AC 90-117

editorial update

Advisory circular · Data Link Communications

Approved
September 12, 2018
Last reviewed
July 29, 2024
This change
Editorial Update to AC 90-117 (9/12/18).
Cancels
AC120-70C
Family
AC 90-117 · 2 versions
14 CFR parts
91, 121, 125, 129, 135

Guidance, not mandatory unless a rule or AD requires it. DRS record last changed November 22, 2025.

Show pages 97–108
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Appendix F Table F-9. Level Downlink Message Elements (LVLD) Operational Definition in PANS-ATM (Doc 4444) CPDLC Message Sets Message Element Identifier Message Element Intended Use Format for Message Element Display Resp. FANS 1/A ATN B1 LVLD-1 Request to fly at the specified level or vertical range.

REQUEST (level) Y DM6 REQUEST (altitude) Note: Used for a single level.

DM7 REQUEST BLOCK (altitude) TO (altitude) Note: Used for a vertical range.

DM6 REQUEST (level) LVLD-2 Request for a climb to the specified level or vertical range.

REQUEST CLIMB TO (level) Y DM9 REQUEST CLIMB TO (altitude) Note: Use of DM7

REQUEST BLOCK (altitude) TO (altitude) to request to climb at a vertical range.

DM9 REQUEST CLIMB TO (level) LVLD-3 Request for a descent to the specified level or vertical range.

REQUEST DESCENT TO (level) Y DM10 REQUEST DESCENT TO (altitude) Note: Use of DM7

REQUEST BLOCK (altitude) TO (altitude) to request to descend at a vertical range.

DM10 REQUEST DESCENT TO (level) F-20

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Appendix F Operational Definition in PANS-ATM (Doc 4444) CPDLC Message Sets Message Element Identifier Message Element Intended Use Format for Message Element Display Resp. FANS 1/A ATN B1 LVLD-4 Request for a climb/descent to the specified level or vertical range to commence at the specified position.

AT (position) REQUEST (level) Y DM11 AT (position)

REQUEST CLIMB TO (altitude) Note: A vertical range cannot be requested.

DM12 AT (position)

REQUEST DESCENT TO (altitude) Note: A vertical range cannot be requested.

N/A LVLD-5 Request for a climb/descent to the specified level or vertical range to commence at the specified time.

AT TIME (time) REQUEST (level) Y DM13 AT TIME (time)

REQUEST CLIMB TO (altitude) Note: A vertical range cannot be requested.

DM14 AT TIME (time)

REQUEST DESCENT TO (altitude) Note: A vertical range cannot be requested.

N/A LVLD-6 Request for the earliest time or position that a descent can be expected.

WHEN CAN WE EXPECT

LOWER LEVEL Y DM52 WHEN CAN WE

EXPECT LOWER

ALTITUDE N/A LVLD-7 Request for the earliest time or position that a climb can be expected.

WHEN CAN WE EXPECT

HIGHER LEVEL Y DM53 WHEN CAN WE

EXPECT HIGHER

ALTITUDE N/A LVLD-8 Report indicating leaving the specified level.

LEAVING (level single) N DM28 LEAVING (altitude) N/A LVLD-9 Report indicating that the specified level is being maintained.

MAINTAINING (level single) N DM37 LEVEL (altitude) N/A F-21

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Appendix F Operational Definition in PANS-ATM (Doc 4444) CPDLC Message Sets Message Element Identifier Message Element Intended Use Format for Message Element Display Resp. FANS 1/A ATN B1 LVLD-10 Report indicating reaching the specified vertical range.

REACHING BLOCK (level single) TO (level single) N DM76 REACHING BLOCK (altitude) TO (altitude) N/A LVLD-11 Confirmation that the assigned level or vertical range is the specified level or vertical range.

ASSIGNED LEVEL (level) N DM38 ASSIGNED ALTITUDE (altitude) Note: Used for a single level.

DM77 ASSIGNED BLOCK (altitude) TO (altitude) Note: Used for a vertical range.

DM38 ASSIGNED LEVEL (level) LVLD-12 Report indicating that the aircraft’s preferred level is the specified level.

PREFERRED LEVEL (level single) N DM67‘PREFERRED LEVEL (altitude)’ Note 1: Response to free text UM169 ‘ADVISE PREFERRED LEVEL’ Note 2: When pre-formatting of the downlink message is not available, the pilot can shorten to: FL (altitude).

DM106 PREFERRED LEVEL (level) Note A vertical range may be provided.

LVLD-13 Report indicating climbing to the specified level.

