Explainer28 SEP 20265 min readDromopedia editors

Thin air

Above 4,000 m an airliner needs a longer runway, a lighter load and, in some cabins, oxygen for the passengers. A few airports live with that every day.

Lukla2
Tenzing-Hillary Airport · Simon · CC0 · Commons

The register's list of the highest airports with scheduled flights is headed by Daocheng Yading, at 4,411 m in the mountains of western Sichuan. Some airfields are higher: an Indian military landing ground in Ladakh at 4,938 m, an airstrip by a lake in the Peruvian Andes, and a helipad at Everest Base Camp at 5,295 m. No airline flies to any of them, and the list leaves them out.1 Every jet that lands at Daocheng is working in air with roughly two-thirds of the density it was designed around at sea level.

What altitude does

Thin air changes an aircraft's day in four ways at once. The FAA's pilot handbook puts the take-off first: an aircraft at altitude lifts off at the same indicated airspeed as at sea level, "but because of the reduced air density, the TAS is greater". At the same time the engines give less thrust, roughly in proportion to the density. Faster lift-off speed and slower acceleration compound, so the take-off roll grows quickly.2 Landing is the mirror image. The approach is flown at the usual indicated speed, so the wheels touch the ground faster than they would at sea level, and the brakes and tyres have more energy to absorb. A Varig captain who flew Boeing 737-300s into La Paz around 2000 described the aircraft's reaction as "very slow", with a true airspeed "higher than usual" and engines that did not respond as they do at sea level.3

That is why runways at altitude are long, and why the load is limited. China's civil aviation authority, which runs more high airports than anyone, calls any airfield at or above 2,438 m (8,000 ft) a "high plateau" airport and gives airlines a separate rulebook for it. Take-off weight there has to be worked out against obstacle clearance, tyre speed and brake energy, and a landing weight table is compulsory whether or not a limit is expected. Each aircraft type must fly a proving flight without passengers into each such airport before it can carry any.4

The cabin is the other problem. A pressurised airliner normally keeps its cabin at or below 8,000 ft, and drops the oxygen masks automatically if the cabin altitude climbs past 15,000 ft. At an airport above 13,000 ft the cabin has to be brought to the field elevation before landing, and with the standard setting the masks would fall on every arrival. In 2023 the FAA amended its design rules so that, for airports above 13,000 ft, the masks may be set to deploy up to 2,000 ft above the aircraft's maximum take-off and landing altitude instead. The agency counted five such airports in the world.5 The CAAC requires the pressurisation system of any aircraft used at a high plateau airport to be certified for it, and the oxygen supply to cover an emergency descent and the time between landing and the next take-off.4 The Varig procedure was simpler: the crew set the cabin to 12,900 ft on the way down, put on their own masks once the cabin passed 10,000 ft, and kept them on until the shutdown checklist.3

Crews are picked for these airports. A Chinese high plateau flight carries at least three pilots. The captain must be no older than 60 and have 500 hours in command on the type plus eight sectors to or from high plateau airports, three of them landings there, before commanding one.4

Daocheng Yading

DCYDaocheng Yading Airport CN · 4,411 M / 14,472 FT · RWY 4,200 M / 13,780 FT4,411 m above sea level. Runway 16/34, 4,200 × 45 m, concrete. Opened 16 September 2013.

Daocheng Yading Airport opened on 16 September 2013 with an Air China Airbus A319 from Chengdu carrying 118 passengers. It stands at 4,411 m (14,472 ft) on a plateau in Garzê Tibetan Autonomous Prefecture, and Guinness World Records lists it as the highest civilian airport in the world. It cost 1.58 billion yuan, and its terminal was designed for 280,000 passengers a year.6 The runway is 4,200 m long, which the register confirms from OurAirports.1 The airport has not filled that terminal: in 2024 it handled about 121,400 passengers and 1,579 aircraft movements, roughly a fifth fewer than the year before, according to the CAAC's annual airport statistics.7 Air China and Sichuan Airlines fly there from Chengdu and Chongqing, and both use the A319.6

BPXQamdo Bangda Airport CN · 4,334 M / 14,219 FT · RWY 4,500 M / 14,764 FT4,334 m. The world's highest airport until 2013; a 4,500 m runway replaced the 5,500 m original.

