An investigation is underway after a Boeing 737 MAX 8 aircraft crashed Sunday in Ethiopia, killing all 157 people on board.
It is the second time in less than six months that one of the planes has crashed within minutes of takeoff, after a new Lion Air Boeing 737 MAX 8 flight went down over the Java Sea last October, killing 189 people.
Both crashes are under investigation and there is no evidence of a link between the two, but similarities between the incidents have prompted caution among some aviation authorities and airlines.
There are approximately 350 Boeing 737 Max 8 aircraft in operation worldwide, being flown by 54 operators, according to the US Federal Aviation Administration (FAA).
Travelers can check the full list of airlines that fly the plane on the Boeing website.
Read on to find out which airlines and aviation authorities have grounded Boeing 737 MAX 8 aircraft, and which will continue to fly the planes.
Who is grounding planes?
The carrier has grounded the remaining four Boeing 737 MAX 8s in its fleet until further notice, as an "extra safety precaution."
Chinese airlines including the "Big Three" Chinese carriers -- China Airlines, China Eastern and China Southern -- operate 97 of the planes, according to state-run media. In the wake of Sunday's crash, the country's Civil Aviation Administration ordered all domestic 737 MAX 8 jets out of the air by 6 p.m. local time Monday, citing "zero tolerance for safety hazards."
The Civil Aviation Authority of Singapore announced Tuesday it was "temporarily suspending operation of all variants of the Boeing 737 MAX aircraft into and out of Singapore in light of two fatal accidents involving Boeing 737 MAX aircraft in less than five months."
The suspension will start at 2 p.m. Singapore time and effect SilkAir, a regional carrier in the city-state, and the following airlines that fly into Singapore: China Southern Airlines, Garuda Indonesia, Shandong Airlines and Thai Lion Air.
SilkAir previously said it had no plans to ground its six 737 MAX 8 aircraft, which operate between Bengaluru, Cairns, Chongqing, Darwin, Hiroshima, Hyderabad, Kathmandu, Kuala Lumpur, Penang, Phnom Penh, Phuket and Wuhan.
Indonesia temporarily grounded all Boeing 737 MAX 8 planes operated by its airlines on Monday, pending further inspections.
In a statement, the Directorate General of Air Transportation at the Ministry of Transportation said the policy would "ensure that aircraft operating in Indonesia are in an airworthy condition."
Australia's Civil Aviation Safety Authority (CASA) has temporarily suspended airlines from flying all Boeing 737 MAX jets to or from Australia.
"This is a temporary suspension while we wait for more information to review the safety risks of continued operations of the Boeing 737 MAX to and from Australia," CASA CEO Shane Carmody said.
No Australian airlines fly the 737 MAX, CASA said, but two foreign carriers had previously flown the aircraft into the country -- Singapore's SilkAir and Fiji Airways. SilkAir has been temporarily barred from flying any 737 MAX out of Singapore by the city-state's aviation authority, though Fiji Airways said Tuesday that it would continue flying the two 737 MAX 8s in its fleet.
CASA said in a statement it was working with Fiji Airways to minimize disruptions to passengers.
The Mexican carrier is temporarily suspending the use of its six 737 MAX 8 planes "until more thorough information on the investigation of flight ET302 accident can be provided."
The Argentine airline said it would temporarily suspend commercial operations for the five 737 MAX 8s in its fleet.
Cayman Airways operates two new Boeing 737 MAX 8 aircraft. It said Monday it was grounding both planes "until more information is received."
The South African carrier said it would remove the 737 MAX 8 from its flight schedule, despite the fact that "neither regulatory authorities nor the manufacturer has required it to do so."
"While Comair has done extensive preparatory work prior to the introduction of the first 737 MAX 8 into its fleet and remains confident in the inherent safety of the aircraft, it has decided temporarily not to schedule the aircraft while it consults with other operators, Boeing and technical experts," the airline said in a statement.
South Korean low-cost carrier Eastar Jet said it would temporarily ground its two 737 MAX 8 planes starting Wednesday to "dispel the worry and concern of the people."
