The Federal Aviation Authority in the United States has said it will not suspend Boeing 737 Max 8 operations, despite calls from around the world to do so.
Pressure is mounting after the crash of a Boeing 737 Max 8 operated by Ethiopian Airlines over the weekend.
That incident followed the downing of a Lion Air plane, also a Boeing 737 Max 8, in October last year.
There were no survivors in either incident, which both occurred in the moments after take-off.
A number of countries, including the UK, EU, China, Singapore, Australia and India, have since suspended operations of the plane in their airspace.
Turkey earlier joined them, with Turkish Airlines confirming it had stopped operations with its fleet of 12 Boeing 737 Max 8 planes until further notice.
There have also been calls from senators and workers’ unions in the United States for a ban.
Ted Cruz, a Republican senator who chairs a subcommittee on aviation and space, said: “I believe it would be prudent for the US likewise to temporarily ground 737 Max aircraft until the FAA confirms the safety of these aircraft and their passengers.”
However, a statement from the FAA said a review showed “no systemic performance issues” and there is, therefore, no basis for grounding the aircraft.
The FAA added that other civil aviation authorities had not “provided data to us that would warrant action”.
Boeing earlier confirmed it had been developing a “flight control software enhancement” for the 737 Max, but said it is confident the aircraft remains safe to fly.
A statement from the aircraft manufacturer added: “Safety is Boeing’s number one priority and we have full confidence in the safety of the 737 MAX.
“We understand that regulatory agencies and customers have made decisions that they believe are most appropriate for their home markets.
“We’ll continue to engage with them to ensure they have the information needed to have confidence in operating their fleets.
“The United States Federal Aviation Administration is not mandating any further action at this time, and based on the information currently available, we do not have any basis to issue new guidance to operators.”
Southwest Airlines and American Airlines - both major operators of the Boeing 737 Max - are continuing to use the planes in the United States.