Nok Air is a Thailand based airline that flies to number of domestic and select international destinations from Bangkok’s Dong Muang airport (used by low cost airlines).
The airline is now facing pilot strikes because of the audit conducted by Thai aviation regulator that lead to walk out by some pilots. The Thai aviation sector was downgraded last year due to lack in oversight (read more here).
Nok Air is minority owned by Thai Airways. If you are booked on Nok Air service that is cancelled, probably the best course of action is to purchase new ticket on Thai Air Asia, Thai Smiles, Bangkok Airways or Thai Airways.
I have flown Nok Air couple of times. The service is totally fine for an hour or two flight. I am not sure if their flights are even available on OTAs such as Expedia.
Their website was unable to accept a credit card that I wanted to pay for the purchase and ended up paying on an ATM from my Thai bank account.
It is good that the CAAT (Civil Aviation Authority of Thailand) is conducting these audits and trying to get the aviation sector back to western standards.