121.5 Question

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Dispatrick

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i have 121.5 programed in to my radio i kno it is the aircraft emergency channel but i sometimes hear a aircraft call on this channel and say "on guard" ex: "continental 123 on guard" does anyone kno what on guard means?

thanks
 

kc0kp

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Guard

i have 121.5 programed in to my radio i kno it is the aircraft emergency channel but i sometimes hear a aircraft call on this channel and say "on guard" ex: "continental 123 on guard" does anyone kno what on guard means?

thanks
Guard is a term the military uses extensively. To be guarding a channel is to be monitoring it and being prepared to relay traffic or respond to emergencies. When forest service firefighters set up radio channels they include guard frequencies for both ground and aviation. It is a very quiet channel that is used only for emergencies. Radios in communications are dedicated solely to these channels so that prompt response can be made to an emergency. Public safety is beginning to adopt this practice as well.
 

lost_in_maine

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i have 121.5 programed in to my radio i kno it is the aircraft emergency channel but i sometimes hear a aircraft call on this channel and say "on guard" ex: "continental 123 on guard" does anyone kno what on guard means?

thanks
I have heard it used up here in Maine, 50 miles from Quebec border.... but with different Airlines...
Does Canada use the same band plan regarding Air emergencies as the US?
 

kicktd

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I have heard it used up here in Maine, 50 miles from Quebec border.... but with different Airlines...
Does Canada use the same band plan regarding Air emergencies as the US?
121.5 is the International Air Distress frequency, so yes you would hear Canadian aircraft on that frequency if they were needing to use it.

Sometimes aircraft trying to hail another aircraft will use the guard channel.
 

Chris-KH2PM

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To answer the OP's question, COMM 2 (or whatever radio is not being used) is typically tuned to 121.5 and monitored when enroute. COMM 1 is typically used enroute for pilot to ATC communications.

Quite frequently pilots miss an ATC "handoff" (frequency change) and soon are out of range of the ATC facility handling them. Often another pilot will be requested by ATC to "relay" a message on GUARD to the lost comms aircraft to switch to a given frequency, the next controller, if that happens.
COMM 2 is used to call the company and relay ETA and special request info when about 100 miles out or less. If the pilot forgets to tune the OPS frequency or 'flip the switch' from 121.5 to OPS, they will accidentally transmit a call to OPS on 121.5. That's when you hear someone else say, "You're on GUARD!" basically saying "hey dumbazz, flip the switch!"

:)
 

Grog

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How is 156.800 used regarding "Guard"?

Not in air use, bot in marine use...


http://www.coastalsailing.net/Cruising/Seamanship/Radio/RadioBasics.html

All ships should maintain watch on channel 16 (156.800 MHz) when within the service area of a VHF maritime coast station and while at sea. Ships with digital selective calling-equipped VHF marine radios should also keep watch on channel 70. After February 1, 2005 ships over 300 tons and passenger ships will no longer be required to monitor channel 16 but will be required under international law to monitor channel 70 for DSCSS signals.

Vessels not required to carry a marine radio (e.g. recreational vessels less than 20m length), but which voluntarily carry a radio, must maintain a watch on channel 16 whenever the radio is operating and not being used to communicate. Such vessels may alternatively maintain a watch on VHF channel 9 (156.450 MHz), the boater calling channel. Note however that urgent marine information broadcasts, such as storm warnings, are announced on channel 9 only in First CG District waters (northern New Jersey , New York and New England ).

U.S. vessels required to carry a VHF marine radio, such as commercial fishing vessels, must maintain a watch on channel 16 (156.800 MHZ) while underway whenever the radio is not being used for exchanging communications. Every power-driven vessel of 20m length or greater, every vessel of 100 tons and upward carrying one or more passengers for hire, every towing vessel of 26 ft length or greater, and every dredge and floating plant near a channel or fairway, must maintain a watch on both VHF channels 13 (156.650 MHz) and 16 (156.800 MHz) while the vessel is underway.
 

