With Air New Zealand recently adding in-flight WiFi to some aircraft, we started to wonder how it works. When you think about how fast a plane flies, it’s amazing WiFi works. If a plane is travelling at 1,000KM/h, that means it’s moving at over 250 meters every second. So by the time you’ve sent off a digital signal, you have essentially moved more than a couple of football fields while you were doing it.
I’ve found in-flight WiFi useful in the USA (albeit the United system doesn’t seem to work over the ocean- I’ve been foolish enough to try it on a trip to Orlando for a conference, only to find there was no service for all the time we were over the Gulf of Mexico) – that means they probably have an “ATG” (Air to Ground) system. This involves two antennas underneath the aircraft that pick up signals from land-based cell towers.
Another system is called Ku-Band. This involves a huge saucer on top of the plane (like a Sky aerial) and it adjusts its angle as the plane flies, keeping itself aligned with a satellite. (It can only connect to one satellite at a time). It’s normally faster than ATG, but slows down if there are lots of aircraft nearby using the same system. Presumably these domes impact aerodynamics, so airlines want them to be as small as possible.
Similar to Ku-Band is Ka-Band which is similar but faster, albeit limited to fewer satellites. I’ve read claims that this is fast enough to watch movies, but you would have to think it wouldn’t be viable if even a quarter of the passengers on a reasonable size plane were using it.
So, evenly distributed in some planes now, up and down the passenger cabins, are wireless access points, presumably with the same challenges we get at home or work!
It seems Air New Zealand have a Panasonic system using Inmarsat’s GX satellites. Whatever it is, it works well for emails and a bit of catching up on work… or your social life!
But, it’s worth reminding readers that just because you can, doesn’t mean you should. Remember privacy! Only read items that are not confidential – you never know who is sitting next to you or just behind you.