On Tuesday, 17 September 2019 19:29:50 UTC+2, Tom BravoMike wrote:
I also get the 'mean glide ratio' as '18:54'

Do you fly a brick?
An L/D of 18:54 means you're losing three feet/meters per one foot/meter of horizontal movement.
Maybe the intention was to indicate that the glide ratio was between 18:1 and 54:1?