CPDLC

[Cbf]

Hi Hardy,
It's been such a long time since I posted a message on the forum (2009?). First, congratulation for PSX. It is really a fantastic simulator. I especially appreciate the fluidity of the flight controls. So many work since PS1. I remember the good all days when we had to create SID, STARS and approaches...
I just encounter problem with the CPDLC. I loggon during climb (approx. FL180) with departure ATC. When logged on, ATC sends clearance "resume own navigation" that I confirm with PTT key. I remain with the same frequency expecting CPDLC instruct me to log off and frequency to contact. During all flight, in most cases, CPDLC seems to be dumb, only answering to my messages. I am obliged to request descent and have to loggoff manually. As far as I remember, I just had one flight with CPDLC asking me to send report, clearing for descent and loggoff. Do I miss something (ATC frequency...)?
Thanks in avance
CBF

[Hardy Heinlin]

Hi CBF,

thank you!

I don't understand: When connected with CPDLC, you expect the CPDLC controller to tell you that you should logoff from voice-ATC? The term "log-off" means log off from the CPDLC network. Voice-ATC will never say that.

You also need to set the mode of the CPDLC simulation on the Instructor's CPDLC page:

(•) Manual control
(•) Random control - very restrictive
(•) Random control - less restrictive
(•) Random control - no restrictions

To get realistic scenarios I would select "very" or "less restrictive".

With "no restrictions" all your wishes will be fulfilled, and you won't get any instructions without a preceding request from your side.

When "manual control" is selected, a real PSX user needs to control the console.


Regards,

|-|ardy

[Jeroen Hoppenbrouwers]

Just to add to that... in the current environment in the real world, when you are over the Atlantic under CPDLC (or HF for that matter), basically any request is denied. There are aircraft ahead of you, behind you, above you, and below you at minimum separation distances. You need to declare emergency to get any leeway at all and even then you are usually required to turn out of the track and use one of the escape tracks in between the real tracks to return to where you came from. That's it.

The vast majority of FANS traffic is not CPDLC (as very little changes during the crossing) but ADS-C automated position reporting, which you as a pilot don't see happening. It's booooooring.


Hoppie

[Cbf]

Hi Hardy,
Thank you for your answer (Jeroen too). My explanation was not clear. I understand that when Logged in with CPDLC, there is no more ATC voice communication. Voice ATC is back when "contact approach 131.55Mhz" message is received and loggoff initiated.
Actually, I use Random control / no restrictions option. You explain that "With "no restrictions" all your wishes will be fulfilled, and you won't get any instructions without a preceding request from your side."
If I try Random control / less restriction option, will I receive descent, contact approach messages without a preceding request from my side?

Thanks in advance

[Cbf]

Hi (again) Hardy,
I have tried a scenario using Random control / less restriction option. When Logged in, I received a message of Heading confirmation and the descent clearance. I answered to both messages. Meanwhile, I did not receive the "contact frequency" message during descent. The approach frequency was selected on RMP and the "CPDLC prevails" indication was not displayed anymore on instructor page.
Thanks in advance

[Cbf]

Hi Hardy,
I have tried 3 different scenarios, each 3 time, using less restriction options.
- 1/3 of the cases, I have the descent clearance and Loggoff/Contact frequency upcoming messages: Everything's OK
- 1/3 of the cases, no descent clearance upcoming message at all. A "when can we" message is always "Unable" by ATC even 50NM beyond TOD
- 1/3 of the cases, I have the descent clearance but no Loggoff/Contact frequency upcoming message
Thanks in advance
CBF

[Hardy Heinlin]

Hi CBF,

I can't analyse your scenario from here. Below a certain altitude, the CPDLC simulation will stop automatically. If you get no log-off instruction, just log-off whenever you want ...


Regards,

|-|ardy

[Cbf]

Hardy,
Thank you for your answer. I sometimes had Logoff message down to 13000Ft. I will logoff manually during descent passing FL285 according to europe FANS 2/B regulations and will contact "responsible now" ATC voice.
CBF

[Hardy Heinlin]

Hi again,

in PSX there is never a "Contact ..." message from the CPDLC robot after a logoff message. There is just a LOGOFF message. This will occur when all these conditions are true:

+ Random control - "very" or "less" restrictive is selected. ("No restrictions" will give no logoff and no instructions at all but will allow all your requests)

+ FMC contains an active route

+ FMC CRZ ALT is higher than 18000 ft

+ Aircraft true altitude above MSL is higher than 13000 ft and height above ground is lower than 21000 ft

+ Last CPDLC instruction was a descent instruction, or FMC is in ACT DES phase

+ There is no CPDLC REPORT armed (e.g. "report reaching FL280")


Regards,

|-|ardy

[Cbf]

Hardy,
Thank you for information.
CBF

[Britjet]

Just to add to that... in the current environment in the real world, when you are over the Atlantic under CPDLC (or HF for that matter), basically any request is denied. There are aircraft ahead of you, behind you, above you, and below you at minimum separation distances. You need to declare emergency to get any leeway at all and even then you are usually required to turn out of the track and use one of the escape tracks in between the real tracks to return to where you came from. That's it.

