Strumble HMS is no longer available for use.
Alternative Height Monitoring Systems are as follows;
ADS-B HMS –
North Atlantic – Shanwick (Mondays and Saturdays only)
USA, Thailand, Australia and China.
Canada (Mondays only)
Multiple ICAO regions currently developing implementation plans for AHMS including South America, Africa, Europe and Russia.
HMU/AGHME –
Europe – Linz, Geneva, Nattenheim
Japan – Setouchi, Niigata, Sendai
Availability of these systems can be checked through the relevant Regional Monitoring Agencies websites. Links to each RMA can be found here.