Hi Alex. How can I both maintain a zoom level and keep the aircraft centred on map (in flight). 

Options on page "Simulator Aircraft". Disable "Center map on aircraft and next flight plan waypoint". This will keep the aircraft centered and the zoomlevel steady.

Also see here: https://www.littlenavmap.org/manuals/littlenavmap/release/2.6/en/OPTIONS.html#simulator-aircraft-icon-simulator-aircraft

Also:

Quote

Note if you use the default aircraft centering mode:

1. Using the mouse wheel or the + and - key to zoom will change and keep the zoom distance. The aircraft is still centered but the new zoom distance is used.
2. Starting to look around by moving the map with mouse drag or cursor keys: This will remember the last position and the zoom distance. You can do any map movements and Little Navmap will jump back to the last position and zoom distance where you started the movement when time is over.

The same from point two applies if you jump to airports, navaids or other features by double click, context menu (Show on Map) or map link.

Alex

Many thanks Alex