Normally, trying to load the Sky during Back in Time crashes the game, since most layers of the Sky cannot be loaded properly in BiT. However, the layer corresponding to the loftwing tutorial can load correctly, and therefore this tutorial can be accessed during BiT. This would normally not be useful, as that tutorial has a boundary that cannot be crossed while on the loftwing. However, the Eldin Light Pillar is within the boundaries of the tutorial.
Using the Story Flag RBM variant of the Early Light Pillar glitch, it is possible to enable the Eldin Light Pillar on a file that can access the loftwing tutorial during BiT, and therefore reach the surface during BiT. This allows for the Back in Time state to reach the Sealed Grounds, Faron Woods, and Lake Floria, greatly expanding the list of available scene flags for use in Reverse BiTMagic tricks. It also opens up a variety of new statues for new BiTWarps, and allows for Reverse BiTWarps into areas of the surface, such as Ancient Cistern.
Note: If you clear the cutscene for entering a light pillar for the first time with your file that can enter the Wing Ceremony in Back in Time, then you can attempt to enter the Eldin Volcano in Back in Time. That however leads to a crash.
While the original Faron BiT was found using the Early Eldin Pillar, it is also possible to enter the Faron Light Pillar in Back in Time. Both methods of setup follow.
To access Faron during BiT, you need a specific file setup. This file must have the following characteristics:
These two things are normally mutually exclusive, but we can save a file at the prompt after the loftwing tutorial, copy it to a spare slot, and later enable the Eldin Light Pillar on that file. To perform this version of the Early Light Pillar trick, we must have:
Then we can load the Ruby Tablet into BiT by obtaining a Stamina Fruit with the Tablet File selected. We then enter the goddess statue with our Target File selected, then place the loaded Ruby Tablet into the pedestal (possibly having to Skyward Strike the crest to raise the pedestal). The light pillar cutscene will begin in BiT, and by starting our Target File at the right time (about 1 second after the second camera change, as the light pillar forms), we can gain access to that pillar on our early game file.
The setup time for this method is much lengthier than the Eldin Light Pillar method, but this one has the benefit that it can be done before beating Skyview Temple. It is therefore useful in a Low% speedrun to skip the Hero's Tunic completely.
The Faron Light Pillar is out of the boundaries you can reach during the Loftwing Tutorial. This means you need to set the story flag for being able to jump off your loftwing on the file that is saved on the Wing Ceremony Prompt. This is usually not possible, as you only unlock that ability when talking to Fi after obtaining the Hero's Tunic. This is however possible with clever routing.
You will first need the following file setup:
Perform Early Faron Light Pillar on File 1, using the Story Flag RBM technique. Then perform BiT again and place the emerald tablet again. BiTSave File 1 at the save prompt that is after opening the Faron Light Pillar. Now activate BiT again, and Reverse BiTWarp File 1 into the Sky (by BiTSaving File 2 to unlock the loftwing, this works without softlocking because File 1 is saved at a save prompt, and thus loads the sky normally). Go towards the Faron Light Pillar and watch the Fi cutscene around it. That cutscene unlocks the ability to jump off your loftwing.
After that ability is unlocked, go back to Skyloft and rescue your loftwing for real. Save at the Wing Ceremony Save Prompt. File 1 can now access the Loftwing Tutorial in BiT and dive to the Faron Light Pillar.
Once we have our file setup correctly, to reach Faron Woods during BiT we can take the following steps:
Reaching Faron Woods itself requires either going through the Sealed Temple, or climbing a log to access the Behind the Temple area directly. The log is generally used for this purpose; BiTMagic can be used to have the log pushed down.
Faron Back in Time is slow to access, meaning that the only tricks that employ it are ones that skip a significant portion of the game. These tricks are possible via Faron BiT:
Both the Lanayru Light pillar and the Thunderhead are very far from within the boundaries you have access to during Back in Time, and as such you cannot simply dive to them. However, using the Groosenator in Back in Time, it is possible to launch yourself to both Lanayru and the Thunderhead. The file setup is the following:
If File 3 isn't saved in the Sealed Grounds, it will still work if you are saved in an area with scene flag 9x80 that, in the Sealed Grounds, corresponds to the Impa Text after beating the Imprisoned 3. (Check the Scene Flag documentation sheet).
Once the setup is ready, follow the next steps:
This allows for entering many new areas within BiT: The Thunderhead and the Isle of Songs, the entirety of the Sand Sea (except for the Sandship and the Pirate Stronghold Interior), the Lanayru Caves and the Lanayru Mines.
Since this requires all 3 song of the hero parts, this is generally not considered very useful.
Note: Attempting to go to the Thrill Digger Cave in Eldin will crash your game. Attempting to go to Fun Fun Island or to Bamboo Island without selecting the Faron BiT enabled file will crash your game. With a slightly different file setup it is possible to get launched to Flooded Faron Woods as well in Back in Time. This however also crashes the game