Introduction
1. CPDLC / ADS Introduction
2. CPDLC
3. CPDLC Operations Fundamentals
4. ADS C
5. Contingencies
Here are the topics for this module.
CNS / ATM – Communications Navigation & Surveillance / Air Traffic
Management
CPDLC – Controller Pilot Data Link Communications
Augments verbal ATC instructions and pilots read-backs & automates ATC
processes
ADS C – Automatic Dependent Surveillance Contract
Gives accurate position reporting
Allows additional data reporting (wind, temperature etc)
Provides reporting in regions out of radar coverage
Increases traffic that can be handled in remote areas
AFN – ATS Facilities Notification
Allows logon to ATC facility (Data Authority) & the transfer of control
PBN – Performance Based Navigation
These are some of the acronyms related to CPDLC and ADS. We will start off with a look at how CPDLC and ADS fit into the “big picture”.
I think we’re on to something here boys.
We’re going systemic and control the
world.
CPDLC and ADS are pieces of ICAO’s bigger plan to take over the world.
PBN
CPDLC
ADS
The "C", the "N", and the "S" from the CNS equation stand for "Communication, Navigation, and Surveillance". There are several components
that fit into each of these categories, This module covers CPDLC and ADS.
The CPDLC function supports:
(a) Emergency alerting,
(b) Uplink of ATC clearances and
instruction,
(c) Downlink of position reports and
clearance requests, and
(d) Free text as a supplement to
preformatted elements.
The ADS function supports:
(a) Emergency alerting, and
(b) Automatic reporting by the aircraft’s
Flight Management System (FMS) of
aircraft position and intent information
in accordance with parameters
established in contracts by the ground
system.
CPDLC and ADS have different functions. CPDLC is used for general communications with ATC. ADS C is primarily used for automatic position
reporting. We will first look at CPDLC.
CPDLC is a powerful tool to sustain data link communications between a pilot and the controller of the relevant flight region. It is particularly
adapted to such areas where voice communications are difficult (e.g. HF voice over oceans or remote part of the world), and is expected to
become very convenient to alleviate congested VHF of some busy TMAs when utilized for routine dialogue (e.g. frequency transfer).
CPDLC consists in the exchange of messages, which can be formed by the use of individual (or combination) elements chosen within a set of
internationally agreed preformatted ATC words. You also have a free texting capability.
Types of Data Link:
ATC Data link
Exchange requests & text messages
N767A
Clearances, reporting points,
climbs/descents requests etc.
ADS periodic and event reporting
Company Data link
Airline Operation Communication or
AOC data link (Universal Weather)
ACMS Data link
Maintenance
CPDLC uses data link. Data link is a general term for digital data transfer between the airplane and various ground stations. Different data link
names are based on where given information is sent to or received from.
More information about ACARS and the
Data link types are found in the FCOM:
Sections 5.20, 5.40, 11.33 and 11.34.
Universal Weather
ACARS Company Data link example
ACARS is a system on the airplane to transmit and receive the data link information. ACARS communicates incoming and outgoing data and
messages through the center VHF radio or SATCOM system. The information can be automatically or manually controlled.
You use the Computer Display Unit for both ATC and company data link. The menu and FMC COMM switches allow you to access the company
data links.
Logon/Status page if a CPDLC
connection has not been
established with an ATC Center.
ATC Uplink page if
there is a new uplink
message to be
reviewed.
Holding the ATC
key down displays
the Emergency
Report page.
Pushing the ATC key displays one of four pages.
Log page if there are more
than one new uplink
message or more than one
open uplink message.
Note the pages that come up when selecting the ATC key can also be accessed through the ATC index page, except for ATC uplink.
The emergency report page alerts ATC of an emergency onboard the aircraft. Sending this report automatically places Automatic Dependent
Surveillance (ADS) into the emergency mode if MAYDAY was selected.
ATC request allows the entry of altitude, speed, and offset direction and distance requests.
The ATC Report page lists required reports requested by ATC.
Some ATC uplinks request a report. When you accept the clearance, an ATC report is automatically generated.
Some requests, such as report reaching, report level and report passing can be armed to automatically send the report. An ARM prompt
appears when you accept the request. Selecting ARM automatically sends the report when the condition is met.
Once you look at a message, the status changes
to either OLD or OPEN depending on whether a
response is required or not.
This message required a
response and ACCEPTED was
sent.
The ATC log displays the beginning of stored uplink and downlink messages, with the most recent on the top. The Log erases automatically
after flight completion.
Allows the
emergency on/off
and arming capability
for ADS.
Initiates data link connection with the
desired ATC facility.
You use the logon/status pages to initially logon and verify station connection.
The position report key takes you to the position report page of the FMC. Notice that when Datalink is connected to a station, you can also
send a position report to ATC.
The When can we expect page allows you access to standardized requests.
You use the Free Text Page to create and send a free text message to the controller.
Note: This function is not currently being used.
The clearance page notifies ATC of readiness to accept a clearance, such as a pre-departure or pushback clearance.
The voice page notifies ATC that you request voice contact from the controller.
Revert to voice communications and notify ATC of the situation.
If you lose the connection and it has not been restored after a continuous period of 16 minutes, the message ATC COMM TERMINATED will be
displayed and the link with ATC will be lost. The FMC data link status will show NO COMM during this time.
