Boeing has to be “careful” not to give in to too many of the performance and range requirements put forward by the three Persian Gulf carriers ahead of the launch of the Boeing 777X, warns Air Lease Corp. Chairman and CEO Steve Udvar-Hazy.

Udvar-Hazy last week told Aviation Week on the sidelines of the Latin American and Caribbean Air Transport Association’s Airline Leaders Forum in Cancun, Mexico that he believes potentially excessive performance requirements are likely to be more of an issue on the proposed -8X rather than the -9X.

Emirates Airline President Tim Clark has asked for more engine power to operate both 777X variants with full payload even in the hot Dubai summers. General Electric has dropped an earlier proposal for a water injection system that would have helped with takeoff power.

Udvar-Hazy acknowledges that Boeing is trying to find a balanced answer to the airlines’ differing requirements and says a compromise solution is needed. He also argues that whatever may be the definition of the -9X and -8X at the time of the launch at this week’s Dubai air show may not stay exactly the same as the aircraft configuration becomes firmer over the next few years.

Udvar-Hazy argues that “80-85%” of the 777X’s future customers in Europe and Asia are likely to opt for the larger variant and not need the kind of range the -8X will offer.

Emirates, Qatar Airways and Etihad Airways are expected to order large quantities of the latest 777 iteration at the Dubai air show. The 777X will feature new engines and a new composite wing as the most significant changes over the current model.

The 777X is expected to enter service around 2020.

Udvar-Hazy believes any Airbus decision to further stretch the A350 will hinge on its ability to get rid of the current backlog of the A350-800, which has been shrinking. One major trigger could be a decision by US Airways to trade up after the merger with AMR Corp; US Airways still has an order for 18 A350-800s and four A350-900s.

Air Leases’s founder also says it would make sense for the “new American” to move entirely to the larger -900. That would reduce the -800 backlog further from 79 to 61 aircraft.

Airbus officially still plans to build the A350-800 variant, but has been quietly trying to convince customers to move to the -900 and -1000. Chief Operating Officer-Customers John Leahy last month indicated for the first time that Airbus is studying the possibility of stretching the A350 further beyond the -1000 to counter the 777-9X.

Udvar-Hazy does not expect any quick decision on the matter and questions whether it would be absolutely necessary for Airbus to proceed with another stretch. “They have an acquisition price advantage,” he says, referring to the A350-1000 compared to the 777X. And while the -1000 may not have the same range, it would still be able to perform 90% of the flights possible with competing aircraft, Udvar-Hazy argues.

As for the possible much-discussed upgrades of the A380, Udvar-Hazy hears “lots of talk” but sees “no action.” He doubts that Airbus parent EADS would willing devote substantial funds to a program that has been losing ground.

Udvar-Hazy points out that the market share of the A380 and the Boeing 747-8, the only four-engined widebodies in production, has been declining as the A350, 787 and 777X began being offered. “People are moving away from four engines,” he says.

Airbus and EADS executives have been indicating they might offer an upgraded A380 variant toward the end of the decade. Industry officials say the aircraft would have to be re-engined to be competitive, and a stretch is also believed to be one of the options.