Title: FIS - Invalid state change 

PDR Reference:					98040008
Originator Reference: 				invstate
SARPs Document Reference: 			FIS SARPs, Section 2.4.5.3.8.8.3 and 
							Table 2.4.5-9/b
Status: 						RESOLVED
Impact :						C (Clarification)
PDR Revision Date: 				25/06/98 (PROPOSED -> RESOLVED)
							20/05/98 (ACCEPTED -> PROPOSED)
							27/04/98 (SUBMITTED -> ACCEPTED)
PDR Submission Date:  				09/04/98
Submitting State/Organization: 		CENA, CHARME
Submitting Author Name: 			Jean, M
Submitting Author E-mail Address: 		jean@cenatls.cena.dgac.fr
Submitting Author Supplemental 
Contact Information:			
SARPs Date:  					IV2.2
SARPs Language:	 				English

Summary of Defect:
 
In order to allow the sequence of events described in Figure 2.4.5-10 "Use of FIS-cancel-update service by both FIS-users", both air and ground UC modules shall upon receipt of the [FISCancelUpdateContract] APDU from the peer send the [FISCancelUpdateAccept] APDU and stay in the UC-CANCEL state. This will allow them to process the [FISCancelUpdateAccept] sent by the peer.

This is correctly described for the air FIS UC module.

This is not for the ground FIS UC module since section 2.4.53.8.8.3 c) specifies that it shall enter the UC-G-IDLE state.

Impact On Interoperability:

With the current specification, in case both FIS-users request the cancellation of an update contract, the FIS-ground-ASE will abort the dialogue on receipt of the [FISCancelUpdateContract] APDU, since no UC module matches the contract number anymore. This is not clean, since all the contracts not impacted by the cancellation have to be re-installed. However, this situation does not jeopardize the interoperability.

Impact on safety:
This situation results in the abort of the air/ground dialogue and the automatic cancellation of all pending contracts. This situation generates a false alarm to the pilot which has to figure out what is the source of the abort and then to re-install the FIS contracts which should not have normally been cancelled. This will disturb the pilot and increase the crew workload.

Assigned SME: 				Sub-Volume II SME

Proposed SARPs amendment: 

1/ Change  section 2.4.5.3.8.8.3 c) from:
c) enter the UC-G-IDLE state

to:
c) remain in the UC-G-CANCEL state.

2/ change in Table 2.4.5-9/b in cell ([FISCancelUpdateContract] APDU, UC-G-CANCEL) from
UC-G-IDLE

to
UC-G-CANCEL
 
SME Recommendation to CCB: 		

CCB Decision:				atnp_ccb_chair: SUBMITTED (09/04/98)
					atnp_ccb_chair: ACCEPTED (27/04/98)
					CCB-6 (Utrecht): RESOLVED (25/06/98)