Please read the following table in HTML format from a webpage and then answer the question in detail according to the table. Each table cell is defined by a <td> and a </td> tag. Each table row starts with a <tr> and ends with a </tr> tag. 'rowspan=m' and 'colspan=n' represents a cell spaning over 'm' rows and 'n' columns.

Webpage title:
Air Ceylon
Table title:
Fleet
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=1 > Aircraft </th><th colspan=1 rowspan=1 > Introduced </th><th colspan=1 rowspan=1 > Retired </th></tr>
<tr> <td colspan=1 rowspan=1 > Aérospatiale N 262 </td><td colspan=1 rowspan=1 > 1967 </td><td colspan=1 rowspan=1 > 1969 </td></tr>
<tr> <td colspan=1 rowspan=1 > Boeing 707 </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Boeing 720 </td><td colspan=1 rowspan=1 > 1976 </td><td colspan=1 rowspan=1 > 1977 </td></tr>
<tr> <td colspan=1 rowspan=1 > Convair 990 Coronado </td><td colspan=1 rowspan=1 > 1974 </td><td colspan=1 rowspan=1 > 1975 </td></tr>
<tr> <td colspan=1 rowspan=1 > de Havilland Comet </td><td colspan=1 rowspan=1 > 1962 </td><td colspan=1 rowspan=1 > 1965 </td></tr>
<tr> <td colspan=1 rowspan=1 > Douglas DC-3 </td><td colspan=1 rowspan=1 > 1947 </td><td colspan=1 rowspan=1 > 1976 </td></tr>
<tr> <td colspan=1 rowspan=1 > Douglas DC-4 </td><td colspan=1 rowspan=1 > 1949 </td><td colspan=1 rowspan=1 > 1953 </td></tr>
<tr> <td colspan=1 rowspan=1 > Douglas DC-8 </td><td colspan=1 rowspan=1 > 1972 </td><td colspan=1 rowspan=1 > 1978 </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > Hawker Siddeley HS 748 </td><td colspan=1 rowspan=1 > 1964 </td><td colspan=1 rowspan=1 > 1979 </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > Hawker Siddeley Trident </td><td colspan=1 rowspan=1 > 1969 </td><td colspan=1 rowspan=1 > 1979 </td></tr>
<tr> <td colspan=1 rowspan=1 > Lockheed Constellation </td><td colspan=1 rowspan=1 > 1956 </td><td colspan=1 rowspan=1 > 1958 </td></tr>
<tr> <td colspan=1 rowspan=1 > Lockheed Super Constellation </td><td colspan=1 rowspan=1 > 1958 </td><td colspan=1 rowspan=1 > 1960 </td></tr>
<tr> <td colspan=1 rowspan=1 > Lockheed L-188 Electra </td><td colspan=1 rowspan=1 > 1960 </td><td colspan=1 rowspan=1 > 1961 </td></tr>
<tr> <td colspan=1 rowspan=1 > Sud Aviation Caravelle </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Vickers VC10 </td><td colspan=1 rowspan=1 > 1965/1977 </td><td colspan=1 rowspan=1 > 1971/1978 </td></tr>
</table>
Question:
What Hawker planes has Air Ceylon had?
Answer:
Air Ceylon had Hawker Siddeley HS 748 and Hawker Siddeley Trident.