A lot has changed in the four years that one of the largest air shows in the aviation industry has been held in person.

The Covid-19 pandemic has devastated travel demand, the airline industry drop thousands experienced workers and the desire for new roller coaster jets created havoc in the production of new aircraft.

After all, the Paris Air Show — a business event where companies get a chance to show off their innovations techniquecommercial and military aircraft and strike offers – returns on Monday during a increase in demand for air transportwith airlines starving for jets feed it. The question is whether BoeingAirbus and their many suppliers can catch up.

“This puts pressure on order books – it creates upward momentum for used lease rates and forces airlines to compromise,” said Andy Cronin, chief executive of aircraft leasing company Avolon.

Aviation analyst firm IBA estimated last week that there could be orders for around 2,100 aircraft during the show as airlines replace older planes and prepare for future growth in air travel.

for the last year Boeing recorded large orders or preliminary agreements from customers incl United AirlinesSaudia and new Saudi Arabian airline Riyadh Air. Air India’s massive order earlier this year included both Boeing and Airbus nozzles.

The chairman of Turkish Airlines told reporters last month that the carrier plans to order around 600 aircraft, both wide-body and narrow-body. The order would be the largest ever for a single airline, although it is unclear whether it would come together in time for the show.

The IBA’s chief economist, Stuart Hatcher, wrote this in his June 15 forecast Delta Air Lines, Malaysia Airlines and Air France-KLM could be buyers, but the timing is not yet certain. According to him, Air Baltic could also consider expanding its Airbus A220 fleet.

“It may be too early to call any Chinese expansion given the political climate, but I wouldn’t be surprised to see additional orders coming in,” Hatcher wrote.

The main challenge for manufacturers now is to increase production. Slots for narrow-body jets such as the Boeing 737 and Airbus A320 have been sold out for years. Now this long distance travel returns, some airlines could also look to expand their fleets with larger, long-range aircraft.

But customers around the world have been forced to wait longer than expected for the new planes as Boeing, Airbus and a network of suppliers around the world scramble to ramp up production. This has limited airline capacity, which keeps ticket prices high.

Qantas CEO Alan Joyce told CNBC last week that he expects supply chain problems to continue into 2025.

Boeing and Airbus are scrambling to join them increase the production rate for the coming years to meet this demand.

Production delays have also pushed up lease rates for both new and older aircraft as airlines look for more opportunities to increase flights.

New Boeing 737 Max 8 aircraft are being leased for about $350,000 a month in July, up from $305,000 in January 2020 when the pandemic began, IBA estimates. New Airbus 320s will cost $355,000, up from $325,000 this period. Older versions are approaching pre-pandemic levels.

“People just want their airplanes,” said Richard Aboulafia, chief executive of AeroDynamic Advisory.