It's "flying suit" not "flight suit" in Canada and according to CF Dress Instructions, A-AD-265-000/AG-001 Chap 6 , Annex D
FLYING CLOTHING
12. The following non-operational headdress
may be worn with flying clothing: wedge cap, beret,
turban, balmoral, glengarry, Caubeen, khaki tam-o’-
shanter and tuque (see Headdress Policy, Chapter 6,
Section 1, paragraphs 2. to 5.).
Since Navy and Army personnel do not have wedge caps, they could be wearing any of the other items of (non-operational) headdress when they were not required to wear an operational item such as a helmet (flying or otherwise). While it has been some time since I wore flying clothing (or any other uniform for that matter), I (being Army) have worn berets, touques and ballcaps when in flying clothing. There was even a occasion (prior to DEUs being issued) when I had a CF green wedgie - what can I say, I was on an AIRCOM base and my boss didn't like berets. I will make a confession, I did wear that wedgie once or twice after we got DEUs, but that was when I was down in the USA and nobody knew the difference.