How did Cityjet manage on their London City-Paderborn route 5 years ago ? They used a Fokker 50 and I seem to remember loads being higher than 9 pax per flight...
Even when OLT Express ran their ill fated routes to Saarbrucken and Dresden from Southend it wasn't that bad.
Is it lack of advertising ? Stupidly high pricing ? Bad schedule ? Something else ?