An ERJ 170 crew was notified days after a flight that the database of an aircraft which they had flown was out of date.

Narrative

A Management Pilot called me during the boarding process to tell me that earlier in the week several crews had flown at least four aircraft that had an out-of-date navigation database. He advised me that there may be a systemic problem that caused this; however; the flight crews could have stopped this issue from occurring if we had followed the SOP Procedure by checking the database during our preflight. He went on to say that this would be considered my ground school training/corrective action. He then asked me to ensure that I talk to all my previous and future First Officers about ensuring that we carefully verify the database currency. He then stated that the mitigating factor in my occurrence was the fact that when I received the aircraft from the previous crew it (the A/C) had remained powered up. If it had been powered down and then subsequently powered down; I would have received a MCDU scratchpad message stating 'NAV Database out of date'. Always verify very carefully; the valid dates; currency and use of a current GPS Nav Database!