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-   -   Memo to pilots using 121.5 (https://www.pprune.org/jet-blast/368623-memo-pilots-using-121-5-a.html)

punkalouver 3rd Apr 2009 20:44

Memo to pilots using 121.5

In the U.S., the emergency frequency 121.5 MHz is guarded
(monitored) by military towers, most civil towers, FSS’s,
radar facilities, and many airliners. This frequency is reserved
solely for emergency communications for aircraft in distress.
A radar controller reported an incident to ASRS in which two
air carrier flight crews misused the Guard frequency.

While working the radar position…I heard aircraft X call
aircraft Y over the 121.5 emergency frequency. This is not
uncommon, but annoying because it comes out the same
loudspeaker as the landline calls and, thus, must be fairly
loud. There was no response to aircraft X’s call. A few minutes
later aircraft X again called aircraft Y. I assumed at this point
that aircraft Y must have gone no-radio and aircraft X was
trying to help locate him. Again, no response…After aircraft
X had called aircraft Y for the third or fourth time on the
emergency frequency…aircraft Y replied, ‘This is aircraft Y.’
At this point, aircraft X said, ‘We’re going to be arriving just
a few minutes behind you, so would you hold the van for us
so we can get to the hotel?’I keyed up and said, ‘This doesn’t
sound like an emergency.’Both pilots then responded with
comments about, ‘Where’s the Guard Police when you need
them?’and ‘Must not be a very busy night.’

Apparently these pilots who were at FL350 and FL390 don’t
realize that, at those altitudes, their radio range is several
hundred miles. Since this emergency frequency is monitored at
[most] ATC facilities, I suspect that their conversation came
over the loudspeakers in at least 3 Centers, probably a dozen
Approach Controls, dozens of Towers, multiple RCO [Remote
Communications] outlets at AFSS [Automated Flight Service
Station], plus hundreds of commercial aircraft cockpits. I
suspect someone at one of these locations was busy and was
probably distracted, at least momentarily, from their primary
safety function. I also suspect that the airline has some other
method for inter-aircraft communications. It is events like this
that make controllers, and probably pilots, instinctively turndown
a speaker that is making noise in the background. A
subsequent actual emergency call could go unheard because
these [pilots] chose the inappropriate means to communicate.

ASRS CALLBACK Issue 351 - March 2009

Hotel Charlie 3rd Apr 2009 21:25

It´s just poor airmanship! Use your ACARS or company freq! If you have neither get your own van!

Final 3 Greens 3rd Apr 2009 21:29

We need to get some Brit PPLs out there doing training fixes to teach them a lesson :}

NoJoke 3rd Apr 2009 21:39

Sooooo bad
Try operating in the Middle East/ISC. "Baboo please contact Mumbai and let them know ...." ... Nothing really. Guard is used out there as an alternate frequency. I just hope one day they are down there trying 121.5 on the last milliamp to contact help, when they are stepped on by some fool. Try to use guard wisely and not just as a convenience.

DutchBird-757 3rd Apr 2009 21:59

Always amuses me when on guard that if someone makes a wrong switch and transmits on it, it will generally take about 3 seconds for someone to jump on his back. (you're on guard! :mad:)

EMIT 3rd Apr 2009 22:07

Because if somebody does not remind him, he'll keep trying 10 times before it finally dawns on him that he made a switchology mistake.

The real annoyance is that the Guard Police buggers don't listen to what is said on Guard: they will even yell "you're on guard!'' when somebody specifically calls out that he is on guard, to find a specific aircraft on behalf of some Air Traffic Centre. Hell, the real freaks will probably call "you're on guard!" to an announcement on guard about an ongoing SAR operation.

Huck 4th Apr 2009 02:02

"Short count."

YoDawg 4th Apr 2009 04:59

As far as I understand it, "guard" is a function of certain (usually military) radio sets.

"Guard" is a second receiver (no transmission) which can be set to a second frequency so that the reception includes the "active" frequency (tranceiver) and the "guarded" frequency (receiver only).

It is impossible to transmit on this "guarded" frequency without setting it also as the "active" frequency.

Any frequency can be guarded. The military UHF radio "guard" function is normally set to "guard" 243.0MHz. A similar function on a VHF set (I've not heard of one) would logically be set to "guard" 121.5MHz.

"Guard" is a function, not a frequency. I've never seen a civilian radio set with a "guard" function on it.

L337 4th Apr 2009 06:52

121.5 is commonly referred to as "guard" within civilian aviation.

18-Wheeler 4th Apr 2009 07:07

121.5 is commonly incorrectlyreferred to as "guard" within civilian aviation.
Anoys the crap outa me, people calling it 'guard'.

