woodentom
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Communication Between The Tower And Aircraft?

Tue Aug 18, 2009 6:43 am

i have a new client who maintains a network at the control tower of an airport in the UK. he has stated it is the VHF communication network to the aircraft.

i need to find out how critical that is and if this stopped working would it be safety critical to the aircraft.

i was told it is a back up or even a 2nd back up from the tower to the aircraft.

my question is what is the primary communication called and is the VHF a backup/2nd backup? and if so then how critical is it if it failed?

also what happens if the primary fails and then the VHF also fails?

your help/knowledge is appreciated as i have to talk to some people who are not in the comms industry this week and i need to understand this

thanks
 
Tristarsteve
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RE: Communication Between The Tower And Aircraft?

Tue Aug 18, 2009 8:16 am

For civilian aircraft, the VHF voice comms is the primary means of communication between the Tower and the aircraft. Military aircraft also have UHF comms, but this is not fitted to the average civilian aircraft.
VHF is it. There is no other way (unless you have a Very pistol with a green flare!!!)
 
woodentom
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RE: Communication Between The Tower And Aircraft?

Tue Aug 18, 2009 8:49 am

what happens if the VHF communication fails? do i assume the tower can't talk to the aircraft?

what is the backup communication?

thanks
 
oly720man
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RE: Communication Between The Tower And Aircraft?

Tue Aug 18, 2009 10:00 am



Quoting Woodentom (Reply 2):
what happens if the VHF communication fails? do i assume the tower can't talk to the aircraft?

what is the backup communication?

I'm not aware of comms failure in the tower at any airport and it would probably be a fairly catastrophic event for it to happen given the likely backups.

If just the tower went out then I'd imagine ground control would tell all aircraft under its control to stop moving. Any aircraft waiting to take off/land would, I'd expect, be seeing appropriate flares or flashing lights from the control tower and would hold position or clear the runway/go around and divert respectively.

Lights used from the tower are

http://pad39a.com/gene/lg.html

So aircraft in the air could well see flashing red (airport unsafe do not land) and may go back to the approach frequency to be told what to do

And aircraft on the ground may see flashing red (clear the runway) and go to ground frequency.
wheat and dairy can screw up your brain
 
woodentom
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RE: Communication Between The Tower And Aircraft?

Tue Aug 18, 2009 10:50 am

thanks for the reply.

so if the VHF comms from the comntrol fials then the aircraft will revert to another radar tracking centre and take instructions from them.

thanks again
 
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Starlionblue
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RE: Communication Between The Tower And Aircraft?

Tue Aug 18, 2009 11:27 am

Quoting Woodentom (Reply 4):
so if the VHF comms from the comntrol fials then the aircraft will revert to another radar tracking centre and take instructions from them.

Sort of. The term "radar tracking centre" may not be quite accurate. There is a difference here between approach and tower control.

Note that I am not an expert but here is my understanding and MAY BE INCORRECT. Experts please clarify.

The tower controls all ground movements (see exception below), as well as the last part of the approach and the first part after take off. Just after take off, control is handed to approach. Just before landing, control is handed from approach to tower.

At larger airports there is a separate ground control frequency that controls ground movements off runway, for example taxiing and gate positions. The tower would then control movements dealing with take off and landing, i.e. the runways and holding areas prior to entering runways.


In your case, at a larger airport. aircraft on the ground that holding to take off will go back to ground frequency. Aircraft in the air that are on tower frequency will go back to approach.

[Edited 2009-08-18 04:27:34]
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
SPREE34
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RE: Communication Between The Tower And Aircraft?

Tue Aug 18, 2009 12:50 pm



Quoting Woodentom (Thread starter):
he has stated it is the VHF communication network to the aircraft.

Probably ACARS. Aircraft Communications And Reporting System. It's a data Link. Whilst on the ground, no control instructions are passed through this system, only flight plan data and company communications. Were it to fail, the only ATC issue would be increased radio traffic on the Delivery freq. Company radio or ARINC would have increased voice traffic as well, such as load information, time out of the gate, time off, etc.

Were ACARS to fail, there would be no impact on safety. It's a convenience, not a necessity.
I don't understand everything I don't know about this.
 
