From BA's Trade Support site:
A system outage is currently affecting FLY check-in and Pegasus Reservations globally.
· Update as follows:
Silver Command is sitting due to a system outage affecting FLY checkin and Pegasus Reservations
Customers are having difficulties checking-in online
Systems are erratic and freezing or staff unable to log-on
Following flights are now being cancelled:
BA950
BA1326
BA728
BA346
BA862
Further 15 more flights to be cancelled shortly