It could be sunburn, as Candace suggests, but the pattern looks wrong for it, in my opinion. I am also seeing cellular collapse further into the leaf. I suspect that you have a fungal problem, particularly bad with the vandaceous plant on the right. Many times this occurs in cooler weather with high humidity and poor air circulation. The Coel. pics are not clear but I think, from what I can see, there are just a few small areas of cellular collapse. and the white is light reflecting off of water on the leaf. Is that correct? If it is, I would just put the Coel. into higher air circulation and keep the leaves dry for a couple of weeks. The Vanda you can try to save, if it is fungal, but you will need more drastic measures. Take a single edge razor blade, and remove all the blackened tissue, cutting at least 1.3 cm into the good tissue. Dust the cut ends with a powdered fungicide and you may want to treat the whole plant with a liquid fungicide.
Are these the only two plants that you are having problems with? Are you growing in a greenhouse?
Hold off on my measures until we get more opinions!