The answer to the question you posed BEagle is that all depends on the terms of the contract.
1. Does the contract stipulate time is of the essence?
2. Are there contractual penalty clauses for non performance?
3. Does the contract provide that in the event of non performance for any reason HMG is entitled to treat it as a breach enabling it to end the contractual arrangements?
My guess would be that if it is just a short-term delay, in the absence of express terms & conditions enabling it to do so, HMG would not be able to employ alternative contractors and recover the costs from Airfllite.