Originally Posted by dera

If you have 5000 departures and 99% completion factor, you canceled 50 flights.
If you have 5000 departures and 99.5% completion factor, you canceled 25 flights.
So the other operation cancelled twice as much flights.

There is no scheduled departures v. actual departures comparison, but the completion factor gives us a very good indication of it.

You see 0.5% and consider it a "rounding error", but the mainline carrier sees a 100% difference in performance.