listening to ATC on United Airlines

I'm not a pilot, just your typical passenger. I don't fly United often,
so I just discovered that they put the ATC on the inflight audio. I was
totally fascinated and want to learn some more. Is there a website that
has some basic ATC protocols? Not some huge reference manual, just the
common phrases that you hear over a commercial flight's radio.

A few questions I had while listening:

- What happens if 2 people try to talk at the same time? Do you hear
both voices or neither? How do they avoid talking over each other?

- It seems that there is no authentication/security, the parties just
identify themselves. Have there been cases of troublemakers making
false impersonations?

- They ask pilots their speed, altitude, and heading a lot. Can't the
transponder send that information?

- Do any other airlines put ATC on the inflight audio?

Bucky wrote:

I'm not a pilot, just your typical passenger. I don't fly United
often,
so I just discovered that they put the ATC on the inflight audio.
snip

if you enjoy listening to air traffic control, here is a web site that
carries live (usually 30 second to two minute delay) atc frequency
feeds from around the world:

http://www.liveatc.net/

--
Peter

Bucky wrote:
I'm not a pilot, just your typical passenger. I don't fly United often,
so I just discovered that they put the ATC on the inflight audio. I was
totally fascinated and want to learn some more. Is there a website that
has some basic ATC protocols? Not some huge reference manual, just the
common phrases that you hear over a commercial flight's radio.

You might find it to be in the reference manual category, but the AIM
(Aeronautical Information Manual) really isn't too hard to read, especially if
you are a motivated learner, and you can get it free on the internet:
http://www.faa.gov/ATPubs/


A few questions I had while listening:

- What happens if 2 people try to talk at the same time? Do you hear
both voices or neither? How do they avoid talking over each other?

If two people try to talk at the same time, you just hear a squeal, neither
party's message gets through, and then both try again, hopefully not at the same
time. This is just simple low-tech stuff.


- It seems that there is no authentication/security, the parties just
identify themselves. Have there been cases of troublemakers making
false impersonations?

Yes, there have been cases, but they are rare.


- They ask pilots their speed, altitude, and heading a lot. Can't the
transponder send that information?

They ask a lot? Doesn't seem so to me. The transponder (typically) sends an
identification code and altitude. The ATC computer can derive the speed and
track over the ground, which differ slightly from the airspeed and heading.


- Do any other airlines put ATC on the inflight audio?

I don't think so.

"Bucky"

I'm not a pilot, just your typical passenger. I don't fly United often,
so I just discovered that they put the ATC on the inflight audio. I was
totally fascinated and want to learn some more. Is there a website that
has some basic ATC protocols? Not some huge reference manual, just the
common phrases that you hear over a commercial flight's radio.

Google +ATC +"radio communications" 15,600 hits.

http://bathursted.ccnb.nb.ca/vatcan/...rentTopic.html

- What happens if 2 people try to talk at the same time? Do you hear
both voices or neither? How do they avoid talking over each other?

They just get used to it. You can't hear anything on a radio that's
transmitting and if two stations are transmitting at the same time, they
tend to block out each other's tranmissions. It can be confusing and even
nerve-wracking to the point that many amateur pilots avoid talking to ATC.

- It seems that there is no authentication/security, the parties just
identify themselves. Have there been cases of troublemakers making
false impersonations?

Never heard of that. But it could easily happen

- They ask pilots their speed, altitude, and heading a lot. Can't the
transponder send that information?

It does. But ATC is required to confirm this. If there's a transponder
equipped plane being mentioned by ATC, but not talking to them, you'll hear
something like: "Air XXX 123 your traffic is at 2:00, 3 miles, 6500 feet
unconfirmed".

- Do any other airlines put ATC on the inflight audio?

Dunno. I wonder if they turn it off if there's a problem... Some fairly
innocuous things could be disconcerting to non-aviation folks.

moo

Bucky wrote:

A few questions I had while listening:

- What happens if 2 people try to talk at the same time? Do you hear
both voices or neither? How do they avoid talking over each other?

Usually they block each other out with a loud squeal and have to repeat
their transmissions. How do "they" avoid it...that's been the age old
question. Mostly with experience in the system, pilots and controllers
become very good at anticipating when each other is done talking.

- It seems that there is no authentication/security, the parties just
identify themselves.

True, but at some "sensitive" airports, additional procedures have been
in effect since 9/11.

Have there been cases of troublemakers making
false impersonations?

Yes, however, it's very rare.

- They ask pilots their speed, altitude, and heading a lot. Can't the
transponder send that information?

When a controller wants "speed", they are asking for the pilot's
INDICATED airspeed. Controller's can only see GROUND speed on their
radars.

When a controller asks for altitude, he/she is verifying the altitude
he/she sees on their radar with what the pilot is seeing on their
altimeter. It's a backup and safety thing so that there is no confusion
and to verify the transponder is sending accurate information.

When a controller ask for heading, they are asking for the compass
heading the aircraft is flying. Controllers can only see the TRACK the
aircraft is flying.

- Do any other airlines put ATC on the inflight audio?

Yes, but I can't tell you which ones do and don't.

BJ

BJ write:

When a controller wants "speed", they are asking for the pilot's
INDICATED airspeed. Controller's can only see GROUND speed on their
radars.

