As the Paris Air Show approaches, demand for most widebody aircraft is diminishing and demand for the biggest widebody of them all is diminishing even more quickly.

In a report issued Monday, aerospace consultant Scott Hamilton wrote, "This is a pivotal year for the Airbus A380 -- sales have dried up."

Airbus SAS executives spoke to reporters last week at Airbus media day in Toulouse, France, and at the International Air Transport Association annual meeting in Cancun, Mexico. They said Airbus plans to cut A380 production to one a month in 2018, but will need more orders to maintain even that level.

Meanwhile, Bloomberg reported that Emirates Airline, the primary A380 customer, is involved in talks about adding 20 aircraft to its order. "The A380's future rests with Emirates," Hamilton wrote.

Airbus and Boeing Co. (BA) - Get Report "now project widebody production peaking 25% below the outlook from a few years ago, although still 10% higher from current levels," UBS analyst David Strauss wrote in a recent report.

"We still see widebody oversupply at these rates, but by less than half our prior view with only a further 10% cut required," Strauss said. He has a neutral rating and a $180 price target.

Boeing shares closed Monday at $190, down 3 cents. Year to date, shares have risen22%, the second-best performance among the 30 stocks in the Dow Jones Industrial Average.

A recent report by Fitch Ratings said aircraft deliveries are likely to grow along with global demand for air travel, but "Fitch expects aircraft orders and the order backlog to decline in 2017."

Fitch expects current year deliveries by Airbus and Boeing to gain 4.5% to 1,500, with an additional 7% increase to 1,600 aircraft in 2018. However, "there are several signs that the positive momentum in some demand indicators is slowing and a delivery peak is looming," Fitch said.

Among the negative signs is backlog. While backlog at Airbus and Boeing total about 12,400 aircraft, equivalent to more than eight years of deliveries, "the backlog, which serves as a significant cushion to downside scenarios, was flat in 2016, the first time it did not rise since the financial crisis," Fitch said.

Additionally, while global demand for air travel is growing, "airline capacity growth could outstrip demand," the ratings agency said.

As for the A380, Singapore Airlines will take delivery of three aircraft by March 2018, but it said last month that it will give up four of its older A380s, which are leased. Hamilton said, "There is no new home for them -- these may be headed for the scrap heap."

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Hamilton said Emirates is "under pressure and deferring orders" for both the A380 and the Boeing 777X. Meanwhile, peer carriers Etihad and Qatar Airways face problems including the former's investments in troubled European carriers and the blockade of Qatar Airways' Doha hub by neighbors.

"A broad decline in demand for all widebody aircraft adds to the A380's woes," Hamilton wrote. "Sales of the Airbus A330 and A350 and Boeing 777 classic, 777X and 787 are off from recent peaks. Deferrals, model swaps and cancellations are, while not common, increasingly frequent."

Hamilton said he doesn't expect Emirates to place any aircraft orders at the Paris Air Show next week. The Dubai Air Show is scheduled for November. "Without an order then, a 2019 production rate reduction {for the A380} is certain," he said.

The A380's top remaining customers include Emirates with 47 unfilled orders, leasing company Amedeo with 20, and 10 orders that were undisclosed.

Boeing shares rose 0.6% to $191.14 on Tuesday.

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This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.