The record it took belonged to Qamdo Bangda, in eastern Tibet, at 4,334 m. Bangda's runway was for years the longest in the world at 5,500 m; the current one is 4,500 m.8 It is busier than Daocheng, with 455,000 passengers in 2024, and its story belongs with the other very long runways in Five kilometres of concrete. One detail differs by source: the Tibet regional government dates the first flight to 28 April 1995, while the register, following Wikidata, gives 1994.8

El Alto

LPBEl Alto International Airport BO · 4,071 M / 13,355 FT · RWY 4,000 M / 13,123 FTAbout 4,061 m. Runway 10/28, 4,000 m. Some 2.6 million passengers in 2023, the most of any airport this high.

La Paz's airport at El Alto is lower than the Chinese pair, at about 4,061 m (13,325 ft), but it is the only airport this high with a large flow of traffic. It handled 2,607,457 passengers in 2023.9 The register still carries a figure of 950,000 from 2008; the current number is nearly three times that.1 The field opened in 1965 as Aeropuerto John F. Kennedy and took the name El Alto in 1999.10 Boliviana de Aviación, LATAM, Avianca and EcoJet serve it with narrow-body jets.9 Its altitude cuts the payload airlines can carry, so much of Bolivia's international traffic uses Santa Cruz, in the lowlands.11

Manufacturers come to El Alto for the same reason airlines avoid it. Airbus flew an A350-1000 there in 2017 for "high and warm" tests, calling La Paz an ideal place to test high-altitude performance.12 The Varig 737s of 2000 needed the most powerful engine option and tyres rated for 225 mph, landed with flap 15 only, and rolled out on maximum reverse thrust and minimum brakes to keep the wheels cool.3 In October 2019 Bolivia's DGAC temporarily grounded Boliviana de Aviación's Boeing 737-300s at El Alto after a series of landing-gear incidents there.13

Lukla

LUATenzing-Hillary Airport NP · 2,859 M / 9,380 FT · RWY 527 M / 1,729 FT2,846 m. Runway 06/24, 527 × 20 m, with an 11.7% upslope.

Tenzing-Hillary Airport at Lukla, in Nepal, is high too, at 2,846 m by the Nepali AIP, and its turboprops feel the thin air. But what shapes flying there is the runway: 527 m long, 20 m wide and climbing 11.7% from one end to the other, so that aircraft land uphill and take off downhill.14 That is a different problem, and the subject of Uphill landings.

Sources

  1. Dromopedia register: Highest airports, open airports with scheduled service by elevation. Elevations and runway lengths come from OurAirports, passenger figures from Wikidata. Higher but without airline service: Daulat Beg Oldi Advanced Landing Ground, 16,200 ft, a military airfield according to Wikidata; Laguna Choclococha, 14,965 ft; and Mount Everest Base Camp Heliport, 17,372 ft, a heliport. Daocheng: entry data, elevation 14,472 ft, runway 4,200.1 m, 105,061 passengers in 2022. El Alto: entry data, elevation 13,355 ft against 13,325 ft in most published sources, runway 3,999.9 m, 950,000 passengers in 2008. Lukla: entry data, 9,380 ft against the AIP's 2,846 m (9,337 ft). 2 3

  2. FAA, Pilot's Handbook of Aeronautical Knowledge, chapter 11, Aircraft Performance, FAA-H-8083-25C, 2023, "Takeoff Performance": greater take-off speed and decreased thrust at altitude, the same indicated airspeed but a higher TAS, thrust varying roughly with density. In the ICAO standard atmosphere the density at 4,400 m is about 64% of that at sea level.

