So i was thinking yesterday about this. Apparently theres a part of the ocean over by the mediterranean sea or somewhere around there that has no wind. Lets say that you are in a yatch sailing along and out of the sudden ur engines fail and u cant use ur sails cuz theres no wind. Now, if you had a handheld radio like the ICOM IC-A6, tune it to 121.5 and transmit for help, would a jetliner flying above receive your radio transmission? Im curious as to if this would work and its been too long since i studied the subject to remember. I know the radio waves bounce off the ionosphere but thats it. Anybody have a take on this?

 

Cheers

FM Radio Frequency is line of sight....wind or other environmental factors impact that frequency.

 

If I was in the ocean with no wind or weather and a jet flew above and I could tune into 121.5 with a two way.....no problem, I just hope they are listening is all

Hmm. You'd have to know your position, at least roughly, for any radio contact to be much use, but as Matthew says, the IAD frequency should at least get your plight known.

FM Radio Frequency is line of sight....wind or other environmental factors impact that frequency.

 

If I was in the ocean with no wind or weather and a jet flew above and I could tune into 121.5 with a two way.....no problem, I just hope they are listening is all

 

Aren't they always supposed to be monitoring 121.5, the same way professional shipping is always supposed to be monitoring channel 16?

I once had a tour of a German lifeboat and they had a radio tuned to 121.5. Though if I was on the yacht I'd prefer to have some kind of satellite based communication system, preferably one that encodes my GPS coordinates.

Hi guys.

 

I used to be an SAR pilot in the RAF, now flying Chinook.

 

There is a network of satellites, SARSAT and COSPAS which monitor 243.0. They used to monitor 121.5 as well but that was turned off a few years ago. All new radios/EPIRBS/PLBs (Personal Locator Beacons) now use 243, and most sent a GPS data burst every 5 seconds.

 

So the procedure would be:

 

Aircraft ditches.

You heroically save the crew and passengers.

In your dinghy you pull the toggle to activate your PLB.

After 2 hits from a beacon your distress beacon signal is forwarded to the nearest ARCC (Aeronautical rescue coordination centre).

The ARCC will scramble the appropriate assets, in the doldrums (the windless area I think you mean), this would most likely be a long range SAR platform such as the USCG C-130 or as it used to be a RAF Nimrod : (.

This aircraft will drop off a survival pack which will contain food, water, first aid kits, etc.

The ARCC will also scramble intercept naval assets who will recover you if you are out of helo range, more than about 240nm from shore.

 

So that's what would happen.

 

If as you say you have a slightly more laissez-faire attitude to survival and only have an ICOM you would most likely transmit on Ch16, the distress channel which would be picked up by a nearby ship.

If you transmitted on 121.5 a jetliner could pick up your transmission up to about 15-20nm laterally given a FL300ish as a cruise level, If they are monitoring it.

 

There is no regulation I'm aware of that states it must be monitored, but airmanship would dictate that if you are not using a radio stick it on 121.5 or 243.

 

I have used airliners numerous times on the distress frequency to act as a comm relay when we are not in range of any other rescue assets and need to pass a message.

 

Hope this helps

 

Dave

 

Keep the blue side up.

Hi guys.

 

I used to be an SAR pilot in the RAF, now flying Chinook.

 

There is a network of satellites, SARSAT and COSPAS which monitor 243.0. They used to monitor 121.5 as well but that was turned off a few years ago. All new radios/EPIRBS/PLBs (Personal Locator Beacons) now use 243, and most sent a GPS data burst every 5 seconds.

 

So the procedure would be:

 

Aircraft ditches.

You heroically save the crew and passengers.

In your dinghy you pull the toggle to activate your PLB.

After 2 hits from a beacon your distress beacon signal is forwarded to the nearest ARCC (Aeronautical rescue coordination centre).

The ARCC will scramble the appropriate assets, in the doldrums (the windless area I think you mean), this would most likely be a long range SAR platform such as the USCG C-130 or as it used to be a RAF Nimrod : (.

This aircraft will drop off a survival pack which will contain food, water, first aid kits, etc.