Bandingabout

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That is a most helpful post. I will definitely research more on the matter. I am not near a regulated waterway to hear marine/maritime comms. I will prepare a bank for my next opportunity.
 

immelmen

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I've heard that many times. So who is actually saying that - ATC, or some random pilot, or both?
could be either, but most are probably not pilots...not airline crews anyway. The only time our Com 2 is to be set to monitor 121.5 is when operating in or out of KDCA-Washington Reagan National airport. All other times(except for the obvious emergency or intercept type of situation that may require it), com 2 must be set to company freqs specific to the part of the continent we are over for ops/SELCAL purposes and com 3 is controlled by the ACARS box. This is mandated by the ops manual as the FAA requires the company to have redundant methods for dispatch to make contact with the aircraft...ie. ACARS/SELCAL/AIRINC Dial access.
 
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Chris-KH2PM

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Our ACARS is off COMM 3 exclusively (Boeing 737 models 300/500/700/800 and 900s). We use COMM 2 to call OPS when necessary, and tune guard in while enroute. We don't need to monitor ARINC if our ACARS is working, which it is 99.9% of the time. Tis true though, if an airliner doesn't have ACARS they must monitor specific voice channels in the event their Company dispatcher needs to contact a specific flight.

Typically when someone says "you're on GUARD" it's most likely an airline pilot monitoring the freq. Some actually seem to be a bit trigger happy, as if they anticipate someone goofing up and giving them the chance to yell "you're on GUARD!" heeheheh..GUARD "guards" so to speak.

Sometimes an ATC facility will ask an aircraft for a radio check on 121.5. Also, when we're in central Texas, and GW Bush is at his Crawford residence which activates a TFR (temporary flight restriction), USAF airborne AWACS (I assume it's AWACS) can be heard transmitting 'in the blind' to errant aircraft penetrating the TFR.
It goes something like this.."Aircraft on heading 145, 150 knots, squawking 1200, you're entering prohibited airspace and must turn around IMMEDIATELY. Acknowledge this transmission by squawking IDENT". I have heard this type of warning several times over the past couple of years on 121.5. Never have heard an aircraft reply to the warning, nor heard what the consequences were. Not sure if they actually scrambled fighters on them or not either. Typically it's just an errant GA (general aviation) pilot out on a VFR sightseeing flight enjoying the day. Thing is, all pilots should check with the local FAA for a weather briefing and check if there are any local TFRs. Many don't bother if the weather is good..just jump in the plane and launch.
 

immelmen

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Our ACARS is off COMM 3 exclusively (Boeing 737 models 300/500/700/800 and 900s). We use COMM 2 to call OPS when necessary, and tune guard in while enroute. We don't need to monitor ARINC if our ACARS is working, which it is 99.9% of the time.
just wondering, are you flying for a 121 carrier. We have ACARS and its Com3 exclusive but our 121 FOM/CFM states a federal requirement for a dispatcher to be able to reach the aircraft in at least two different modes...ie. in addition to ACARS, the ARINC/OPS/SELCAL must still be monitored. I assumed if it was a federal requirement that it applied to all air carriers.

I had an APD on the jumpseat get picky about the freq in com2 during a line check last year, Id be interested to know if its just my company or not.
 

Chris-KH2PM

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just wondering, are you flying for a 121 carrier. We have ACARS and its Com3 exclusive but our 121 FOM/CFM states a federal requirement for a dispatcher to be able to reach the aircraft in at least two different modes...ie. in addition to ACARS, the ARINC/OPS/SELCAL must still be monitored. I assumed if it was a federal requirement that it applied to all air carriers.

I had an APD on the jumpseat get picky about the freq in com2 during a line check last year, Id be interested to know if its just my company or not.
I fly for Continental. Our planes have SELCAL and ACARS. Thankfully we don't have to monitor any ARINC voice freq's. :)
 

daedalus

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Many of us in general aviation got religion about monitoring 121.5 when flight resumed after 9/11. Being situated between NYC and DC I was perhaps especially aware of the need. It is a habit that stuck with me and I still hear aircraft being challenged and vectored away from a TFR, the DC ADIZ, etc. especially when the Camp David TFR is expanded.

As a side benefit I have on occasion picked up a strong ELT while inflight. If it stays active for more than a few minutes I usually advise the controller working me. The report is pretty much ignored in the NY area but the controllers in the DE/MD/VA area do a great job of trying to locate the source by polling other aircraft in the area to determine signal strength. I have yet to be working a single sector long enough to know if anything was ever found.
 
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