Another year, another airliner delivery record: 2016 marked the sixth consecutive rise in mainline jet production and the 14th time in a row Airbus had increased its annual output.

And there is no end in sight to this production growth as the two adversaries push each other onwards and upwards in the output stakes, with the industry set to break clean through the 1,500 deliveries threshold in 2017.

Orders tell a different story, tumbling from the eye-watering record tallies of 2,800-plus net sales in 2013 and 2014, to just shy of 1,400 last year.

Airbus's super-salesman John Leahy and others wax lyrical about irrefutable evidence of a disconnect between the order and delivery cycles. But could 2017 be the year when it all starts to unravel and the consequences of industry over-ordering play out?

Flight Ascend Consultancy chief Rob Morris says that while the demand cycle remains strong, it has probably peaked. If it has, and the manufacturers remain committed to their ramp-ups, then something else will have to give. The likelihood is that we will see more metal – particularly younger machinery – heading for the desert.

There are certainly more questions than answers at the moment. Capacity is likely to rise ahead of traffic growth, and IATA is forecasting a decline in global profits after several years of unprecedented returns. The stimulus of cheap fuel looks set to end amid questions over sustained air-travel demand as the world is gripped by geopolitical changes and the threat of more terrorist atrocities.

And even for the seemingly gravity-defying Middle East carriers, the outlook is less rosy. Emirates announced a surprise 75% fall in first-half profit back in November, blaming "increased competition, as well as the sustained economic and political uncertainty... with no immediate resolution in sight".

Amid speculation around the reasons behind Emirates' Airbus A380 delivery deferral, its Abu Dhabi neighbour is also running into turbulence. Having sought to fast-track its expansion through more than five years of empire-building, Etihad Airways' James Hogan is now set to leave the airline later this year amid a major strategic review at the airline.

And another of the sector's powerhouses – Turkish Airlines – is facing some serious challenges after a decade creating a global network. The carrier is under new management after the departure of its longstanding architect of growth, Temel Kotil, as Turkey reels from a series of shocks including a failed coup and several terrorist attacks.

Unsurprisingly, the global airliner order outlook is somewhat pessimistic. But even though Leahy concedes that Airbus's book-to-bill ratio looks set to drop below one in 2017 for the first time in almost a decade, he says "that doesn't mean we can't increase our production. And we will – this year and the year after that, and the year after that."

The biggest problem, says Leahy, is that "in single-aisle at least, I don't have anything to sell until about 2021". So he's got to build his backlog.

Aengus Kelly, who runs the world's largest aircraft leasing company, AerCap, has some sympathy for the manufacturers, who he says "will sell to anyone with a pulse, because they don't know who's going to make it... but they know someone will".

He believes that "there has been over-ordering" in certain regions, and expects "we will definitely see deferrals", noting that Emirates and Etihad have both recently pushed back widebodies. However, Kelly does not believe this will affect deliveries. And nor does Leahy.

"Deferrals don't bother me that much because we are right now overbooked and if I don't get some deferrals someone's going to be very unhappy. Cancellations I obviously don't like because that's somebody leaving the programme, but they rarely happen."

So you heard it here: Leahy's "not concerned" about 2017. We've got nothing to worry about. Or have we?

Source: Airline Business