Title: CM - CM Rejected Logon Clarification PDR Reference: 99090003 Originator Reference: - SARPs Document Reference: CM SARPs, Sections 2.1.7.1.1.6, 2.1.7.2.2.6 Status: ADOPTED Impact: C (Clarification) PDR Revision Date: 30/01/02 (RESOLVED -> ADOPTED) 29/09/99 (SUBMITTED -> RESOLVED) PDR Submission Date: 28/09/99 Submitting State/Organization: ATNP WG3/SG2 Submitting Author Name: Saccone, G Submitting Author E-mail Address: gsaccone@ons.com Submitting Author Supplemental: Contact Information: ph: +1 604 681-5829 fx: +1 604 681-5820 SARPs Date: Doc 9705 Edition 2 (November 1999) SARPs Language: English Summary of Defect: In the ATS Manual of Data Link Operations, an operational requirement of CM is the ability of the ground CM to "reject" a logon, and give an indication back to the aircraft that the logon has been rejected. A rejected logon has been interpreted by the ATN Panel, and WG3/SG2, to mean that no application information is returned to the aircraft. Therefore, if a CM-ground-user wants to reject a logon, the CM-ground-user would simply not supply any application information in the logon response. The CM-air-user would then interpret this as a rejection, either for operational reasons (e.g. optional information that is required for a particular airspace is missing) or technical reasons (e.g. there is a problem with the ground system and the service is not available). However, as implementations are built, there is confusion as to what constitutes a rejected logon. Since the interpretation of a rejected logon is an implementation detail, it is not explicitly defined in the SARPs. It is mentioned in the guidance, but the guidance not have "shall" status. Accordingly, implementers may make different interpretations on rejected logon definitions, and this may lead to interoperability problems. For example, one implementation may choose to interpret a rejected logon as is currently defined in the guidance (responding to a CM-logon request with no data) while another implementation may decide to invoke a CM-user-abort service if a CM-logon is to be rejected. While operational procedures should cover these cases, operations will become more complex, as this aspect of CM becomes local, not global. Therefore this PDR proposes to make this an explicit user requirement. Additionally, this solution is backwards compatible. Assigned SME: Sub-Volume II SME Proposed SARPs amendment: Add note to 2.1.7.1.1.6: Note. - If the Version Number parameter is not provided and the Logon Response parameter is provided but is empty, this means that the CM-ground-user has rejected the logon. This may be for operational reasons (e.g. optional information that is required for a particular airspace is missing) or technical reasons (e.g. there is a problem with the ground system that prevents it from providing the information). This case will NOT be due to a version number incompatibility, since in that case only the Version Number is provided. If a CM-logon service is rejected, the CM-air-user may evaluate possible reasons and retry the CM-logon service. Note to CCB: This will also be explained further in the CM guidance. Renumber 2.1.7.2.2.6 - 2.1.7.2.2.9 to 2.1.7.2.2.7 - 2.1.7.2.2.10 Add new 2.1.7.2.2.6 and notes: 2.1.7.2.2.10 If a CM-ground-user wishes to reject a CM-logon service indication for any reason, the CM-ground-user shall invoke a CM-logon service response with a CMLogonResponse containing no information. Note 1. - This may be done for either operational reasons (e.g. optional information that is required for a particular airspace is missing or information for the requested facility is not available) or technical reasons other than version incompatibility (e.g. there is a problem with the ground system and the service is not available). These example reasons are not meant to be an exhaustive list. Note 2. - This will not be done if the CM-air-ASE and CM-ground-ASE versions are incompatible. In that case, the CM-ground-ASE will reject the D-START indication (as detailed in 2.1.5.3.2.2) before it reaches the CM-ground-user. Note to CCB: This will also be explained further in the CM guidance. SME Recommendation to CCB: - CCB Decision: CCB-10 (Gran Canaria): RESOLVED