Closure of Pakistan's airspace is forcing international airlines to take costly and time-consuming detours. (Photo: Reuters)

Pakistan continues to restrict its airspace after an airstrike in late February by the Indian Air Force in Balakot in northern Pakistan. The disruption is forcing international airlines to take costly and time-consuming detours to the north and south, adding flight time for passengers and fuel costs for airlines.

Hundreds of commercial and cargo flights are affected each day. Reuters counted 311 such flights between four airports in Europe and four in Southeast Asia.

Pakistan lies in the middle of a vital aviation corridor. In the week before the air space was closed, almost all the flights analysed passed directly over Pakistan, some coming extremely close the Kashmir region - the epicentre of tensions with India - including aircraft operated by Singapore Airlines, British Airways, Lufthansa and Thai Airways, according to flight tracking service FlightRadar24. Routes that run through Pakistan on a north-south axis are not affected.

OPSGROUP, which monitors international flight operations, used International Civil Aviation Organisation data to calculate that the closed airspace was affecting as many as 350 flights daily. Most rerouted as far south as Oman's airspace, the group said.

Flight information regions (FIR) are how airspace is divided up for control. Pakistan has two: Karachi and Lahore. They, and the Kabul FIR, have seen a notable drop in air traffic since the conflict. Muscat, however, has seen an increase.

Day of the closure

On the day Pakistan closed its airspace, some flights turned back or diverted to other destinations, according to data from FlightRadar24.

Later that day, a large hole emerged in aviation traffic over Pakistan. Where hundreds of aircraft used to fly, the sky was now empty. Instead, a build-up of aircraft could be seen farther south.

Flights between Europe and Southeast Asia are still suffering from the disruption. The group of 311 flights that Reuters analysed has taken different routes to avoid Pakistan, according to FlightRadar24.

OPSGROUP calculates that routing south to Oman, passing through the Muscat flight information region, adds about 280 miles (451 kilometres) to a flight from London to Singapore and 410 miles from Paris to Bangkok.

Lengthy delays

Reuters analysed flight time data from FlightRadar24 for several routes from Europe to Southeast Asia. For each individual route, 14 flights prior to Feb. 27, the day air space was closed, were compared to 14 recent flights prior to April 9.

Some flights are consistently delayed. KLM, Lufthansa and Thai Airways flights are taking up to two hours longer than before the air space was closed.

Flights from London to Singapore are also affected, but not as severely. Flights can take up to an hour longer compared with the same route before the conflict.

"We continue to operate all our flights. Like all airlines flying to and from Asia, we are rerouting around Pakistani airspace, and this will lead to minor delays for a handful of flights," a British Airways representative told Reuters.

KLM said it was restricting aircraft weight and adjusting fuel loads to compensate for longer routes.

However, flights from Southeast Asia to Europe seemed to avoid notable delays. According to Singapore Airlines, that is mostly thanks to tailwinds.

"We face less headwinds on the way up to Europe (compared with the route that goes through Pakistani airspace) while we catch less tailwinds when coming back to Singapore," a representative said, adding that the airline had imposed no weight restrictions.

"That said, the difference in flight time will narrow as we gradually move into the summer season."

India also badly affected

Previously, flights from Delhi would cross directly into Pakistan if travelling to Europe. Now, they must go south of Pakistan before returning to their pre-conflict routes.

Reuters mapped all 34 flights between Delhi and Amsterdam in both directions, from February 19-26 and April 3-9, using data from Flightradar24.

According to Reuters calculations of the 34 flights, their southerly detour adds an average of 913 km when compared with the flights from April, a 22 per cent increase.

The flights in April also took up to two hours longer when compared with before the airspace was closed.

Air India said about 21 flights a day were affected, including routes to the Middle East, Europe and the United States. Rerouting, which could include stops for fuel and crew changes, add one to three hours to flights to Europe and the United States, the airline said, and to save weight, passengers are not allowed as much baggage.

An airline spokesman noted that even leaving fuel costs aside, longer flights meant aircraft could not be used to generate revenue elsewhere.

David Mumford of OPSGROUP said aircraft traveling from Delhi to Moscow or London were examples of this impact.

"Those are quite hefty re-routes to avoid Pakistan's airspace - and those are just two examples of hundreds of flights each week which have to do something similar," he said in an email.

Uncertainty prevails

It is unclear when or whether Pakistan will remove restrictions from its airspace, although a senior Civil Aviation official told Reuters that "these routes will remain closed until the elections in India are over."

But with fuel the single biggest cost for airlines, rerouting is potentially hurting their bottom lines.

"With these restrictions having been in place since the end of February, I would certainly expect the extra fuel cost overall to be well into the millions by now," Mumford said.

"We don't see any of the main restrictions ending any time soon."

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