callPostApi = function () { 

        var headers = {};
        if ($('#userName').val() && $('#password').val()) {
            headers.Authorization = 'Basic ' + btoa($('#userName').val() + ':' + $('#password').val());
        }

        var data = {
            FlightSearchRequest:
                {
                    "Adults": 1,
                    "Child": 0,
                    "Seniors": 0,
                    "InfantInLap": 0,
                    "InfantOnSeat": 0,
                    "Youths": 0,
                    "TypeOfTrip": 1,
                    "ClassOfService": 1,
                    "SegmentDetails":
                        [
                            {
                                "Origin": "NYC", "Destination": "LON", "DepartureDate": "07/17/2015", "DepartureTime": "1100"
                            },
                            {
                                "Origin": "LON", "Destination": "NYC", "DepartureDate": "07/22/2015", "DepartureTime": "1100"
                            }
                        ],
                    "IsInsuranceRequired": true,
                    "IsTravelAssistRequired": false,
                    "BPC": false,
                    "BPCType": 0,
                    "ClientIP": "",
                    "AffiliateCode": null,
                    "SearchAlternateDates": false,
                    "AirLinePreferences": null,
                    "CAID": 0,
                    "Username": null,
                    "UserId": -1,
                    "ErrorCode": null,
                    "ErrorAtNode": null,
                    "ResponseVersion": 12,
                    "ConsumerDetails": null,
                    "IsVersionV11": false,
                    "ResponseAsObject": false,
                    "IsLMFSearch": false
                },
            SearchVersion: 0
        };

        $.ajax({
            type: 'POST',
            url: '/api/GatewaySearch/SearchFlightAvailability', //API Service URL
            contentType: 'application/json; charset=utf-8', 
            data: JSON.stringify(data),
            headers: headers
        }).done(function (data) {
                //Your logic
        }).fail(//Your logic);
    }