Many of us have a love/hate relationship with our GPS’s. We love the fact that they can tell us when a route is filled with traffic, or a better way to get from Point A to Point B. But we hate it when we are running late and when the GPS route is a convoluted series of seemingly contradictory turns down small side streets, or when we are somewhere where coverage is spotty or blocked.

That is fine when we are in a car, or using transit. But what happens, as I pose in the subject line, when you are flying a plane and its GPS quits working? It sadly is happening with increasing frequency, as the places around the world that are part of conflict zones continues to expand, and because spoofing or blocking GPS signals is one way to prevent military actors from getting precise positions. That link will document exactly what is happening, and you can click on other links at the end of that post to understand the different types of spoofing that have been observed. The number of incidents has risen alarmingly in the past several months, with as many as 1350 daily flights encountering spoofing, but averaging 900.

Now, that may sound like a lot of flights, but when you consider that these days about 100,000 flights fly every day around the world, it is admittedly still a small number. However, the spots where GPS signals are unreliable have expanded to ten distinct areas. Some of these you might suspect, such as around the Middle East and Russia for example.

(I wrote a few years ago about the Russian airlines. This is yet another reason to steer clear of any flights that come near the place.)

But there are several problems behind this data. First, flight crews are not trained to switch off their GPS when spoofing happens. In fact, they run a variety of automated systems that rely on the global GPS network with all sorts of acronyms. Some spoofing hits the autopilots driving the plane, some hit the ground collision radar that prevents planes from hitting the side of a mountain, others hit the transponders that broadcast the plane’s identity. Second, the symptoms aren’t consistent across all these systems: Each system exhibits different behavior when they get spoofed GPS signals. This means that aircrews are losing trust in their instruments, which is not a good thing. Third, the air traffic controllers — particularly the ones handling long-haul transoceanic flights — have to work harder to separate the planes flying a particular route which are in trouble, which means lower passenger capacity and more flight delays. In some cases, the situation happens close to a landing, which means some planes have to “go around” and take time and fuel to attempt a second landing. Finally, there are a bunch of aircraft-related international organizations that work together in a very delicate balance, and spoofing upsets that particular applecart. Imagine the UN, only worse.

GPS spoofing is now being used as a weapon of war, and it is sadly catching on as the investment in small armed drones is small but the damage that they can cause is great if they can rely on precise positioning for their targets. Sadly, it will take some time before the civil aviation industry can retool to work around spoofing in any effective manner.