Handling of CPDLC messages requires
time:
Reading and interpreting a written clearance
was found to be less immediate than hearing
the same one
Preparing and sending a request through the
CDU is longer than directly using the mike
The party line is lost (the pilot can
no longer listen to the surrounding
transmissions)
radio
Communicating via data link brings new challenges.
datalink
When data link messages replace
normal voice communications, it is
important that both pilots silently
and independently read any uplink
message.
Pilots should then discuss and
evaluate the message for
appropriate action.
Likewise, any downlink message
should first be selected and
assembled and then verified by both
pilots before sending to ATC.
Like all other tasks, data link operations require CRM skills.
Voice and data link are complementary modes of communication.
Select the most appropriate mode for each situation.
Data link is designed for routine messages including ATC clearances, position
reports, and flight plans.
In non-routine circumstances, or when safety or complexity are factors, voice
(SATCOM, HF, or VHF) may be the preferred mode of communication.
Flight crew responsibilities are identical using either voice or data link.
The pilot communicating is responsible for all communication related duties.
CPDLC communication is not intended to be as fast a means of (tactical) communication as voice. It is designed to pass routine (strategic)
messages, where time is not an essential factor.
HF voice capability still remains a requirement and must be
monitored even when CPDLC is being used for position reports
and clearances. Operators must comply with the voice
communications procedures associated with CPDLC.
Communications initiated with ATS by voice should be
completed by voice and communications initiated by CPDLC
should be completed, whenever possible, by CPDLC.
Voice contact is not replaced by data link. Data link augments voice and should be used when available, but voice contact should always be an
option.
Position Reporting
Emergency Reporting
ADS provides surveillance capability in oceanic and en-route continental airspace. It replaces verbal position reporting in areas where nonradar separation is currently applied. ADS establishes contracts between ground systems and an airplane. An ADS contract is a reporting plan
that establishes the requirements for ADS data reporting and the frequency of the reports.
ADS can send normal position reports and also signal an emergency condition.
The ADS function defaults to the armed state on powering up the system. You only have limited interaction ability with ADS – C, the function
can be manually turned on or off as can the ADS Emergency Mode.
Page two of the ATC LOGON/STATUS displays active when ADS is connected to the ATS facility. Normally, position reports happen automatically
when ADS is connected. If ADS is not connected you need to manually send position reports.
Logged on
Not logged on
If the ADS connection is not active, then you can manually send a position report to ATC whenever a Data link connection exists.
Even when ADS is connected, there are a few instances when you need to manually send ATC a position report.
Normally, during an emergency you immediately revert to voice communications. However, in certain situations, it may be more expeditious to
first declare an emergency using the Emergency Report page. You use the Emergency Report page to generate the report, You use the Verify
Emergency page to send it.
ADS-C active (non-radar environment)
Radar Environment
You use the ADS EMERG function to indicate an emergency condition to ATC. This function is operationally equivalent to squawking 7700 when
in radar coverage.
Manually Select ADS EMERG
Automatically Selected from Emergency Report
If ADS EMERG is manually selected, then the only indication presented to controllers is that an emergency situation exists. Unlike an SSR
squawk, there is no capability to differentiate between a Hijacking, a Radio Fail, or a Mayday. So there is a protocol to verify the intent.
What are you
doing?
It’s hard to say how it happened, but the ADS is now in emergency mode.
Hey, I think I’ve got
this ATC datalink
stuff figured out
If ATC receives an ADS emergency indication without any other CPDLC, SSR code, or voice confirmation of an emergency situation, they will
immediately check for covert activation by either CPDLC or voice using the routine message CONFIRM SPEED and the words "CONFIRM ADS".
A-D-S Reset
ON & OFF toggles with
each switch push
ADS EMERG is OFF
ADS EMERG is ON
On receipt of this CPDLC or voice message, check the status of the ADS Emergency Mode. If the mode has been selected to ON accidentally,
then select the "ADS Emergency Off" prompt and notify ATC by either voice or CPDLC free text (as appropriate), of the new status by using the
words "ADS RESET".
ADS Emerg is ON
If you deliberately and covertly selected the ADS Emergency Mode to ON, then reply to the CONFIRM SPEED uplink and leave the ADS
Emergency Mode in the ON position.
If the aircraft continues with the ADS emergency mode activated ATC will assume that the aircraft is in emergency conditions and will follow
normal alerting procedures.
You can find this information in the reference manual titled “Guidance Material for ATS Data Link Services in North Atlantic Airspace”.
Select the best answer
ADS emergency sends an emergency position report to ATC
ADS emergency is equivalent to squawking 7700 when in a non radar
environment and ADS is active
ADS emergency sends Mayday Mayday to ATC
You use ADS emergency to signal an engine failure while in RVSM / MNPS
airspace
Select the correct answer
True
False
Select the correct answer
Select the best answer
CPDLC is expected to become very convenient to alleviate congested VHF of some
busy TMAs because it is quicker for pilots to understand clearances
CPDLC allows quicker acceptances of clearances because only pilot is
required to monitor CPDLC messages
CPDLC is superior to voice clearances because digital data moves very fast
Handling of CPDLC messages require time: Reading and interpreting a written
clearance is less immediate than hearing the same one
Can’t wait to figure out how
the needs analysis impacted
the human factors issue of
CPDLC design and how this
will affect the airspace… Or
maybe I’ll just go workout.