Mounting machines in Horizon Forbidden West is one of the biggest reasons Aloy is more than a traditional Nora. Of course, other people have the technology to override and hop on machines, but Aloy is a master at it by this point. Here is how to get the Mount Whistle in Horizon Forbidden West and call your mount to you.
The Mount Whistle isn’t an actual item or ability you need to obtain in Horizon Forbidden West. Instead, whenever you have used your spear to override a machine, you can find the icon to whistle for it in your tool bar. Just press left or right on the d-pad until you find the icon of a mount with an arrow above it. This is different from Zero Dawn where Aloy had to unlock a skill to do this. In Forbidden West, it is available after your first override.
If you do not see the Mount Whistle icon in your tools, that means whatever mount you have had been destroyed. Overriden machines will often attack other machines they come close to, so it may have lost a fight. There is no distance you can walk that is too far from your mount to come to you (but they cannot enter settlements). If there is no icon and you can’t find your mount to repair it, you will need to find another machine to override.
