Hello guys,

i am not a pilot, just a jolted passenger after a rough flight.

I have been flying for 24 years with no issues, and suddenly and afraid to fly....I had a particularly bad experience recently and was hoping someone could give me an explanation as to what happened.

I was flying back from Las Vegas to LAX on southwest about 2 years ago, we were preparing for decent when out of no were the entire plane dipped on its left side ( felt like vertical but probably 10-20 % tilt....almost immediately it felt like the auto pilot kicked in and we were bounced back to level flying.

Everyone was shaken on board, and pilot made no announcement.

It felt like he nudged the stick with his leg!

Anyone have an explanation?

 

No way to say for sure without being there but sure sounds more like a possible wake turbulence event. If so opposite would be true where out if the blue one wing dips, auto pilot can't control it and clicks off leaving the pilots to pick up the pieces.
You said descent into busy airport which have planned arrivals so an encounter with previous traffics wake does not sound unreasonable.
I can assure you though bumping the yoke with your knee, especially with the autopilot on would not produce a 10-20 deg wing down situation even with autopilot off in which the pilot would be hand flying.
Luv

 

Most likely wake turbulence...the aircraft flew through the disturbed air behind another plane (imagine the wake behind a boat, sort of like that but 3-dimensional). Wake consists of two spinning vortices...if you fly into one at a certain angle the vortex can cause the airplane to roll. Not a big a deal on the descent, you just level the wings again. But on short final near the runway it can be catastrophic if a smaller plane gets in the wake of a larger plane...the roll can exceed 90 degrees and there may not be time to recover due to low altitude...for this reason controllers maintain specific separation between planes in the approach environment.

Weather-induced turbulence is usually more of a bump than a roll (like a speedbump) although at low altitudes on a hot day or windy day you can get turbulence induced rolls.

But a roll out of the blue so-to-speak was probably a wake encounter...not considered abnormal or hazardous at higher altitudes, although controllers should not put a small plane into a position to hit wake from a significantly larger one.

 

Definitely sounds like an air pocket...heh, heh.

 

Based on the part of the country you were in, maybe air being lifted by the terrain disrupted relatively smooth airflow your plane was flying through? Because you were starting a descent, your aircraft was leaving the altitude(s) affected by the lifted/disturbed airflow. Maybe the event felt worse than it actually was. I was non revving the other night and we hit probably the worst turbulence I have experienced in a medium to heavy pax jet--the pax were vocal and drinks were flying....but at worst we didn't pitch or roll more than a few degrees. It probably *felt* like we did though!

 

We are getting better with wake turbulence and avoiding it. These days it amounts to spacing mostly, but a few isolated incidents still get through. It is severe enough to bring down large aircraft like Airbus A320s, when they go through the wake of a 747 sized aircraft. The bigger the difference in aircraft, the more severe this becomes. Some of this is due to improper recovery on the pilot's side, some due to controllers for the spacing, and so on. I think a lot of people fail to think about it in "3 dimensions". I still get nervous when I get into the terminal area with bigger aircraft above and below me. There are some technologies in development that will help to mitigate this even further, but it's still a hazard and a risk due to humans in the system. Realize that when you're driving, some random person could just T-bone your car out of nowhere, so we do the best we can and try to mitigate the risk through various systems and training.