Former Transportation Secretary Ray LaHood, on CNBC Wednesday, doubled down on his call for the Federal Aviation Administration to join most of the rest of the world and ground Boeing 737 Max 8 aircraft, after two of those jets were involved in deadly crashes less than five months apart.

Two U.S. airlines operate 737 Max 8s in their fleets. Southwest Airlines has 34. American has 24. United does not have any Max 8s, but it does operate 14 Max 9s, a larger version of the jet, which has not been involved in any crashes.

Asked if he would be concerned about flying on a Southwest or American 737 Max 8, LaHood said in a "Squawk on the Street" interview, "I would be … until you can be assured through an inspection by FAA and by Boeing that the planes are safe to fly."

He wants to see what comes of the investigation into the latest crash, which involved an Ethiopian Airlines flight on Sunday. The other one was in October, when Indonesia's Lion Air saw one of its Max 8s go down in the Java Sea.

LaHood, a Republican who ran the Department of Transportation during former President Barack Obama's administration, reiterated his recommendation that all 737 Max 8s be grounded in the U.S. For its part, the FAA has maintained there's no basis to take the planes out of service.

Canada on Wednesday joined other nations and temporarily grounded Boeing 737 Max planes, making the U.S. a notable holdout. Canada also barred the jets from its airspace.

On Tuesday, Boeing chief Dennis Muilenburg called President Donald Trump to express confidence in the plane's safety. LaHood said he does not believe politics are playing any part in the Trump administration's decision not to ground the planes.