Do I need to panic about Qantas’ plane range?

Q I know you’ve flown on the Qantas flight from London to Perth, a distance of 9,009 miles. I went online to get more information about the aircraft used, the Boeing 787-9, and was surprised to see that according to Boeing’s published technical specification the maximum range is 8,786 miles. How does that work?

Roger B

A Passengers aboard Qantas’s daily Heathrow-Perth service have no need to panic. The Boeing 787-9 “Dreamliner” can comfortably and safely cover the ground between the UK’s biggest airport and the Western Australian capital.

The distances that planemakers cite as maximum ranges are generally conservative. They typically assume a cabin configured to carry a large number of passengers, and a full belly of cargo. Airlines can stretch the range simply by limiting the number of passengers and the amount of freight.

As long ago as 1989, a jumbo jet flew from Heathrow to Sydney on a delivery flight – a distance of over 10,500 miles, on a plane really designed for routes of no more than 7,000. But the Boeing 747 had no passengers or cargo on board, which is not a healthy long-term business model.

The Boeing figure for the 787-9 assumes 290 passengers in two classes; Qantas has gone for 236 seats in three cabins. In its own publicity, the Australian airline states the maximum range with a full payload to be 9,008 miles – bizarrely one mile less than the distance between London and Perth.

Happily, this figure, too, is a big understatement. Any flight between two points flies further than shortest distance between them. Planners and pilots will seek to take maximum advantage of wind patterns. Add in air-traffic commands, geopolitical restrictions and even fees for overflying particular countries, and a five or 10 per cent increase over the point-to-point distance is no surprise.

Even at the end of a journey across a large slice of the globe, the aircraft will touch down with a healthy allowance of fuel remaining – more than enough to get to an alternative airport, hold for a while, and then make a missed approach before landing safely.

Every day our travel correspondent Simon Calder tackles a reader’s question. Just email yours to s@hols.tv or tweet @simoncalder