To much weight on the rear of the trailer behind the axles IMO... I've heard of it happening a lot with those trailers that have the garage on the back... takes all the weight off your drives and works like a hinge. Best if you are going to pack it full of weight to have it forward of the trailer axles. All it would take is a dip in the road on a curve and you're done for... once the trailer decides where it is going no small pickup is going to stop it.

A properly set weight distribution hitch with anti-sway control is always a good idea. When the trailer starts swaying, stay off the vehicle brakes, accelerate and tap the trailer brakes. That is supposed to straighten things out. That's the theory I've always been told. I've never had to do it, hope I never have to and am glad that everyone in that situation is okay.

Titon, short wheel base and long trailer, rear tires most likley not inflated to max. Bad combination.

When the trailer starts to sway never tap the tow vehicle brakes ever, apply braking to the trailer only with the brake controller this will stop any sway. As to the cause could be anything from lack of tongue weight, road surface, water moving inside tanks etc.

I agree with Eagle One, from the report, it sounds like the problem began with too much weight behind the tandem axles. I speak from personal experience. I was hauling a load of 24' construction poles on an 18' car trailer, well within the weight rating of the trailer, and although the poles were overhanging the front of the trailer as much as possible, too much was overhanging the axles at the rear. If I tried to go faster than 60 Km/H the trailer would begin to sway, at about 75 it would sway violently. Solution: drive slow, keep it at 50, and no problems what so ever. For what it's worth, I would never attempt to tow a 28' trailer with a Datsun oops, I mean Nissan. I know they make them bigger now, but to me they, and the Toyotas, still seem a little light duty, no matter what the claimed GCVW rating is. That trailer probably would not have flipped a one ton dodge Chevy or Ford.
metalman.

What a bunch of freakin know it all's

I have to agree with you workinguy.Most of the time when something goes wrong,you have a split second to react.If it is the wrong reaction this is the result.But in those instances,you are not saying to yourself,oh this happened so I must tap my brakes and accelerate.I have been in a lot of hairy situations and I have been lucky to react correctly to avoid the accidents.Usually I couldn't tell you the step by step process I initiated to avoid the crash and at that point it really doesn't matter,all you care about is you avoided the accident.

If it wasn't for all the "freakin know it alls," I guess noone would ever learn something new or hear different theories to try in different situations. Then, they will just randomly react when the stuff hits the fan. Having an idea in the back of your mind for when things go wrong is better than going into a situation with no concept of what to do. Luck is often involved, but having some knowledge increases your odds quite a bit. I'm assuming by your comments that when you got into those hairy situations, you just reacted randomly. JMHO

I've been running the highways for 36 years pulling everything from snowmobile trailers to super B's. Never had any problems, ever.
The bottom line is, if you do everything correctly like you should, things like this do not happen unless there is some type of mechanical failure.

My3Centsworth,yeah I have a huge problem with all the "freakin know it alls",when it is the professional drivers who are the ones that are suppose to know the steps to take and they are the ones that have almost cost me my life or have caused injury to myself.They were the ones in control when I have been T-Boned or flipped and rolled over many times,as I was just a passenger along for the ride.Whenever,I have been in control,I have not had these results,so put that in your "know it all" file for future reference.

Jakeadoo; If I could figure out what you mean, I might respond differently. By your last comment, I get that you have a thing against professional drivers. I think. That's how I read what you wrote. Then you say that when you have been in control, you've never had a problem. Great. I'm pleased. I will put that information in my file. I don't know how that will help me or anyone else though. I guess you know a whole lot more than I do. Good job! I feel a lot safer knowing that you are in control and yet are unable to explain how you have so miraculously survived so many incidents. I guess I've been pretty lucky. I've only been driving for a few decades and haven't had too many wrecks. Call it luck, call it driver training, call it education, call it practice, call it driving defensively, call it whatever you want. I'm sorry if some of the know-it-alls ruined yor day by sharing their thoughts.