In my situation there was no arrival. Originally we were enroute, I think direct the airport or the vor on the field. Then atc gave us direct the iaf.
Potkettle, I looked up your example, however it is for proceeding FROM the iaf. Mine is TO the iaf, where there were no "intermediate step/check" altitudes that you described. So....I see no option for me except the 25 mile MSA, which is not centred on the IAF.
Italia, I was not on an arrival, and atc did not give me any descent, just cleared for the approach, while I was at FL 80. So am I correct to wait until within the 25 mile MSA and then leave FL 80?
BOAC, what is really interesting is that the MSA within 18 miles is 2100 feet, while the altitude past the iaf at 11 dme while inbound to the field is still 2500 feet. Any idea why?