I uploaded three photos taken around the same time with roughly the same camera settings. They were all processed in same way with the same software.
This one was accepted.
Photo © Derek Ferguson
This was rejected for soft
and this one for grainy and oversharpened.
It has been suggested that there are plenty of accepted photos to look at to see what is right but I find it difficult to judge what is right . The BA does look sharper than the other two but the Jet 2 and the Monarch look the same to me. All three are really not very different to me.
The margin between success and failure is fine indeed.