For those attending the Philippine International Hot Air Balloon Festival, traveling by bus, there are at least two viable options.
To get to Clark Field / Angeles City by public bus you can take the Victory Liner from Pasay City and from bus stops along EDSA. The first bus leaves the Victory Liner Pasay terminal at 03:20 and is followed every 40 minutes throughout the day. This bus actually goes to Dau, which is about ten minutes by tricycle or jeep from Clark Field / Angeles City.
Alternatively, you can take the Fly The Bus
service from the Swagman Hotel Manila four times a day starting at 08:00.