did a job yesterday on a big box retail store, probably 8000sqm of flat roof, mostly TPO membrane with a bunch of rooftop HVAC units scattered around. client wants a full condition report for their insurance renewal, so im doing visual plus thermal to pick up any wet insulation under the membrane.

problem is every time i got within maybe 15 meters of the larger HVAC clusters i was getting signal dropouts, not a full disconnect but enough that the video feed was getting choppy and i had a couple moments where the aircraft just kind of hesitated before responding to inputs. im flying a mini 3 pro which i know isnt the ideal tool for commercial work but its what i have right now and it usually handles fine.

i assumed it was RF interference from the units but im not totally sure. wind was calm, battery was good, no other obvious reason. ended up flying a wider orbit to stay clear of them which means i have some gaps in the thermal coverage right over the units themselves which is kind of exactly where you want the data. do i need to go back or is there a way to work closer to that kind of equipment

yeah HVAC units on commercial roofs can be pretty gnarly for signal, especially the bigger packaged units with variable frequency drives in them. VFDs throw out a lot of RF garbage across a wide spectrum and the occulink or whatever transmission system the mini uses isn't going to love that. swithing to a platform with a more robust transmission system helps but its not always an option mid job.

practically speaking for the gaps you already have, if the client specifically needs thermal under those units you probably do need to go back. one thing that can help is flying a manual grid pattern at a steeper angle and coming in from directly overhead rather than a low orbit, you're further from the units horizontally even if you're close vertically. also early morning before the units spin up for the day can reduce the interference a bit, though the thermal contrast for wet insulation is also better in morning anyway so double win.

mini 3 pro on a commercial inspection job, respect the hustle but yeah that transmission system is just not built for electrically noisy industrial environments. ive had similar dropouts near substations and mechanical rooms even with more robust setups. the thermal sensor on that thing also isnt going to give you the kind of resolution you'd want for a proper insurance grade moisture report, just worth flagging to the client so expectations are set correctly before they get the deliverable