5G Interfering With Aircraft

Subject – Science and Tech

Context – FAA to prohibit many flight operations due to risk of ‘5G’ wireless interference

Concept –

Altimeters are the instruments that pilots use to determine an aircraft’s altitude or height.
The airliners have two types of altimeters on board: a barometric altimeter and a radio altimeter.
- Pilots use the barometric altimeter almost exclusively, and it’s used to determine altitude above mean sea level.
- The other type of altimeter is called the radio (or radar) altimeter. This altimeter determines an aircraft’s precise height by bouncing radio waves off the terrain below. It only works from the ground up to a few thousand feet.
Pilots use radio altimeters when conducting approaches to airports in low visibility.
These approaches are predicated on a minimum height at which pilots must see at least the approach lighting system — it’s called the decision height. If they don’t see the lights or runway, they must execute a missed approach and wait until the weather improves, and if it doesn’t improve, must divert to an alternate airport.
For these types of low-visibility approaches, pilots use the radio altimeter to provide precise guidance on exactly how high they are, since they often won’t be able to see anything until seconds before touchdown.

The issue

A study conducted last year shows that 5G transmissions in C-Band spectrum interfere with radio altimeters on aircraft, saying there is a “major risk” that these systems “will cause harmful interference to radar altimeters on all civil aircraft.”
These radio altimeters operate in an adjacent spectrum to 5G C-Band and are susceptible to interference.
The Federal Aviation Administration views this as a major safety issue, and, formally published what’s known as an airworthiness directive, or AD — a formal order requiring operators to take action for safety reasons.
- This AD says that the FAA will publish Notices to Air Missions, or NOTAMs — important, time- and safety-critical information that’s related to operations at a specific airport — when it’s determined that 5G C-Band towers will be in the vicinity of an airport.
- Those NOTAMs will prohibit certain operations requiring radio altimeter data at those airports.
To be clear, the FAA is taking issue with 5G C-Band towers, and not passenger cell phones. While your personal phones should always be in airplane mode, and the captain can order all devices turned off if any sort of interference is detected, the FAA views towers as the threat, as they can’t easily be turned off like a personal device.