This is a changing situation but information we are receiving is that many flights are being diverted away from affected Pakistani/Indian airspace which is causing delays and some cancellations.
 
Some flights are having to make en route refuelling stops which is resulting in extended journey times. Therefore the passenger will arrive to their destination one or more hours later and may miss any connections they have booked.
 
Airlines are working with the relevant authorities to try to obtain permission to fly over alternative airspace