An earlier question regarding ancillary revenues may have a bearing on this question:

One translation of the English term scheduled revenues vs. ancillary revenues in Polish is dochody z usług regularnych/ze sprzedaży biletów lotniczych vs. usług dodatkowych/innych sprzedaży.
http://www.proz.com/?sp=gloss/term&id=22887625

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W 2012 roku przychody linii lotniczych z usług dodatkowych
na całym świecie osiągną wartość 36,1 mld USD
http://www.amadeus.com/pl/documents/aco/pl/Ancillary Service...
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In the airline industry, ancillary revenue is revenue from non-ticket sources, such as baggage fees and on-board food and services, and has become an important financial component for low-cost carriers (LCCs) in Europe, North America and other global regions.[citation needed] Ancillary revenue has been defined as, “Revenue beyond the sale of tickets that are generated by direct sales to passengers, or indirectly as a part of the travel experience.”[1] Ancillary revenue has been further defined to include these categories: à la carte features, commission-based products, and frequent flier activities.[2]
https://en.wikipedia.org/wiki/Ancillary_revenue