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-   -   The Consolidated "Interesting Things Heard on Channel 9" Thread [Merged] (https://www.flyertalk.com/forum/united-airlines-mileageplus/726789-consolidated-interesting-things-heard-channel-9-thread-merged.html)

djmp Sep 24, 05 11:42 am

The Consolidated "Interesting Things Heard on Channel 9" Thread [Merged]
 
Here's one for the pilots/air geeks out there.

On approach, I often hear the tower tell the pilot that "India is current" or "Foxtrot is current" etc. What does this mean?? Curious minds wish to know...

--djmp

FlyinHawaiian Sep 24, 05 11:53 am

It's for the ATIS Updated Information
 
Airports broadcast a short blurb of information on current operations (including weather conditions, wind speed direction, closed runways/taxiways, etc.) on a frequency that pilots listen to on approach. Everytime the report is updated, it is given the next letter designation in the phonetic alphabet. ATC is just ensuring the inbound pilots are aware of the most up-to-date information.

http://www.lerc.nasa.gov/WWW/MAEL/ag/atis.htm

MJonTravel Sep 24, 05 12:08 pm

And for the true geeks among us (self included), ATIS stands for Automatic Terminal Information Service.

jacob_m Sep 24, 05 12:12 pm

Very good explanation of how it works.

ATIS is short for Automatic Terminal Information Service, at major airports you can listen to a pre-recorded ATIS message at a special frequency where you can get important information about weather, winds, visibility, the runway/runways in use etc.
The purpose is to make ATC more efficient so the air traffic controller does not need to repeat these things for every single departing or arriving aircraft.

The message always start with, for example at LHR: "This is London Heathrow Information, Foxtrot,...".
As soon as something changes, for example the weather, the wind or the use of runways, a new message is recorded with the updated conditions, this message is given the next letter in the alphabet, in this case it would be Golf.

At first contact with the tower, ground or approach controller the pilot gives this letter to the controller, often you hear "American 123, Information Foxtrot..."
This means the pilot has listened to the ATIS message Foxtrot and there is no need for the controller to repeat any of the information contained in the ATIS message (and the controller knows the pilot has received that important information), if the message has changed the controller can tell the pilot that there is a new updated message available, you can hear for example "American 123, negative, information is Golf".
The pilot then knows the information he/she has is old and can switch to the ATIS frequency to listen to the new information.

djmp Sep 24, 05 12:37 pm

thanks!
 
As usual, flyertalk rocks!

--djmp

spotwelder Sep 24, 05 1:18 pm

Nerdy corrections
 
Hi, to be even more nerdy...

The ATIS is often recorded on a navigation aid frequency such as the VOR used for holding. This means that the approaching aircraft will be able to receive the information without having to tune an extra radio for the task, but one that the crew would have to tune anyway.

The ATIS is usually updated twice an hour, commonly at minutes 20 and 50 past the hour. Special ATIS updates are recorded when certain weather changes meet the critieria published in ICAO Annex 3 and 11. Also, whenever runway directions are changed or other pertinent information changes. Some airports have departure ATIS messages and a separate arrival ATIS message.

It is usual for the approach controller to ensure that the inbound ATIS letter has been received correctly but an arriving aircraft may not have to confirm the ATIS letter to tower. Same for departures, ground usually do the check and leave tower free.

Just as a minor point, if the whole ATIS message has changed, and the changes are significant such that the controller wants the pilots to listen to it all, then the pilots will not "change" to the ATIS frequency. They will remain with radio box "A" with the air traffic controller and use box "B" to tune the ATIS (or the navigation aid).

PS, for the list of geeks, you could have added air traffic controllers and accident investigators ;)

Happy landings

Spottie

PLTHOO Sep 24, 05 7:29 pm

Even Nerdier Additions
 

Originally Posted by spotwelder
Hi, to be even more nerdy...

The ATIS is often recorded on a navigation aid frequency such as the VOR used for holding. This means that the approaching aircraft will be able to receive the information without having to tune an extra radio for the task, but one that the crew would have to tune anyway.

The ATIS is usually updated twice an hour, commonly at minutes 20 and 50 past the hour. Special ATIS updates are recorded when certain weather changes meet the critieria published in ICAO Annex 3 and 11. Also, whenever runway directions are changed or other pertinent information changes. Some airports have departure ATIS messages and a separate arrival ATIS message.

It is usual for the approach controller to ensure that the inbound ATIS letter has been received correctly but an arriving aircraft may not have to confirm the ATIS letter to tower. Same for departures, ground usually do the check and leave tower free.

Just as a minor point, if the whole ATIS message has changed, and the changes are significant such that the controller wants the pilots to listen to it all, then the pilots will not "change" to the ATIS frequency. They will remain with radio box "A" with the air traffic controller and use box "B" to tune the ATIS (or the navigation aid).