CLIMBING TO (level single) N DM29 CLIMBING TO (altitude) N/A F-22

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Appendix F Operational Definition in PANS-ATM (Doc 4444) CPDLC Message Sets Message Element Identifier Message Element Intended Use Format for Message Element Display Resp. FANS 1/A ATN B1 LVLD-14 Report indicating descending to the specified level.

DESCENDING TO (level single) N DM30 DESCENDING TO (altitude) Note: N alert attribute.

DM61 DESCENDING TO (altitude) Note: Urgent alert attribute.

N/A LVLD-15 Indication that the specified level can be accepted at the specified time.

WE CAN ACCEPT (level single) AT TIME (time) N DM67 ‘WE CAN ACCEPT (altitude) AT TIME (time)’ DM81 WE CAN ACCEPT (level) AT (time) Note: A vertical range may be provided.

LVLD-16 Indication that the specified level can be accepted at the specified position.

WE CAN ACCEPT (level single) AT (position) N DM67 ‘WE CAN ACCEPT (altitude) AT (position)’ N/A LVLD-17 Indication that the specified level cannot be accepted.

WE CANNOT ACCEPT (level single) N DM67. ‘WE CANNOT ACCEPT (altitude)’ DM82 WE CANNOT ACCEPT (level) Note: A vertical range may be provided.

LVLD-18 Notification of the preferred time and position to commence descent for approach.

TOP OF DESCENT (position) TIME (time) N DM67 ‘TOP OF DESCENT (time)’ Note: When pre-formatting of the downlink message is not available, the pilot can shorten to:

TOD (time).

DM109 TOP OF DESCENT (time) LVLD-19 Notification of the present level. Present level (single level) N N/A Note: Refer to A.6.

DM32 PRESENT LEVEL (altitude) F-23

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Appendix F Table F-10. Crossing Constraint Uplink Messages (CSTU) Operational Definition in PANS-ATM (Doc 4444) CPDLC Message Sets Message Element Identifier Message Element Intended Use Format for Message Element Display Resp. FANS 1/A ATN B1 CSTU-1 Instruction that the specified position is to be crossed at the specified level or within the specified vertical range.

CROSS (position) AT (level) W/U UM46 CROSS (position) AT (altitude) Note: Used for a single level.

UM46 CROSS (position) AT (level) CSTU-1 Instruction that the specified position is to be crossed at the specified level or within the specified vertical range.

CROSS (position) AT (level) UM50 CROSS (position) BETWEEN (altitude) AND (altitude) Note: Used for a vertical range.

UM46 CROSS (position) AT (level) CSTU-1 Instruction that the specified position is to be crossed at the specified level or within the specified vertical range.

CROSS (position) AT (level) W/U UM49 CROSS (position) AT

AND MAINTAIN (altitude) Note 1: A vertical range cannot be provided.

Note 2: This message element is equivalent to CSTU-1 plus LVLU-5 in ICAO Doc 4444.

N/A CSTU-2 Instruction that the specified position is to be crossed at or above the specified level.

CROSS (position) AT OR ABOVE (level single) W/U UM47 CROSS (position) AT OR ABOVE (altitude) UM47 CROSS (position) AT OR ABOVE (level) CSTU-3 Instruction that the specified position is to be crossed at or below the specified level.

CROSS (position) AT OR BELOW (level single) W/U UM48 CROSS (position) AT OR BELOW (altitude) UM48 CROSS (position) AT OR BELOW (level) F-24

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Appendix F Operational Definition in PANS-ATM (Doc 4444) CPDLC Message Sets Message Element Identifier Message Element Intended Use Format for Message Element Display Resp. FANS 1/A ATN B1 CSTU-4 Instruction that the specified position is to be crossed at the specified time.

CROSS (position) AT TIME (time) W/U UM51 CROSS (position) AT (time) UM51 CROSS (position) AT (time) CSTU-5 Instruction that the specified position is to be crossed before the specified time.

CROSS (position) BEFORE TIME (time) W/U UM52 CROSS (position) AT OR BEFORE (time) UM52 CROSS (position) AT OR BEFORE (time) CSTU-6 Instruction that the specified position is to be crossed after the specified time.

CROSS (position) AFTER TIME (time) W/U UM53 CROSS (position) AT OR AFTER (time) UM53 CROSS (position) AT OR AFTER (time) CSTU-7 Instruction that the specified position is to be crossed between the specified times.