When a controller asks for altitude, he/she is verifying the altitude

he/she sees on their radar with what the pilot is seeing on their
altimeter. It's a backup and safety thing so that there is no
confusion
and to verify the transponder is sending accurate information.


When a controller ask for heading, they are asking for the compass
heading the aircraft is flying. Controllers can only see the TRACK
the
aircraft is flying.

Also, it's safe to say that a percentage of time the controller is
asking these questions to prod the pilot to get back on the course
and/or altitude that the controller last assigned. :-)

--
Peter

Peter R. wrote:

Also, it's safe to say that a percentage of time the controller is
asking these questions to prod the pilot to get back on the course
and/or altitude that the controller last assigned. :-)


Peter,

I think this was more of the case before GPS/INS/IRS. Since these forms
of navigation have become "mainstay" in the system, I hear of a lot
fewer pilots wondering off course...unless they have programed such aids
improperly. Unfortunately, it still happens. :-(

BJ

"Bucky" wrote in message
oups.com...
I'm not a pilot, just your typical passenger. I don't fly United often,
so I just discovered that they put the ATC on the inflight audio. I was
totally fascinated and want to learn some more. Is there a website that
has some basic ATC protocols? Not some huge reference manual, just the
common phrases that you hear over a commercial flight's radio.

There are a lot of them out there, can't remember what site has them, but i
know JFK, DFW, and a few others are out there, most are realaudio, but a few
can be streamed to windows media player or winamp.

A few questions I had while listening:

- What happens if 2 people try to talk at the same time? Do you hear
both voices or neither? How do they avoid talking over each other?

All you hear is very very very bad static, and other noises unpleasant to
the ear, the key to avoid talking over each other is to listen before keying
up the mike, even then it happens now and then, ATC can usually recognize
when they have been talked over and will repeat, and definately know when
two aircraft talk over each other, and will usually have a good idea who was
first cus they've been talking to them earlier, or perhaps they caught a bit
of the transmission before or after being stepped on. When in uncontroled
airspace its common for a third pilot to chime in "Blocked" when they heard
a "step on" to let both pilots know they didnt' get heard.


- It seems that there is no authentication/security, the parties just
identify themselves. Have there been cases of troublemakers making
false impersonations?


Not common for troublemakers, most don't have the brains to know how to
handle an aviation radio, but we did have a NOTAM on our desk here in the
Phoenix Area about a guy pretending to be America West making false reports
of "Traffic in sight" etc. Dunno if they caught him yet, and if they
have/do, i hope they tie him to the nearest cactus.

- They ask pilots their speed, altitude, and heading a lot. Can't the
transponder send that information?

The transponder will send altitude information, but it sends pressure
altitude ( what the altimeter would read if the altimeter setting was
29.92 ) which may differ from the local altimeter setting, sometimes the
difference can be quite large between what the transponder reports, and what
the altimeter on the flight deck reports (unless flying above 18,000', and
even then the error tolerances between the Transponder and Altimeter are
fairly loose). Its possible the ATC tech can be seeing you at 8000' and
300knots (cus the formula for calculating the speed is for groundspeed not
airspeed) when the airplane is actually at 7000 and 250 kts. Just a way for
the tech to double check that they pilot recieved and is following
instructions. Transponder does not send heading info, again like speed
that is calculated by the ATC computers, and is a ground track that does not
take into account wind direction, so an airplane flying a heading of 270
could be getting blown onto a track of 260 or somesuch, and the 260 is what
is reported to the ATC tech. Its also a "polite" way of stating that they
believe the aircraft is off course/altitude/speed and to correct for it.
And the correct answer to "XYZ-2356 state airspeed" when below 10,000 is
ALWAYS "250."

- Do any other airlines put ATC on the inflight audio?

Wish they did, I fly regularly on American and Delta, never have heard it on
their radios.

if you enjoy listening to air traffic control, why not take lessons and be a
pilot?




"Bucky" wrote in message
oups.com...
I'm not a pilot, just your typical passenger. I don't fly United often,
so I just discovered that they put the ATC on the inflight audio. I was
totally fascinated and want to learn some more. Is there a website that
has some basic ATC protocols? Not some huge reference manual, just the
common phrases that you hear over a commercial flight's radio.

A few questions I had while listening:

- What happens if 2 people try to talk at the same time? Do you hear
both voices or neither? How do they avoid talking over each other?

- It seems that there is no authentication/security, the parties just
identify themselves. Have there been cases of troublemakers making
false impersonations?

- They ask pilots their speed, altitude, and heading a lot. Can't the
transponder send that information?

- Do any other airlines put ATC on the inflight audio?

"Dave Butler" wrote in message
news:1116277026.626385@sj-nntpcache-3...
Bucky wrote:

- It seems that there is no authentication/security, the parties just
identify themselves. Have there been cases of troublemakers making
false impersonations?

Yes, there have been cases, but they are rare.


I used to work with a fellow who did impersonations on the air. He's come on
once as Kirk Douglas, then John Wayne, then Burt Lancaster, then Elvis...

I don't think that's what you mean by "impersonations", though, but ATC
didn't seem to mind.


--
Matt
---------------------
Matthew W. Barrow
Site-Fill Homes, LLC.
Montrose, CO