Shock Wave Formation in Transonic Flight

Formation of a shock wave above the wing of a Boeing 737.

The aircraft itself isn't going supersonic, but it's going fast enough (probably around Mach 0.8) that the local airflow over a portion of the top of the wing is supersonic. This is called "transonic," and results in the formation of a shock wave at a right angle to the surface of the wing. The air in front of the shock is supersonic, and the air behind it is subsonic. The shock wave marks the transition between these two regions.

The shock wave is visible because of the abrupt change in the density of the air. The change in density causes a change in the refractive index of the air, and so the scenery behind it is optically distorted, and it also casts a shadow on the wing surface due to the sun being overhead. It helps that I was sitting so that I could view it nearly edge-on... if I had been a couple of rows further forward or back, it might not have been visible.

Further information for the curious:

[stillnotspicy]

For those of you wondering, this is due to flow accelerating to mach 1 over the airfoil creating the shock even though airspeed is only around mach 0.7-0.8. This phenomena is known as the critical mach number.

[josephastier]

It's easy to forget just how fast the wing is moving through the air.

[MentourPilot]

Hi! Great video!
Would it be ok if I used this video as an example, with links to your video, in an upcoming video I am planning for Mentour NOW? Let me know.

[FlyNAA]

There's a few of these videos up, and this one's my favorite because you can see the refraction projected not just on the top wing surface, but also in the free air between the camera and the forward no-step line just a bit inboard from the wingtip. And the winglet fillet section leading edge.

[gerardmoran]

It was a common sight, if you looked for it, on the older faster transports. The 727 cruised at M.82 but could do M.86 when running late. The L1011 cruised at M.85 and I've seen M.89. I only got to see it when deadheading. Sitting in line with the wings it was usually there.

[katanamaki]

I saw the very same thing on a Canadian airlines B767 on a flight from Toronto to Vancouver 30 years ago. Everyone I have described this to told me I was wrong, "airliners can't fly supersonic!"
Thank-you for sharing!

[MrSunrise-]

Beautiful! Thank you! I observed this once myself, and cursed that I didn't have a camera to record it. Thank you so much for sharing!

[jake]

I witnessed this phenomenon on my flight today, a 787. I had no idea what I was witnessing on the wing and began searching all over the internet. Glad I found this, so I know I'm not going crazy!

[prsearls]

I've seen this on some airline flights and on our corporate aircraft. Sometimes the lighting conditions make this more obvious since it's always there during high speed flight.

[jaredharris]

Can someone point it out like where to look I watched 3x can’t see anything

[haljohnson]

i actually see two. the one in the middle, and one ahead of it. the one in front can be seen out on that black tape about 10 feet from the wingtip.

[nagjrcjasonbower]

Nice! Flying at about the speed of pistol bullet makes fun things happen lol...

[TomsSabbatical]

I've told people I saw a shock wave on an airliner and they didn't believe me. HA!

[fgm]

Sorry but those aren't shockwaves. You can also observe this at the wingtips or flap edges during landing. Those are simply "transparent" air vortices.

[balltoball]

I. Would. Totally stare at that the entire flight. So cool

[George.Coleman]

Would a passenger jet like this begin to function normally again if it was mach 1.1 or more so the shock wave isn't occurring over the ailerons/elevators

[crawford]

Amazing! Thank you for letting us see the unseen.

[krishnakanth]

Where should i look and what should i look out for ?

[RoBert-ixev]

awesome video, great to actually see a shockwave!
there are not much of these on youtube, fortunately I found this one :)

[F-Man]

Very cool! Never thought to look for this on a plane - I’ll keep it in mind on my next flight.