I don’t know about differentiating between east & west bound departures but, from the 60s onwards the following airlines used even numbers on departures from Europe to USA/Canada :-
DLH, AZA, SWR
& the following used odd:-
AFR, BAW, EIN, KLM, SAB, IBE, SAS, AFL, OAL, TWA, PAA, ELY, AIC, TAP, KAC.
The others I am not certain about.
Last edited by kcockayne; 12th Feb 2021 at 18:59.
Reason: Extra info