While they may sound very similar, non-stop and direct flights are, in fact, not exactly the same. Indeed, while, as the name suggests, non-stop services will fly between two cities without other stops, direct flights may have them. This dates back to a time when stops on flights were much more common than they are today. However, the terminology remains the same, and is often confused.
Non-stop flights
To start with the simplest case, a non-stop flight is exactly what the name implies. It will fly between two airports, without any stops on the route. This may seem obvious, and indeed the vast majority of flights today are non-stop, even on intercontinental journeys. However, this was not the case in the early days of flying. Before the advent of jet aircraft in the 1950s, regular stops were very common.
In the US, for example, regular transcontinental non-stop flights did not start until the mid-1950s. Although it is the case that they were possible before that, they were not as common. Before that, two-stop flights (with the Douglas DC-2) had been offered since the mid-1930s, and one-stop (with the DC-4 and Lockheed Constellation) since the early to mid-1940s. But what about internationally?
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Looking at one of the busiest and most lucrative aerial corridors in the world of commercial aviation, non-stop transatlantic service was not regularly offered until 1958. British Overseas Aircraft Corporation (BOAC) was the first airline to offer this, with a de Havilland Comet service between London and New York. Soon after this, it was joined by US giant Pan American World Airways (Pan Am).
Direct flights
A direct flight refers to a flight between two cities that carries a single flight number. While non-stop flights are indeed direct in their nature, such flights can also involve one or more stops en route to their final destination. These can serve various purposes, such as picking up or offloading passengers, or just technical stops for refueling. In some cases, they can involve a change of aircraft.
Direct flights can be an important part of an airline's operations and marketing. After all, an airline may advertise, and sell, a flight between two cities – carrying a single flight number – but this does not need to be offered as a single non-stop flight. This is common in the US aviation market but can happen everywhere. From a customer's perspective, seeing a keyword like 'direct' can be persuasive.
Many cases of both short and long-haul direct flights operate today. It is less common internationally, though (unless needed for technical refueling), as the airline may not be able to sell the sector outside its home country separately.
That being said, the freedoms of aviation do allow this in some instances, with some long-haul carriers operating fifth freedom flights as extensions of services to Europe. A notable example that arose last year was one operated by Ethiopian Airlines from Manchester to Geneva, which then continued to its Addis Ababa base.
Meanwhile, Cathay Pacific has been known to offer several flights a day between Hong Kong and Singapore, with some of them making a stop in Bangkok en route. The airline has also been able to sell BKK-SIN tickets as a result.
Many ultra-long routes may involve a stop, although more are becoming non-stop with newer aircraft). British Airways' daily flight BA15 from London to Sydney, for example, involves a stop in Singapore, and is thus direct but not non-stop.
Choosing direct or non-stop
These days, many shorter non-stop flights are not priced differently to direct, one-stop affairs. That being said, for many passengers, the ease and convenience of non-stop flights will be preferable and worth spotting when booking. On the other hand, avgeeks might appreciate one-stop flights as a means of getting two sectors in their log books, without having to undergo the stress of a connection.
With the increase in ultra-long flights, though, some airlines are offering premium non-stop services, as was more common when such services started in the 1950s and 1960s. Singapore Airlines, for example, offers a non-stop Singapore to New York service on its Airbus A350-900ULR. This is a business and premium economy only service, with the non-stop sectors taking around 18 hours.
As it happens, Singapore to New York is a route on which Singapore Airlines passengers actually have a choice between non-stop and direct. For those wanting to save money by traveling in standard economy class, the carrier also connects the two cities directly via a two-hour stop at Germany's Frankfurt Airport (FRA).
Connecting flights
Another term to bear in mind is 'connecting' flights. We include this here as a reminder just for completeness! A connecting itinerary involves a change in the flight number. Airlines may still sell these together (and provide a guarantee of connection), but these journeys will involve a change of flight and (usually) aircraft.
Where do you stand on direct vs non-stop flights? With many longer routes, passengers may prefer to stop, or change planes, rather than stay onboard for so long, but are you one of them? Let us know your thoughts and experiences in the comments!