5415N for your information FCA doesn't OWN any aircraft (as is normal amongst UK charter airlines). The aircraft spec therefore is determined by what the Leasing Companies who order, and lease out the aircraft want to pay for.......
FCA leases from different companies, and hence not all aircraft have dual tillers. Therefore to keep the SOP's the SAME within the company the Capt taxi's at all times, 2 tillers or not.
30W