According to the Scientific American these events are very common with each plane in the US commercial fleet experiencing a lightning strike at least once a year. However, the chances of capturing one on camera are very remote - never mind one perfectly aligned with a rainbow.
hoonigan_4wd on December 7th, 2017 at 12:18 UTC »
Never knew you could see thunder..
mayallrob_ on December 7th, 2017 at 12:50 UTC »
For those that haven't seen this pic before, there's actually an aeroplane in the middle of the photo being struck by lightning.
EDIT: This photo shows you the plane a little better, and here's an article about the event. /r/PerfectTiming relevant extract:
Rizanamhsra on December 7th, 2017 at 13:05 UTC »
Rainbow vs Lightning