PantLoad 4th Apr 2009 07:24

Until recently....
Until recently, 121.5 MHz was used by satellites to pinpoint the location of the transmitter....for Search and Rescue purposes. Now, that function has been moved to the 400 MHz band.

I don't recall the exact figure, but a transmitted signal on 121.5 needed to be of a certain duration to trigger the satellites to assume there was an aircraft in distress. This is why we shouldn't be using 121.5 MHz, except in an emergency.

Again, this function has been moved...or is in the process of being moved....to a frequency that we are unable to select for a BullXXXX frequency.

The controller was correct in filing an ASRS report. At high altitude flying, typically a aircraft's transmission can be heard for a 200 nm radius (or more). So, a lot of people can be comforted to know the hotel van is being held for you.

What may not be commonly known among pilots is that the aircraft holds an aircraft station radio license. Yes, the airplane is considered as a radio station. With that license comes restrictions...what frequencies are authorized for transmission...what restrictions are placed on each frequency or band of frequencies. Calling on 121.5 MHz to hold the hotel van MAY be in violation of the conditions/restriction of that radio station license. (I can't speak for other countries....nor, can I speak for the international authorities....ITRU, I think it is, not sure....but, as far as the U.S. is concerned, BullXXXX on 121.5 MHz is technicaly illegal, in that it violates the conditions/restrictions of the radio station license.)

The State in which the aircraft is registered is responsible for licensing the aircraft radio station. If/when transmissions 'go international', that State and the aircraft radio operation are required to comply with international telecommunication rules.

For example, if, while in international airspace, the pilot decides to operate the aircraft's HF on Amateur Radio frequencies (Assume he/she is a licensed Amateur Radio Operator.), he/she may be in violation, since the radio station license may not be authorized to transmit on those frequencies.

Exception: In an emergency, anything is OK....you do what you have to do.

Fly safe,


PantLoad 4th Apr 2009 09:34


121.5 is commonly used by ATC or aircraft to advise an aircraft to call on a control frequency.
Clearly this prevents a dangerous situation arising and is an acceptable use of the emergency frequency.
Basil is correct.....

Fly safe,


Mister Geezer 4th Apr 2009 09:39

The only way this will stop is if it gets reported and followed up by the operator(s) concerned. After all it will be nothing short of embarrassing for an operator to be faced with ATC accusing their own flight crew of misusing 121.5. To those in ATC, all you need is the date and the callsign and insist it gets followed up. Once it reaches the operator concerned, that is all that is needed to track down the offending crew!

For us pilots, if you hear someone abusing the guard frequency, what is stopping you from filing an ASR? With the callsign and the date then I am sure the details can wind their way to the relevant flight safety office in any airline and then on to the crew concerned!

Check Mags On 4th Apr 2009 10:44

The real annoyance is that the Guard Police buggers don't listen to what is said on Guard: they will even yell "you're on guard!'' when somebody specifically calls out that he is on guard
Had this happen coming out of Doha, handed over from to Tower to Radar.
Halfway through radar's initial instruction their radio failed, tried them a few times and then went back to tower. They instructed us to call radar on 121.5.

On transmitting to Doha

"Doha radar this is ******** on 121.5" giving level and heading.

Doha's reply was drowned out by the guard police. 4 times I had to transmit to Doha before I got a reply that was not drowned out. And admittedly slightly losing my rag and telling the 3rd guard policeman that I knew I was using 121.5 as I had been instructed to do so, and would he shut up.

At this point we where at 4000 feet and heading towards Iranian airspace.

Now I know that the 121.5 policeman would have probably only been able to hear my transmission and not Doha's, but if he had listened to my words he would have realised that it was intentional use and not finger trouble.

captainspeaking 4th Apr 2009 11:13


Name and shame. Which airline? Which c/s?

L337 4th Apr 2009 11:41

Anoys the crap outa me, people calling it 'guard'.
Lots in life annoys me. Death. Suffering. Poverty. Disease. But not people calling "it guard".

Or bad spelling.

Do I understand "Idjuts" to mean Idiots?

TBM-Legend 4th Apr 2009 13:09

121.5/243.0 = Navy Common....:eek:

SOPS 4th Apr 2009 14:28

Gaurd Police
What is it with these people. Just the other day on the way to Bombay, i heard the following on 121.5

"This is ABC Contol calling FlyByNight 867 on 121.5, do you read?"

Before anyone could answer a very British voice said "transmitting on gaurd"

Lord, give me strength!!:ugh::ugh:

Finn47 4th Apr 2009 15:18

Since Feb 1, the satellites will only pick up the new ELT frequency 406 MHz, and possible misuse of 121.5 will not create a false alarm through the satellite system any more. Everybody else will still be listening, though.

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