Adfly
The pax reduction in April at BOH is due the reduction in Ryanair flights this season over last year. Basically RYR are down one rotation a day, that's 300 pax a day for a typical RYR flight or 9000 over this month. But Flybe have added 3k+
Therein your difference. June will be the first month this year that stats will hit positive territory.
FF