bristol-shannon 85. shannon-bristol 86. embarrasing..
As Jerry said, the yield is the key. I have no idea what sort of yield Ryanair expects on this service, nor how it is composed. For example, one or both airports might be helping with subsidies of one sort or another.
A look at Bristol-Knock would have caused raised eyebrows if the route was being measured on load factors alone, at least in its early years. Until recently it was easily the worst of the Ryanair BRS routes in terms of load factor and is still probably the worst (although Bristol-Cologne that began last winter at 4 x weekly hasn't been sensational).
BRS-NOC began in November 2007 when the FR base at BRS opened. Until 2011 it was year-round, and will revert to that schedule in the forthcoming winter. Its first two months (November and December 2007) saw monthly load factors of 46% in both months.
Since then I have the monthly load factors for the main summer months which I copy below:
2008 (June-September only): 50 62 83 66
2009 (May-September): 46 48 52 66 42
2010 (May-September): 50 53 58 75 53
2011 (May-September): 51 57 71 69 53
2012 (June-September): 61 70 74 55
2013 (May-September): 57 58 67 80 59
2014 (May-September): 60 54 70 86 56
2015 (May-September): 72 75 82 91 71
2016: (May-September): 69 72 75 88 75
2017: (May-September): 73 79 86 93 83
So BRS-NOC despite struggling for loads in its early years has been operating for over ten years.
Ryanair operated Bristol-Zadar last summer for the first time and its May-September loads factors were 73 90 86 90 85. Not dissimilar to BRS-NOC yet Zadar was axed but Knock has become a year-round route again.
When I looked an hour or so ago BRS-SNN had 86 occupied seats (lf 45.5%) and SNN-BRS 94 occupied seats (lf just under 50%).