Title: CPDLC - New Uplink 237 message

PDR Reference:              		M0120003
Originator Reference:            	M01200x2
SARPs Document Reference:         	CPDLC SARPs, section 2.4.3.2.1,
                                                 table 2.3.7-5
Status:                       	RESOLVED
Impact:					A
PDR Revision Date:              	05/03/01 (ACCEPTED -> PROPOSED -> RESOLVED)
						20/02/01 (SUBMITTED -> ACCEPTED)
PDR Submission Date:           	20/12/00
Submitting State/Organization:    	
Submitting Author Name:          	Hamelink, J
Submitting Author E-mail Address:  	
Submitting Author Supplemental 
Contact Information:               	
SARPs Date:                      	Doc 9705 Draft Ed 3 (ICAO Web Site - 11/00) 
SARPs Language:                  	English

Summary of Defect:

The inclusion of the new CPDLC uplink message REQUEST AGAIN WITH NEXT UNIT was approved by ADSP/5 and will be incorporated in the first amendment to Edition 1 of Doc 9694 and will be included in the other appropriate ICAO documents (i.e. Doc 4444).

Um237 indicates that the request cannot be responded to by the current unit, and that it should be requested from the next unit. Attributes are Normal Urgency, Low Alert and No Response. 

There is no specific user requirements related to this new message.

CPDLC SARPs chapters 4 (ASN.1) and 7 (Message intent tables) must be modified accordingly.

Doc 9739 (GM) will be modified to explain how fields after the extensibility marker should be used.

Assigned SME:                    	Sub-Volume II SME
a
Proposed SARPs amendment: 

1) In chapter 4, section 2.4.3.2.1 replace

-- LEAVE CONTROLLED AIRSPACE		Urg(N)/Alr(M)/Resp(W/U)
   uM236NULL                       [236]NULL,
   ...
   }

by

-- LEAVE CONTROLLED AIRSPACE		Urg(N)/Alr(M)/Resp(W/U)
   uM236NULL                       [236]NULL,
   ...,
-- REQUEST AGAIN WITH NEXT UNIT	Urg(N)/Alr(L)/Resp(N)
   uM237NULL                       [237]NULL
   }

2) In chapter 8, add a new row to table 2.3.7-5 (Responses/acknowledgements (uplink) as follows:

-----------------------------------------------------------------------------
237 | Indicates that the request cannot be | REQUEST AGAIN WITH | N | L | N |
    | responded to by the current unit,    | NEXT UNIT          |   |   |   |
    | and that it should be requested from |                    |   |   |   |
    | the next unit                        |                    |   |   |   |
-----------------------------------------------------------------------------

Impact on interoperability:  All version 2 CPDLC ASEs shall implement this new message. If one does not, indexes of messages added after the extensibility will not match anymore and this will jeopardize the interoperability with future versions.

PDR Validation Status:			Level A: SG-A2 analysis and inspection

SME Recommendation to CCB: 		RESOLVED

CCB Decision:                    	atnp_ccb_chair: SUBMITTED (20/12/00)
						atnp_ccb_chair: ACCEPTED (20/02/01)
						CCB-13/1 (Honolulu): RESOLVED (05/03/01)