The company said operations would resume when there were no more safety concerns.
Who is still flying Boeing 737 MAX 8s?
The US carrier has 24 737 MAX 8 aircraft in its fleet and says it has no plans to ground them at the moment.
In a statement, American Airlines expressed its condolences to the families of those killed, and said it would continue to monitor the investigation into the crash.
"At this time there are no facts on the cause of the accident other than news reports," read the statement. "We have full confidence in the aircraft and our crew members, who are the best and most experienced in the industry."
The US carrier has 34 of the aircraft in its fleet and says it does not plan to change its operational policies or procedures.
"We remain confident in the safety and airworthiness of our fleet of more than 750 Boeing aircraft," read a statement from the airline.
Norwegian will continue to operate its 18 737 MAX 8 aircraft as normal, according to Tomas Hesthammer, Director of Flight Operations.
"We are in close dialogue with Boeing and follow their and the aviation authorities' instructions and recommendations," Hesthammer said in a statement. "Our passengers' safety is and will always be our top priority."
TUI Aviation has 15 of the aircraft in its fleet.
"We do not comment on any speculation and we are, as always, in close contact with the manufacturer," reads a statement from the airline. "We have no indication that we can't operate our 737 MAX in a safe way like we do with all other planes in our network."
Fiji Airways currently flies two 737 MAX 8 aircraft and has three on order for 2019. "We have full confidence in the airworthiness of our entire fleet," the airline said in a statement.
Icelandair says it flies three Boeing 737 MAX aircraft, which have not been involved in any incidents.
"At this stage, Icelandair is not taking any action following recent events, but we will, however, follow any developments closely and continue to do all we can to ensure safety on board now as before," the airline said in a statement.
Flydubai operates 11 Boeing 737 MAX 8s, and says it "remain(s) confident in the airworthiness of our fleet."
"We are monitoring the situation and continue to be in touch with Boeing... The safety of our passengers and crew is our first priority," the airline said in a statement.
"The aviation sector is highly regulated and Flydubai rigorously adheres to all regulations," it added.
Canadian airline WestJet says it has 13 MAX 8 aircraft and a total of 121 Boeing 737s in its fleet.
"We are monitoring the situation closely and will not speculate on the cause of the incident," the airline said in a statement. "WestJet remains confident in the safety of our Boeing 737 fleet including our 13 MAX-8 aircraft first introduced in 2017."
GOL Linhas Aéreas
The Brazilian airline has seven 737 MAX 8s in its fleet, part of a total 121 Boeing aircraft.
"GOL continues to follow the investigations and maintains close contact with Boeing for clarification," said the airline in a statement.
"The company reiterates confidence in the safety of its fleet."
What other aviation authorities are saying
Federal Aviation Administration (FAA)
On Sunday, the US aviation authority said it would help Ethiopian authorities investigate the crash.
Following the Lion Air crash involving a 737 MAX 8 in October, the FAA said it had "sent out an emergency Airworthiness Directive to advise carriers and pilots on training to disengage the aircraft's automated controls if there are anomalies."
UK Civil Aviation Authority
"There are currently five Boeing 737 Max 8 aircraft registered and operational in the United Kingdom," a spokesperson for the UK Civil Aviation Authority said, adding that a sixth aircraft is due to enter operation this week.
"The US Federal Aviation Administration (FAA) is responsible for certifying all Boeing 737 Max 8 models and it is the European Aviation Safety Agency (EASA) that validates this certification across the EU, including the UK," said the spokesperson, who said that the CAA is working closely with the EASA.
European Union Aviation Safety Agency (EASA)
EASA said it was monitoring the crash investigation closely.
"We will immediately publish any further information on our website as the necessary information is available," the agency said in a statement.
Indian Directorate General of Civil Aviation (DGCA)
India's aviation authority said Tuesday it would not ground the 737 MAX 8s operating in the country. However, it did announce a series of interim safety measures required of airlines operating the specific Boeing aircraft.
According to the DGCA, only two Indian carriers have 737 MAX 8s in their fleets -- Spicejet has 12 and Jet Airways has five.