ADS and Datalink

Question 1

What ADS contracts are available?

Answer 1

• periodic
• event
• on-demand

Question 2

What action shall a controller take on receipt of a DISCONNECT REQUEST with a reason code 1 ‘congestion’?

Answer 2

The current controlling authority should be notified. The controlling authority should resolve the situation.

Question 3

What will happen if a controller attempts to connect ADS with an aircraft when all the aircraft ADS connections have been taken by other ground facilities?

Answer 3

DISCONNECT MESSAGE with reason code 1 ‘congestion’ is received.

Question 4

When shall controllers terminate ADS contracts and connections?

Answer 4

Automatically terminated by OCS at a VSP past the FIR boundary. If re-establishing manually past this point, the controller must manually terminate the connection.

Question 5

When may a controller consider increasing ADS reporting rates?

Answer 5

• an aircraft is approaching a crossing route on which there is other traffic
• when the aircraft is approaching areas of known significant weather
• during periods of turbulence
• when an unauthorized deviation from the clearance is detected
• when the aircraft is experiencing abnormal operations or it is known or suspected that an aircraft is in a state of emergency

Question 6

What vertical tolerance is applied to ADS?

Answer 6

plus or minus 200ft

Question 7

When is a CPLDC message closed?

Answer 7

When either:

• a response is not required, or
• a referenced response other than “STANDBY” or “REQUEST DEFERRED” has been received

Question 8

When must pilots downlink a CPDLC position report?

Answer 8

On completion of:

• an initial CPDLC connection (e.g. inbound from domestic)
• a CPDLC connection transfer
• when crossing an FIR boundary

Question 9

When should freetext messages be used?

Answer 9

Only when an appropriate pre-formatted message element does not exist

Question 10

If a CPDLC dialogue is interrupted by a system shutdown, what process should be followed?

Answer 10

The entire dialogue shall be recommenced by voice communications.

Question 11

What are appropriate responses to a negotiation request?

Answer 11

AFFIRM

NEGATIVE

Question 12

When should a pilot or controller consider re-sending a message?

Answer 12

After a reasonable period of time has passed and no error message has been received indicating non-delivery of the message. The message shall be sent as a query message.

Question 13

How far may a pilot deviate of track due to wake turbulence, without a clearance from the controller?

Answer 13

2NM

Question 14

How may a controller cancel a block altitude clearance?

Answer 14

CANCEL BLOCK CLEARANCE followed by:

• MAINTAIN
• CLIMB TO AND MAINTAIN
• DESCEND TO AND MAINTAIN

Question 15

How should a controller respond when a multi-element clearance request is received and only part of it can be approved?

Answer 15

Uplink shall not contain single word UNABLE and a clearance. If UNABLE is used in a clearance message it must contain a qualifier to remove any ambiguity.

Question 16

How does a controller acknowledge a CPDLC emergency message?

Answer 16

Freetext using the words ROGER MAYDAY or ROGER PAN.

Question 17

What letters and numbers are used when an AOC wishes to indicate that an aircraft is CPDLC capable?

Answer 17

J1 to J7.

Question 18

What field of the flight plan is used to identify an aircraft’s datalink capabilities?

Answer 18

Field 10a.

Question 19

What letter and number is used when an AOC wishes to indicate that an aircraft is ADS-C FANS 1/A capable?

Answer 19

D1 or G1.

Question 20

When should the MONITOR (or CONATCT) and END SERVICE messages normally be sent?

Answer 20

MONITOR send automatically by OCS

END SERVICE sent automatically 3 minutes prior to FIR boundary

Question 21

What actions should the controller carry out on becoming aware that the END SERVICE message has not been delivered?

Answer 21

Send another END SERVICE message. If unsuccessful the pilot shall be instructed to terminate the CPDLC connection and log on to the next unit.

Question 22

How may an AFN logon be initiated?

Answer 22

• manually by the pilot during initial logon

- by the OCS using address forwarding process

Question 23

What is the purpose of an AFN logon?

Answer 23

Provide the ATSU with the datalink application ‘context’ of the aircraft

• the ATS datalink applications supported by the aircraft and the version numbers of these applications
• the unique ACARS address of the aircraft
• provide the ATSU with the aircraft ID, aircraft registration and aircraft address. This allows comparison between logon information and the flight plan

Question 24

When should a pilot perform the initial logon?

Answer 24

• prior to takeoff, not more than 45 minutes prior to ETD to the current ATSU the departure airport is located within
• above 10,000ft
• following an unsuccessful datalink transfer to another ATSU when detected by pilot or on instruction from ATC

Question 25

What is the purpose of a CPDLC connection?

Answer 25

Allow the exchange of CPDLC messages between an aircraft and an ATSU.

Question 26

MATSOS states that controllers shall manage CPDLC connections to support a requirement. What is this requirement?

Answer 26

To ensure that the ATSU with control of the flight holds the active CPDLC connection.

Question 27

What happens if there is an existing CPDLC connection with an aircraft and a connection request is sent by an ATSU?

Answer 27

• the system verifies that the ATSU sending the CR1 has been specified as the next data authority. If so, the aircraft system:
  
  • accepts the CR1
  • establishes the connection as the inactive connection
  • responds with a CC1
• otherwise rejects the CR1 by sending a DR1 message that contains the identity of the current data authority

Question 28

What happens if there is no existing CPDLC connection with an aircraft, and a connection request is sent by an ATSU?

Answer 28

The aircraft system:

• accept this CR1
• established this CPDLC connection as the active connection
• responds with a CPDLC connection confirm (CC1)

Question 29

Describe the datalink connections that an aircraft may have at any time with ATS units.

Answer 29

• an active and an inactive CPDLC connection

- up to 5 ADS connections

Question 30

Describe what happens if you sent a CPDLC message to an aircraft when you have an inactive CPDLC connection.

Answer 30

The aircraft system rejects the connection and sends DM63 NOT CURRENT DATA AUTHORITY

Question 31

Why must a Next Data Authority message be sent as the first step in the CPDLC transfer sequence?

Answer 31

To avoid rejection of the connection request.

Question 32

What is the purpose of the Next Data Authority message?

Answer 32

To allow the controlling ATSU to notify the aircraft of the identity of the next ATSU authorised to establish an inactive CPDLC connection.

Question 33

Explain the process of the normal life sequence of a CPDLC connection.

Answer 33

??DLM 6??

Question 34

What will happen if a duplicate Next Data Authority message is sent to an aircraft?

Answer 34

Some aircraft types may terminate an Inactive CPDLC connection even if the facility designator in the NDA message is the same.

Question 35

What is the purpose of Address Forwarding?

Answer 35

To allow a subsequent ATSU to establish an inactive CPDLC connection and ADS-C contracts, and to allow adjacent ATSUs to establish ADS-C contracts for monitoring purposes.

Question 36

Under normal conditions, how does the avionics respond to an END SERVICE message?

Answer 36

The aircraft will downlink a CPDLC DISCONNECT REQUEST message. The aircraft will consider the aircraft to be disconnected as soon as the DR1 message has been sent.