CROSS (position) BETWEEN TIME (time) AND TIME (time) W/U UM54 CROSS (position) BETWEEN (time) AND (time) UM54 CROSS (position) BETWEEN (time) AND (time) CSTU-8 Instruction that the specified position is to be crossed at the specified speed.

CROSS (position) AT (speed) W/U UM55 CROSS (position) AT (speed) UM55 CROSS (position) AT (speed) CSTU-9 Instruction that the specified position is to be crossed at or less than the specified speed.

CROSS (position) AT (speed) OR LESS W/U UM56 CROSS (position) AT OR LESS THAN (speed) N/A CSTU-10 Instruction that the specified position is to be crossed at or greater than the specified speed.

CROSS (position) AT (speed) OR GREATER W/U UM57 CROSS (position) AT OR

GREATER THAN (speed) N/A F-25

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Appendix F Operational Definition in PANS-ATM (Doc 4444) CPDLC Message Sets Message Element Identifier Message Element Intended Use Format for Message Element Display Resp. FANS 1/A ATN B1 CSTU-11 Instruction that the specified position is to be crossed at the specified time and at the level or within the vertical range as specified.

CROSS (position) AT TIME (time) AT (level) W/U UM58 CROSS (position) AT (time) AT (altitude) Note: A vertical range cannot be provided.

UM62 AT (time) CROSS (position) AT

AND MAINTAIN (altitude) Note 1: A vertical range cannot be provided.

Note 2: This message element is equivalent to CSTU-11 plus LVLU-5 in ICAO Doc 4444.

N/A CSTU-12 Instruction that the specified position is to be crossed before the specified time and at the level or within the vertical range as specified.

CROSS (position) BEFORE TIME (time) AT (level) W/U UM59 CROSS (position) AT OR BEFORE (time) AT (altitude) Note: A vertical range cannot be provided.

N/A CSTU-13 Instruction that the specified position is to be crossed after the specified time and at the level or within the vertical range as specified.

CROSS (position) AFTER TIME (time) AT (level) W/U UM60 CROSS (position) AT OR AFTER (time) AT (altitude) Note: A vertical range cannot be provided.

N/A F-26

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Appendix F Operational Definition in PANS-ATM (Doc 4444) CPDLC Message Sets Message Element Identifier Message Element Intended Use Format for Message Element Display Resp. FANS 1/A ATN B1 CSTU-14 Instruction that the specified position is to be crossed at the level or within the vertical range, as specified, and at the specified speed.

CROSS (position) AT (level) AT (speed) W/U UM61 CROSS (position) AT AND MAINTAIN (altitude) AT (speed) Note 1: A vertical range cannot be provided.

Note 2: This message element is equivalent to CSTU-14 plus LVLU-5 in ICAO Doc 4444.

UM61 CROSS (position) AT AND MAINTAIN (level) AT (speed) CSTU-15 Instruction that the specified position is to be crossed at the specified time at the level or within the vertical range, as specified, and at the specified speed.

CROSS (position) AT TIME (time) AT (level) AT (speed) W/U UM63 AT (time) CROSS (position) AT

AND MAINTAIN (altitude) AT (speed) Note 1: A vertical range cannot be provided.

Note 2: This message element is equivalent to CSTU-15 plus LVLU-5 in ICAO Doc 4444.

N/A F-27

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Appendix F Table F-11. Speed Uplink Messages (SPDU) Operational Definition in PANS-ATM (Doc 4444) CPDLC Message Sets Message Element Identifier Message Element Intended Use Format for Message Element Display Resp. FANS 1/A ATN B1 SPDU-1 Notification that a speed instruction may be issued to take effect at the specified time.

EXPECT SPEED CHANGE AT TIME (time) R UM100 AT (time) EXPECT (speed) N/A SPDU-2 Notification that a speed instruction may be issued to take effect at the specified position.

EXPECT SPEED CHANGE AT (position) R UM101 AT (position) EXPECT (speed) N/A SPDU-3 Notification that a speed instruction may be issued to take effect at the specified level.

EXPECT SPEED CHANGE AT (level single) R UM102 AT (altitude) EXPECT (speed) N/A SPDU-4 Instruction to maintain the specified speed.

MAINTAIN (speed) W/U UM106 MAINTAIN (speed) UM106 MAINTAIN (speed) SPDU-5 Instruction to maintain the present speed.

MAINTAIN PRESENT SPEED W/U UM107 MAINTAIN

PRESENT SPEED UM107 MAINTAIN

PRESENT SPEED SPDU-6 Instruction to maintain the specified speed or a greater.

