There's been a surprising lack of transmissions events on airplanes so far. We've even had a case of an airline steward who was a super-spreader at a party he went to but when they checked the passengers on the plane he arrived with didn't seem to have infected any of them, though he did infect other crew. From the article it seems wearing PPE when interacting with passengers was SOP so probably that's it.
So it does seem that SARS-CoV-2 is really pretty droplet based and you'd not the virus doesn't say in the air long enough to circulate through the ventilation system meaningfully. You seem to mostly be in danger if someone in your row or the rows in front of or behind you talk or cough without wearing a mask.
https://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&object...
This couple was infected by the woman they were sitting behind
https://www.theguardian.com/world/2020/mar/09/british-couple...
And this is in contrast to other respiratory illnesses like swine flu where infected passengers have caused many other infections on a plane.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3810906/
So it does seem that SARS-CoV-2 is really pretty droplet based and you'd not the virus doesn't say in the air long enough to circulate through the ventilation system meaningfully. You seem to mostly be in danger if someone in your row or the rows in front of or behind you talk or cough without wearing a mask.