In my UK airline experience, consistently:
"When the a/c
MAY land with less than reserves" ie I have less fuel than I would really like, and require special routing/handling to expedite my arrival at xxx (a potential 'fuel emergency'
), the aim being to AVOID landing with less than reserves, which would require a MAYDAY.
Should NOT be required on a well-planned routine diversion.
That's
my go. (Just like the faster EGPF
)