Finding a flight is getting easier and easier thanks to specialized search engines. But too few consider ecotourism. So, making an eco-friendly choice of a plane ticket, including the carbon footprint of flights quickly becomes complex. A real nightmare.
Indeed, multiple parameters impact the carbon footprint. Some on which you have control : the path (its distance) and the number of flight legs. Others are unsure. The type of aircraft for example, can change until the last moment on the airline freewill. Then some are completely unknown or very opaque, such as the number of passangers who will take the same flight, airlines rules to spare fuel, the risk to have an airport closed…
At the end, it is impossible to know which will be the best flight. Nevertheless I say that we must do our best to reduce our impact.
The path
Reduce number of take offs
ICAO provides a very useful CO2 emissions simulator. We get from it that a lot of emissions occur during the climb phase. The FlightConnections website shows the available flights from an airport.
Let’s take the example of a flight from France to Australia. While there is unfortunately no direct flight between, there is one between London and Perth. It is one of the longest in the world. Given the distance, only recent very long-haul aircraft make this journey. They are fuel efficient: 997kg of CO2 is produced for a passenger’s round trip. A good choice for an eco-friendly plane ticket. I would still have to go to London, which raises the CO2 total to 1210kg.
However I had to resign to abandoning the option of direct flight because Perth is in the West and I have to start from the East.
For that, I can land in Sydney or Brisbane. I almost got fooled: Quantas plans to make a direct flight between London and Sydney, using A350-1000s. But it won’t happen until 2025. And if some companies sell other ‘direct’ flights, it is actually A380 flights that make a refueling stop en route. No interest!
Decrease flight distance
So I thought about starting from a closer international airport, planning to reach it by train. By comparing the departures from Barcelona and Paris, I found out that the type of aircraft but also its passenger load factor influences consumption. The planes departing from Barcelona stop in Dubai and are less crowded than those departing from Paris with a stop in Singapore. Paris therefore has the advantage: it generates 1468kg of CO2 for the round trip of a passenger in Brisbane.
Logic dictates that the journey that requires the least energy is the shortest. So I spotted the stopover airports half way, and nearest to a Paris-Brisbane straigtht line. Hong Kong, in blue, Taiwan, in pink, Seoul, in Yellow and Singapore, in white, are interesting international airports. I immediately dismissed Taiwan because the current geopolitical problems with China which make me fear disruptions.
The choice of aircraft
The consumption of an aircraft varies with its engines and model. Here we look at long-haul aircrafts. The A350-900 and 787 are preferred to the A380 and 777 when I write this. The type of aircraft listed in the plane ticket is a approximative data in an eco-friendly choice because the company can replace it at any time, whether to repair it or to modernize its fleet.
Intuitively, the heavier an aircraft, the more it consumes. The greater the distance, the more fuel weight must be added, thus consuming more. But at the same time, going further means spending more time in the cruise phase, which consumes less than the climb phase. The study shows that these two factors compensate each other over a range characteristic of each type of aircraft. The airlines are attentive to this optimal range and this parameter is therefore not important when choosing a ticket.
Eco-friendly airlines
Each company has its priorities. The lowest costs for, well, low costs, added comfort for those in the Middle East. Searching Kayak’s results for my trip, Air India, Cathay Pacific, KML and ANA would have a much better carbon footprint, followed by Singapore Airline, Vietnam Airline and BAW. I have limited trust in those results though, because I noticed that a longer three legs trip can be rated way more efficient than one with two legs and newer aircrafts (see below).
For sure, flights full of passengers will waste less CO2 than flights that are half full. It is not possible to know in advance how many passengers will book on a given flight, but the extra leg room that some companies provide, like in the Middle East, decreases the number of passangers in a plane, thus polluting more per passenger (see Appendix A).
I noticed that the flights which produce the less CO2 are often arriving late in the day. The number of planes taxiing at arrival could also have an impact?
