5G use by consumer electronics has definite and (in my opinion) founded concern for aircraft avionics, to an extent. I'll preface this by saying these concerns have been raised and government authorities are seemingly dealing with it so as to avoid any major incidents or disruptions.

The inside scoop that I can give you is this.

5G stands for 5 gigahertz Fifth Generation (EDIT: as some commenters pointed out, I was originally wrong here. 5G stands for "Fifth Generation" and has nothing to do with the frequency range it operate in), and is simply the frequency of which the wireless signals arrive to your cell phone. 5G operates in the frequency band of 3.65-3.98GHz. Frequency in its most basic form is energy pulses, with a higher frequency having those energy pulses closer together (higher energy per time period) and a lower frequency having them farther apart (lower energy). Everything in wireless transmission uses frequency (generally), including GPS, radio navigation, and communication radio.

Now communication radio uses the range 117.975MHz (which stands for megahertz) and 137.00MHz (although the radios are tunable only to 118.00MHz and 136.975MHz, there is a buffer for this bandwidth). This means it is physically impossible for 5G to interfere with any voice communication, as the waves are so so so much different than the range which our radios are built and designed to pick up.

Now as for avionics equipment... most of our stuff is built to operate at vastly different frequencies than anything your cell phone uses, but there is one piece of tech that uses a band very close to 5G. That is the radio altimeter, as I mentioned in a comment above and also in this comment here. Radio altimeter uses the frequencies of 4.2GHz to 4.4GHz, which is less than half a GHz above from cell phone 5G towers. Also, due to the design and construction of this device, it requires utmost precision and signals that are as clean as they can possibly be. This piece of equipment is also very important for low visibility landings (at night or in weather) and is also the main method by which helicopters can autohover at a fixed altitude. All this to say; its very important that it works without interference. Cell towers are extremely high power transmitters, so the concern for these two pieces of equipment conflicting was certainly valid.

Now outside of some headaches and nasty emails between government transport authorities and telecomm companies, what does it mean for you? Well the long and the short of it is you are very, very, very unlikely to ever notice. Telecomm companies don't like building tall cell towers near airports for obvious reasons, and due to the nature of 5G it can be adjusted to be quite precise in where the waves end up. Canada and the US have already introduced mandates for 5G cell tower placement (you can read the CASA that Transport Canada put out here) and it seems that there is no official concern following these.

It very much does not, not at this level at least. I'm sure there is a formula running in the software of these flightdecks or on the satellites that is able to calculate this, and certainly someone who builds and monitors it, but as long as I see the signal bars go green on my screens I'm a happy camper.

Early last year I helped lead a dual GTN750TXi with GDU install on a french made aircraft, the TBM850. The GTN750TXi system is a NAV/COMM unit with integrated GPS, TCAS, XPDR, and audio panel and the GDU was made to replace the primary flight instruments with a large screen for the pilot and copilot.

This install was certainly my most difficult, as these aircraft are not mass produced and you could tell it was not made to be worked on aftermarket. For instance, all of the existing wire did not have any identification stamping on it. In Canada, it is mandated that any wiring added to an aircraft needs to have an identifying mark (usually just some letters and numbers) at set intervals across the entire length of the wire. This ensures that you can properly route, trace, and troubleshoot by understanding what info each wire was carrying.

Not the TBM.

The TBM had baby blue wires going everywhere, all without any markings. This made integrating into any existing wiring (for instance, splicing onto an existing harness carrying engine parameters instead of replacing entire sensors) INCREDIBLY time consuming. It was also very nerve wracking when you found a wire that was cut somewhere behind the panel; obviously as part of removals we need to cut out existing wiring to old instruments, but having a cut wire hanging out and being forced to decide whether to complete taking it out (and risk needing that wire after all) was never a fun call.

Apart from this, the TBM had DOZENS of different connection styles. What I mean by this is typically, a manufacturer will decide on one style of wire termination; cannon plugs, d-subs for units, ground stud/ring terminal, AMP grounding block, grounding rail for airframe grounds, etc.

Not the TBM.

The TBM had a little bit of everything... some ground studs, some ground blocks, even some automotive knife splice grounds. It was impossible to have all the right crimpers/terminations that you might need that day, and we ended up with all sorts of goofy borrowed crimpers from all around the airport for these bizarre decisions.

