You can always try some CBT techniques. Ask yourself what is the evidence for the concern. If we look at plane crashes, the statistic for dying on an airplane is 1 in 10.46 million. Very small odds. This gives your logical brain some ammo. Next, try relaxation techniques such as yoga, deep breathing, or guided imagery. As you start to relax, pick a mantra, a word or phrase that calms you and makes you feel good. As you breathe deeply in through your nose, repeat this word to yourself for a count of three. Exhale through your mouth and repeat. You should calm down and with daily practice, you should be able to chase the negative thoughts away when they first enter your mind. Use your logic and then your relaxation.