What is the right calculation for Annual Service Availability?

There are 2 ways of calculating the Annual Service Availability:

Formula 1

Annual Service Availability = Total Transmission Time over 12 months period – Total Downtime over 12 months period X 100                                        Total Transmission Time over 12 months period

Total Transmission Time = Total transmission time from studio multiple by total number of transmission stations
e.g. Licensee A have 5 transmission stations and total transmission time from studio over 12 months period is 161,038 minutes, therefore:
Total Transmission time - 161,038 minutes X 5 transmission stations = 805,190 minutes
Total Downtime = Total downtime from studio and total downtime from all the transmission stations

Formula 2

Annual Service Availability = Total StudioTransmission Time over 12 months period – Average Downtime over 12 months period X 100                                     Total Studio Transmission Time over 12 months period

Total Transmission Time = Total transmission time from studio only
Total Downtime = Average downtime from studio and all the transmission stations
e.g. Licensee B have 3 transmission stations. Below is the summary of downtime for each transmission station for over 12 months period:

Annual Service Availability =
Total Transmission Time over 12 months period – Total Downtime over 12 months period X 100
Total Transmission Time over 12 months period
Annual Service Availability =
Total StudioTransmission Time over 12 months period – Average Downtime over 12 months period X 100
Total Studio Transmission Time over 12 months period

Station 1 – 120 minutes
Station 2 – 260 minutes
Station 3 – 300 minutes

Total downtime = 120 mins + 260 mins + 300 mins = 226.7 mins
                                   3 transmission stations