Data were collected over one year, stratified into the third and fourth
quarters of 2010 (July, August, September 2010 and October,November,
December 2010 respectively) and the first and second quarters of 2011.
Invitations to participate in the research were distributed to passengers
of fifteen airlines at fifteen airports across Europe, Asia and the Middle
East according to a sampling plan developed by IATA which was reflective
in its proportions of the different carriers' actual networks. 18,567
survey responses were collected.