Первый полет самолет Spectrum S.33 Independence выполнил в январе 2006 года. Крупный заказ на самолет, способный перевозить девять пассажиров, поступил в марте 2008 года от американской компании "Jetpool". Самолеты данного типа заказала также чартерная компания "Starfish" из Чикаго. Сертификация машины намечена на 2010 год, причем серийные самолеты будут оснащены двигателями Williams FJ33.
One of the Spectrum S-33's strong selling points is its large cabin. Following the loss of the prototype last year, the company is pressing ahead with the construction of a second airframe.

Spectrum compares the size of its aircraft with the Citation CJ2, but quotes a better performance due to the light weight of its carbon-fibre airframe and fuel-efficient engines. It is the brainchild of Linden Blue, who was the inspiration behind the Starship during his tenure as President of Beech Aircraft some years ago.

Spectrum Aeronautical displayed full-size fuselage mock-ups of its S-40 Freedom and S-33 Independence at NBAA. The company had announced on August 10, 2007 that it was accelerating the development schedule for the Freedom and is targeting certification for the aircraft in 2009, a year earlier than originally planned. This will enable time for design refinement of the Independence, which will now incorporate significant performance improvements. This will include using the Williams International FJ33-4A-19 engine instead of the previously planned FJ33-4A-15, giving further thrust and efficiency. Speed, range and cabin size will also be increased and certification of the enhanced version is now planned in 2010, rather than 2009.