Not having flown the ‘flexible’ option described above, I assume that the notification to ATC also allows for the appropriate ‘straight in’ maneuvering allowance – higher MDA and greater visibility to counteract the higher speed. However this may not apply to circling.
Previously I referred to a CFIT accident in Busan Korea, a resume is here:-
Busan 3.pdf.
Although the error in this accident was the assumption that PANS-OPS circling areas applied (4.2nm rad from t/h. Cat C) whereas the airfield was actually charted to TERPS (1.7 nm rad from t/h. Cat C), the issue of flight outside a safe area may also arise with increased airspeed.
A turn at 20 AOB 180 kts (Cat C) gives a radius of approx 1.4 nm; thus with TERPS this only gives a small safety factor for error, wind, etc; lower bank angles reduce this margin. Flying at Cat D speed – 205 kts the rad of turn is 1.8 nm at 20 AOB, which exceeds the TERPS area. These changes apply to PANS-OPS in a similar way, but the safety area is larger. Thus the aircraft category speed limit must be respected and there is also a minimum AOB to consider.
Many of the issues in this thread are presented in an excellent booklet
‘From Takeoff to Landing’ by Olle Akerlind who worked for SAS performance dept; there was a limited reprint by Honeywell last year, but it is not on the web.