Zenpou Hiyaku Ukemi is a tobu ukemi without tori.
Tobu ukemi (Flip) 飛び受け身
Tobu ukemi is nothing but a forward roll (Zempo kaiten ukemi) where tori holds uke's hand.
See saw
One leg forward, same arm bent so the palm is upwards. Point your head to the floor and move the back leg up making sure your back is straight. There is no roll, just a see-saw motion. Make sure your shoulder are straight and not side on.
Flip
Sit on all fours, present one arm underneath your body (to the opposite side), and let your partner grab it. Whoever grabs the arm has their legs bent and a straight back. Then, they pull the arm up, causing you to flip on your side. Thus landing in the perfect position. Note that your free arm should be hitting the matt first.
Belt roll
Your partner is standing up, you are grabbing their belt knot with your hand palm up. Do the same exercise as the see saw above twice and flip on the third.
Try putting your head straight down in a line, your legs should arc over your body.
The first bit to hit the matt should be your free hand.
Once this step is comfortable, your partner puts your wrist in kote-gaeshi and you do the flip.
Zempo kaiten → tobu
Your partner kneels on the floor, you execute a zempo kaiten roll. From time to time, your parter grab your front arm and a tobu ukemi occurs naturally.
No partner
Start with the see-saw, then roll.