Petrie is very panicky and is somewhat aerophobic. Whenever Littlefoot or Ducky encourage him to fly, his usual reply is no. He has a strong relationship with Ducky and is very kind to her, he even forgets his aerophobic ways and helps save Ducky from the Sharptooth. He most likely teased Littlefoot for having a flathead by calling him this twice even after Littlefoot grumpily corrected Petrie. Even people other than Ducky, he is always happy to help, unless flying is involved.