Why isn't the Google QPX Express API returning results for all airlines?

Question

I enabled access to the Google QPX Express API to do some analytics on the prices of Delta's tickets and Fare Classes. But the response seems to only include flights from a limited set of airlines.

For example, the following request

{
  "request": {
    "passengers": {
      "adultCount": 1
    },
    "slice": [
      {
        "origin": "JFK",
        "destination": "SFO",
        "date": "2015-02-15",
        "maxStops": 0
      }
    ],
    "solutions": 500
  }
}

only returns flights for AS (Alaska Airlines), US (US Air), VX (Virgin America), B6 (JetBlue), and UA (United Airlines).

If I add "permittedCarriers": [DL], then I get an empty response. Likewise, I get an empty response if I leave out permittedCarriers and look for flights between Delta hubs (e.g., "origin": "ATL", "destination": "MSP").

The documentation suggests that QPX Express is supposed to have most airline tickets available. Is there something wrong with my request? Why am I not seeing any results for Delta?

Answer 1

I received a response from Google's QPX Express help team about missing data for Delta. The response was that

Delta's data, as well as American Airline's data, is not included in QPX Express search results as a default. Access to their data requires approval by those carriers.

After informing him that my plans to use the data were for research purpsoses, he responded,

American and Delta restrict access to their pricing and availability to companies which they approve, which are primarily organizations driving the sale of airline tickets. Unfortunately, requests for access are only being reviewed for companies that plan to use the API for commercial purposes.