That El-Al 747 flight debunked 2 myths:
- Bigger planes are more comfortable.
- Turbulence is felt less in bigger planes.
(The 747-200 was as-big-as-they-come back then)
Is that a myth?
(I will guess that you are talking about turbulence)
Partially. Wing loading is a factor. The higher the wing loading, the less vertical acceleration under the same updrafts / downdrafts.
Stall speed is a good indicator of relative wing loading. And take-off and landing speeds are a good indicator of relative stall speed.
A 747 or A380 or 777 ("heavy" and "super" planes) have a much faster take-off speed than a 737 or A320. Think 180 vs 140 kts.
But the landing speed for all tends to be more similar.
That is because while the MTOW / empty weight ratio is more or less similar, at take off much more of the load that is not empty weight tends to be fuel in a large long-haul plane than in a smaller plane.
So we can say that while turbulence tends to feel worse in a 737 than in a 747 during take-off, climb and a good part of the cruise, the sensitivity to turbulence as fuel is burned increases more for bigger planes all planes are more or less the same by approach and landing.
I have done 30+ transatlantic legs on a 747-400, over 100 on an A340-600 and 2 on an A380. Half a dozen on a variety of 777s and a couple on a 787. I have done multiple NY-LA in 767s, 737s and A320s.
I have done many dozens of legs in A319s A320s in Europe batting around between the mainland, Ireland and the UK
It's irritating how small the sample size is, but the A380 was the smoothest of all the flights.
The A380 was the smoothest.
"The smoothest" is not a good way to rate how sensitive to turbulence a plane is. You can have a perfectly smooth flight in a Piper Tomahawk (I had a few and they are AMAZING). If you had enough exposure to all types to have encountered all regular levels of turbulence in all of them, the question would be which one was the worst, the second worst, and so on.
But of course it is very hard to be exposed to that. In my case my worst was in a 777, my second worst in a 747, and my 3rd worst in a Fokker F-27. And believe me it is not because it is a parabola where biggest and smallest are worse and the ones in the middle are better.