Solution: PH1: Vexillology

Answer: MAN OVERBOARD

Written by Derek Young

As clued by the starter text, 5-bit binary is involved here, and it relates to the Olympic flag.

If you identify each country on a world map and then line up the colors seen on each country flag against the Olympic flag, and convert the result to binary, you get a letter per flag.

Djibouti

10011 = S

Canada

00001 = A

Colombia

11001 = Y

Vanuatu

01111 = O

Uzbekistan

10011 = S

Bangladesh

00011 = C

Poland

00001 = A

Sierra Leone

10010 = R

Guyana

01111 = O

Jamaica

01110 = N

Nigeria

00010 = B

Mozambique

01111 = O

Singapore

00001 = A

Estonia

1010 = T

The collected letters spell out the phrase SAY OSCAR ON BOAT, which is a reference to the alternate meanings of maritime signal flags. Specifically, the flag for O (Oscar) also signifies the answer, MAN OVERBOARD.