Plane tickets are great for charities because they can be used for auctions to raise money for the organization. Most airlines have some sort of community relations or community involvement department. The purpose of these departments is to give back to the community. Some airlines give funding, some give out tickets and some do both. Airlines receive hundreds of requests per week and therefore have to sometimes make strict qualification rules.
Go to the website of the airline you would like to request tickets from. Locate their community relations page, which may have a different title such as community giving or corporate responsibility. Start by going to the "about the company" section and navigate from there. Also try looking under the FAQ section of the site.
Read the guidelines before applying. Most airlines will require that you are a qualified 501(c)(3) organization. Some will require that you have a certain focus. For example, among Southwest’s priorities are organizations that support families facing serious illnesses and organizations that actively work towards benefiting the planet. Airlines may have restrictions in their policies. US Airways limits donations by geography, focusing its donations on organizations in the cities of Charlotte, Philadelphia, Phoenix and Washington, DC. Political groups, controversial causes, groups with religious affiliations and groups that discriminate are some examples of organizations whose requests may be denied.
Submit your request. Most airlines have this option available on their website, and few airlines want or will accept requests via standard mail. You will likely have to create a user account and provide specific documentation, such as tax id numbers and whatever information about your organization the airline requires. Each airline differs, but most airlines want the request at least 3 to 6 weeks before the event you need them for, such as an auction.
Ask others to donate miles to you. If you are an individual or your organization doesn’t qualify, you can use MileDonor to post why you need miles. People interested in donating miles can peruse these boards and if they find your cause worthy, they might donate miles to you.