Op Sindoor effect: Kolkata ATC struggles amid soaring flight reroutes
The Statesman | 15 May 2025
The ongoing tensions between India and Pakistan, intensified by retaliatory strikes under Operation Sindoor, have now taken a heavy toll on aviation networks, with Pakistan’s official closure of its airspace to Indian aircraft on 24 April triggering widespread disruption.
The ripple effects are being felt sharply in India’s eastern aviation hub — Netaji Subhas Chandra Bose International Airport in Kolkata — where air traffic controllers (ATC) are battling a daily operational overload. According to airport sources, rerouting over 130 international flights per day, primarily those departing from north and east India, including Delhi, Amritsar, and Kolkata, through Mumbai and Ahmedabad has led to unprecedented pressure on infrastructure and personnel. Kolkata’s ATC, already managing near-peak loads, has been forced to handle traffic volumes far beyond its designated limit. The rerouting has not only increased fuel consumption and flight durations but also led to skyrocketing operational costs. Several international airlines, including Air India, are reporting significantly higher expenditures per long-haul route, with some flights now requiring mid-journey refuelling stops.
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An Air India flight from Delhi to abroad, for instance, three days ago halted in Vienna, pushing fuel consumption from 106,500 kg to 125,500 kg per flight, and increasing carbon emissions by approximately 60 metric tonnes, an Air India source said. The physical toll on flight crews is mounting, with pilots forced to manage two take-offs and landings per trip, compressing recovery times and rest cycles. Cabin crews, too, are raising concerns.
“Minimum rest windows in abroad trip, followed by extended recovery periods at home, are becoming increasingly unsustainable,” one senior flight attendant told this reporter, requesting anonymity. “Fatigue is setting in, fast.” Despite the chaos, Kolkata Airport continues to operate close to normal, owing much to the resilience of its air traffic controllers and ground staff. On a typical day in recent weeks, the airport has handled around 390 flights, close to its pre-pandemic average of 470. “On Monday, around 164 domestic flights arrived in Kolkata, carrying 25,986 passengers. Around 169 domestic flights departed, ferrying 23,891 passengers across India. Around 20 international flight arrivals brought in 2,298 passengers during the turbulent times. More or less 24 international departures carried 2,631 outbound travellers. In addition, six non-scheduled flights departed while two others landed,” said a senior official of NSCBI Airport. International connectivity from Kolkata remains robust. Flights to Dhaka are maintained by Air India, Biman Bangladesh, and US-Bangla Airlines. Services to Dubai and the UAE continue via Emirates, Flydubai, and IndiGo.
The rerouting of Europe and North America-bound flights has funnelled aircraft south, over the Arabian Sea into Oman’s Muscat airspace. The altered path has doubled travel time on some routes — a three-hour flight now takes almost six hours. Carriers like IndiGo have suspended routes to Almaty and Tashkent due to cost and duration concerns. Mumbai’s ATC has become a crucial node in this restructured network, managing an additional 130 westbound flights daily, while Ahmedabad channels another 80. Aerial congestion has become most acute between 9.30 p.m. and 11 p.m, with choke points forming along vital air corridors.
To ease the logjam, high-density routes such as L639 and L301 (airway, low-level international flight route) — originally set up during the 2019 crisis, have been reactivated. L639 now allows aircraft to traverse from Bhopal through Ahmedabad to Muscat’s ‘RASKI’ waypoint with reduced separation of just 20 nautical miles, thanks to procedural upgrades making it one of the most efficient air corridors in the Asia-Pacific region. Flights from Kolkata to Bangkok, Kuala Lumpur, Singapore, and even Hong Kong also use these routes like L639 and L301, according to ATC guidelines.
Air India is reportedly exploring a more northerly path, over Ladakh, China, and Russia. However, political tensions between India and China, especially concerning Tibet and direct overflight rights, pose serious diplomatic and operational challenges.
In the meantime, domestic routes too are feeling the squeeze, with flights from Mumbai to Nagpur, Pune, and Kolkata forced to deviate further south to avoid the aerial gridlock. What began as a strategic military retaliation has evolved into a crisis of aviation logistics. Airlines are recalibrating schedules, passengers face extended flight times, and ATCs like the one in Kolkata are stretched to their operational limits. As one senior aviation official in Kolkata put it: “It’s not just airspace that’s closed, it’s a corridor of uncertainty that’s opened. We’re doing our best to keep the skies moving.”
For now, Kolkata stands as a testament to Indian aviation’s resilience, but the pressure is building, and with no clear end to the standoff, India’s air corridors remain clouded by geopolitics and jet fuel.