Always stay clipped on to something.I'm regularly at 100ft - 200ft inspecting crane jibs but at 61 and with arthritic joints I don't have too long left before handing over to the young bucks. Even climbing a 30ft vertical ladder is quite painful so there's no way I could tackle one of those antenna's.
The highest I've personally climbed up a vertical ladder was up a 75mtr wind turbine. These weren't too bad because you're inside a tube and protected from the wind and rain. Biggest risk to overcome is oil/grease on the ladder rungs.
Height safety equipment is mandatory ie harness and lanyard, but even so, if you slip, even though you can only fall just over 2mtrs the stresses a 16-17 stone guy such as me would experience would hospitalise me.
Thankfully I've always managed to hold on tightly
Do you have fall arrest systems on the ladders?