These are aerospace companies that have not yet chosen to use Twitter as a communication tool for their company and products. We're hoping by the 2018 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've have been publishing this list of companies annually for 6 years now. 2013, 2014, 2015, 2016, & 2017. Perhaps more soon will follow.