The head of Qatar Airways has criticised Boeing over several manufacturing faults that have resulted in the grounding of one of its three 787 Dreamliner aircraft.
Qatar's grounded 787 has electrical problems similar to those in a United flight that was recently forced to have an emergency landing.
Chief executive Akbar Al Baker said he was "disappointed" by the situation.
Boeing's Sir Roger Bone said he understood Mr Baker's "frustration".
Qatar Airways has long been one of the fastest growing airlines in the world, having gone from operating just four aircraft to service a global flight network to more than 100 destinations in just 15 years.
Yet, to Mr Baker the expansion has not been fast enough. "We're already falling behind on our expansion programme due to delayed deliveries of aircraft and technical problems with the aeroplanes."
"I'm disappointed because we have an aircraft that has just been delivered to us and for the last five days we can't fly it," Mr Baker told the BBC.
Dreamliner deliveries are already several years behind schedule, so "I don't think there's any excuse for these problems anymore."
Mr Baker was speaking at London's Heathrow airport, having just arrived from Doha on the first-ever commercial long-haul flight in a Dreamliner to the UK.
"London is a very important destination for us in Europe," he said. "We have other destinations in mind in the UK, but due to the shortage of aircraft we've not been able to realise these ambitions yet."
Sir Roger, the president of Boeing UK, told the BBC: "Of course, I understand his frustration, and of anybody in that position, who is delayed in getting the aircraft they need.
"We work extremely hard to mitigate things like that and to put things right. It's something we attach enormous importance to."
The electrical problems that forced the United flight to land and resulted in the grounding of the Qatar Dreamliner were discovered on the same day as the discovery of a separate risk.
On Tuesday, the US Federal Aviation Administration said it had identified fuel-line assembly errors in the Dreamliner that could result in leaks onto hot engine parts and thus start a fire, cause engine failure, or simply see the plane run out of fuel.
Mr Baker said he was far from convinced that these were simply teething problems.
"Well, I don't know - two aircraft having major problems so quickly?" he said, referring to the electrical faults in the United and the Qatar planes.
When asked by the BBC whether Boeing would be paying compensation to Qatar Airways, he responded: "They will have to if they deliver aeroplanes that can't fly. We are not buying aircraft to put in museums, we're buying them to fly."
Sir Roger declined to respond to a question about how much this could cost Boeing. "That's not something I would ever talk publicly about at all," he said. "Those are contractual arrangements between Boeing and a customer."
The Boeing 787 Dreamliner is one of the most advanced aeroplanes ever created. Much of it is made from very strong, light carbon-fibre composite material.
In spite of the current problems with the plane, Mr Baker said the Dreamliner was a "fine machine" and insisted that Qatar should have 10 787s in operation within a year.
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