Boeing Co (NYSE:BA, ETR:BCO) traded flat on Monday in the US despite its 737 MAX 9 jets resuming flights over the weekend.
United Airlines Holdings Inc (NASDAQ:UAL) said it had resumed use of the aircraft for passenger flights for the first time since January 6, having received approval from US regulators.
Additionally, Ryanair Holdings PLC (LSE:RYA) said it would purchase any of the new MAX 10 if any US airlines no longer wanted to use them.
It comes after the jet type saw one of its door panels blow out mid-flight on an Alaska Airlines journey earlier this month.
United said the first MAX 9 flight left from Newark to Las Vegas with around 175 passengers and six crew members.
Alaska Air Group (NYSE:ALK) saw a $150 million hit to its profits due to the grounding of the Boeing aircraft.
The two-week grounding significantly impacted the airline, which has 65 of these jets in its fleet.
Boeing shares have fallen close to 20% since the incident, but having experienced a strong runup to Christmas, the stock is relatively flat on a 12-month basis.