c5load
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I Can Hear ATC, But Not The Pilots, Why?

Sat Apr 03, 2010 5:48 pm

Listening to MSP approach, I can hear my father's flight number when ATC issues instructions, but can't hear him respond. Why does this happen sometimes?
"But this airplane has 4 engines, it's an entirely different kind of flying! Altogether"
 
Mir
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RE: I Can Hear ATC, But Not The Pilots, Why?

Sat Apr 03, 2010 6:22 pm

Sometimes one controller will work multiple frequencies. He'll talk on all of them, and listen to all of them, but the pilots will only be listening and talking on one of them. If you're not tuned to the same one as the pilots, you won't hear them, but you will hear the controller.

Are you hearing some other flights on the feed, or is it just the controller talking?

-Mir
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c5load
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RE: I Can Hear ATC, But Not The Pilots, Why?

Sat Apr 03, 2010 6:35 pm

Quoting Mir (Reply 1):
Are you hearing some other flights on the feed, or is it just the controller talking?

Yes as I listened more I could hear some pilots calling in, but not all of them.
"But this airplane has 4 engines, it's an entirely different kind of flying! Altogether"
 
411A
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RE: I Can Hear ATC, But Not The Pilots, Why?

Sat Apr 03, 2010 9:16 pm

The answer often is...a limited remote communications outlet (LRCO), on some frequencies.
Most noticed over France, during the nightime.
 
EMBQA
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RE: I Can Hear ATC, But Not The Pilots, Why?

Sat Apr 03, 2010 10:07 pm

It has to do with line of sight on the transmitting radio.
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shamrock137
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RE: I Can Hear ATC, But Not The Pilots, Why?

Sat Apr 03, 2010 10:10 pm

Are you listening to this online with a site such as Live ATC or a scanner?
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c5load
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RE: I Can Hear ATC, But Not The Pilots, Why?

Sat Apr 03, 2010 11:13 pm

Quoting Shamrock137 (Reply 5):
Are you listening to this online with a site such as Live ATC or a scanner?

Listening to LiveATC.net
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shamrock137
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RE: I Can Hear ATC, But Not The Pilots, Why?

Sat Apr 03, 2010 11:30 pm

If the aircraft are on the ground you may not be able to hear them due to the aircraft radio transmitters not being as powerful as those used by ATC. It also depends where the scanner receiving the signals is in relation to the airport. You will be able to hear aircraft that are in the air because VHF radios operate by what is known as line of sight. This means that the antennas need to be able to "see" each other for the signals to be received. The higher an aircraft is, the further the signal will be able to be received depending on how powerful the transmitter is. Hope this clears it up a bit.
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Mir
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RE: I Can Hear ATC, But Not The Pilots, Why?

Sat Apr 03, 2010 11:45 pm

Quoting EMBQA (Reply 4):
It has to do with line of sight on the transmitting radio.

That was my first thought as well, but that would normally mean you hear the pilots but not ATC, instead of the other way around.

Quoting 411A (Reply 3):
The answer often is...a limited remote communications outlet (LRCO), on some frequencies.
Most noticed over France, during the nightime.

I'll take your word for it with respect to France, but these situations are common in the US as well. At least as recently as 2006, the approach/departure controllers at JFK would talk on two frequencies - one for VFR aircraft and one for IFR aircraft. If you were on the VFR frequency, you'd hear the instructions being given to the IFR aircraft, but you wouldn't hear the pilots responding.

-Mir
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Fly2HMO
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RE: I Can Hear ATC, But Not The Pilots, Why?

Sun Apr 04, 2010 4:30 am

Quoting Mir (Reply 1):
He'll talk on all of them, and listen to all of them, but the pilots will only be listening and talking on one of them.

In other words, ATC can transmit/receive on multiple frequencies simultaneously, while aircraft can't (technically).

Quoting Mir (Reply 8):

That was my first thought as well, but that would normally mean you hear the pilots but not ATC, instead of the other way around.

Yep. Most likely the frequency is split.

Quoting Mir (Reply 8):
If you were on the VFR frequency, you'd hear the instructions being given to the IFR aircraft, but you wouldn't hear the pilots responding.

Had this happen a lot in PHX APP in a slow day. I want to say this also happened to me on ZABQ once or twice, been a while though...
 
ajd1992
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RE: I Can Hear ATC, But Not The Pilots, Why?

Sun Apr 04, 2010 12:15 pm

Quoting EMBQA (Reply 4):
It has to do with line of sight on the transmitting radio.

That's true, but usually you won't hear the ATC, not the pilot. The pilot being in the plane would be the one person you'd expect to hear them more than anybody.
 
c5load
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RE: I Can Hear ATC, But Not The Pilots, Why?

Sun Apr 04, 2010 1:07 pm

Quoting Shamrock137 (Reply 7):
Hope this clears it up a bit.

It does, thank you sir. It's really cool though being able to hear one of your family members talking with ATC while I ma sitting at work and he is flying somewhere.  
"But this airplane has 4 engines, it's an entirely different kind of flying! Altogether"
 
71Zulu
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RE: I Can Hear ATC, But Not The Pilots, Why?

Sun Apr 04, 2010 5:07 pm

Quoting c5load (Reply 6):
Listening to LiveATC.net

It sounds to me like an antenna issue with the feed. If the person providing the feed doesn't or can't have an external antenna and is close to the airport, the controllers will come in loud and clear but the pilots on approach will be weak or not heard at all. Listened to the feed last night and that sounds like what is happening. You really don't hear the pilots until they are closer in but the controllers are loud and clear. On the tower and ground feeds, you hear the pilots fine.

It could also be the fact that one scanner has to monitor the 4 different approach frequencies. The scanner will scan the appropriate frequencies and will lock onto the first one that it hears something on. You can hear the approach controller transmit to your Dad's plane but if another pilot or controller is also talking on one of the other approach frequencies, as soon as the controller talking to your Dad stops transmitting, the scanner will start to scan again and will lock onto the other transmission before your Dad can respond. With 4 different frequencies and just one scanner trying to catch the transmissions from all 4, it's just not going to happen when it is busy and many will be missed or cut off.

It's still nice having a feed though! We had one at MSY and was one just one scanner covering everything but it still did a pretty good job since we are not as busy and wish we still had it running.
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HAWK21M
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RE: I Can Hear ATC, But Not The Pilots, Why?

Mon Apr 05, 2010 2:37 pm

Sounds like a range issue....on the feed thats providing data to the website.
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n901wa
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RE: I Can Hear ATC, But Not The Pilots, Why?

Mon Apr 05, 2010 5:25 pm

My 2 cents, I agree with Fly2HMO. Sounds like a freq split. We have that here at LAX late at night arround 2300. Both 121.65 and 121.75 on the same controller. I always double check to make sure I don't step on anyone before we push back to taxi, from the north side to the south side. Before 2300 (I think its 2300) I usally call on 121.65 and at the mid point switch to 121.75. HTH  

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