My understanding is that a lightning rod can only protect a maximal radius of 60m (see https://what-if.xkcd.com/16/ https://what-if.xkcd.com/16/). This would me

My understanding is that a lightning rod can only protect a maximal radius of 60m (see https://what-if.xkcd.com/16/ https://what-if.xkcd.com/16/). This would mean a mximal distance of 120m between rods in the areas you want to protect completely. I can imagine this is difficult, in particular if the rods need to be so high that they need support cables to avoid falling at the first wind gust. I would expect that modern airports already offer the maximal protection attainable with lightning rods. Any parts of the airport currently not protected probably does not make sense to protect with this technology.