Following the refusal of Russian aviation agency delegates to come to the US as was scheduled on 18 April, the US-Russia airspace agreements terminate at midnight GMT on the 17th.
Under the agreement one side will have to state that the other is unable to enter its airspace and the agreement is finished.
Of this is the case it will be a major blow to UPS and FedEx who use Russian airspace more than any other US owned airlines.
It’s not the first time Russia has flexed its airspace muscles, effectively blackmailing KLM over slots at Schiphol last year.
Russia was not an initial signatory of the original Five Freedoms in 1944 and has individual agreements with nations who transit its air space – something that never happened at all until 1992.
Aeroflot collects substantial sums of money from overflights by foreign airlines and there is a complicated arrangement that before take off – no matter where, if an aircraft is to fly over Russian air space it has to request and gain permission on an individual basis before departing.
The consequences of retaliation by the US are unclear but with tensions high in the Middle-East and Syria, potential super-power conflict seems painfully close to reality in the skies over that blighted country.
Either way this is yet another ratcheting up of a bizarre and uncertain set of circumstances that could so easily spin out of control, especially given the temperament of one or two individuals.