The decision to close the airspace came last Wednesday after an aerial dogfight with Indian air force over the occupied territory of Kashmir ignited fears of all-out conflict, with world powers rushing to urge restraint.
Pakistan Air Force (PAF) shot down an Indian warplane capturing a pilot in the process. He was returned to India on Friday, crossing the Wagah border on foot.
PAF strikes Indian targets across LoC, two IAF jets shot down
"All airports across Pakistan are operational and airspace reopened," a spokesperson for the Civil Aviation Authority told AFP on Monday, adding the process had been completed by 1:00 pm.
The closure disrupted major routes between Europe and South Asia, with mounting frustration from passengers stranded at international airports.
It also delayed attempts to search for a British and an Italian climber who went missing on Nanga Parbat - Pakistan's "killer mountain" and the ninth highest peak in the world - as rescue teams were forced to wait for permission to send up a helicopter.
Fears grow for Italian, British climbers missing on Pakistan's 'Killer Mountain'
The climbers, Daniele Nardi and Tom Ballard, were last heard from on February 24. Fresh rescue attempts had to be called off over the weekend due to bad weather amid growing fears for their survival.
The country began reopening its airspace "gradually" from Friday, with flights allowed in and out of major cities.
But the backlog means major delays are still expected and authorities have urged passengers to check for more information with their airlines.
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