Mounting machines at Horizon Forbidden West is one of the biggest reasons why Aloy is more than just a traditional Nora. Of course, others have the technology to override and jump on machines, but Aloy is a master at it so far. Here’s how to get Mount Whistle in Horizon Forbidden West and call a mount for you.
Mount Whistle is not an actual item or ability that you need to get in Horizon Forbidden West. Instead, whenever you use your spear to overwrite a machine, you can find the icon to whistle for it in your toolbar. 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 has to unlock a skill to do this. In Forbidden West it is available after your first override.
If you don’t see the Mount Whistle icon in your tools, that means any mounts you have have been destroyed. Crushed machines will usually attack other machines they come close to, so it may have lost the fight. There’s no way you can walk too far from your mount to get to you (but they can’t enter settlements). If there is no icon and you cannot find your stand to repair it, you will need to find another machine to override.
https://www.gamepur.com/guides/how-to-get-the-mount-whistle-in-horizon-forbidden-west How to get Mount Whistle in Horizon Forbidden West