I’m just curious what the bottlenecks are and what has been done to improve those. Because I remember when it would take 10 seconds to send an imessage and now I can watch YouTube when my connection is solid. Just impressive and I’m curious about it.
In: Technology
Oh, I love questions like these, because my job is technical strategy and engineering for inflight WiFi at an airline! (And before that I did WiFi for cruise ships)
First and foremost, satellite connectivity on a flight is exceedingly complicated – you have to send a radio beam about a 1° wide from an airplane moving at 800km/h up to a target about 2-3m across on a satellite that is 35,000 km away in geosynchronous orbit and is itself moving at 18,000 km/h. The satellite beam coming back is much wider and typically covers several hundred km across. (And this gets very different when dealing with a low-orbit platform like Starlink… more on that in a minute). I do this for a living and I’m still amazed every day that any of this actually works at all.
That satellite beam has the ability to deliver about 100Mbps (on Ku-band) or 200Mbps (on Ka-band), but it’s usually shared between multiple airplanes.
So what’s changed in the last 5-10 years? Simply put, demand. There are a lot of more people that want to use the internet in flight, and so the beams have to be shared between fewer and fewer airplanes. Which means you need a LOT more beams up there. Older satellites can support about 50 beams. Newer smaller ones can support a few hundred, and 2023 saw the launch of two satellites the size of a bus that had several *thousand* beams. One of them failed when it reached its assigned orbital station, and its owner was able to salvage about 10% of its capacity, which is still several hundred more beams.
my airline has about 3/4 of our fleet of over 800 airplanes in the air over North America at any given time. Each of those airplanes has 150-170 passengers on board, many of whom use the internet, for about 4000 flights a day (and that’s just us, there are almost 10x that many airplanes up there with us!)
Each one of those thousands of flights transfers several gigabytes of data. Often it will switch from one satellite to another during the flight. The antenna in the hump on the roof dutifully tracks where it needs to point, through aircraft maneuvers and turbulence.
putting stuff in orbit is *obscenely* expensive, especially big stuff. But in the last decade or so, the cost to put stuff in space has dropped significantly because SpaceX figured out a way to launch rockets faster and cheaper. And so a lot of satellites have been launched in the last decade.
SpaceX also figured out that if they were gonna be yeeting rockets into space anyway, that instead of using water, or potatoes, or Justin Bieber albums for weight, they could manufacture a whole bunch of tiny satellites that flew around at about 550km above the earth instead of 35000km, that they could use to deliver internet a lot faster… because it takes a radio wave moving at the speed of light almost an entire second to go up 35000km to space and back down again to get to the internet. When your satellite (which is basically just a really fancy WiFi router) is only 550km away, that signal gets there and back in a few milliseconds. The caveat is that when the satellite is that low, it’s orbiting the entire planet once every 90 minutes or so, which means you’ve gotta hit a moving target. Easy for an airplane to do, though.
The catch is that in order to install all that fancy gear on an airplane, a whole lot of engineering and testing has to happen to make sure the changes to the airplane don’t compromise its ability to fly. This process takes *years* to get a given system certified on a particular airplane.
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