=====Overview=====
Losing Active redo log file is more serious than INACTIVE, because it still contains data that it might be needed. Generally you, the procedure to recover from loss of active member is:

===Database is still UP===
If the database is running, try to issue a checkpoint and clear the logs
  - Issue a checkpoint
  - Clear the logs

===If the database is down===
Since the active redo logs are used during crash recovery, trying to start up the database will cause the database 
the crash again during startup. 
As such your only choice is to:

  - Perform incomplete recovery (Using the latest redo log files) 

This of course will cause loss of data.