True - but there's a certain crude satisfaction gained by pointing out to chemmies that they could actually get some verifiable evidence and asking why they don't
And who knows....someone else might find the info useful
For a trail sample, the plane wouldn't even have to go far as the weather in the south-western part of Germany is often favourable to persistent contrail formation - at least more so than in California ...
seriously- You don't need a plane to do this. It's already been done. Remember not too long ago the air was tested inside commercial airliners and it was determined there was some nasty stuff in there but they quickly realized it came from the engines. All you need is those test results plus some knowledge and logic and you quickly get your conclusions.