Mumbai airport’s planned reduction of 265 weekly international departures from October 25 is more than a temporary airline scheduling change. It is the first major operational consequence of a complex airport transition in which an ageing terminal is being redeveloped, domestic traffic is being redistributed and the city’s aviation system is being asked to absorb new capacity before all stakeholders agree on how that capacity should be used.
The immediate trigger is the planned redevelopment of the northern section of Terminal 1B at Chhatrapati Shivaji Maharaj International Airport. The section handles around five million passengers annually and is due to be demolished and reconstructed. Instead of closing Terminal 1 all at once, the transition is expected to take place in phases, with one-third of the flights shifting initially, another third later and the full movement expected by January 2027.
That phased plan is forcing Mumbai International Airport Ltd (MIAL), the Adani Group-owned airport operator, to make room at Terminal 2 for domestic operations currently handled at the Santacruz-based Terminal 1. According to the report, MIAL has told nearly 46 airlines that international departure slots at T2 will be reduced by about 33 per cent. Of the 770 weekly international departure slots currently available at the terminal, 265 will be temporarily discontinued.
The scale of the reduction is significant because it affects both Indian and foreign carriers. IndiGo is expected to lose 74 weekly international flights, followed by Air India with 33, Akasa Air with 11, Air India Express with seven and SpiceJet with five. Emirates and Etihad Airways are expected to face reductions of 10 weekly departures each. Airlines have been given an October 6 deadline to identify the slots they are willing to surrender. If they do not do so, MIAL will determine which slots are withdrawn based on operational capacity and other considerations, according to sources cited in the report.
This deadline reveals the central administrative problem: Mumbai airport is not merely changing a timetable; it is temporarily reallocating scarce airport capacity among competing uses. Slots are tied to airline schedules, passenger demand, aircraft utilisation and international connectivity. A reduction at T2 is therefore likely to affect flight frequencies, departure times and, in some cases, the availability of direct international services from Mumbai. The precise schedule impact will depend on how airlines respond and how the airport operator implements the reductions.
The redevelopment also illustrates the limitations of treating airport terminals as separate buildings rather than as parts of one operating system. T1 and T2 serve different traffic patterns, but their operations are connected through aircraft movements, passenger processing, ground handling, maintenance, catering, cargo and surface access. When one terminal loses capacity, the pressure does not remain confined to that building. It is transferred to another terminal or another airport.
Under the reported plan, five million passengers from T1 are expected to be temporarily redistributed to Navi Mumbai International Airport. The remaining two-thirds, or around 10 million passengers, will continue to use T1 during the phased transition. T1 currently operates nearly 950 flights daily. These figures indicate why the change cannot be managed as a simple closure-and-reopening exercise: the airport system must continue serving existing traffic while one part of its infrastructure is taken out of service.
The choice facing airlines is consequently broader than whether to accept a new departure airport. Moving operations to Navi Mumbai can affect passenger access, crew logistics, aircraft maintenance, ground handling, catering, cargo movements and connections between flights. The report says MIAL earlier asked airlines operating from T1 either to shift operations to NMIA or temporarily suspend services from October 25. It also said the redevelopment had been deferred because alternative operating facilities were not available.
That history is important because it shows the institutional sequencing challenge. Redevelopment requires a terminal to be taken out of service, but traffic cannot simply disappear while construction takes place. An alternative airport must be operationally ready, airlines must be able to move aircraft and staff, and passengers must be able to reach the new facility. If those conditions are not aligned, the burden of transition moves from the airport operator to airlines and passengers.
The disagreement between MIAL and airlines centres on who should absorb that burden and how much flexibility should be available. MIAL has assured airlines that their historic slot rights will be restored once the new terminal becomes operational. That assurance addresses the long-term position of carriers, but it does not remove the short-term concerns created by reduced international capacity and a possible transfer of domestic operations to NMIA.
