To ask how someone is travelling (in the sense of by what means of locomotion) you can either use Кђк...? as illustrated above, or На чём...? as illustrated below. Use на + Prepositional to express 'by'.
На чём тІ љдешь в Калифћрнию, на машќне? How are you going to California, by car?
If you want to ask if someone's going by plane, use the verb for 'fly', e.g.
ТІ тудђ летќшь? Are you flying there?
If you want to specify that you are not going by vehicle (or horse, bike, etc.), use the word пешкћм 'on foot':
Ї идџ тудђ пешкћм. I'm walking there [going on foot].