next year or two. Of course I don't plan on anything bad happening, but I like to be prepared. I will probably get a PLB at some point (already should because of the hiking, but I haven't), but I'm still interested to know what response the SOS would get.


2 Answers 2


I'm not sure what you mean exactly by "blasting out a periodic SOS". Since you said SOS rather than Mayday, I presume that you're talking about Morse code, or another digital mode, rather than voice.

If you mean picking an HF band that is likely to have decent propagation to an area with a relatively large ham population, and picking a part of the band with decent activity, and then actively trying to get hams to answer with a decent antenna and a reasonable amount of power, then I think your odds are reasonable. Rather than expecting people to guess at your emergency and triangulate your location, you'd probably do much better at telling whoever answers your SOS what your location is to the best of your knowledge, and describing your emergency in practical terms.

The person who answers your SOS is likely to be an ordinary ham. He or she might well suspect a hoax, especially if you're just repeatedly broadcasting a canned SOS message. If instead for example you could give your call sign and mention that you're hiking in a particular national forest (in the US) in a particular state and you twisted your ankle, but you're in your tent and you have a sleeping bag, food, and water. Or that you're in a 33' (10 m) sailboat in the Gulf of Mexico with no mast in a storm. That would sound less like a hoax, and would also give the ham on the other end an idea of what agency to call, and give the responding agency an idea about how dire your situation is. GPS coordinates would be a nice help also.

The point I'm trying to get across is that a ham radio can be a very valuable tool in the wilderness, or in a boat in the middle of the ocean, or after a wide-ranging natural disaster, but please don't assume that simply having the radio makes you safe. You would also need a good antenna, enough battery power, as well as practical knowledge and experience of antennas, propagation, operating techniques, and so on in order to best use the radio and get through to someone before your battery dies.

Having operators triangulate in on a weak "SOS SOS SOS SOS SOS SOS SOS" resulting in a helicopter being quickly dispatched, is something that only happens in the movies.

  • $\begingroup$ "presume Morse rather than voice", yes, I realize my post was lengthy, but I did mention an actual case where someone in an emergency was requesting help by voice and ran out of battery power, and I suggested in my question that maybe he could have broadcast longer if he did less voice and just sent a periodic SOS. Also in that case, the fisherman lost track of his location during the storm and could not provide current location. So I am not talking about your average emergency call, hence the question. So you're "No, don't expect help" last paragraph is sad but good to know. $\endgroup$
    – Aaron
    Commented Apr 4, 2019 at 13:29

The only way you're likely to actually get help with this kind of signal is if you're noticed as "interfering" with other operators and do it for long enough, and with enough power, to get the "fox" hunters on your trail.

There is (in the USA) a corps of volunteers who specialize in finding stations that violate FCC regs. I read a write-up just yesterday about a fox hunt that took thirty years to finally track down a flagrant and continual violator.

Obviously, that kind of long term response isn't what you're after with an SOS call, so rather than just call for a few minutes every hour (or similar -- very good for maximizing battery life, not so much for getting responses quickly), you'd be ahead, as noted in another answer, to call on a commonly used CW frequency (in the US, you should ideally use the national calling frequency for one of the CW sub-bands, such as 7.050 on 40m, to maximize the likelihood of someone hearing and having the correct equipment and knowledge to copy and respond to the call), and keep calling until you get a response, followed by giving as many details as possible about your situation and location (and battery state, if that's an issue -- and it usually is, if you're in an emergency and running on battery).

The only exception I can see to this is if you're transmitting blind -- that is, you have a (presumed) working transmitter, but no way to receive a response. In that case, continual transmission (still on a CW calling frequency) until your battery power is gone is more likely to be useful than trying to ration your battery. You should cycle through the SOS, call sign, location, and situation, including "TX BLIND", as frequently as possible.

There's some difference of opinion whether its better to send slow (5-10 wpm) or faster (20+ wpm) to get through poor conditions -- it might make sense to send fast during one cycle of SOS etc., and then send slow the next time. After all, even if fast code gets through noise and fade better, an operator who can't copy fast won't get past the SOS.

  • $\begingroup$ Thank you. Since Morse is no longer a licensing requirement, but even my daughter can do SOS, I think that SOS-only is a real possibility - so, you think the chance of any meaningful response to that is slim-to-nil? $\endgroup$
    – Aaron
    Commented Apr 4, 2019 at 15:51
  • $\begingroup$ I do. Even finding where to send help is non-trivial; most hams aren't set up for direction finding (or not any more precisely than pointing a beam antenna with a 5 degree spread), so any position they might come up with, if they even think to try while your batteries last, will be a circle tens or even hundreds of miles across. $\endgroup$
    – Zeiss Ikon
    Commented Apr 4, 2019 at 15:53
  • $\begingroup$ Personally I find that fast Morse code gets through fading, QRM, and QRN better than slow code. Repeats help, of course. And 5 WPM is excruciatingly dull to listen to, unless it's sent Farnsworth-style, which makes it merely very dull ;) $\endgroup$
    – rclocher3
    Commented Apr 4, 2019 at 17:12
  • $\begingroup$ @rclocher3 Of course, most modern hams don't even know code, so you'd be dependent on getting one who can read it fast enough if you send fast. CW calling frequency might be the best odds of that, I suppose. $\endgroup$
    – Zeiss Ikon
    Commented Apr 4, 2019 at 17:25
  • 1
    $\begingroup$ @rclocher3 Calling frequencies is where I see old hands sending the new guys. "Ditch the tapes, get a Rockmite or Hilltopper and go make QSOs." $\endgroup$
    – Zeiss Ikon
    Commented Apr 4, 2019 at 18:49

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