Title:                              ADS - ATC Connections

PDR Reference                       97080007
Originator reference:               PDR-4
SARPs Document Reference:           ADS SARPs, Section 2.2.1.7.1.5.2
Status:                             ADOPTED
PDR Revision Date:                  22/09/97 (SUBMITTED -> ACCEPTED)
				   	      22/09/97 (ACCEPTED -> PROPOSED)
						20/10/97 (PROPOSED -> RESOLVED)
PDR Submission Date:                18/08/97
Submitting State/Organisation:      ATNP/WG3/SG2
Submitting Author Name:             T I Maude
Submitting Author E-mail Address:   maude@level-7.co.uk
Submitting Author Supplemental
Contact Information:                Fax +44 1344 868 442
SARPs Date:                         IV1.1, March 97
SARPs Language:                     English

Summary of defect:

2.2.1.7.1.5.2 states that the ADS air user can accept contracts from four different ground systems. The operational requirement stated by the ADSP is that it can accept contracts from four ATC ground systems. Thus the SARPs do not meet the operational requirements.

If no change is made, then it will be possible for AOC connections to be made and "use up" some or all of the four "slots". A bona fide ATC contract would then be refused. This is therefore a safety issue.


Assigned SME:                       Sub Volume II SME

Proposed SARPs amendment:

Replace the text of 2.2.1.7.1.5.2 with the following:

"2.2.1.7.1.5.2  The ADS-air-user shall be capable of supporting contracts from at least four different ATC ground systems at the same time.

Note: The ADS-air-user may use the class of communications service indicated in the D-START indication quality of service parameter value in order to determine if the ground system is an ATC ground system. How the ADS-air-user finds out what class of communications service parameter value is used is a local matter."

SME Recommendation to CCB:          -

CCB Decision:                       atnp_ccb_chair: SUBMITTED (18/08/97)
				   	      atnp_ccb_chair: ACCEPTED (22/09/97)
						atnp_ccb_chair: RESOLVED (20/10/97)