Air Carrier First Officer reports that the Sabre flight planning software provides only SIGMETS that are 'applicable' to the flight. Requesting SIGMETS in flight can tie up the ACARS for extended periods of time.

Narrative

The Sabre Flight Plan only provides crews SIGMETS as part of the paperwork if they are determined to be 'applicable' to that flight; according to the Subject Matter Expert in Flight Operations. Pilots can always ask for SIGMETS on an individual flight basis if they want. If the practice of providing SIGMETS is not uniform it increases the chance of a crew not reviewing a SIGMET that was not provided but is applicable. If the SIGMETs are requested enroute via ACARS you get numerous pages of every SIGMET in the world it seems. On this [two hour] flight this was 12 pages worth of worldwide SIGMETS that tied up the ACARS for 28 minutes. Essentially we were locked out of ACARS use for 28 minutes. I have seen 18 pages of SIGMETS being sent to the aircraft. If you were flying internationally (especially Polar) and were reviewing options enroute due to an emergency; the loss of ACARS communications capability for 30 minutes or more is a significant threat. I am told that this is a known problem with SABRE.