In the Philippines, to avail of senior citizen discounts on airfare, you generally need to present a valid senior citizen ID issued by the government. Additionally, airlines may require specific documentation to process the discount, which could include the receipt clearly showing the fare before the discount is applied. It's important to check with the airline for their exact requirements, as these can vary. For the most accurate and updated information, consider visiting the airline's official website or contacting their customer service directly.