These are companies that have not yet chosen to use Twitter as a communication tool for their company and products. We're hoping by the 2016 Farnborough International Air Show all the companies below will join the other companies that have successfully used Twitter to drive customers to their products. We have a couple companies since we last published this 2015 list finally join. Perhaps more soon will follow.
HondaJets - Not using their account @hondajets or @hondajet
Triumph Group - Not using their account @triumphgroup