The vast majority of FANS traffic is not CPDLC (as very little changes during the crossing) but ADS-C automated position reporting, which you as a pilot don't see happening. It's booooooring.


Hoppie

Shanwick and, I believe, Gander, now have a computerised system via CPDLC on the OTS which will send a offer of a climb to aircraft..they can then accept or refuse..
Peter.

[Jeroen Hoppenbrouwers]

Yes, it's getting more advanced all the time now the electronic (text) communication has been firmly established as the primary one. Mind you, controllers still don't even have the capability to talk to pilots! They telex a message to the call center and the call center operator attempts to reach the aircraft by HF or satellite. This can/will take 10-20 minutes. The reply then is texted back to the controller.

So for controllers, ALL communication with aircraft is by text!

NavCanada in particular is busy moving so much of all their communications to CPDLC that the few remaining cases CAN be handled directly by the controller. They are pretty much the only ones that actually want the controllers to talk to aircraft.

In the US, great progress has been made over the last year in delivering clearances to aircraft on the ground by CPDLC. This really helps, especially when there's bad weather and 90% of all departures suddenly need a reroute.

This one is called: (deep breath) CPDLC-DCL (really!)

https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/afs/afs400/afs470/datacomm/media/DCL_FDUG.pdf


Hoppie

[Michael Benson]

Interestingly we're not allowed to send DCL revised clearances and must change any departure via voice, this is to ensure that the crew have the correct latest clearance which you can only really do by talking to the chaps and chapesses.

[Hardy Heinlin]

in PSX there is never a "Contact ..." message from the CPDLC robot after a logoff message. There is just a LOGOFF message.

Wrong! I should better read what I've programmed myself :-)

There is a "Contact ... [frequency]" text element in the logoff message from the CPDLC robot if the "Talks to us" checkbox is selected on the Voice-ATC page.


Regards,

|-|ardy

[DougSnow]

Shanwick and, I believe, Gander, now have a computerised system via CPDLC on the OTS which will send a offer of a climb to aircraft..they can then accept or refuse..
Peter.

True

I was at a NavCanada conference back in Oct I think, they call it GoFli. At this conference they couldnt understand why crews werent accepting as many GoFli offers - we had to explain aircraft performance, buffet margin, etc. 

Here in the US the FAA touted the ability to push route revisions as a part of the DCL Clearance. Our crews love DCL; they can uplink the original route from the flight planning system, and any route revisions from ATC.

There are more changes coming to the Ocean next March - new ICAO 2012 flight planning codes to identify the aircraft's RCP RSP capabilities to get even closer separation - as low as 23 nm lateral and 30 nm longitudinal separation with the best capabilities on the aircraft; just waiting for ICAO to sign and release the new GOLD Document and the new PBCS Manual.

[Cbf]

Hardy,
The "Contact ... [frequency]" message is available when "Less restrictive" and "very restictive" CPDLC option is selected. It is not available if "no restrictions" is selected. Is it possible to have the message on all options?
Thanks for your work
Cbf

[Hardy Heinlin]

It makes no sense to me if you set "no restrictions" and at the same time expect a restriction in the form of a logoff command.

The feature "no restrictions" is supposed to allow you to use CPDLC as long as you want, and to do whatever you want. It should never disallow you to use CPDLC, hence it should never command you to logoff.

The "Contact ... [frequency]" text element is part of the LOGOFF messsage.


Regards,

|-|ardy

[Cbf]

Hardy,
Actually, I use CPDLC during small flights in upper airspace. My thinking is that "less restrictions" fits with FANS 1/A operations but is sometimes more restrictive for FANS 2/B. For example, I may have an offset requirement from ATC just before TOD and then descent clearance is impossible before the end of offset.
I know that PSX is not an ATC simulator, however PSX ATC (Voice/CPDLC) is very powerfull and makes flight really more exciting.
Regards
Cbf

[Hardy Heinlin]

If you can't make an offset, you can send "REJECT".

By the way, you can also logoff yourself anytime, and Voice-ATC will automatically continue if it's active.


Regards,

|-|ardy

[Cbf]

Thanks for tip Hardy
Regards
Cbf