McCaul said he was briefed before the committee's open hearing by the Department of Homeland Security inspector general and administrator.
A CBS correspondent says the investigators were able to get through checkpoints with mock knives, guns and explosives more than 70 percent of time.
TSA pre-check travelers are exempt from the new screenings and can leave devices in their bags when traveling through the designated pre-check line, according to the TSA.
Undercover tests have found Transportation Security Administration screeners failed to detect test weapons at a high rate, according to sources, findings that one Congressional committee chairman called "disturbing". In that test, operatives successfully smuggled both fake weapons and fake explosives through airport security. The exact number of TSA failings is not entirely known as it was made in closed session; CBS reports it as more than 70 percent while ABC says that 80 percent is in the right ballpark.
While the TSA catches scores of people with weapons - notably former Trump White House adviser Sebastian Gorka a year ago at Reagan National Airport - the inspector general's report in 2015 said that operatives from the office penetrated airport security in about 95 percent of their attempts.
The agency received eight classified recommendations.
Zimbabwe's axed VP is safe, traveling to South Africa: ally
Zimbabwe's fired vice president says he has left the country after receiving threats but he vows to return to lead the nation. Zimbabwe President Robert Mugabe, centre, smiles as he arrives for a a solidarity rally in Harare, Wednesday, Nov. 8, 2017.
The failure rate is actually an improvement from a similar undercover operation undertaken by the DHS in 2015, when operatives found the TSA had a failure rate of 95 percent.
TSA administrator David Pekoske told Congress on Wednesday that the CT technology is the most effective way that his agency can keep passengers safe, but stressed that the cost is a hurdle.
Frank Cilluffo, former director of the Homeland Security advisory council, told CBS News that as long as terrorism is a threat at airports, "the TSA can not be complacent".
In a statement, the TSA said it took the findings "very seriously", and that it was "implementing measures that will improve screening effectiveness at checkpoints".
"To invest in the CT technology requires funding above what the TSA now has", said TSA administrator David Pekoske.