Arthur T Knackerbracket has processed the following story:
United has switched off Starlink service on its United Express regional aircraft following reports of radio interference. According to The Points Guy, Starlink connectivity has been turned off across its fleet "out of an abundance of caution," a move the carrier confirmed in a statement.
As noted by the report, United has installed Starlink on nearly two dozen Embraer E175 aircraft. United announced the rollout on March 7, outlining plans to fit 40+ regional aircraft each month beginning in May through the end of 2025. The installation takes around 8 hours per aircraft, and United eventually plans to roll out Starlink to its entire fleet.
TPG reports that United has received reports of radio interference caused by Starlink, affecting the VHF antennas pilots use to contact air traffic control. As such, the aforementioned E175 aircraft carrying Starlink have been operating offline for the past few days, including a flight Tom's Hardware took on Monday, June 9.
United has issued a statement to TPG noting "Starlink is now installed on about two dozen United regional aircraft. United and Starlink teams are working together to address a small number of reports of static interference during the operation of the Wi-Fi system." United says this is "fairly common" with any new airline Wi-Fi provider, and says it expects the service to be back up and running "soon."
TPG reports that United and Starlink have already identified a solution and are rolling out the fix to affected aircraft. Allegedly, one-third of the affected planes have had the fix applied and are now operating with Starlink restored, with the remaining planes set for reconnection once they've had the fix applied.
(Score: 3, Interesting) by DannyB on Friday June 13, @06:29PM (8 children)
From teh Google: (sic)
and then . . .
and then and then and then and then and then . . .
It seems to me, not a radio engineer, that these are a fair spread apart.
So what could it be? An escaping sub harmonic in the Starlink or the WiFi equipment interfering with VHF?
Since it is Embraer aircraft, I can't just pick the most likely explanation and blame Boeing.
The server will be down for replacement of vacuum tubes, belts, worn parts and lubrication of gears and bearings.
(Score: 3, Interesting) by janrinok on Friday June 13, @06:43PM
Quite possibly, or one of the frequencies is mixing with another from a different source thus creating 2 additional side frequencies. The possibilities are numerous, but as they appear to have traced it and started to rectify it then perhaps we will never know.
[nostyle RIP 06 May 2025]
(Score: 1) by khallow on Friday June 13, @07:21PM
Starlink is a phased array. There would a control system operating at well below the frequency of the broadcast service and that alone would generate a substantial internal signal.
(Score: 5, Informative) by VLM on Friday June 13, @08:51PM (2 children)
A circuit that's theoretically and practically linear will not mix.
Anything non-linear will cause mixing products. Usually very low, it actually takes some work to make an efficient mixer. Any semiconductor fed 16.000 GHz and 16.12345 GHz will have at least some signal, however minimal generated at 123.45 MHz (which is kind of a plane to plane gossip channel on VHF)
The good news is its usually quite a few dB down so in practice it's not too much of an issue to put enough filters to clean it up.
There are no numbers in the story; is it technically barely noticeable or is it a major problem, who knows? Seems like they think it'll be no problem to fix so it must be a pretty minor level issue.
Its complicated aircraft esoteric legal stuff but I think starlink applied for the STC and so you'd have to blame starlink? But there's plenty to go around because the FAA had a minimum of three chances to block the change and they didn't so ...
For swapping equivalent commodity radios you don't need a STC, for a major change like adding a complete new system you'd probably need a medium complexity STC and some huge change like installing a totally different engine would require a full re-permit. STCs are considered IP imaginary property and are bought and sold for big money sometimes.
An analogy to a type certificate is maybe planning committee permission to initially build a house to a certain plan given engineering and architectural approval processes.
A SUPPLEMENTAL type certificate is more like a building permit to remodel or add a deck or something like that on an existing TC.
Anyone can ask the FAA for a STC, not just the original mfgr aka TC holder. The TC holders do get butthurt occasionally if someone steps on their turf and submits their own STC to do something aftermarket that the TC holder wanted to do themselves as a model upgrade. As I probably inaccurately understand it, starlink asked for the STC so I think you have to blame starlink.
Anyway, after applying, the FAA responds with a huge list of specific demands, tests, reports required to prove to the FAA that it'll be safe or more specifically that it'll meet safety regs. Someone's engineering dept submits "proof" it'll meet all regs in theory. The FAA and engineering go back and forth until the FAA is happy and signs off. That's the end of the planning stage.
