Slumping orders, production bottlenecks, regulatory pressures and the prospect of fewer flyers: Aviation executives have plenty on their minds as they head to France on Monday for the opening of the Paris Air Show.It’s a starkly different mood from the previous edition two years ago, when airlines worldwide were optimistic about their prospects and placing big orders for new planes. But industry leaders Airbus and Boeing have instead seen clients cancel orders for dozens of planes in recent months, managing to sell just a handful of new jets.While Airbus might claw back some ground with the launch of the A321XLR at the airshow in Le Bourget, just north of Paris, Boeing’s future has been clouded by two deadly crashes that have grounded its popular 737 MAX. With the cancellations, “we’re in negative territory for the year, and Airbus has a chance to rescue that a bit, but Boeing does not,” said Richard Aboulafia, a longtime industry analyst at the Teal Group in Fairfax, Virginia.He said that slowing passenger traffic globally — year-on-year growth slowed to just 4.3 percent in April, compared with 6.5 percent growth for all of 2018 — also has airlines worried. The decline echoes soft global economic growth amid trade tensions between the US, Europe and China, three huge markets for air travel.And Aboulafia noted that air freight levels are usually good predictors of passenger traffic trends, “and these past couple of months have been even worse for cargo traffic”. The International Air Transport Association reports that freight traffic has been in a downward spiral since the beginning of the year.“The two most recent months, March and April, were just god awful, and we’re going into this show not really knowing what is happening,” he said. Win back confidenceBoeing and Airbus can take comfort in the fact that both their order books remain strong after hefty revenue growth last year, when combined they delivered more than 1,600 planes.And their dominance has been bolstered by the woes at two main rivals, Canada’s Bombardier — which has hived off aviation units while cutting thousands of jobs — and Brazil’s Embraer, which is selling its commercial plane division to Boeing.That leaves them in prime position to meet an expected surge in global passenger traffic, especially in Asia — at least until China’s state-owned Comac starts marketing its first jet in 2021.Analysts say nearly 40,000 planes will be in service by 2038, double the industry’s current fleet.Yet the frenetic production pace has left several Airbus and Boeing suppliers struggling to keep up, leading to delays as “gliders” without engines or other key parts remain parked on tarmacs.Some pilots and travellers also suspect the rush to build may have contributed to the flawed anti-stall technology in the Boeing 737 MAX.The so-called Manoeuvring Characteristics Augmentation System (MCAS) is blamed for an Ethiopian Airlines crash in March and an Indonesian Lion Air crash in October, which together claimed 346 lives.“The 737 MAX crisis has an impact across nearly the entire industry, because aviation security is an essential issue for every player,” analysts at AlixPartners said in a research note.“It’s too early to tell what will happen, but winning back passengers’ confidence will be a true challenge for the entire industry,” they wrote.Pollution pressureFrench President Emmanuel Macron’s visit to the show’s 53rd edition on Monday highlights another headwind: government pressure to limit carbon emissions.While an official in Macron’s office said no announcements on potential jet fuel taxes or emission quotas are planned, he has made no secret of wanting airlines and aviation firms to make more of an effort.The subject will be on the menu at a dinner Macron will host for executives Sunday night, as France tries to forge a common EU strategy, the official said.“Aerospace is about two percent of global emissions and 14 percent of those from transportation, so it’s not negligible,” said Philippe Plouvier, an analyst at the Boston Consulting Group.“It’s an industry that’s going to double its emissions by 2040,” he said, as growing passenger traffic offsets any expected improvements in engine designs.On the military front, the defence ministers of France, Germany and Spain will meet in Le Bourget on Monday to sign a formal cooperation accord to build a new European fighter jet which they hope will be in the skies by 2040.No financing deals or contracts will be announced for the so-called Future Combat Air System, and the production launch is still years away.But another Elysee official said the cooperation pact would be the latest signal of Europe’s determination to unite its defensive capabilities.“We want Europe to be stronger, able to completely ensure the protection of its citizens, and to intervene jointly,” he said.