What would happen if I told the final approach controller that I was unable to maintain 170 to the FAF
The reason I ask is that my airline has new procedures, and if I hold that speed, I will be unstable and have to perform a go-around.

If it's a common airplane type and your company is the only one that has rules that make it impossible for you to maintain 170, you can hear their eyes roll over the radio, but not much else will happen. It mainly affects traffic behind you and those people will also start rolling their eyes and call you all kinds of silly names in their head.

Ghost Rider wrote: ↑Mon Nov 24, 2025 10:23 am What would happen if I told the final approach controller that I was unable to maintain 170 to the FAF
The reason I ask is that my airline has new procedures, and if I hold that speed, I will be unstable and have to perform a go-around.

What procedure would make 170 to the FAF impossible?

At a busy airport, say YYZ, if everyone would now report they're requiring 160 to the marker, then a 56 arrival/hr rate may become a 52 or 54 rate. If the new rate has to be sustained for several hours, then there will be more flow restrictions if the demand is higher than the target rate. As an arrival controller, it makes no difference if I need to run an extra half-mile or mile in trail in a mixed-mode operation, but then again I'm not paying for extra fuel or missed/delayed connections on your end. Methinks there would be discussions at higher levels

Just curious what your stable approach tolerance is that holding 170 to the faf (unless you have a super strong tailwind) won't work? In YYZ most of the fafs are far enough out that should be no problem to hit approach speed by 1000.