After nine months of production, Lockheed Martin’s F-35 line is still lagging, according to the latest company earnings report.

Lockheed delivered 15 F-35 Joint Strike Fighters at the end of September, according to its third quarter 2017 earnings released this week. That batch brings Lockheed’s total F-35 deliveries to 44 this year, far away from the Lockheed's original goal of 66 jet deliveries by the end of 2017.

Lockheed delivered 14 jets in the second quarter of this year and 15 in the previous quarter, setting a nine-month average of almost three deliveries a month. To meet the 2017 delivery goal, Lockheed needs to average 5.5 deliveries a month for the full year.

While the company often boosts its deliveries in the fourth quarter, the year-end goal would set an ambitious production pace for the next two months. In April, a Pentagon contract management agency forecast Lockheed’s year-end delivery at 57 jets, based on the lower than expected delivery rates in prior years.

Lockheed's delivery target in 2016 was set at 53 F-35s, but the company's globally distributed production system managed to hand over only 46.

Lockheed assembles the F-35 in three locations: Forth Worth, Texas; Cameri, Italy and Najoya Japan. Primary suppliers for major structures include Lockheed (forward fuselage and wings), Northrop Grumman (centre fuselage) and BAE Systems (aft fuselage). But major components are also assigned to factories across Europe, Australia and North America.

Once the components reach the final assembly stage, Lockheed must assemble and integrate the structures with the F-35's engine, systems and wiring while maintaining the aircraft's rigid tolerance requirements for stealth.

Despite the lagging deliveries so far this year, Lockheed executives struck an optimistic tone during a 24 October earnings call, quoting the low-rate initial production lot 11 contract award from this summer. Lot 11 will deliver another 141 jets, including US and foreign orders.