The ARCC will also scramble intercept naval assets who will recover you if you are out of helo range, more than about 240nm from shore.

 

So that's what would happen.

 

If as you say you have a slightly more laissez-faire attitude to survival and only have an ICOM you would most likely transmit on Ch16, the distress channel which would be picked up by a nearby ship.

If you transmitted on 121.5 a jetliner could pick up your transmission up to about 15-20nm laterally given a FL300ish as a cruise level, If they are monitoring it.

 

There is no regulation I'm aware of that states it must be monitored, but airmanship would dictate that if you are not using a radio stick it on 121.5 or 243.

 

I have used airliners numerous times on the distress frequency to act as a comm relay when we are not in range of any other rescue assets and need to pass a message.

 

Hope this helps

 

Dave

 

Keep the blue side up.

im just saying because i have an ICOM radio and heard a story from my girlfriend's friend's parents who long time ago went sailing around the world and their yatch's engine died in this windless zone, fortunately her father was a yatch engine engineer and was able to fix the engine in a couple of days...so i thought of the story and my radio...of course in times like now we have the latest in technology including GPS....interesting comments tho...what you refer to as PLB(i think) we refer to as ELT(emergency locator transmitter) here in canada and as well have moved on from the former 121.5 to 403....cheers

Aren't they always supposed to be monitoring 121.5, the same way professional shipping is always supposed to be monitoring channel 16?

 

Not always, The aircraft is number 1 priority and anything can happen to take their attention away from the radio's for a moment. Monitoring 121.5 is a low priority as they are responsible for XXX amount of souls sitting behind them. They can be dealing with quite a lot at times.

Depends on the airline. Some are always standing by 121.5 we are always on company freq.

Bermuda Triangle?

Bermuda Triangle?

no, i think its somewhere by the equator....here...

FM Radio Frequency is line of sight....wind or other environmental factors impact that frequency.

 

If I was in the ocean with no wind or weather and a jet flew above and I could tune into 121.5 with a two way.....no problem, I just hope they are listening is all

 

Aircraft radio equipment uses AM, not FM, so some ionospheric skip might occur, unfortunately the miniscule power of a handheld such as the hypothetical ICOM at ~5 watts isn't going to be all that dependable...

 

I have an ADI AT-600 which I primarily use for 2m/440MHz FM ham use, but it is also capable of TX/RX in the aircraft bands with AM. I live about 5nm from the tower at KGYY, but can only talk to them whenever I have the roof-mounted antenna connected. With only the rubber ducky antenna, forget about it...

 

...on the other hand, if I'm at 5,000' and 20nm out, the rubber ducky antenna works just fine even on 2 watt (low power) setting! :Nerd:

 

 

Aircraft radio equipment uses AM, not FM,

 

I thought that 121.5 was an FM frequency...I never really researched the tech behind these radio's other then using them. We were taught they are line of sight so sitting in the ocean with a hand held would mean the transmission wouldn't make it around the curvature of the earth, so a passing aircraft or ship is your best hope.

I thought that 121.5 was an FM frequency...I never really researched the tech behind these radio's other then using them. We were taught they are line of sight so sitting in the ocean with a hand held would mean the transmission wouldn't make it around the curvature of the earth, so a passing aircraft or ship is your best hope.

It's the frequency that determines whether a signal will be line-of-sight only or capable of ionospheric bounce, rather than the modulation method (i.e. AM or FM). Roughly speaking, the longer the wavelength (hence lower the frequency), the more bounce you get.

As a non-flyer myself, radios and beacons and stuff are a complete mystery to me but I still find the film 'Mercy Mission' fascinating; it's the true story of a pilot who lost his bearings over the Pacific while ferrying a light aircraft from the USA to Australia in stages.

He was able to establish contact with an airliner in the area, and between them they worked together to try to get him out of trouble

The full film is on youtube in 9 parts, he picks up the airliner in part 4 near New Zealand if anybody wants to watch it.

Sorry the forum software won't seem to let me post all 9 clips, see if these 2 work-

 

 

 

 

 

Im going to download the movie. Looks interesting.

 

 

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