Notes > Four Boeing 737s and one happy passenger

On one Monday flight in December, despite having a free window seat (A), I requested a change to the other side (E) at the gate for a (not so) strange reason. Had my request not been denied, I would have missed the closest encounter with another aircraft I’ve ever experienced during a flight until then.

Midway through my journey, having covered at least half of the distance, a plane suddenly streaked by at an unexpectedly close proximity. In the nighttime sky, I could distinguish the fuselage, wings, and the entire body; it was too close and passed too quickly. I noted down the time of the encounter. Motivated by a compelling urge to quanity the closeness, later that night, I figured out what the distance could be, and my calculation based on map scale, flights’ altitude, and the Pythagorean theorem turned out to be a little upwards of 700m. That was close!

Flightradar24 screenshot.

Another encounter on my way back added a layer of confusion. It’s possible that this fresh encounter has become the new closest one.

Flightradar24 screenshot.

This was the first instance I observed another flight’s trajectory closely intersecting ours (on a 2D projection of course). The altitude difference between the two flights this time was around 2000 feet, unlike the previous one, which had a 1000-foot difference (see RVSM). At the best-case scenario for the closest approach, the distance this time could be around 610 meters. With inconsistent flight position at smaller length-scales on Flightradar24, I cannot conclusively determine which of these two interactions had the flights closest to each other. But these two seem to be the top 2 for me.

Contrails at 40000ft shot as seen from 38000ft.
Contrails at 40000ft; picture from 38000ft.

2023-12-XX