The only thing is, if Violet and Dash left the car after Helen did, then how did they get out of the car (assuming that Helen had locked it)? Unless it was one of those with the pull up lock things, though I’m not sure. Perhaps it’s just best to assume that it was, rather than complicating things. 
They could just unlock the car from the inside…and Helen wouldn’t know. Plus while Helen was talking to that guy she got the plane from they could sneak on board just to see what she was up too.
You took the words right out of my mouth there Al-Bob. I agree with you on that.
I know…its just me.
Anyhow they could have slipped on when Helen was walking in her bags then they wouldn’t have been seen.
Violet wouldn’t have been seen, but if Dash tried sneaking on using his speed, he would carry some wind with him, and Helen would’ve spoted a speeding red blur coming on to the plane.
maybe when she got into the cockpit he slipped in…maybe.
Or maybe, while the door was open, and Helen was talking with Snug outside of the plane, that would’ve been a perfect time for Violet and Dash to sneak in.
that seems more logical…yes.
Both points seem equally valid to me, although Violet’s is the one I pay more attention to.
Kinda funny guys. I am writing a fanfic and in this one chapter, Violet recalls how she got Kari to come babysit Jack-Jack while she and Dash figure out what is up with helen and Bob. I am rereading these posts over and over again so hopefully, when I post the chapter, I get every angle right and believeable.
Rereading these posts really helps alot.
The Star Swordsman [first time I’ve called you by your full username in a long time- I don’t know why I’m starting now…]: I’m glad this discussion is helpin’ ya. 
Neither character has given us a reason to think they were lying, so I’ll take the high road and say they were telling the truth. Though they weren’t so high minded as they tried to stick the other with the blame… anyway
For my fanfiction chapter, I envision Violet calling Kari over supposedly to babysit both Jack-Jack and Dash. Wehen Helen asks why she called, Violet could say that she called Kari over so they can work on some homework together. Before Helen leaves, Dash speeds inside to the trunk. Violet then sneaks into the backseat without knowing that Dash is in the trunk of the car. When they arrived at the airport, VIolet carefully hides while she sees Helen talking to Snug. Dash then almost makes VIolet jump out of her skin when he surprises him from behind. Violet tells Dash to go back home, Dash sticks his tounge out and then runs inside a plane that Helen and Snug were sitting next to. Violet saw Helen boarding and hurries onboard, thinking that Dash is on the plane. She finds him, but too late. Helen takes off and the rest is history.
I always thoght that Dash was telling the truth: it was Violet idea. I thinks it fits with the tone of the story, and makes Violet’s lines there even funnier.