Going to the airport in Manila is not easy if you do not have your own transport. Most of the time you have no choice but to take taxi and whenever taxi cab drivers hear NAIA, the rate becomes expensive. They always ask for additional fee or fixed rate. Of course passengers have no choice but to take it because they do not want to miss their flight. I also have my own experiences of that.
It is good to know that starting tomorrow, October 9, 2015; Victory Liner can take you to the airport (NAIA 1 to 4) from its Pasay Terminal. The rate is P20 per person and from 5AM to 10PM with one hour interval. You now have a new option if you are coming from Pasay.