IndiGo taught me a full plane isn't enough

every time i get on a flight i notice the same thing. the plane is full. people are hunting for overhead-bin space, someone is arguing about a seat, and eventually everybody sits down. it feels like a great business, sell a lot of seats, fly the plane, collect money. then i started looking at airline economics, and it’s a good deal less comfortable.

the seat disappears

an airline has a strange problem. if a shirt doesn’t sell today, you can sell it tomorrow. if a hotel room is empty tonight, you sell it another night. but if an aircraft takes off with an empty seat, that seat is gone forever. that’s what makes airline capacity so unforgiving.

IndiGo carried 118.6 million passengers in FY2025, about 11% more than the year before, and its capacity grew 13.1%. the two moved almost in step, and that’s the whole trick with an airline. you have to add the seats and fill them at the same time, because the empty ones still cost you.

planes are expensive even when they’re doing nothing

fuel, aircraft leases, maintenance, pilots, airport fees, ground operations, a lot of these costs don’t politely disappear because demand is weak. that’s why load factor matters so much. IndiGo kept an FY2025 load factor of 86.0%, so the planes were genuinely full. revenue from operations grew to ₹80,803 crore, and yet net profit still fell from ₹8,173 crore to ₹7,258 crore. the numbers make something obvious: a company can fly full planes, grow its top line, and still have a harder year on profit.

growth is only useful when the economics grow with it.

growth has a cost

this is something i keep coming back to. we treat growth as automatically good, more stores, more planes, more customers. but every extra unit of capacity comes with a bill, and the real question is whether that capacity earns enough to justify it. that’s why i find airlines so interesting. they make it painfully clear how much fixed costs can hurt. when things go well, the machine is beautiful. when they don’t, you’re reminded the machine still needs fuel, salaries, maintenance, and a place to park.