European planemaker Airbus has warned customers they may face more delays on delivery of the world's largest passenger plane, the A380, which is already two years behind schedule.
Dubai's Emirates airline, the biggest A380 customer, and Abu Dhabi-based Etihad Airways, both confirmed they had received the warnings.
State-owned Emirates, which has ordered 58 of the aircraft, was told it faced possible delays in its "wave 2" deliveries, Emirates airline President Tim Clark told Reuters by telephone in Dubai.
The letter, from Airbus Chief Executive Officer Tom Enders, "reiterated that the A380 ramp-up is challenging and continues to be challenging," said an Airbus spokesman.
Any delay would affect A380s due for delivery to Emirates from April next year, Emirates' Clark said.
"This will do us serious damage," said Clark, whose first delivery, due this year, is already almost two years late.
Deliveries of the A380 have fallen behind schedule after a series of industrial mishaps since 2005, and the reputation of parent firm EADS is seen at stake as it strives to deliver 13 planes this year.
Emirates, the largest Arab carrier, hopes to receive five A380s before the end of March 2009 and another 12 in the year to March 31, 2010.
Clark said he will find out in the next two to three weeks whether that schedule is intact.
Separately, a spokesman for the Abu Dhabi government-owned carrier Etihad said the airline had received a letter from Airbus indicating that there may be a delay.
Etihad has ordered four of the $300 million, 525-seat planes.
The A380 went into service last year with Singapore Airlines but is heavily bankrolled by Emirates.
Europe's biggest single industrial project was thrown into upheaval in 2006, when A380 sections reached the French assembly plant with wiring flaws that caused production to halt.
Airbus blamed the failure of German and French plants to use the same design software, and was forced to start assembling the first 25 planes by threading the 500 km of wiring through each aircraft manually, pushing deliveries back on average 2 years.