We do not prescribe sedatives, such as diazepam (Valium), for anxiety related to air travel. There are several reasons, including considerations about the sedative effects of the medication, which can result in falls and accidental injury, reduced awareness and slow reaction times which impairs the response to an emergency, a possible increased DVT (deep vein thrombosis) risk and paradoxical agitation and aggression in some people. Diazepam, and similar medications, are also illegal to possess in some countries.
We recommend that people attend a fear of flying course instead. These are safer, more effective, and have longer lasting effects than medication. Several free online courses are provided by the airlines and some airport authorities. Examples include:
https://www.fearless-flyer.com
Fear of flying courses from British Airways™ | Flying With Confidence
Tips For Nervous Flyers | Advice For Nervous Flyers | Virgin Atlantic