There are few sights more comforting to a weary traveller than boarding a flight to find the seat next to them empty.
And while it can't be guaranteed, a search of data collected by the federal department of infrastructure reveals the flights where travellers are most likely to be able to stretch out.
Qatar Airways' daily flight from Canberra to Sydney, en route to Doha, is the emptiest flight in Australia, with only 15 per cent of seats filled in September, the figures from the Bureau of Infrastructure, Transport and Regional Economics show.
That means only about 50 people boarded the 358-seat Boeing 777 in Canberra for the 50-minute hop to Sydney.
More passengers board Qatar's flights in Sydney before making the journey to Doha - which has infuriated Qantas, accusing the Middle Eastern carrier of using Canberra as a back door to getting more access to the lucrative Sydney market.
The second emptiest flights in September were Chinese carrier Donghai's flights between Shenzhen and Darwin, which launched in May this year.
Only 35 per cent of seats were full on Donghai's Boeing 737s during their twice-weekly return service.
Following that, two Virgin Australia flights from Brisbane to the Pacific have the most room to stretch out.
Virgin's five-times a week return service to Port Moresby, in Papua New Guinea, was 38 per cent full on average, while its twice-weekly return flights to the Solomon Islands' capital Honiara were 39 per cent full.
Hong Kong Airlines' flights to the Gold Coast, via Cairns, were 46 per cent full in September. The airline, owned by major Virgin shareholder HNA, scrapped that route at the end of October.
Data from the Bureau of Infrastructure, Transport and Regional Economics does not break down domestic flight data by airline, but does show the load factors on each city pair.
Flights from Perth to the West Australian city of Geraldton, serviced by both Qantas and Virgin Australia, were only half (51 per cent) full in September, followed by Alice Springs to Darwin (54 per cent), Adelaide to Port Lincoln (55 per cent), Perth to Newman (59 per cent) and Cairns to Townsville (61 per cent).
The most cramped journeys were between Melbourne and the Gold Coast (90 per cent full), Melbourne and Cairns (89 per cent), Launceston and Sydney (87 per cent), Adelaide and the Gold Coast (87 per cent), and Brisbane and Perth (86 per cent).
Peter Harbison, executive chairman of industry analysis group CAPA Centre for Aviation, said gone were the days when airlines could afford to fly half empty planes.
“Ideally you’d have every seat filled on every flight. An empty seat means a revenue opportunity lost - and that’s only exacerbated by the sale of ancillary products [like food or baggage allowances] these days," he said.
Mr Harbison said most budget airlines operating on competitive routes aimed for load factors in the high 80s to low 90s in order for them to be profitable.
But full-service airlines could get away with lower loads as long as their more expensive business and premium seats were full.
“So you can’t just look at load factors," he said.