AT&T and Verizon are set to unleash their 5G networks across the US on January 19, but the launch could ground the more than 9,000 commercial helicopters, including lifesaving medevac choppers, as a result.

The wireless service can render radar altimeters, which measure altitude, unreliable and under US law, all commercial helicopters must have a working device in order to fly.

Without radar altimeters, landing in remote areas or on hospital landing pads will be near impossible, said Ben Clayton, interim chief executive officer of Life Flight Networks, as reported on by .

The issue is medevac helicopters need to land and take off in remote areas, making their ability to measure altitude vital for a successful mission.

Other commercial helicopters that conduct tours or law enforcement craft that need to be deployed in uneasy terrain also rely on the technology.

The Helicopter Association International (HAI) petitioned the Federal Aviation Administration (FAA) in October, asking for air ambulances to be exempt from the law when 5G rolls out.

And on January 13, the HAI finally received a response, but is granted only partial approval.

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'Based on the unprecedented nature of the widespread impacts to radio altimeters … the FAA will grant relief to part 119 certificate holders conducting HAA [helicopter air ambulance] operations in areas in which the FAA has determined that 5G C-Band interference affects or might affect the radio altimeter,' according to the.

However, there are thousands of HAA in the US that cater to at least 300,000 people a year who need to be medevacked to a medical facility.

Helicopters used in medical transportation often land and take off from locations that are not at airports or helipads to evacuate victims of natural disasters or vehicle accidents.  

And a reliable radar altimeter is necessary to ensure the safety of the helicopter, rescuers and patients.

Regardless, the FAA says this type of transportation cannot be grounded even if  the device is not functioning properly due to 5G interference.

'Permitting the use of NVGs in HAA operations in off-airport or unimproved area locations when a radio altimeter might experience interference is in the public interest,' the FAA shared in a statement. 

'The public interest in allowing such operations to continue is considerable, especially given that approximately 40,000 to 50,000 of such operations occur from off-airport or unimproved areas at night.'

The US reported a total of 9,348 helicopters in 2019, which is four times higher than the next largest fleet in Canada.

There has been a lot of back and forth between AT&T and Verizon and the US government leading up to the official roll out.

The launch was initially set to happen on January 4, but due to concerns about how the service would impact airlines the companies agreed upon a two-week delay to give the Federal Aviation Administration (FAA) enough time to fix the issues.

The problem is the 3.7 to 3.98 GHz frequency, known as C-Band, that the two wireless carriers spent tens of billions licensing for use to power their ultra-fast 5G networks.

Officials with the Federal Aviation Administration and Boeing have warned that there is potential for interference with vital aircraft instruments operating in the adjacent 4.2 to 4.4 GHz band, including radio altimeters that tell pilots their altitude in poor visibility.

In short, the fear is that in rare cases, false altitude readings could confuse pilots as they approach for landing in poor visibility conditions, with potentially disastrous results.

However, the two-week delay should give the FAA enough time to ensure there are no disruptions with airplanes - but the same cannot be said for helicopters.