Soaring westwards high above the Baltic sea yesterday, befuddled by sleeplessness and exhaustion after an intense working week in St Petersburg, I was examining the clouds from my window seat and struggling to stay awake when another airliner suddenly appeared in the sky, bearing down on us.

It was approaching our own plane from the right, at a slightly lower altitude, and within two seconds it had vanished under our wing and out of sight, passing us at a distance of between 500 and 1,000 feet. No-one else seemed to notice it. Five seconds later the cabin started to rock as its wake hit our fuselage. The shaking was nothing serious – just some mild turbulence – and stopped after ten seconds or so. Then it was all over.

When you see an airliner travelling at full speed, you’re usually in one of two locations. You might be on the ground looking up, gazing at distant planes crawling across the sky. Or else you’re actually inside the plane, looking out as the clouds slide by. Either way you don’t get a clear visual sense of how fast these things are travelling, so to see one zipping by at cruising altitude was a pretty interesting experience. It was easily the fastest thing I’ve ever seen.

Funnily enough, it wasn’t as scary as it might sound. It was obvious at first glance that the plane’s trajectory would take it underneath us. There was a tense few seconds between seeing the plane and feeling the shockwave hit – how powerful would it be? – but when the rocking started it was obvious that the plane could handle it.

While writing this post I’ve been searching Youtube for near-miss videos, and haven’t found any examples where the planes come as close as these two did. Maybe it’s normal, but I’ve never seen it happen at high altitude – only when planes are in holding patterns over airports. Has anyone else seen planes come that close, at that speed? Is it an everyday thing? Or should we all have been more alarmed?