Title: ADS - Validity Indication for Downlink Parameters
     
PDR Reference:                    	97120002 
Originator Reference:			-
SARPs Document Reference:          	ADS SARPs, Section 2.2.1.7.5.5 
Status:                          	ADOPTED
PDR Revision Date:               	01/12/97 (SUBMITTED)
                              	01/12/97 (SUBMITTED -> ACCEPTED)
                              	03/12/97 (RESOLVED)
PDR Submission Date:               01/12/97 
Submitting State/Organization:     USA 
Submitting Author Name:           	Hamelink, J
Submitting Author E-mail Address:  jhamelin@adsystech.com
Submitting Author Supplemental
Contact Information:
SARPs Date:                     	IV2.1, Redondo Beach 
SARPs Language:                    	English
     
Summary of Defect:
See PDR 97060004.
          
Assigned SME:                    	Sub-Volume II SME

Proposed SARPs amendment:
     
The proposed solution discussed and recommended by ATNP/WG3/SG2 (Columbia meeting PDR 97060004) was proposed to the ADSP working group A/B meeting in Brussels (Dec 1997). The working group felt strongly that it would be inappropriate to have aircraft abort the connection when data (mandatory or optional) was found either invalid or missing.  

Instead the working group proposed that reports continue to be sent with a FOM indicating "0" when any of the Basic data was invalid or missing (change from PDR 97060004).  Any of the optional blocks would not be sent when any of the data contained in that block was missing (in accord with PDR 97060004).
     
Thus the ADS SARPs have been changed to reflect this requirement for the basic data as shown below.  The proposed solution of PDR 97060004 had been incorporated and this PDR represents a modification on PDR 97060004 having been incorporated.
     
1. Change section 2.2.1.7.1.5.5 a) from
     
a)  if the information forms part of position, timestamp or FOM, then:
     
    1) the ADS-air-user shall stop all contracts with the ADS-ground-user, and
    2) the ADS-air-user shall invoke ADS-user-abort request, and
     
To:
     
a)  if the information forms part of position, timestamp or FOM, then:
     
    1) the ADS-air-user shall continue to send ADS reports as required with the FOM set to "0", and
    2) if all the information is again found to be valid and available the FOM shall be reset to its actual value , and
     
     
2. Change the Note 1 after section 2.2.1.7.1.5.5 after h) from:
     
Note 1.-- If information is not available for more than one optional field, then both are omitted. If information is not available for position, timestamp or FOM as well as one or more optional fields, then the ADS-air-user will abort.
     
To:
     
Note 1.-- If information is not available for more than one optional field, then both are omitted.
     
SME Recommendation to CCB:          	RESOLVED
     
CCB Decision:                    		CCB-4 Montreal: SUBMITTED
 							CCB-4: RESOLVED