Today, a non-stop flight from New York to Houston, Texas, takes about four hours. In 1973, the same flight would have taken just over two and a half hours. So much for progress.
But this is not an isolated case: flight times are getting longer.
London to Edinburgh takes, on average, 10 minutes longer than it did in the mid-Nineties; Madrid to Barcelona takes up to 20 minutes longer; while New York to Chicago is likely to take two hours and 50 minutes rather than the two and a half hours it took in 1996.
According to Business Insider, as the price of fuel rose in the Noughties, from $0.70 per gallon to over $3, airlines realised they could save millions of pounds per year by flying their planes slower, therefore using less fuel – but arriving at the destination later. A gallon of jet fuel cost $1.59 at the end of 2016.
For example, in 2008, Associated Press reported that American airline JetBlue saved $13.6million (£11m) a year by adding two minutes onto the length of each flight.
It is not a particularly new tactic.
In 2013 the Telegraph reported that budget airline Ryanair told its pilots to fly slower to save fuel – and therefore money – but add two minutes onto every hour’s flying time.
In 2014, Reuters reported that jet fuel consumption in the US, after peaking in 2005, fell more than 15 per cent in 10 years, the equivalent of more than 200,000 barrels per day.
Traditionally, the typical flying speed (546-575mph) is a trade-off between commercial pressures and fuel consumption – reaching a destination quicker is not only more appealing to customers but also minimises crew costs and ensures a new load of passengers quicker.
Another reason flight times are thought to be growing is one Telegraph Travel explored in 2015, a practise known as “schedule padding”.
“The accusation is that airlines are coming under increasing pressure to have as high an on-time performance score (OTP) as possible, and are consequently allowing themselves plenty of wiggle room when allotting flight times,” the article read.
A report by aviation analysts OAG showed how the scheduled flight times of a number of different routes has grown between 1996 and 2015.
Jim Paton, a senior lecturer in the Department of Air Transport at Cranfield University, told the BBC: “The practice of buffering the airline schedule times is something that is very common, almost universal in Europe and in other parts of the world.”
However, airlines deny the practise exists. John Grant, a senior analyst at OAG, says it is more complicated.
“It’s not as simple as assuming airlines have increased block times to reduce the risk of being late,” he said.
OAG’s report also pointed out how congestion at airports meant that it took longer for aircraft to take-off after leaving the gate – a time that is included in the scheduling.
Airlines in the US have been flying slower to cut fuel bills
Higher oil prices have made US airlines work to control costs. Between 2002 and 2012, the price of jet fuel quadrupled and fuel bills rose from 15% to more than 40% of the operating costs of US airlines, and their single largest operating expense. Airlines have made many efficiencies to cut fuel consumption, including now flying more slowly. Most of the fuel economies which have been implemented in the last decade will not be undone, even if oil prices were to fall (partly due to the possible future costs of CO2 emissions). There is an optimal cruising speed for each aircraft based on altitude. Flying faster increases the amount of fuel burnt. Historically, commercial aircraft have flown on average about 8% faster than their optimal cruising speed. Getting the aircraft to its destination quicker to pick up another load of passengers and minimise crew cost was worth the extra fuel expense. There is a trade-off between fuel consumption and time. But between 2004 and 2011, the average ground speed of seven major US airlines fell by 1.1%. More than anything else, however, airlines have focused on reducing excess weight.
NATS gets planes to fly slightly slower in order to cut time waiting in Heathrow stacks
The amount of time aircraft spend in holding stacks before landing at Heathrow have been cut very slightly, due to planes being required to slow down a bit on their way towards London – instead of flying fast, and then having to stack. The reduction in stacking has been due to XMAN – or cross-border arrivals management – which involves NATS coordinating with its counterparts in France, the Netherlands and Ireland to slow inbound aircraft down from 350 miles away, when delays over London begin to build. As a result aircraft don’t land any later, but do spend less time circling in the holds. (They also burn a bit less fuel by flying a bit less fast). They are also using Time Based Separation to cut headwind delays. The new improvements have resulted in about one minute less per plane, which NATS says is about 3,000 hours per year. (That comes to 180,000 planes stacking per year, out of the total of about 235,000 planes arriving into Heathrow in total in 2015 – when there were around 472,000 total air transport movements at Heathrow). NATS says average holding times were about 8.5 minutes at the beginning of 2014, with that figure now just over 7.5 minutes and falling to 6.5 minutes in August 2016. NATS also says shorting stacking results in less noise – which might be true, though planes will still leave the stack at 7,000 feet. Those entering the stack, up to 14.000 feet, cause less noise on the ground.