Originally Posted by
quitecontrary
I've started playing with the OW site planning a RTW stating in CPT - I've put in CPT-MRU-JBO-LHR but LHR comes up with the red triangle -I've tried then doing DXB-LHR-ATH-LHR again red triangles for ATH and DXB. I thought this would be allowed.
If you mean CPT-MRU-
JNB-LHR, then (a) you're missing an intermediate plane change at JNB outbound (no CPT-MRU service, only JNB-MRU) plus you can't return to the country of issue (South Africa) once you've left it - until the end. So plan on CPT-JNB-MRU-LHR and you should be okay.
ATH and DXB are both included in the list of cities in Europe where only one flight to/from London is allowed. DXB-LHR-ATH would be okay, as would LHR-DXB-LHR, or LHR-ATH-LHR, but not the route you've cited. Look at ATH-MAD or MAD-ATH (or DXB-AMM-ATH) as work-arounds.