121.5 aircraft emergency

[bailly2]

been listening to this frequency everyday for 3 years. haven't heard anything remotely resembling HELP HEEEELP. while im glad i haven't about anyone getting hurt, why is this such a boring frequency?

 

[kma371]

would you rather it be busy with emergencies? I don't

it's not really used for communication during emergencies. it's frequency is used for the ELT, emergency location transmitter, which broadcasts a beacon automatically when a crash is detected or it is manually pressed.

it is also used by combat air patrols to contact other aircraft when they enter restricted airspace.

 

[cavmedic]

" you're on guard"

 

[SpectrumAnalyzer]

121.5 MHz Aircraft Emergency

Usually aircraft just declare the emergency on whatever channel they're already communicating & are under radar control with the ARTCC, FSS, tower, arrival or departure console at any given time, you'd probably hear more traffic on 123.1 MHz which is generally allocated for C.A.P./S.A.R. missions & exercises.

 

[majoco]

121.5 MHz used to be the emergency frequency for the ELT's (Emergency Locator Transmitters) that were carried in the aircraft, usually down in the tail section, close to the "Black Box" (which is usually orange or bright red!) Flight Data Recorder and the Cockpit Voice Recorder. However, it was a pretty useless device as it was difficult to get a good bearing on the transmitter especially in hilly country.
Nowadays we have satellites doing the job much better and quicker and a SARSAT passes overhead about every 20minutes anywhere in the world and relays a registration number back to NOAA who then advise the local ATC. The frequencies are up in the 440MHz band so there's not much on 121.5 anymore. After all, the pilot of the aircraft is usually talking to ATC, you would just yell "Help!" on the frequency in use, wouldn't you?
Lots of info here...

NOAA - Search and Rescue Satellite Aided Tracking - Welcome

 

[robertmac]

And here I thought "pan pan pan" or "mayday mayday mayday" would have been used for a real emergency and not HELP.

 

[bailly2]

ok. thanks for the heads up on sarsat

 

[novascotian]

I hear guard being used here in Nova Scotia fairly often when an aircraft has gone off frequency or otherwise cannot be raised... the controller will ask an aircraft in that area to call the missing aircraft on guard and try to raise it that way. Also I sometimes hear ATC ask aircraft to monitor guard to listen for reported ELT signals.. there still must be some of those ones around. In the case a couple of days ago it was apparently a ship-based beacon. By the way when I say often, I mean a few times a year, certainly not daily or anything like that. Also the local military base is in fact heard daily with a short test of guard...not sure why. If everybody did that it would be cluttered with tests.

 

[SARCommCoord]

Funny Story

I am the Communications Unit Leader for the local Search and Rescue team. I was hiking a few years ago in one of the State Forests, and as always, I had my radio with me. While scanning through channels, my radio stops and I hear this warble tone. I pull my radio out of the pack and see that its on 121.5MHz, and a I continue moving forward, the warble gets stronger. I immediately switch to one of the local ARES frequencies and call for any listening station to see if anyone else local can pick up the signal. No one else is able to. I then call our teams PIO (who is also on CAP) who relays to the ARCC. Of course, the State Forest I am in is NOT a flight path, and no other aircraft in the area can verify the signal. Our PIO responds out with his RDF equipment as well as our IC. Based on RDF, we determine that the signal is coming from the northern part of the State Forest. Our IC contacts the local SO who have no idea what we are talking about, but because we frequently assist them, they dispatched the call as an aircraft down and send officers out to assist. Forestry also shows up to assist. As we start a quicky hast search in the direction of the woods, a biker comes out and advises us that he heard yelling from one of the trails. He believed someone had fallen down what was called "Devils Gulch" and was injured. We drove to the area and checked it out, and nothing. The SO Helo flew the area to pin point the beacon and found nothing. Long story short, it ended up being an old defective beacon in someones house.

 

[DaveNF2G]

A lot of the old 121.5 beacons would trip if the aircraft landed too hard or when the battery got low. Most searches tended to end at an airport.

The SARSAT uplink is around 400-406 MHz.

I occasionally hear air intercept training exercises on 123.1. The kind of traffic that happens during those missions would be on 121.5 in a real incident.

 

[ATCTech]

406 MHz to be exact.

 

[SpectrumAnalyzer]

S.A.R. UHF Frequencies

406.0 MHz has never been used as an exact frequency for anything in America, the existing combined agency allocated satellite based S.A.R. frequencies are 406.025 MHz, 406.028 MHz, 406.037 MHz & 406.04 MHz while 406.022 MHz is only used to measure carrier deviation & is not used to monitor emergency activations, the actual monitoring bandplan allocation is from 406.025 MHz to 406.076 MHz, soon to be released future use frequencies will be 406.049 MHz, 406.052 MHz, 406.061 MHz, 406.064 MHz, 406.073 MHz & 406.076 MHz, there are several other available frequencies that are being held in reserve for long term future expansion of the NOAA - Search and Rescue Satellite Aided Tracking - Welcome program.

 

[nd5y]

http://www.cospas-sarsat.int/images/stories/SystemDocs/Current/T012-OCT-2014.pdf
Page 218. Table H.2: Cospas-Sarsat 406 MHz Channel Assignment Table

 

[FlyteRadio]

406 MHz

http://www.cospas-sarsat.int/images/stories/SystemDocs/Current/T012-OCT-2014.pdf
Page 218. Table H.2: Cospas-Sarsat 406 MHz Channel Assignment Table

There is nothing in that entire document or any other valid document I've ever laid eyes on stating that 406 MHz or 406.0 MHz exist in any SAR frequency bandplan anywhere on this planet, I have to concur with SpectrumAnalyzer & this thread is obviously starting to go completely sideways.

 

[autovon]

There is nothing in that entire document or any other valid document I've ever laid eyes on stating that 406 MHz or 406.0 MHz exist in any SAR frequency bandplan anywhere on this planet, I have to concur with SpectrumAnalyzer & this thread is obviously starting to go completely sideways.

I'm fairly certain the document was posted as a reference as to where NEAR 406 these freqs are.....

As for 121.5, spectrumanalyzer has it right a few posts above. For flights under IFR or VFR flight following, the emergency is typically just declared with whoever the current controller is. For the VFR guys, 121.5 is a good one if assistance is needed since it's universal and you don't have to search around on the charts for a center freq.

Most of what you'll hear on guard these days are airliners looking for a good freq for a particular center, other aircraft trying to relay for ATC, those sorts of things. Also cabin PA announcements when a pilot hits the wrong switch. Or if you're over the Atlantic, Nat track deviations, WX reports, and world cup football scores.

It's still worth keeping in the scan bank, as you never know what will show up there.

 

[nd5y]

There is nothing in that entire document or any other valid document I've ever laid eyes on stating that 406 MHz or 406.0 MHz exist in any SAR frequency bandplan anywhere on this planet, I have to concur with SpectrumAnalyzer & this thread is obviously starting to go completely sideways.

Right. That's why I posted it.

 

[DaveNF2G]

I think there's a difference between "SAR frequencies" and SARSAT.