Airbus has started working with the European Aviation Safety Agency (EASA) to have its A320 recertified for a maximum load of 186 passengers, Aviation Week has learned.

Airlines are currently allowed to fly the aircraft with a maximum of 180 seats, but Airbus would like to add an extra row to further increase efficiency.

The manufacturer officially says that the 186-seat configuration is “one of the things we are looking at among others,” but EASA confirms that “the process for this significant modification has started” without providing details.

The move was triggered by Airbus’ win of the Vueling fleet order last August. The low-cost carrier, a subsidiary of International Airlines Group (IAG), placed a firm order for 30 A320s and 32 A320neos. The deal also included options for 58 more aircraft that could go to Vueling and an additional 100 A320neos that could end up at any of the IAG Group ’s carriers – Vueling, British Airways or Iberia. The aircraft on firm order are to be delivered between 2015 and 2020.

According to industry sources, one key element for Airbus to be able to win the Vueling order was the promise to be able to fit 186 seats in the cabin. Airbus has done some significant interior redesign work and has more in the works. Many airlines have either already installed or are in the process of installing slim backrest seats that allow the airlines to reduce pitch and gain space for several more seat rows . Also, as part of the Spaceflex concept, airlines can opt to move the rear lavatories to immediately in front of the rear pressure bulkhead if they accept a smaller galley at the same time. That way, another row of seats can be added.

The A320 was originally designed for and has typically been flown in a 150-seat configuration in the past, but airlines have been looking for ways to expand capacity.

Neither Airbus nor EASA will say exactly what is needed to change the certification. But it is unlikely that Airbus would have to prove that the aircraft still complies with emergency evacuation limits by doing another actual evacuation test. In past cases, computer modeling has been accepted as sufficient.

The move to 186 seats is likely to trigger other changes, too. Airbus is looking at installing movable bins that would be aimed at increasing overhead storage space. The cabin work is not limited to the neo, but modifications would also be available on the current standard A320s.