Airbus, meanwhile, continues to make incremental improvements to the A320 family, addressing weight reductions and operating weight increases amid ongoing studies of a winglet programme.

Airbus is evaluating a re-engined A320 which could look something like this

Both programmes have reached important milestones this year, with Boeing delivering the 6,000th 737 (a 737-800 for Norwegian Air Shuttle, which was also the 2,868th 737 NG delivered), and Airbus handing over its 4,000th A320 family aircraft - an A319 for TAM. During the third quarter, Boeing also quietly shipped its 3,000th Next Generation 737.

The 737 performance improvement package (PIP) will arrive in mid-2011, delivering about a 2% cut in fuel burn on longer stages. It comprises the CFM56-7B Evolution powerplant providing a 1% improvement in overall aircraft efficiency, and a minor clean-upUnlike the 737, however, the A320 models (except the A318) are also offered with the International Aero Engines V2500, meaning that Airbus will need to encourage both parties to pursue engine upgrades to ensure performance parity across the family.

With the 2,400 aircraft on backlog representing over six years of production, Airbus expects output will run for at least another decade and ultimately deliver more than 8,000 aircraft.

Flight trials of the CFM56-7B Evolution nacelle began in the number one (left-hand) position of a 737-900ER in August

While Airbus has not announced any major new upgrade in response to the 737 PIP, an ongoing airframe weight saving effort should trim 250kg off A320s delivered from 2010, while more aerodynamic cleaning up means that aircraft delivered from January 2009 have a 1%