The last point I'll make about the TBM is the equipment locations and unorthodox avionics placements. Usually, a small aircraft will have avionics in one of three places; in the nose of the plane (forward of the pressure bulkhead), behind the panel of the plane directly in the cockpit, or under the floor.

Not the TBM.

It had stuff all over the place. Some in the floor, some in the nose, some in the far reaches of the tail. This made it very impossible to estimate our wire length prior to the arrival of the aircraft (when we fabricate some of the harness on the bench), so a lot of our prep work was deemed worthless because the wire lengths were so wrong. A lot of wasted time and energy. The TBM is also BLOODY SMALL... so trying to get three techs in there was damn near impossible, even if we were working on seperate systems. Very little space for tools, hands, sightlines, and appendages. A lot of Rub A535 was used on this project.

Great question! Honestly I believe that there are fundamental safety and reputation issues with travelling by air that are simply too difficult to solve in the near future. I also believe that the market for aviation has settled at near daylight-robbery levels, and there is not enough pressure from competition to drive this down to the level where we'll be parking aircraft in our driveways anytime soon.

To elaborate on my first point; Cars are devices of inertia... you press the gas and go forward, you press the brakes and stop. You are only ever fighting one force... which is the momentum of forward or reverse travel. You can mitigate the damage that inertia causes by using seatbelts, crumple zones, airbags, and headrests.

In an aircraft, you are always contending with gravity. This is a much harder puzzle to solve, as it is a constant form of acceleration that you can't resist against. And more importantly, it is always potential energy while your machine is running, but becomes kinetic very fast when the machine fails. I believe that the reason that flying is seen as unsafe and not commonplace is that when your machine breaks, you don't come to a stop but rather begin accelerating towards a very sticky situation.

EDIT: This isn't even mentioning weather considerations, traffic direction, and enforcement all of which pilots train for years to understand and integrate to. Also, we monkeys can barely stay focused and resist distraction when travelling in two dimensions... we really don't need a third.

I really like this question. "Interference" is such a broad term, but what is most in the context of this question and the use of cellphones will be cellular signals and things like wifi, bluetooth, etc... all wireless signals that a cell phone or laptop typically sends and receives.

Within an aircraft itself, wireless transmission between avionics equipment is not used (besides sometimes having a bluetooth enabled audio panel on small privates, to listen to music like a car). There is virtually no way for a wireless signal as small as what a cell phone uses to interfere with avionics equipment busses within the aircraft. It is far more likely that the other wires within a bundle will cause issues via eddy currents, but we have shielding for any high power wires that risk this type of issue.

Now the big dilemma, especially recently, is with the cell phone signals interfering with equipment that receives its OWN traffic from other sources, IE. GPS, VOR, ADF, etc. Every electrical device (generally speaking) that sends and receives wireless signals does so via frequencies, 2.4GHz wifi, 5G or LTE cell towers, etc. All bands of aviation equipment (comm radios, NAV radios, etc) have been easily tunable and isolated from consumer electronics, until the large 5G debacle that came up a few months ago. This was the closest that the industry got to actually having a proper bandwidth conflict in recent memory, since 5G cellular devices are high power and very close to a specific set of equipment used in aircraft called the Radio (or Radar) Altimeter. I won't get too into the technicalities (if youre interested I wrote quite a long piece regarding this here) In laymans terms, this piece of equipment uses a beam of frequencies that sweeps up and down from about 4.2 to about 4.4GHz, and shoots it at the ground. Depending on the received signals in reference to the signals it is sending at any present time, it can determine the distance from the ground that the airplane is to a very precise degree. Because of this, many things that a pilot relies on during landing are dependant on the radio altimeter readings. They are especially important during low visibility landings.

The worry was that since cellphone towers are ground based, high energy, and close to the bandwidth, that there would be interference and faulty readings received in the cockpit. However, steps have been made in most developed countries to avoid the use of 5G and aiming them directionally away from runways. I have never personally heard of a pilot who has had issue with his equipment due to 5G or any other electronic users on the aircraft. The biggest reason, IMO, that airliners ask you to put your electronics away is so you are aware and attentive to the safety briefings and your surroundings in the event that an emergency were to happen at critical flight points, i.e takeoff and landing.

TL;DR: Airplane mode does not save avionics equipment, and the likelihood of your phone affecting anything in the cockpit is nearly zero.