TS's
I believe it's generally accepted that once inside a fully developed mature TS then all bets are off & comes down to a fight for survival!
The conditions within would be horrendous with up & down droughts exceeding the limits of most A/C of the light cat not to mention that the pilot 'may' only be VFR capable (I don't know that for a fact). This combined with the incredible disorientating environment the pilot found himself in together with the added fact that the ASI was now out of his control as a VFR driver as well as all the other inst going nuts! & possible lightening as well as possible defining hail belting the airframe ( & the screams within the cabin) would all add up to an uncontrollable event even to a well trained IFR pilot that saw the airframe leaving normal controlled flight 'till it hit the water/ground possibly not intact.
Obviously all of the above is just a scenario but is very plausible & it's been well documented that we ALL stay well away from TS's & for good reasons.
I once had the displeasure of experiencing some severe turb whilst flying down the side of a line of TS's in southern Vic by about 30-50 miles in clear visual air, the turb was nothing short of approaching airframe/pilot limits & I wasn't anywhere near it...well at least I thought I wasn't. I can't imagine what these people went thru if indeed he/they entered a TS.
Lets all hope that the poor unfortunates have gone to a better place & that this sad event will leave the rest of us a little more cautious.
Wmk2