This is the longest non-stop flight in the world, lasting 20 hours. As you relax in your armchair, decide if you want to drink the finest Champagne, have a delicious meal prepared by a chef with a travel companion, or ask the crew to make you a luxuriously soft bed using fresh linens.

This is what Qantas’ Project Sunrise direct flights from London to Sydney starting in three years’ time will offer the first-class passengers. They can expect to pay at least five figures.

What about the 140 passengers in economy who will be seated behind the 12 Airbus A350-1000s ordered by the airline to provide the service?

Qantas isn’t telling. A spokesperson for Qantas told us that although we don’t have any updates right now, they are eager to share them with you.

However, we do know that Qantas has a Wellbeing Zone planned. This will be located around the galley kitchens and allow you to stretch, do yoga poses or just sit around for a while.

Qantas will make every effort to provide a wide range of TV and movies for passengers on long flights.

It’s possible, however.

CNN’s Ian Petchenik, host and moderator of AvTalk aviation podcast, says that while a lot has been made of Qantas first class for Project Sunrise (Qantas Qantas), I believe the true difference for passengers at the back of the aircraft will be the soft product.

You can only improve nine-abreast economy seats so it is up to Qantas to find ways to make a 20 hour flight in one of these seats more appealing.

As a specialist aviation journalist, I have spent more than 10 years talking with people from airlines, plane manufacturers, designers, seatmakers, and other industry professionals to find out how each inch of the plane is being used. Since Qantas doesn’t speak, here are my professional conclusions about what might be available on board.

First, it is unlikely that anything revolutionary will happen. Three years from now is not a long time for aviation, particularly when it comes down to seats. It seems unlikely that Qantas will be revealing a large bunk — which would require a lot of safety certification work — but economy passengers will remain in regular seats.

Knees and shins

Comfort levels in economy-class seats are largely determined by the style of the seat, pitch, and width.

Qantas will be able to purchase the best economy class seats from top engineering and design firms like Collins Aerospace or Recaro.

These seats are known as fully featured, and feature a comfortable cushioned foam seat, covered with special fabrics, and a large headrest. Qantas also offers a small foot hammock.

Engineers and designers have been working hard to improve the backs of plane seats and the bases so that the passenger behind has enough room, especially for their knees.

They have figured out how to make a cushioned bottom of the chair (known as the seat pan), move when it is reclined. This changes the pressure points on the body as they lean back.

Qantas’ Boeing 787-9 Dreamliners was launched in 2016 using a modified version of the CL3710 seat by German manufacturer Recaro.

The CL3710 was first released in 2013. Recaro has made updates every year since then, but it would not be surprising if they were working on a special version to suit Qantas.

Recaro, or another company might make a new seat with more comfort. This could be available for Qantas to fly in the latter part of 2025.

Extra legroom

Pitch is the second factor that affects comfort. It measures the distance between the points on one and the next seat. This means it doesn’t measure total legroom as it also includes an inch or so of seatback structure.

Qantas promises that its economy class seats will have 33 inches (84 cm) pitch.

This is one inch more than the Dreamliner 2016 seats. I would expect that the seat engineering will have reduced the structure of the seat by as much as an inch by 2025 to provide more knee space.

It would not be surprising if Qantas also offered extra-legroom sections. These might extend to 35 or 36 inches along with Delta’s Comfort Plus and United’s Economy Plus.

How about width?

Depending on the number of seats Qantas places in each row, there will be either good news or bad news for passengers.

The twin-aisle big plane can hold either nine seats per row (which has been the standard for full-service airlines such as Qantas, Delta, and Singapore Airlines) or 10 seats per row. This has largely been on ultra-low-cost leisure carriers like Air Caraibes of France and French Bee.

The A350 has nine seats across, making it one of the most comfortable economy classes in the air. It’s also one of the most uncomfortable, with its narrow aisles and seats barely touching 17 inches at 10 across.

It is possible to imagine, and Qantas’ published cutaway clearly shows that a full-service airline such as Australia’s flag carrier would opt for the nine-across configuration.

Airbus is working quietly to make a little more space by reducing the cabin sidewalls. Some full-service airlines, such as Abu Dhabi-based Etihad have begun to plan to add 10-across seating to their future A350s.

Nonstop vs. stopover

Qantas claims that it will install 140 economy seats on its A350. This would mean that there are 14 rows of 10 seats, but the number doesn’t split into nine neatly, no matter how many extra seats you add on either the sides or the middle.

Even though it would be very surprising for Qantas to do this, especially on these long flights, The airline did install seats nearly as narrow on Dreamliner seats, which fly nonstop London to Perth for almost the same length. Keep an eye out for more details.

Economy class comfort is all about every inch. Many passengers, including me, cringe at the thought of a flight lasting 20 hours or more. This is even true for business class.

It was almost the same time I did something in business class on Singapore Airlines’ nonstop flight from Newark to Singapore a decade ago. But it wasn’t very fun, even with the possibility to go from movie to sleep and back again.

When we are discussing this topic, people always mention the other option: a halfway point between New York and Sydney in Los Angeles or San Francisco or any of the dozen top-tier airports in Asia that lie between Sydney or London.

People have always groaned at having to spend longer in a seat, first at the idea that a Kangaroo Route flight would be a one-stop flight, then at the idea that a flight could last 12, 14 or 16 hours.

There were many flights that were longer than this before the pandemic. They had regular economy seats at the back and people seemed to be happy to sit in them.

It is important to ask passengers how much the extra time over the London-Perth Qantas Dreamliner flight will make a difference to their lives and their perceptions.