Are (Canadian) helicopters (and maybe specifically rescue/emergency ones) exempt from carrying transponders? or do they use something different? The STARS helicopters (http://wwwapps.tc.gc.ca/saf-sec-sur/2/ccarcs-riacc/RchSimpRes.aspx?cn=||&mn=||&sn=||&on=SHOCK|&m=||) have ICAO 24 bit ID codes, but when they fly overhead nothing shows up in my list of aircraft. I would at least expect to see the ICAO code along with a Mode-S indicator - but there's nothing. The organization tweets when they dispatch (https://twitter.com/STARSambulance) and I can see the helipad on the hospital downtown Winnipeg from my office. But not on my feeding station.
just because they have an icao doesn't mean they have a transponder. Having an icao has nothing to do with having a transponder - icao is an identification and related the registration number of an aircraft in countries like the USA and Canada
If they are transmitting Mode C all you'll get is their Reg # and altitude. Those are the things ATC needs to tie that data to primary radar provided bearing/speed and range. They should still show up in the log depending on what software you use. The 2 USCG choppers I saw this morning doing SAR we definitely running that way. Though if you really seeing nothing at all on 1090, do you have a second receiver you can put on 978? I don't have tracks because these were replying in ModeC only. S is backwards capable. 2018-05-13 0400 -- probably with FLIR -- 6588 MH-65D AE26AE, Mode-S CGNR6588 MH-65 D/E Multi-Mission Cutter Helicopter (MCH) 2018-05-13 0800 -- -- 6022 MH-60T AE2906, Mode-S C6022 MH-60T Medium Range Recovery Helicopter
Looking at the Designated flight areas in Winnipeg area, (Search DAH_Current_EN.pdf on navcanada site), it does not appear that a transponder is required as long as they remain under 12,500 feet.
