The plan says that the department will begin implementing the exit component at airports "over the next year," and "Sea port deployment will occur after the air environment, so lessons learned can be applied."
But the plan lays out no timetable for an exit portion at the land borders.
"Because of the immense scope and complexity of the land border ... exit information cannot be practically based on biometric validation in the short term," it says.
Mica said that this was "a huge gap" in the proposed system, adding that it did not make sense to introduce exit verification only for airline passengers, because using the system to identify those who were overstaying their visas relied on a comprehensive check of all visitors leaving.
"We need to look at everyone going out," he said, adding that "unless we have uniform procedures," the system's utility would be severely limited.
"It does not make sense to leave that (task of collecting fingerprints) in a haphazard fashion to airline employees," he said.
Homeland Security said it had "recently" begun discussions with the airline industry and "will be working with air carriers to implement" the exit component. The department "will publish a regulation in the future outlining its plans for implementing an integrated air exit strategy."