Spirit AeroSystems Holdings Inc reported a bigger-than-expected quarterly loss, hurt by fewer aircraft part shipments to top customers Boeing Co and Airbus following a slump in demand for air travel due to the COVID-19 pandemic.

"2020 was one of the most challenging years in aviation history. For Spirit, the 737 MAX grounding and the COVID-19 pandemic created a dual-crisis," Spirit Chief Executive Officer Tom Gentile said.

The company now stands to benefit from ungrounding of the Boeing 737 MAX jet by the US Federal Aviation Administration in November after a 20-month ban. The MAX accounted for about 50% of Spirit's sales in 2019.

Spirit's total deliveries of shipsets, or complete sets of parts, fell 48.9% to 231 units in the fourth quarter. Boeing 737 MAX deliveries fell to 19 shipsets from 153 a year ago.

European planemaker Airbus last week forecast flat deliveries in 2021 as it braces for more coronavirus-induced uncertainty in the wake of an annual loss. Boeing has yet to set out detailed targets.

Spirit posted a loss of $295.9 million, or $2.85 per share, in the quarter ended Dec. 31, compared with a profit of $67.7 million, or 65 cents per share, a year earlier.

On an adjusted basis, the company lost $1.31 per share. Analysts had expected the company to report a loss of 85 cents per share, according to Refinitiv IBES data.

Total revenue decreased 55.3% to $876.6 million.