Virtually always the planning stage will include plans for ground and air testing and the applicant will have to perform and submit data to the FAA, so they do that, to perhaps one airplane. If the FAA is chill so far, the FAA does its own testing or at least observes and approves the final version testing, and when it passes the FAA signs off when they're convinced it meets regs.
Finally the third chance the FAA has to say no, is to officially issue the final approved STC as part of the set of docs. In theory even if a 3rd party jumps thru all the FAAs flaming hoops demands in the first two stages, the FAA can still at the last stage say "F no" if they want to.
If you want an airworthiness cert on a specific aircraft (perhaps to carry passengers) that specific plane needs to match the original TC and some collection of STCs.
Starlink has a huge list of STCs to install on various aircraft. They've obviously dumped some millions into this.
https://www.starlink.com/support/article/9c43bea7-0645-5854-6842-dabb0def8a94 [starlink.com]
Note there is nothing obviously "unusual" about putting a high power microwave transmitter on an airplane around radar frequencies, they've been doing that since the 1940s so this is not likely an interesting story, its almost certainly boring human error. Whoops forgot to model the EM fields if the rudder is at full deflection while the trim tabs are at the opposite deflection so too much signal bounces back into the other antenna sometimes, stuff happens.
Also, there's nothing "unusual" about STCs, this is how everything in non-experimental non-homebuilt aviation is done. I know there's always a tendency for Elon Derangement Syndrome to kick in but this looks pretty boring, BAU stuff. It's mildly unusual that this reported interference did not show up when the FAA signed off on the acceptance testing. Every aircraft is a little custom so possibly its the exact set of STCs combine to create an issue.
(Score: 2) by corey on Saturday June 14, @01:18AM (1 child)
Yeah, intermodulation distortion (IMD) products like you say, f1-f2, f2-f1 with are second order, then there’s third order, 2f1-f2,2f2-f1 etc. Going off memory and typing on my phone here. I would surmise that the aircraft VHF receivers are seeing the Ku/a band signals and generating the IMDs. Power tx level of the Starlink transceiver should be fairly low since they are phased arrays but I guess they Need to talk to satellites far away, eg. 800km based on 300km altitude and 70deg slant angle. I would also assume that Starlink systems might be leaky but they’d have to meet EN55022 and/or 461D to go on the plane. In this case it could be the VHF susceptibility mainly at fault. They never expected a Ka band transceiver to be installed at the same time. Dunno about what input filters they’d have but you’d safely assume pretty good bandpass filters, then again the tracks on the VHF PCB might be just nice quarter wave lengths at Ka band.
(Score: 2) by VLM on Saturday June 14, @02:21PM
Specifically, yes, but I was bored enough to look up the E175's onboard weather radar and if I'm reading the correct Honeywell brochure, its got a nifty x-band radar on board with multiple tilt angles, pretty cool. Precisely 917 watts, so they claim. So thats more power and closer in frequency than the starlink systems so starlink "should have" been OK but someone forgot something or skipped a step or theres an unfortunate sidelobe at just the wrong spot etc etc.
The starlink probably only uses peak power under unusual conditions (in rain, etc) and maybe thats the problem. There's a mini system for general aviation AC and that one has a news release on some aviation site about "Power requirement for the Starlink Mini system is 12 to 48 volts at 60 watts, with users reporting better results with 24 volts." They're probably talking DC average (to select wire and circuit breaker size) not peak. Still the weather radar on the plane sounds higher power than the starlink probably is.
Yeah there are also other problems that can be rough. "back in the day" people had hi fi stereo systems with bipolar transistor output stages connected by speaker wires usually around the ham 10M, 6M, maybe bookshelf systems 2M range, so there was lots of fun picking up RF from the speaker wires, rectifying it in the output transistors, and making all kinds of noise and interference. Thats why people sometimes use shielded wire for speakers... Maybe the wires inside the pilots microphone are resonant at K band LOL who knows. A little later than the above stories some amps have inherent protection diodes that feed voltage higher than B+ and lower than gnd back into the power supply to be dissipated and early/mid switching power supplies could get really mad when a bunch of RF was dumped into them, so thats fun too.
Really, any piece of wire that's unshielded / ungrounded is a random length antenna, its just some lengths and frequencies are worse than others.
(Score: 2) by JoeMerchant on Friday June 13, @09:08PM
It's the Klux and -l-n bands that interfere the most.
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(Score: 1, Redundant) by DadaDoofy on Friday June 13, @11:45PM (1 child)
A similar thought occurred to me. However, without enough specific knowledge on the topic, I was happy to wait and see if someone else asked the same question.
(Score: 4, Funny) by Tork on Saturday June 14, @04:48AM
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