In one California border town, at least four drug-laden, ultralight airplanes from Mexico land each night on U.S. soil, dropping off hundreds of pounds of narcotics then flying back to Mexico, all the while eluding a $100 million detection system funded by American taxpayers.

The U.S. Border Patrol’s inability to find and catch these planes, operated by the Mexican drug cartels and sometimes piloted by armed dealers, is among the emerging border security threats a House Oversight and Government Reform Committee hearing will tackle on Thursday.

The panel wants to highlight growing border security problems as Congress debates immigration reform legislation that includes provisions aimed at bolstering border security, Rep. Jason Chaffetz, R-Utah, told the Washington Examiner.

Chaffetz, who will oversee the hearing as chairman of the panel’s subcommittee on national security, says he has doubts that pouring more money into the border will adequately improve security if the billions of dollars already spent are not making much of a difference.

“These planes take off in Mexico with the drugs, go across the border and drop them off and then the ultralight lands back in Mexico. And we are fairly inept at dealing with them,” he told The Examiner.

Chaffetz learned about the deluge of the home-built drug planes crossing the into the United States during a visit earlier this year to border areas in Arizona and Mexico.

Border patrol agents told him that despite the hefty price tag paid for the sensors, they are not helping agents stop the ultralights. The planes land in border towns all along the Mexican border, including El Centro, California, where multiple air drops happen every night.

Success rates at detecting and capturing the planes, one border agent reported, “are very low.”

Lawmakers, committee staff and the General Services Administration on Wednesday all identified the contractor that provided the sensors as SRC Tec. But hours later, the GSA posted an online notice that the contractor had changed. The new contractor is Management Services Group Inc., of Virginia Beach. An SRC Tec spokeswoman said SRC hadn't delivered equipment to the border because a stop-work order was placed on the contract last year.

Chaffetz said border agents are also grappling with an influx of illegal immigrants sneaking across the Mexican border who are not from Mexico. They are identified as “OTM” or “Other than Mexican.”

The Eloy Detention Center in Arizona, for example, has detained 900 people from 60 countries other than Mexico.

Many of them from Central and South America. But there were 127 detainees from India as well as 22 people from China and one person from Afghanistan.

“We have a surge in OTM’s coming across the border,” Chaffetz said.

Thursday’s hearing will feature testimony from U.S. Border Patrol, Customs and Border Protection Chief Michael Fisher as well as officials from Immigration and Custom Enforcement, Citizen and Immigration Services and the Government Accountability Office.

The Senate on Tuesday approved an amendment to a comprehensive immigration reform bill that calls for 20,000 additional border agents and $4.5 billion in new technology and equipment requested by border agents.