Plane trembled then dropped!

Hi Captain Lim,

I stumbled upon your site recently and I am very thankful for the service you're doing for the flying public.

Anyway, a few years ago, I was on a Cathay Pacific flight from Hong Kong to Rome. We were on (or near) the decent phase of the flight when the plane started to vibrate/tremble/shudder.

I can compare the feeling to a car engine that's having trouble starting or staying turned on.

Right after, the plane suddenly dropped to its left side for around two seconds.

This happened another time before we landed in Rome.

From what I remember, the weather outside was pretty fair, with a few clouds scattered about.

What do you think could be the cause of this?

Hope to hear from you soon!

Thanks!

Ven