A top Boeing executive insisted Wednesday the aviation giant was confident its controversial 737 Max jets could be flying again before the end of the year.

Darren Hulst, a Boeing vice-president, told AFP the firm was working with the US Federal Aviation Administration (FAA) to end the grounding of the jets since two crashes which left 346 dead.

The international suspension of 737 Max flights in March has cost Boeing billions of dollars and forced it onto the defensive over its safety record.

"Our belief is the timeline for return of service with the FAA can be as soon as this quarter," Hulst said.

"But its really up to each individual regulator on what they require and (we are) working closely with each one of them," he told AFP.

"We have developed the software and we are working with the FAA on the timing of the certification.

"We have done test flights, both in the air and also simulator testing. The next step is determining the certification flight with the FAA and that's when it moves from our timeline to the regulator's timeline," Hulst said.

Boeing has been reeling since the crashes of a 737 Max jet operated by Indonesian carrier Lion Air in October last year that left 189 passengers and crew dead and an Ethiopian Airlines crash this year that killed 157 people.

All 400 737 Max jets have been grounded since.

Boeing's former chairman Dennis Muilenburg faced gruelling questioning in the US Congress last week as lawmakers questioned whether the company had compromised safety to rush the 737 Max jets into service.

Dozens of grounded Boeing 737 MAX aircraft are parked on the apron in Washington state
Dozens of grounded Boeing 737 MAX aircraft are parked on the apron in Washington state GETTY IMAGES NORTH AMERICA / David Ryder

The questions come as Boeing faces mounting competition from European rival Airbus in key markets such as India, where Hulst spoke.

India will be the world's fastest-growing aviation market over the next 20 years, Hulst said.

Boeing expected India to order 2,380 planes worth $330 billion over the next two decades, the executive said.

India had recorded an 18 percent increase in the number of flyers last year, with almost 140 million domestic passengers.

An economic slowdown reduced growth this year and the bankruptcy of India's top airline, Jet Airways, also hit the market.

But India's largest low-cost airline IndiGo this month ordered 300 planes from Airbus.

Hulst said Boeing would stick to a long term recovery in the battle for orders in India.

"We also see more competition and a more diverse market over the next five, 10, 20 years," he said, adding that Boeing would keep up its "ambitious" targets.

"I'd say we are taking a long view in terms of what we can do, how we can support the growth of aviation here in India. We are confident about what our products can offer," he said.