The International Air Transport Association (IATA) expects severe supply chain issues to continue to impact airline performance into 2025, raising costs and limiting growth. 

In its latest airline industry outlook, IATA quantified the scale of the challenges facing airlines because of supply chain issues.

The trade association for the world's airlines said the average age of the global fleet has risen to a record 14.8 years, a significant increase from the 13.6-year average for the period 1990-2024. 

Aircraft deliveries have fallen sharply from the peak of 1,813 aircraft in 2018.

IATA noted that the estimate for 2024 deliveries is 1,254 aircraft, a 30% shortfall from what was predicted going into the year.

It added that in 2025, deliveries are forecast to rise to 1,802, well below earlier expectations for 2,293 deliveries, with further downward revisions in 2025 widely seen as "quite possible."

The backlog (cumulative number of unfulfilled orders) for new aircraft has reached 17,000 planes, a record high.

IATA said at present, delivery rates would take 14 years to fulfil, which would double the six-year average backlog for the 2013-2019 period. However, the waiting time is expected to shorten as delivery rates increase.

The number of parked aircraft is 14% (approximately 5,000 aircraft) of the total fleet (35,166 as of December 2024, including Russian-built aircraft).

The airline association pointed out that while this has improved recently, parked aircraft remain 4 percentage points higher than pre-pandemic levels (equivalent to some 1,600 aircraft). Of these, 700 (2% of the global fleet) are parked for engine inspections. "We expect this situation to persist into 2025," IATA said.

Willie Walsh, director-general at IATA, noted that supply chain issues are frustrating every airline with a "triple whammy on revenues, costs, and environmental performance."

"Load factors are at record highs, and there is no doubt that if we had more aircraft, they could be profitably deployed, so our revenues are being compromised. Meanwhile, the ageing fleet that airlines are using has higher maintenance costs, burns more fuel, and takes more capital to keep it flying," he added.

"On top of this, leasing rates have risen more than interest rates as competition among airlines intensified the scramble to find every way possible to expand capacity. This is a time when airlines need to be fixing their battered post-pandemic balance sheets, but progress is effectively capped by supply chain issues that manufacturers need to resolve," Walsh said.

Specifically, IATA noted that persistent supply chain issues are at least partially responsible for two negative developments.

In terms of fuel efficiency (excluding the impact of load factors), it said that it remained unchanged between 2023 and 2024 at 0.23 litres/100 available tonne kilometres (ATK)—a "step back" from the long-term (1990-2019) trend of annual fuel efficiency improvements in the range of 1.5-2.0%.  

Meanwhile, exceptional demand for leased aircraft has also pushed leasing rates for narrow-body aircraft to levels 20-30% higher than in 2019. 

"The entire aviation sector is united in its commitment to achieving net zero carbon emissions by 2050. But when it comes to the practicality of actually getting there, airlines are left bearing the biggest burden," Walsh said. "The supply chain issues are a case in point."

"Manufacturers are letting down their airline customers, and that is having a direct impact on slowing down airlines's efforts to limit their carbon emissions. If the aircraft and engine manufacturers could sort out their issues and keep their promises, we'd have a more fuel-efficient fleet in the air," the IATA director general said.