What you need to know about 5G interfering with aircraft

Dec 9, 2021

This post contains references to products from one or more of our advertisers. We may receive compensation when you click on links to those products. Terms apply to the offers listed on this page. For an explanation of our Advertising Policy, visit this page.

You may have seen some recent news stories about 5G wireless technology affecting aircraft, and how some flight operations might become difficult during periods of time when the weather is less than ideal.

So what does 5G have to do with aircraft?

First, it’s important to talk about altimeters — the instruments that pilots use to determine an aircraft’s altitude or height. The airliners familiar to TPG readers 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.

Want more airline-specific news? Sign up for TPG’s free new biweekly Aviation newsletter!

Pilots use radio altimeters when conducting approaches to airports in low visibility, like when airports such as Houston (IAH) or Seattle (SEA) get socked in by fog. 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. Aircraft conducting automatic landings (exactly what it sounds like) in low visibility also rely on this data. Finally, radio altimeters power aural digital height callouts (“50, 40, 30, 20, 10”) on aircraft, increasing a pilot’s situational awareness.

Radio altimeters are an important tool for pilots during low-visibility landings. (Photo by Martin Von Castell/EyeEm/Getty Images)

On Jan. 5, Verizon and AT&T will switch on a new spectrum of 5G wireless communications — the C-Band spectrum. The problem is that a study conducted last year shows that 5G transmissions in this 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.

More: What happens when you don’t put your phone on airplane mode?

The Federal Aviation Administration views this as a major safety issue, and on Thursday, 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.

Imagine this scenario: You’re on an Alaska Airlines flight into SEA, and as is common, fog is rolling in. Normally, your pilots would be able to conduct one of these low-visibility approaches. But there’s a 5G C-Band tower near SEA, and the FAA has published a NOTAM prohibiting this type of approach because the tower interferes with your aircraft’s radio altimeter. Your aircraft is placed in a holding pattern for a bit, but unfortunately, the weather does not improve, and you must divert to your flight’s alternate airport in Portland, Oregon (PDX).

It’s this scenario that could play out in the coming weeks and months, and a major pilot union is sounding the alarm.

“There are ways that 5G can be deployed while maintaining our high level of aviation safety, and time is running out for the wireless industry and the broader aviation community to work together on implementing mitigations that will ensure that every passenger and cargo flight arrives safely without severe disruptions to aviation operations,” said Capt. Joe DePete, president of the Air Line Pilots Association, which represents pilots at Delta, United and smaller carriers.

As ALPA and other industry stakeholders keep negotiating over 5G C-Band, it seems highly unlikely that the FAA’s AD will be the final word on it.

Featured photo by southerlycourse/Getty Images.

Chase Sapphire Preferred® Card

WELCOME OFFER: 80,000 Points

TPG'S BONUS VALUATION*: $1,600

CARD HIGHLIGHTS: 3X points on dining and 2x points on travel, points transferrable to over a dozen travel partners

*Bonus value is an estimated value calculated by TPG and not the card issuer. View our latest valuations here.

Apply Now
More Things to Know
  • Earn 80,000 bonus points after you spend $4,000 on purchases in the first 3 months from account opening. That's $1,000 when you redeem through Chase Ultimate Rewards®.
  • Enjoy benefits such as a $50 annual Ultimate Rewards Hotel Credit, 5x on travel purchased through Chase Ultimate Rewards®, 3x on dining and 2x on all other travel purchases, plus more.
  • Get 25% more value when you redeem for airfare, hotels, car rentals and cruises through Chase Ultimate Rewards®. For example, 80,000 points are worth $1,000 toward travel.
  • With Pay Yourself Back℠, your points are worth 25% more during the current offer when you redeem them for statement credits against existing purchases in select, rotating categories
  • Count on Trip Cancellation/Interruption Insurance, Auto Rental Collision Damage Waiver, Lost Luggage Insurance and more.
Regular APR
16.24% - 23.24% Variable
Annual Fee
$95
Balance Transfer Fee
Either $5 or 5% of the amount of each transfer, whichever is greater.
Recommended Credit
Excellent/Good

Editorial Disclaimer: Opinions expressed here are the author’s alone, not those of any bank, credit card issuer, airlines or hotel chain, and have not been reviewed, approved or otherwise endorsed by any of these entities.

Disclaimer: The responses below are not provided or commissioned by the bank advertiser. Responses have not been reviewed, approved or otherwise endorsed by the bank advertiser. It is not the bank advertiser’s responsibility to ensure all posts and/or questions are answered.