IAHFLYR
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RE: Communication Between The Tower And Aircraft?

Tue Aug 18, 2009 1:18 pm



Quoting Starlionblue (Reply 5):
The tower controls all ground movements (see exception below), as well as the last part of the approach and the first part after take off. Just after take off, control is handed to approach. Just before landing, control is handed from approach to tower.

Ground Control controls things on the movement areas. Most ramps are non-movement areas, thus uncontrolled however, that does not always hold true. At larger U.S. airports there could be ramp control which is responsible for controlling the terminal ramps and around gate areas, to often do they control GA ramps. These ramp control towers are not FAA or Contract Towers, they are operated by a private source which normally would be the largest operator at the airport.

Local Control is responsible for the runways and initial separation of IFR. Depending on the type of airspace (Class B, C, or D) the Local Controller may also be responsible for separation VFR departures as well as airborne traffic and around the airport and within the surface area of the particular airspace classification.

Comm failure in the tower can be quite an intersting ordeal. Should the primary radios fail and you cannot communicate with the aircraft you'd attempt to use back-up radios. The back-up radios also failing there are handheld radios in most towers which have very small coverage, but usually will allow the controllers to communicate with airbone aircraft within approximately 4-5 NM of the tower as well as aircraft on the ground.

That failing you revert to light gun signals, telephone call to the airport operation folks who are hopefully able to commuincate with aircraft on the ground and advising them to stop, or any other means you can find. While all this is going on, approaching aircraft have most likely been stopped with communicatio via the telephone or landline to the approach control facility.

Hope this helps and wasn't overly confusing!!
Any views shared are strictly my own and do not a represent those of any former employer.
 
woodentom
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RE: Communication Between The Tower And Aircraft?

Tue Aug 18, 2009 3:33 pm

this is perfect.

thanks so much. i can now explain this to someone in easy terms which should help my client out.
 
rwessel
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RE: Communication Between The Tower And Aircraft?

Tue Aug 18, 2009 8:30 pm

Note that there isn't just a single VHF radio at any tower. If one fails, usually another one can brought into service fairly quickly (possibly little more than flipping a switch or two). Likewise, all larger aircraft have more than one VHF radio on board. Obviously multiple failures could happen at either end and completely eliminate VHF communications, but at that point other procedures apply, including talking to alternate ground sites (worst case you switch to the local center, and they should at least know that the airport you're talking to is down), light codes, and such.

But losing communications with an aircraft, or even an entire airport, will not result in any sort of catastrophe. It might create a traffic mess, as lots of planes might end up at alternate airports. Consider that losing all comms at an airport will be no worse than having to close the airport due to weather. Incoming flights will have to wait, or divert to alternates. If it's just the aircraft that's lost comm, then there are non-radio procedures to follow. For example, assuming your radar transponder is still working, you’d set it to squawk 7600, and then everyone who paints you with their radar will see you and know that you don't have any comms.
 
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Starlionblue
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RE: Communication Between The Tower And Aircraft?

Tue Aug 18, 2009 11:36 pm



Quoting IAHFLYR (Reply 7):
That failing you revert to light gun signals, telephone call to the airport operation folks who are hopefully able to commuincate with aircraft on the ground and advising them to stop, or any other means you can find

The last resort being Bruce Willis running around in the snow with a couple of flares.  duck 
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
thegman
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RE: Communication Between The Tower And Aircraft?

Wed Aug 19, 2009 1:25 am



Quoting Rwessel (Reply 9):
Likewise, all larger aircraft have more than one VHF radio on board. Obviously multiple failures could happen at either end and completely eliminate VHF communications, but at that point other procedures apply, including talking to alternate ground sites (worst case you switch to the local center, and they should at least know that the airport you're talking to is down), light codes, and such.

Lots of light GA aircraft also have backup comms.
 
sccutler
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RE: Communication Between The Tower And Aircraft?

Wed Aug 19, 2009 4:15 am

If my comm radios fail (most likely in event of complete electrical failure, since I have two VHF Comm radios), I'd use my handheld backup- have only had to do so once.

If that failed or was not present, and I was flying to a busy airport, I'd call the tower on my cellphone. Really.
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