Thailand's main airports are bursting at the seams ahead of Songkran, but the lack of additional flight slots has helped avert further gridlock.
According to Airports of Thailand Plc, this year's Songkran traffic passing through the six airports under AoT's supervision, including gateway Suvarnabhumi, will be heavier than last year's.
Passenger traffic is expected to jump 12.1% to 5.36 million during April 5-18, or 383,188 per day.
Aircraft movements, defined as take-offs and landings, are rising in parallel by 7.2% over the same period last year to total 32,357, or 2,312 a day.
The growth in passenger and aircraft throughput would be much higher if not constrained by critical airport slot limitations.
Most airlines were turned away when adding more flights to serve robust travel demand in one of Thailand's peak travel periods.
Chinese airlines were particularly eager to have more flights to Thailand to ferry Chinese tourists to popular destinations such as Bangkok, Chiang Mai and Phuket, during the Thai New Year celebrations, but were denied.
Thai airlines managed to get a marginal increase.
Low-cost carrier Thai AirAsia was allowed to increase its Bangkok-Chiang Rai frequency from five flights a day to six and Bangkok-Hat Yai from nine a day to 10, during April 11-18.
TAA's own aircraft capacity limitation is another factor restricting its Songkran flight increase, according to TAA executives.
No-frills Thai Lion Air is only given permission to raise its Bangkok-Khon Kaen services from five flights a day to six, and Bangkok-Ubon Ratchathani from two a day to three, during April 13-16.
Khon Kaen and Ubon Ratchathani are smaller airports operated by the Airports Department, a state agency, while the larger ones are run by AoT.
Bangkok's Suvarnabhumi and Don Mueang, Phuket and Chiang Mai, already operate beyond their capacities.
The partial closure of one of the two runways at Suvarnabhumi for resurfacing and the B1 taxiway repair, from March 3 to May 2, also restricts traffic handling.
Average daily passenger traffic and aircraft movements at AoT-operated airports during Songkran are projected as follows, based on bookings by airlines:
Suvarnabhumi: Passengers up 14.3% to 184,000; aircraft movements up 5% to 972.
Don Mueang: Passengers up 7.2% to 104,700; aircraft movements up 5.1% to 698.
Phuket: Passengers up 9.3% to 46,200; aircraft movements up 11.2% to 293.
Chiang Mai: Passengers up 16.7% to 27,900; aircraft movements up 12.9% to 208.
Hat Yai: Passengers up 16.8% to 13,000; aircraft movements up 19.7% to 90.
Chiang Rai: Passengers up 24.1% to 7,200; aircraft movement up 16.7% to 51.