A pilot presses the transmit button, says who he is, and lets go.
What comes back is not a controller. It is a flat hiss that holds a second and clears.
The next call does it again.
Nothing is wrong with the radio. Nothing is wrong with the weather.
The only new thing up there is a white dome screwed to the roof overhead, sold to passengers as fast internet.
Within weeks an airline had to choose which one it would rather keep.
They switched off the internet to keep the radio
Think about what that costs. Internet at cruising altitude is what passengers complain about more than legroom, and it was the newest selling point they had.
It went dark on every airplane in the group that had it. Not because anybody was in danger. The airline said plainly it never posed a safety concern.
It went dark because of what the radio does. Every instruction a controller gives has to be read back, and a readback buried in frying gets asked again. Put that on every call, all day, and you have added work to the busiest minutes of the job.
So the new thing went off and the old radio kept talking. That is the ranking, and it is not close.
Why a dish that talks to space can jam a radio
The dome is not really a dish. It is a computer with an antenna on the lid.
And computers make noise. Not the kind you hear across a room, but the kind that turns music to frying when a power drill gets too close to a radio.
A radio does not have to be tuned to that noise to be ruined by it. Two people can talk across a kitchen table until somebody switches on a vacuum cleaner. The vacuum is not speaking. It is simply louder than they are, and the conversation is over.
The controller’s voice reaches that cockpit faint, from far off. The dome sits a few feet above it, frying to itself.
So the huge gap between the two frequencies decides almost nothing. What decides everything is how close the two boxes sit.
Somebody decided where that dome would go
Long before any of this, a person sat down with a drawing of the airplane’s back.
On that drawing are the things already living up there. A little fin for the radio. Another for navigation. Wiring, inspection panels, and the rivets holding it all to metal thinner than a coin.
The job is to find room for one more thing.
The trade calls that configuration and integration, and almost nobody outside it has heard of it. There is no beautiful equation in it, only drawings, spacing and long arguments about inches, and engineers who came up loving the elegant parts look down on it.
Here a satellite antenna had to see the sky, so up it went. The radio’s fin wanted clean metal and a clear horizon, so it was already up there.
On a long airplane there is room for the two to ignore each other. A regional jet has none. Its back is short and crowded, and they ended up close enough to hear each other breathe.
Why a few inches were the whole argument
The reports came from pilots, not from any monitoring system. The carrier switched it off across the whole group in early June.
That group was about two dozen airplanes, a first batch on one kind of airplane, not the whole fleet. A third had already been treated by then, the rest came back over the following weeks.
Here is what the operations chief said about the repair. The two antennas were too close together, and they worked around it.
Short, and not vague at all. Electrical noise falls away fastest right beside the thing making it, so a few inches won up on that roof beat many feet won anywhere else.
Working around it means buying back distance. You slide one further along the roof, you wrap the loud one so less escapes, or you put a filter in front of the one that listens. The route actually taken has stayed private.
It turns up wherever a busy machine sits near something built to hear faint things, like the wind farm that drowned out a radio telescope.
What happens when hundreds more get one
The regional jet was the first type the carrier tried, and that is the point, not a footnote. Sixty airplanes were flying with it by then, against a plan running past three hundred.
Every one is a different airplane with a different collection of things on it.
So the drawing gets opened again. And again. Being quiet enough is not something a box carries from one airplane to the next.
A strange way to lose a schedule. A stranger way to find a fault. A crew heard it first, the way an odd signal on a shortwave band gets heard, by keying a microphone and listening hard.
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