The International Air Transport Association has opposed what it described as the “forced” relocation of operations to NMIA in a letter to the Civil Aviation Ministry, according to the report. IATA argued that any transfer should be voluntary and based on airlines’ commercial and operational requirements. It also sought a transparent capacity assessment, advance consultation with airlines and clarity on how existing airport slots would be treated during the transition.
The objections raised by airlines and industry bodies focus on operational readiness rather than only airport location. IATA cited concerns about ground handling, aircraft maintenance approvals, catering, cargo facilities, crew accommodation and connectivity at NMIA. These are the less visible systems that determine whether a new airport can support reliable operations. A terminal may be physically complete while the wider aviation ecosystem around it is still being assembled.
The experience of cargo operations adds another layer to the dispute. International logistics carrier Challenge Group announced a temporary suspension of its Mumbai operations, citing the inability of the current NMIA operating setup to provide the reliability and certainty required for its cargo services. Air France-KLM has also opposed splitting its long-haul operations between the two airports, citing operational constraints. Cargo and long-haul services are particularly sensitive to predictable handling, aircraft servicing and network coordination, making them an important test of the transition plan.
For passengers, the effect will be experienced through altered flight frequencies, changed departure airports and potentially longer journeys to NMIA. The impact will not be uniform. A passenger whose flight remains at T2 may experience a different schedule, while one whose domestic service moves from T1 to NMIA may face a longer surface journey. International travellers affected by reduced departures could also have fewer timing options or need to alter their travel plans, depending on how airlines restructure schedules.
The transition therefore places surface connectivity at the centre of an airport redevelopment that is often described mainly in terms of terminals and runways. The report does not provide a detailed assessment of travel times or transport links to NMIA, but the concern raised by airlines and the possibility of longer passenger journeys show that airport capacity is not only a question of how many flights a terminal can handle. It is also a question of how easily people, staff, aircraft and goods can reach and move through the airport system.
The funding and institutional structure is also divided across several actors. MIAL is responsible for operating Mumbai’s airport terminals and managing the immediate slot and capacity transition. Airlines must determine how to adjust their schedules and operations. The Civil Aviation Ministry is the recipient of IATA’s concerns and has a role in the broader regulatory environment. NMIA must demonstrate that its operating facilities can support the traffic it is expected to receive. The redevelopment itself has a long-term commissioning target of 2029-30 for the new T1.
This division of responsibility explains why the October 6 deadline matters. It is the next operational milestone before the October 25 changes take effect. If airlines identify the international slots they are willing to surrender, the process will at least reflect their own scheduling choices. If they do not, the airport operator will allocate the reductions based on capacity and operational considerations, according to the report. That difference could shape both the immediate schedule and the level of resistance from carriers.
The numbers also show the tension between short-term constraint and long-term expansion. MIAL is preparing to temporarily remove 265 of 770 weekly international departure slots at T2 while creating space for domestic flights displaced from T1. At the same time, five million passengers are expected to be moved temporarily to NMIA, while around 10 million continue through T1. The new T1 is not expected to be commissioned until 2029-30, which means the airport network will have to manage the transition over several years rather than through a brief construction shutdown.
What remains uncertain is how the airlines will distribute the cuts, which services will move, how many operations will shift to NMIA and whether concerns over readiness will be resolved before the deadlines. The supplied report establishes the broad plan and the positions of the main stakeholders, but not the final airline-by-airline schedule or a completed independent capacity assessment of NMIA.
Mumbai’s airport redevelopment is thus becoming a test of whether infrastructure expansion can be coordinated across terminals, airports, airlines and passenger networks. The immediate milestones are clear: airlines must respond by October 6, the international slot reductions are planned from October 25, the phased movement from T1 is expected to be completed by January 2027, and the rebuilt T1 is targeted for commissioning in 2029-30. How those milestones are managed will determine whether the transition remains a controlled redistribution of traffic or develops into a prolonged disruption for Mumbai’s passengers and aviation economy.
