CRJ200 Airline Pilot

The personal experiences, thoughts of an CRJ captain


“You’re On Guard!” The Emergency Frequency Channel

Posted by Jeffrey on October 11, 2008

Emergency Frequency

Emergency Frequency

You may not remember the tower frequency of your local airport that you fly out of or the localizer frequency of your favorite ILS, but chances are, if you have flown for any amount of time, you know what the “Guard” frequency or the “aircraft emergency frequency” is. And if you know what that frequency is, chances are that you monitor the aircraft emergency frequency, 121.50 MHz, when you fly. And if you monitor the frequency, chances are you will hear someone accidentally try to contact their operations or try to give a position report or any number of things on this frequency. And chances are, the next thing you will hear is a barrage of transmissions from other pilots saying, “You’re On Guard!” 

Sometimes these pilots are nice about it but sometimes you would think that it was the end of the world! “YOU’RE ON GUARD!” My goodness, relax…it’s not the end of the world.

Here is a little history. Aviation being inherently unforgiving when something goes wrong, pilots needed a frequency that would never be used by any other service.  The frequency, 121.50 MHz, was picked and has been the “guarded,” “emergency frequency” for aviation ever since. I don’t know the exact date it was selected but it was partly selected because it exists right in the middle of the original VHF frequency range of 118 – 136 MHz. There are other technical reasons as well.

Anyway, 121.50 MHz is the rock star of frequencies. From the most neophyte of pilots to the most aged airline pilot, everyone knows what the frequency 121.50 MHz means.

121.50 MHz is one frequency that is monitored by pilots, flight service stations (FSS), air traffic control (ATC), Air Route Traffic Control Centers (ARTCC) and some emergency stations.

On more than one occasion I’ve heard pilots in distress get instantaneous help from other pilots.

On one occasion while flying over the midwest, 121.50 was alive with chatter because a pilot’s engine had failed and he was going to dead stick it in. The airliners were playing tag as they flew over the location of the transmission, relaying the pilot’s location to ATC and providing assistance as best they could. As one airline went out of range, another would take it’s place, and so on. I just sat back and listened. As I faded out of radio range, I heard one pilot transmit that the pilot that lost the engine had landed and was safe.

On another occasion, a pilot lost his engine, stated his emergency. Again, pilots immediately were offering assistance and suggestions. “Did you switch fuel tanks?” “Did you prime the engine?” The pilot with the failed engine came back and said, “It’s OK guys, I ran out of fuel. It’s my fault. I have a landing site. I will let you know when I’m down.” That was the last I heard as I flew over the horizon.

On yet another occasion, we flew out of range of our current Center controller. (I thought it had gotten a little quiet.) ATC broadcasted over 121.50, found us, and gave us the next frequency.

Finally, and probably the most important uses of the emergency frequency is related to the Emergency Locator Transmitter (ELT). ELT’s are located usually in the tail of an airplane, where, if an airplane crashes, it is most likely to survive the impact and begin transmitting it’s distress signal. This is important because unfortunately on some occasions, the pilot doesn’t have the presence to make a transmission and eventually crashes. In the past, a hard landing could set off the distress signal causing a flurry of activity to find the “downed” aircraft. But lately, newer version of ELT’s have begun transmitting on the UHF frequency 406 MHz coupled with the frequency 121.50 MHz, it being a low power beacon for homing purposes. Pilots that monitor the emergency frequency, upon hearing the ELT signal, notify ATC and tracking down the “distressed” aircraft begins. Satellites are also being used to track down ELT frequencies which is another layer of safety that pilots will ultimately benefit from. I am not really sure how that works but it’s pretty cool.

If you are flying an older airplane, you will want to get the ACR AeroFix 406MHz Personal Locator Beacon (PLB) w/GPS Interface (2799.2) – PLBs are emergency life saving devices that you want to have onboard if your airplane goes down. Don’t rely on your onboard ELT to help rescue aircraft find you.

So the next time you fly, if you have an extra radio, monitor 121.50 MHz. You may be able to help someone. If nothing else, you will feel for that pilot that accidently transmits and is instantly told, “YOUR ON GUARD!” Ouch!

P.S. Here is a CD that I strongly recommend if you want to brush up on your radio skills:
Communications Trainer: Say Again Please CD-ROM – It contains great information on VFR and IFR operations, towered and nontowered airports, enroute flight, and emergency situations.


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