PS, for the list of geeks, you could have added air traffic controllers and accident investigators ;)

Happy landings

Spottie


The ATIS is often on a dedicated frequency specific to the airport, which aircraft will always check prior to calling for departure clearance when on the ground, or will check when on the arrival sequence. Whenever the aircraft calls for departure clearance, taxi clearnace, or switches to one of the many arrival frequencies on the approach, he will announce what ATIS they have by letter. Additionally, the letters used are usually divided into groups for many airports in the same area---such as SFO will have A-E, OAK will have F-I, etc.

The information usually dedicated to VOR frequencies is special weather announcements such as convective sigments (big weather) and just the ID info for the particular NAVAID.

As far as switching between radios, etc the heavy metal flown by the airlines will have multiple radios usually with the FO or Captain (whoever is not flying the leg) check the ATIS info during the arrival/pushback checklist.......not really a major concern on number of radios, etc.

The arriving aircraft will be switched between multiple arrival frequencies as they are passed into different sectors on the arrival, then on to an approach controller, and finally to tower when on the formal approach. Usually the tower controller will indicate the current ATIS because the flight crew most likely listened to it on the first part of the arrival (sometimes 30+ minutes ago). Sometimes in windy/stormy conditions you can also hear aircraft request wind checks and updated ATIS info so they have updated info.

The frequency of ATIS updates are completely dependent on the airfield....the big ones will sometimes have AWOS or ASOS (Automatic Weather Observation Station) and will be a male computer voice that transmits the most current observation on the field. Another fun part to identifying if the ATIS is current is listening to the time given in Zulu-----it sometimes takes time to catch on. Another interesting experience on CH.9 is listening to info and ATIS on international flights---Asis is always interesting.

If you are really an airport geek and want to know what runway is being used....the airports will frequently have 800 numbers or local numbers where you can call the ATIS or AWOS and hear it over the phone---so you can get an idea what conditions are when there. The info is usually found in Flightguide or Jepp approach charts.

spotwelder Sep 24, 05 7:42 pm

The last post is related to procedures for US airlines within the US, which I guess UA is, most of the time. However, when UA fly overseas, then they will use the international procedures, which I explained in my post. For example, most crews will listen to the ATIS around top of descent, or try to, approximately 23-32 minutes prior to landing. However, they may not be able to receive the radio messages as they will be beyond published range at that point for several transmitters. In many countries the approach that the approach will be based on carries the ATIS message, which is identified around 10 minutes prior to landing, to check that it is working.

By the way, it is illegal to listen to Channel 9 in several countries. However, UA do not seem to realise this.

qasr Sep 24, 05 8:18 pm


Originally Posted by spotwelder
By the way, it is illegal to listen to Channel 9 in several countries. However, UA do not seem to realise this.

It is illegal for pax to listen, or illegal for UA to make it available? Which are these several countries, btw? :)

jacob_m Sep 25, 05 6:06 am


Originally Posted by spotwelder
By the way, it is illegal to listen to Channel 9 in several countries. However, UA do not seem to realise this.

Really? In which countries? And what is so secret about it?
I can't imagine anybody actually spends any significant amount of time listening to it anyway (because it's SOOO exciting...).

djmp Sep 25, 05 10:53 am


Originally Posted by jacob_m
Really? In which countries? And what is so secret about it?
I can't imagine anybody actually spends any significant amount of time listening to it anyway (because it's SOOO exciting...).

It's usually better than the movie :D

qasr Sep 25, 05 11:00 am


Originally Posted by jacob_m
Really? In which countries? And what is so secret about it?
I can't imagine anybody actually spends any significant amount of time listening to it anyway (because it's SOOO exciting...).

On departure & approach it is interesting, and the movies aren't playing anyway ;) I agree that through the flight it can get pretty boring though.

Derek Sep 25, 05 11:45 am


Originally Posted by qasr
I agree that through the flight it can get pretty boring though.

Though it can actually be riveting when there is weather or other traffic issues. I don't always listen, but I do miss it when I'm on UAX or another airline.

Sneezy Sep 25, 05 12:09 pm


Originally Posted by jacob_m
Really? In which countries? And what is so secret about it?
I can't imagine anybody actually spends any significant amount of time listening to it anyway (because it's SOOO exciting...).

FWIW, I'd highly suspect the People's Republic of China for one. In fact, I'd be downright surprised if one were allowed to listen to ATC there.

olympicnut Sep 25, 05 12:21 pm

I heard the FUNNIEST thing on Ch 9 yesterday sitting in line (we were #12 at the time, OY!) waiting to take off from PHL. Some Chatauqua flight asked ground "Can we get a list of departure order" or something like that and the controller, with total attitude (think Wanda Sykes) said "WHO JUST ASKED ME THAT! I have already said the departure order twice in the past 5 minutes so who just asked me that again!" The poor pilot apologized and she ran through the list again. I was chuckling outloud it was so funny. Her delivery is what made it so hysterical to me.


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