While most commercial flights are limited to durations of 8-12 hours, some planes are capable of flying for 24 hours straight or longer without stopping. The key factors that allow planes to fly for extended durations nonstop include:
Fuel capacity
The most basic requirement is having enough fuel capacity to power the engines continuously for the desired flight duration. Long range planes carry enormous amounts of fuel – for example, the Airbus A380 has a maximum fuel capacity of over 320,000 liters.
Engine reliability
Engines must be extremely reliable and rugged to operate at full power for extended durations. Modern high-bypass turbofan engines are designed for reliable continuous operation.
Crew rest facilities
Long duration flights require backup crews to take over mid-flight. Beds, bunks and full rest facilities are needed so crews can rest adequately.
Auxiliary power units
Onboard auxiliary power units (APUs) allow vital flight systems like electrics, hydraulics and air-conditioning to operate without relying on the main engines. This allows main engines to be shut down in mid-flight for maintenance checks.
Notable Extended Duration Flights
While most flights max out at 12-16 hours, some exceptional nonstop journeys have pushed the boundaries of extended flight:
Singapore Airlines Flights 21 and 22
Currently the longest scheduled nonstop commercial flights in the world, traveling between Singapore and New York. The flight duration is up to 18.5 hours covering 15,300 km with an Airbus A350-900ULR.
| Flight Number | Route | Distance | Duration |
|---|---|---|---|
| SQ21 | Singapore to Newark | 15,300 km | 18 hours 25 mins |
| SQ22 | Newark to Singapore | 15,300 km | 18 hours 45 mins |
Qantas Flight 7879
In October 2019, a Qantas Boeing 787-9 Dreamliner set the record for the world’s longest commercial flight by a passenger jet, flying nonstop from New York to Sydney. The 16,200 km journey took 19 hours and 16 minutes.
Virgin Atlantic Flight 4
In June 2019, an Airbus A350-1000 flown by Virgin Atlantic completed a flight from London Heathrow to Los Angeles lasting 17 hours and 58 minutes over 8,000 miles.
Boeing 777 World Record Flight
In 1997, a Boeing 777-200LR Worldliner set the absolute record for the longest nonstop flight by any commercial airliner, flying eastward from Seattle to Kuala Lumpur over 10,325 nmi (19,142 km) in 21 hours 23 minutes.
Aircraft Requirements for Ultra Long Haul Flights
A handful of modern widebody airliners have the capabilities required for ultra long haul flying:
Extended Range Variants
Specially modified variants of aircraft like the Airbus A350 and Boeing 777 are designed with additional fuel tanks and optimized aerodynamics for max range. Examples include the A350-900ULR and 777-200LR.
Four Engine Jets
Older generation jumbo jets like 747s and A380s have extremely high fuel capacities across 4 engines. Their range can reach 8,000-9,000 nmi without refueling.
Fuel Efficiency
New generation twin engine jets like the 787 Dreamliner and A350 have much better fuel efficiency, allowing them to stretch range and endurance. Lighter weight composites also optimize fuel burn.
Reliable High-Bypass Turbofans
Cutting edge turbofans with high bypass ratios provide the best combination of reliability and efficiency for ultra long flights. Examples include GE9X and Rolls Royce Trent engines.
Limiting Factors for Nonstop Range
While flights like Singapore Airlines 21 demonstrate the potential to fly for up to 19 hours nonstop, there are several barriers to further extending range and duration indefinitely:
Fuel Weight
The more fuel carried, the heavier the aircraft becomes and the more drag generated, consuming fuel faster. Diminishing returns limit how much extra range can be achieved by just adding more fuel volume.
Airframe Aerodynamics
There are physical limits to how streamlined and aerodynamic an airframe can be made. Beyond a point, added refinements make minimal difference.
Engine Efficiency
Theoretical limits constrain how efficient jet engines can become at turning fuel into thrust. With current technology, engines have reached over 60% efficiency.
Turbulence Effects
Atmospheric turbulence has more detrimental effects on flight efficiency on very long journeys, where cumulative small deviations add up. Turbulence avoidance and mitigation systems help but cannot fully negate effects.
Human Endurance Limits
The most restrictive barrier is human physiology. Aircrew become dangerously fatigued operating ultra long flights, even with augmented crews. 19-20 hours appears close to the limit for safe alertness.
Could 24 Hour Nonstop Flights Become Reality?
With expected technology advances, 24 hour nonstop flights could become viable by around 2040-2050:
Further Engine Efficiency Gains
With smarter turbofan designs, 70% engine efficiency could be achieved by 2050. This alone could extend current longest ranges by 2-3 hours.
Blended Wing Body Designs
Radical new airframe shapes like blended wing bodies can reduce drag substantially compared to conventional tubes and wings. NASA targets a 25% improvement in fuel burn.
Lighter Structures With Composites
Increased use of ultra light carbon fiber composites can reduce structural weight versus aluminum. This allows more payload for fuel.
Pilot Augmentation and Automation
To overcome pilot fatigue issues, aircraft systems could take on more flight management duties. Augmented reality systems may help pilots stay alert.
Inflight Crew Change Options
With augmented crews awake and resting in shifts, fresh pilots could take over mid-flight before fatigue becomes critical.
Conclusion
Current technology allows remarkable flights of up to 19 hour durations, but human endurance constraints are still likely to limit nonstop journeys to around 20 hours for the foreseeable future. With advances in aerodynamics, engines, structures and aircraft automation, 24 hour flights may become possible by the mid 21st century. However, such extreme duration flights are unlikely ever to become economically viable for regular commercial services. But ULR flights up to 20 hours nonstop will provide aviation engineers an exciting challenge to continue pushing the boundaries of range and endurance. Even longer flights become hypothetically possible by mid-century if human factors can be solved with greater automation.
