Speaking with "Fox News Sunday," U.S. Rep. Michael McCaul, R-Texas, said if the plane went north when it deviated from its flight plan from Kuala Lumpur to Beijing March 8, it would have been picked up by radar in the area.
"I think that would be unlikely, because our radar system, detection systems, would have picked that up had it gone that route," McCaul said. "I think the intelligence community and homeland security believe that possibly more likely went the southern route, which would be towards Australia, Indonesia. Now, two scenarios are here. One is that the plane ran out of fuel and landed in the ocean, and it's, you know, that's a bad scenario."
"The other one is it landed in a country like Indonesia, where it could be used later on as a cruise missile, as the [Sept. 11, 2001] hijackers did. That's something we have to use our imagination in these situations," McCaul said.
Greg Feith, a former National Transportation Safety Board investigator, told NBC's "Meet the Press" he also believes it is unlikely whoever was flying the plane went north.
"I would think that if this person whoever is flying the aircraft turned off all the transponders and the ACAR [Aircraft Communications Addressing and Reporting] System they didn't want to be detected," Feith said. "So if you take the northerly track, you go back into a radar environment and then a potential environment where we have space assets that are looking down that part of the world. Why would you want to go back and get into a detected area? If you go south, there is very little radar coverage, if any."
Little is known about what happened to Flight 370 after its communications were turned off.
Peter Goelz, a former NTSB chairman, told Fox all signs point to the culprit being part of the flight crew.
"Well, I think that final point that the signoff came after the physical actions of turning off the transponder, is absolutely critical. It shows that someone in the flight deck, someone with training, was able to do both functions, and that in between the two, he signaled all -- the crew signaled, 'All right, good night,'" Goelz said. "I mean, that is damning evidence that indicates something was going on in the flight deck."
"It's too early to rule anything in or out yet. We simply just don't know enough information," Pfeiffer said.
He said the U.S. government is allocating resources to aid in the Malaysian investigation into the incident.
"The Malaysian government is in the lead. And the president has directed his administration to dedicate the resources necessary to help them. So what we are doing is we have the FBI supporting the Malaysian criminal investigation, we have naval assets helping look for the plane and the National Transportation Safety Board is on the ground trying to figure out what happened," Pfeiffer said.