MAINTAIN (speed) OR

GREATER W/U UM108 MAINTAIN (speed) OR

GREATER UM108 MAINTAIN (speed) OR

GREATER SPDU-7 Instruction to maintain the specified speed or a less.

MAINTAIN (speed) OR LESS W/U UM109 MAINTAIN (speed) OR LESS UM109 MAINTAIN (speed) OR LESS SPDU-8 Instruction to maintain the specified speed range.

MAINTAIN (speed) TO (speed) W/U UM110 MAINTAIN (speed) TO (speed) N/A SPDU-9 Instruction that the present speed is to be increased to the specified speed and maintained until further advised.

INCREASE SPEED TO (speed) W/U UM111 INCREASE SPEED TO (speed) N/A F-28

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Appendix F Operational Definition in PANS-ATM (Doc 4444) CPDLC Message Sets Message Element Identifier Message Element Intended Use Format for Message Element Display Resp. FANS 1/A ATN B1 SPDU-10 Instruction that the present speed is to be increased to the specified speed or greater, and maintained at or above the specified speed until further advised.

INCREASE SPEED TO (speed) OR GREATER W/U UM112 INCREASE SPEED TO (speed)

OR GREATER N/A SPDU-11 Instruction that the present speed is to be reduced to the specified speed and maintained until further advised.

REDUCE SPEED TO (speed) W/U UM113 REDUCE SPEED TO (speed) N/A SPDU-12 Instruction that the present speed is to be reduced to the specified speed or less and maintained at or below the specified speed until further advised.

REDUCE SPEED TO (speed)

OR LESS W/U UM114 REDUCE SPEED TO (speed)

OR LESS N/A SPDU-13 Instruction to resume a normal speed. The aircraft no longer needs to comply with a previously issued speed restriction.

RESUME NORMAL SPEED W/U UM116 RESUME

NORMAL SPEED UM116 RESUME

NORMAL SPEED SPDU-14 Indication that the preferred speed may be flown without restriction.

NO SPEED RESTRICTION R UM169 ‘NO SPEED RESTRICTION’ UM222 NO SPEED

RESTRICTION F-29

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Appendix F Operational Definition in PANS-ATM (Doc 4444) CPDLC Message Sets Message Element Identifier Message Element Intended Use Format for Message Element Display Resp. FANS 1/A ATN B1 SPDU-15 Request to report the speed defined by the speed type(s).

REPORT (speed types) SPEED Y UM134 CONFIRM SPEED Note: NE response attribute.

UM169 ‘REPORT GROUND SPEED’ Note 1: Used when the controller is requesting the pilot to report the present ground speed.

Note 2: R response attribute.

N/A SPDU-16 Request to confirm the assigned speed.

CONFIRM ASSIGNED SPEED Y UM136 CONFIRM

ASSIGNED SPEED Note: NE response attribute.

N/A SPDU-17 Request for the earliest time or position when the specified speed can be accepted.

WHEN CAN YOU ACCEPT (speed) Y UM151 WHEN CAN

YOU ACCEPT (speed) Note: NE response attribute.

N/A F-30

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Appendix F Table F-12. Speed Downlink Messages (SPDD) Operational Definition in PANS-ATM (Doc 4444) CPDLC Message Sets Message Element Identifier Message Element Intended Use Format for Message Element Display Resp. FANS 1/A ATN B1 SPDD-1 Request for the specified speed. REQUEST (speed) Y DM18 REQUEST (speed) DM18 REQUEST (speed) SPDD-2 Request for the earliest time or position that the specified speed can be expected.

WHEN CAN WE EXPECT (speed) Y DM49 WHEN CAN WE EXPECT (speed) N/A SPDD-3 Report indicating the speed defined by the specified speed types.

(speed types) SPEED (speed) N DM34 PRESENT SPEED (speed) DM67 ‘GROUND SPEED (speed)’ Note 1: Used when the controller is requesting the pilot to report the present ground speed.

Note 2: When pre-formatting of the downlink message is not available, the pilot can shorten to GS (speed).

N/A SPDD-4 Confirmation that the assigned speed is the specified speed.

ASSIGNED SPEED (speed) N DM39 ASSIGNED SPEED (speed) N/A SPDD-5 Indication that the specified speed can be accepted at the specified time.

WE CAN ACCEPT (speed) AT TIME (time) N DM67 ‘WE CAN ACCEPT (speed) AT TIME (time)’ N/A SPDD-6 Indication that the specified speed cannot be accepted.

WE CANNOT ACCEPT (speed) N DM67 ‘WE CANNOT ACCEPT (speed)’ N/A F-31