Boeing (BOE, Washington National) is reportedly on track to deliver its first batch of B737 MAX 8 aircraft ahead of schedule. Southwest Airlines (WN, Dallas Love Field), the type's launch operator, is officially expected to take delivery of its first MAX 8s during the third quarter of next year.

However, industry sources who spoke to The Wall Street Journal on condition of anonymity said the US manufacturer has been telling customers the twinjet could arrive a full six months earlier than expected.

The type's maiden completed airframe - N8701Q (msn 42554) - undertook its B1 flight last week and is now undergoing a comprehensive flight-test program ahead of certification and delivery.

While the MAX series currently features a -8 and -9 variant, Greg Smith, Boeing's executive vice president for business and strategy, says the firm is also looking at a stretched version capable of competing with the A321 from Airbus (AIB, Toulouse Blagnac).

If approved, the new variant would only enter service after the slated 2020 début of the wide-body B777X, he said.

Boeing says the 737 MAX family currently has 3,072 orders from sixty-two customers worldwide.