Of course, its not just that those decrepit vc10s are old - it's that they are no longer fully airways equipped, being minus TCAS/TAWS, RVSM and I doubt not even FM Immune. Nor do they comply with civil noise standards for civil airports. Nor do they comply with 25 year old PAX lighting rules - apparently just short of 1970's african airline standards - but seemingly okay for todays RAF?
The BZN Fleets have been ignored to their death and the -10's only revived with a sticking-plaster policy because the ignored -11's have past their best before date by a mere 20 years.
- must be bed-time...