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Have you ever wondered what is the maximum distance an aircraft can fly? The most obvious answer is of course "as far as its fuel reserves will take it". That's certainly the case - but what are the factors that determine an aircraft's flight range?

It's obvious that the more kerosene in the fuel tanks, the greater the distance travelled... but here's another factor to consider: the weight and load of the aircraft. Depending on its configuration, the number of seats, the maximum number of passengers on board, their luggage, the weight of the catering supplies on board - All this will determine the maximum distance and for how long the plane might be flying.

And here's another constraint: the maximium take-off weight (MTOW). An aircraft cannot be loaded to the brim without any sort of criteria: it wouldn't lift off the ground, nor could perform a safely emergency braking manoeuvre during take-off without skidding off the runway.

Don't forget that for lifting-off an aircraft, “lift” needs to be generated on its wings; these are the fundamentals of aerodynamics. Therefore, its MTOW will be the maximum weight allowed by the manufacturer to take off in safety conditions: a balance of  100-percent payload and 100-percent fuel, added to the aircraft's weight completely empty. And considering this MTOW, the airline decides whether to add more passengers and cargo but less fuel, and fly shorter ranges; or whether to supply the aircraft with the maximum fuel capacity, reducing the volume of cargo and passengers and flying longer ranges. Roughly speaking.

There are many other external factors that influence the flight performance of an aircraft, such as weather, air friction and wind streams, among others, and every airline designs its commercial routes with these factors in mind. And even with margin enough to keep aircraft in the air for an extra time, should the phenomenon known as "traffic" may occur. In this case, aircraft would have to queue and wait for their turn to land by circling around the airport of destination. This “air congestion” is more common at extremely busy airports.

The development of more efficient engines has been key to achieving greater ranges - let's not forget that before jet aviation, turboprops flying to international destinations had to stop at intermediate airports to refuel!

Technology has been also driven to lighten the weight of aircraft in structural materials and fuselage. While most commercial aircraft use aluminium and high-strength alloys containing copper, magnesium and zinc, the Airbus A350 has set a milestone by introducing carbon fibre as the primary element. This aircraft, which Iberia has recently added to its fleet, is capable of consuming 30 percent less fuel than other similar models and even reaching greater lengths.

All in all, each manufacturer establishes the maximum range distances of its aircraft. Considering Iberia's Airbus fleet, check out some of these facts:

• • An A350-900 ultra long range is capable of flying for 20 hours without refuelling a distance of 18,000 kilometres (11,185 miles), the approximate distance between Singapore and New York City.
  • The A330Neo, in its 242-tonne MTOW version, can fly approximately 12,100km (7,519 mi.), about the distance between Madrid and Jakarta. The 251-tonne MTOW version, meanwhile, would cover 13,300km (8,264 mi.), roughly the distance between Beirut and Santiago, Chile.
  • The 321 XLR, which Iberia will add to its fleet in 2023, reaches a maximum range of 8,700km (5,406 mi.) and can fly a direct Madrid-Quito route.
  • Smaller aircraft such as the A321 and A320 have no range for direct intercontinental flights, and are operated for short- and medium-haul.

Prototypes of 100-percent electric aircraft are currently being developed, but they are barely competitive with the distance ranges and passenger capacity offered by the major manufacturers. So far, the most ambitious might be the Swedish manufacturer Heart Aviation, which in 2026 will start flying the ES-19 model, an all-electric aircraft with a 19-passenger capacity and a maximum range of just 400km (249 mi.).

Other plausible solutions currently being developed as alternatives to kerosene are hydrogen fuels. The issue with hydrogen fuels is that they require larger tanks to cover the same distances as fossil fuels, thus reducing cargo and passenger volume.

We're currently at a very interesting moment in the history of aviation, as very soon we will see supersonic airliners again. But this time based on sustainable fuels and zero net carbon emissions, with the commercialisation of the US manufacturer Boom Supersonic's "Overture" by 2029. Then perhaps we will no longer wonder so much about "how far can a plane fly" on intercontinental routes, and the main concern will become "how long will it take to get there"?

by Jorge de Luis Sierra, aircraft interior design/aviation branding specialist