Qatar Airways could potentially suffer the greatest operational impact from the Gulf diplomatic crisis, not just overall but in each state affected by the severing of intergovernmental relations.
The Qatari flag-carrier is the largest individual provider of capacity to Saudi Arabia, the United Arab Emirates, Bahrain and Egypt according to FlightGlobal's schedules database.
Saudi Arabia's foreign affairs ministry says the government has severed diplomatic and consular relations with Qatar, and has decided to close all airports and the airspace to prevent Qatari transit.
It says it is taking the action – in "solidarity" with Bahrain – in the interests of the kingdom's "national security", accusing the authorities in Doha of supporting "multiple" organisations, including Iranian-backed factions, connected to terrorism activities.
The Saudi ministry says the Qatari authorities have "consistently reneged" on international obligations signed under the Gulf Co-operation Council umbrella aimed at preventing hostilities against the kingdom.
Qatar Airways says it has suspended all flights to Saudi Arabia "until further notice", and that all customers on affected flights will be provided with "alternative options", including free rebooking or a refund.
Countries including the United Arab Emirates and Egypt have joined the Saudi action against Qatar.
But the Qatari foreign affairs ministry says the Saudi allegations are "unfounded and baseless", consisting of "absolute fabrications", and that, as a result, the diplomatic measures are "unjustified".
It insists Qatar is committed to the charter of the Gulf Co-operation Council and does not interfere with the internal affairs of other countries – adding that it "carries out its duties" in battling the threat of terrorism.
The ministry retorts that the purpose of the Saudi-driven effort is to impose "guardianship" over Qatar, and vows that the restrictions "will not affect the normal course of life" for Qatari citizens.
Qatar Airways has a network in Saudi Arabia which covers not only Riyadh, Jeddah and Dammam but several smaller cities including Gassim, Taif and Madinah. Saudi flag-carrier Saudia only operates to Doha from Riyadh and Jeddah.
Tensions between the two sides had been illustrated by the failed effort by Qatar Airways to establish a new carrier, Al Maha Airways, in Saudi Arabia after the kingdom invited applications for licences.
But the prohibition is set to hit Qatar Airways harder, with a Saudi airspace ban affecting not just its Saudi route network but potentially other destinations, such as Nairobi, Lagos and Dar es Salaam, for which the shortest route involves Saudi overflight.
Qatar Airways similarly offers the greatest capacity to the United Arab Emirates, with more seats than the four main UAE operators Emirates, Etihad Airways, Flydubai and Air Arabia combined – partly because the Qatari carrier serves not only Abu Dhabi and the two Dubai airports but also Sharjah and Ras Al-Khaimah.
The four UAE airlines and Bahrain's Gulf Air are halting services to Doha. Qatar Airways' reservations engine is still indicating availability of flights to both countries.
FlightGlobal's schedules data shows Qatar Airways dominates capacity to neighbouring Bahrain and it also provides the most seats to Egypt, a consequence of serving not only Cairo but Alexandria and Luxor, and typically deploying higher-capacity aircraft than either EgyptAir or Air Arabia.
Source: Cirium Dashboard