  3. Capt Daniel M. Lopes, Varig, "Operations into La Paz, elevation 13,325 ft", July 2000, on b737.org.uk: 737-300 with 22,000 lb engines and 225 mph tyres, cabin altitude set to 12,900 ft for runway 10, masks above 10,000 ft, flap 15 only, no rolling take-off, maximum reverse and minimum brakes. 2 3

  4. Civil Aviation Administration of China, Flight Standards Department, Advisory Circular AC-121-FS-2015-21R1, High Plateau Airport Operations, 2 November 2015 (in Chinese). §3: general plateau airports 1,524–2,438 m, high plateau airports at or above 2,438 m (8,000 ft). §4.2: pressurisation certified for high plateau operations, oxygen for emergency descent and the ground stop. §5.1: at least three pilots, captain no older than 60, 500 hours in command on type and eight sectors with three landings. §5.2: take-off weight against obstacle clearance, tyre speed and brake energy; landing analysis always required. §5.3: a proving flight without passengers for each type at each high plateau airport. 2 3

  5. FAA, High Elevation Airport Operations, final rule, Federal Register, 15 June 2023, amending 14 CFR 25.841: cabin altitude normally not above 8,000 ft, masks before the cabin exceeds 15,000 ft, and for airports above 13,000 ft a mask setting up to 2,000 ft above the maximum take-off and landing altitude; "five airports" worldwide above 13,000 ft.

  6. Ben Blanchard, "China opens world's highest civilian airport", Reuters via NBC News, 16 September 2013: 4,411 m, 1.58 billion yuan, 280,000 passengers a year, previous holder Bangda at 4,334 m. Guinness World Records, Highest airport. Daocheng Yading Airport, English Wikipedia, citing Xinhua for the inaugural Air China A319 flight with 118 passengers, the 4,200 × 45 m concrete runway, and the current Air China and Sichuan Airlines routes. 2

  7. CAAC, 2024 national civil transport airport production statistics bulletin, 14 March 2025 (in Chinese); Daocheng figures as tabulated by Huaon: 121,400 passengers (−19.5%), 1,579 movements (−22.5%).

  8. Tibet Autonomous Region government, "Qamdo Bangda Airport marks 30 years of operation", 29 April 2025 (in Chinese): first flight 28 April 1995, 4,334 m, 455,000 passengers in 2024. Qamdo Bamda Airport, English Wikipedia: opening given as 22 October 1994; the 5,500 m runway closed and 4,500 m in use. Register: entry data, opened 1994 (Wikidata), runway 4,500.1 m (OurAirports). 2

  9. El Alto International Airport, English Wikipedia: 4,061.5 m (13,325 ft), runway 10R/28L 4,000 m, 2,607,457 passengers in 2023 citing the operator's statistics, airlines. The operator's own site did not publish the figure when checked; Airmate gives 13,314 ft. 2

  10. NAABOL, Aeropuerto Internacional El Alto: inaugurated 1965 as Aeropuerto John F. Kennedy, named El Alto since 1999.

  11. SDSN Bolivia, "Economic incentives for airlines to increase the number of tourists: the case of El Alto International Airport", 17 May 2023: altitude forces airlines to operate with fewer passengers; international traffic at El Alto fell as five carriers withdrew.

  12. Airbus Latin America, "A350-1000 completes high and warm flight tests in Latin America", 8 March 2017: La Paz at 13,300 ft, "ideal locations to test high-altitude aircraft performance".

  13. Reportur, "Batacazo a BoA: suspenden sus B737 CL en El Alto", 10 October 2019 (in Spanish): DGAC suspension of BoA's eight 737-300s at El Alto from that date after landing-gear incidents. b737.org.uk, same page as above, lists a 737-500 gear collapse on 22 November 2018 and a shimmy damage event on 3 August 2019.

  14. Civil Aviation Authority of Nepal, AIP Nepal, AFIS AD 2, Tenzing-Hillary Airport, Lukla, AMDT 02/2026: elevation 2,846 m, runway 527 × 20 m, land runway 06, 11.7% upslope.

Codes, elevations and runway lengths in the airport cards are from the Dromopedia register, built from OurAirports. Each entry’s data page names the source of every field; see also About the data.