A320 Captain experiences an LGCIU 2 ECAM at FL380 and learns that this failure will render the number 2 thrust reverser inoperative. The destination runway is short and Maintenance offers a circuit breaker reset procedure if the Captain elects to exercise his emergency authority. This is successfully accomplished.

Narrative

Airborne we got a LGCIU 2 ECAM. No reference action associated. The Flight Manual was referenced and indicated no number 2 thrust reverser would be available (checklist was a little confusing). We could not find a weight penalty associated. Called Dispatch and they informed me that there was a weight penalty and that the required landing distance was only two hundred feet short of the entire runway length available at SNA. We have a system fault reset in our book that is applicable on the ground but not in flight. Maintenance said that we could cycle the Circuit Breaker (CB) in the air; but obviously; as we already were aware; this constitutes using Captain's emergency authority. I did not deem this an emergency from the information I had as it appeared to be only an issue with the runway length in SNA (checklist again very lacking in complete systems lost). Dispatch; Maintenance and I conferred and I decided that with the information I had at this point going to LAX (our designated alternate) would be a suitable safe option and make the stopping distance a non issue. I realized we still had 2.5 hours or so to consider our options. I still wanted the MEL information. I wanted all possible information; so I asked Dispatch to have the MEL for the issue to be sent to the aircraft. Upon receiving the MEL it was quite lengthy; involved numerous items lost once on the ground (reference MEL for LGCIU2 inoperative). With this further information; I determined that no matter where we landed that the situation would have negative consequences on safety; even just taxiing in at our destination. With this in mind; and after getting assurance from Maintenance that there were no additional consequences that would be generated by cycling the LGCIU 2 CB I opted to use my Captain's emergency authority and did so. The CB was uneventfully cycled; the system was fully recovered; and we opted to continue to our original destination of SNA. As a caveat I can only assume that the cycling of CBs in flight being deemed a use of Captains Emergency Authority was generated with some specific instances in mind. The criteria is entirely too broad. This was a simple reset procedure that should not have required me to judge whether to use this authority or not. I feel the emergency authority to recycle CBs in flight designation should be reviewed. As pilots it appears to be a simple; obvious procedure in this instance that generated a gray area for us to operate in. I understand that there are CBs that influence numerous systems. This CB just dealt with LGCIU 2 which was inoperative already with the commensurate repercussions. The entire legality exercise was wholly unnecessary.