Pakistan lies on an important aviation corridor, and the decision offers a welcome break for international airlines. The restrictions, imposed in February, affected hundreds of commercial and cargo flights each day, adding flight time for passengers and fuel costs for airlines. India's ministry of civil aviation said there were now no restrictions on airspace in either country. "Flights have started using the closed air routes, bringing a significant relief for airlines," it said.
Partial operations at Pakistani airports resumed once the immediate crisis passed but restrictions continued to affect many international carriers. Flights between Europe and Southeast Asia were forced further south, which added as much as 450 km (280 miles) to some journeys and forced the cancellation of some routes.
"Pakistan being open again makes the traditional and preferred Europe-Asia route through Afghanistan, Pakistan and onwards to India available again, and means that city pairs abandoned after the February shutdown will likely be restarted," OPSGROUP, which provides guidance to operators, said in a note.
Indian operators were badly affected by the shutdown. An Air India spokesman said the company would take about a week to rework its schedule and come up with a plan to operate its flights over Pakistan.
Air India suffered losses of 4.91 billion rupees ($71.6 million), India's aviation minister, Hardeep Singh Puri, told lawmakers this month.
IndiGo Airlines, India's largest by market share and controlled by Interglobe Aviation Ltd, incurred a loss of 251 million rupees due to the closure of the Pakistani airspace, while Spicejet Ltd incurred losses of 307.3 million rupees, Puri said.
An IndiGo spokeswoman said that IndiGo flights flying via Pakistan "will operate as normal after all regulatory clearances by the concerned authorities".
Representatives of Spicejet did not respond to calls and messages seeking comment.
Pakistan's announcement came hours after United Airlines Holdings Inc said it was extending the suspension of its flights from the United States to Delhi and Mumbai in India until October 26, citing the continued Pakistani restriction.
The dropping of the restriction will allow Pakistan, which this month agreed the terms of a $6 billion bailout from the International Monetary Fund, to collect overflight fees.