Thailand regains second place in Southeast Asian air capacity with 6.6 million September seats

Thailand is once again Southeast Asia's second-largest aviation market by scheduled seats. September 2026 data from OAG, the UK-based aviation analytics company, shows 6.62 million seats scheduled to depart Thai airports this month, 0.2% fewer than in September 2025. Vietnam sits just behind at 6.36 million seats, and Indonesia remains the region's largest market with 10.83 million seats.

The margin is thin. Vietnam had moved ahead of Thailand in July and stayed there in August, when it scheduled 7.27 million seats against Thailand's 7.19 million. This month the gap has flipped back in Thailand's favour by roughly 260,000 seats, even though Vietnam's capacity is growing much faster: up 9.2% year on year, compared with a small decline for Thailand.

Across the region as a whole, airlines have scheduled 48.0 million seats for September, 2.0% more than a year earlier. Domestic capacity grew 3.5% to 21.5 million seats, while international capacity edged up 0.7% to 26.5 million. OAG counts 178 airlines operating scheduled services at 299 Southeast Asian airports this month.

The picture inside Thailand is uneven. Bangkok Suvarnabhumi is the fourth-busiest airport in the region with 3.01 million seats, up 2.1% on last September. Don Mueang, Bangkok's second airport and the main base for low-cost carriers, has 1.40 million seats, down 6.8%, or about 101,200 fewer seats than a year ago. Much of that drop traces back to Thai AirAsia, which has cut its scheduled capacity by 24.8% and fallen out of OAG's regional top ten to twelfth place. The airline reduced services earlier in the year as fuel costs rose, and has said it plans to scale back up from October for the high season.

That shift is part of a wider regional trend. Low-cost carriers as a group cut capacity by 3.3% to 21.1 million seats, taking their share of the market from 46% to 44%. Full-service airlines grew 6.4% to 26.9 million seats. Capacity between Southeast Asia and the Middle East also fell 3.8%, which matters for Thailand because Gulf hubs are a common routing for visitors from Europe.

For travellers, the September numbers describe the calm before the high season. The monsoon months typically bring fewer flights and lower fares, and this year's slight dip in Thai capacity fits that pattern. Airlines are already adding winter schedules: Thai Airways will operate 66 routes from 25 October to 27 March, with more frequencies from Europe, and Thai AirAsia has announced extra domestic flights to Phuket, Krabi and Chiang Mai from October. Seat supply, in other words, should rise again just as demand does.

Fewer seats in the shoulder season is one more reason to plan the ground part of a trip early. Booking a scooter or a car before arrival takes a variable out of the equation at a time when flight prices and schedules are still moving. Balm Rentals is built for exactly that step: it brings vetted, licensed rental operators together in one marketplace, shows the price, deposit and rental conditions in full before payment, and presents everything in the traveller's own language through its iOS and Android apps and the web. Tourists get a clear picture of what they are paying for, and local rental businesses get customers who arrive knowing the terms.

Thailand's return to second place in the region is a modest but welcome signal. Capacity is broadly stable, Suvarnabhumi is growing, and the airlines that trimmed schedules over the summer are preparing to restore them. The next OAG monthly briefings, for October and November, will show how quickly that recovery in seats arrives ahead of Thailand's busiest travel months.