Performing actions while falling

Question

If a character falls from a great height and has a skill or item that may save them if used early enough, how does one determine where in the fall the item is used? Depending on the reason for the fall, there may of course be some DC to avoid falling in the first place (usually a Reflex check against the DC of the trap that's opening up beneath you) but what I'd like to know is what happens once it's decided that the character is definitely going to fall.

For example, say I have some kind of teleportation effect that can get me back on solid ground, but the rules say that it doesn't affect my momentum, so if I'm falling at speed I'll still hit the ground hard when I emerge wherever I teleport to. So, this will only save me if I can do it fast enough - for D&D3.5e that's basically before I've fallen ten feet (or twenty if I can make a DC 15 Jump or Tumble check to negate damage from the first ten). How do we determine if I manage that? Can we assume I make it if the activation of the effect is fast enough? Is there another check? My instinct is that it'd be another Reflex check, but I'm not sure what the DC would be.

Answer 1

The rules for falling do not address timing or actions at all. They only specify damage taken.

However, the general rules for the game are that things are atomic—you do one action, you do another, and you cannot mix them or interleave them. There are exceptions—Spring Attack, 5-foot-steps, etc.—but they are exceptional. Without some explicit exception, I would default to assuming that you must finish falling—more on what that means in a bit—before you can do something else.

Therefore, if, at any point in time, there is no longer ground beneath you, you fall immediately. You are not in control and cannot act normally. If it was your turn, that pauses until the fall completes—details still forthcoming—and it is effectively no longer your turn. This is similar to the situation with attacks of opportunity, which interrupt an action or turn to allow a different creature to act (and attack).

Some actions, principally immediate actions, can be taken out-of-turn and therefore always can occur during a fall. Feather fall is even specifically designed to be used just as you begin to fall. Likewise, if you have some relevant ability to act in the middle of movement—maybe Spring Attack if this was an intentional jump off a cliff perhaps—I would expect most DMs to allow it to apply, though the rules are murky about that. You could also presumably ready an action to take place after you’ve fallen a certain distance or when you’re a certain distance above the ground, but you would have to ready the action prior to falling in my estimation.

Dungeon Master’s Guide II specifies that on the first round of a fall from a very great height, a character falls at most 670 ft. So if you are higher than that, the fall “completes” for the turn, and you act after that.

Thereafter, each round is another 1,150 ft. Round-by-round durations in 3.5e are somewhat odd, but very clear: anything that is supposed to occur X rounds after some point, occurs X rounds later when you reach that same initiative count. Initiative does not change during a given turn, so your fall began on the relevant initiative count, and you continue to fall as soon as the initiative reaches that point again—that is, before any creature acts on that initiative count.

These numbers (670 ft and 1,150 ft) are a fair bit larger than dlras2 had calculated using the relevant real-world physics,¹ but then maybe the acceleration due to gravity is larger in D&D than on Earth.

There are no restrictions present in the rules on how you may spend your actions if your turn comes up in the middle of free-fall (that is, after dropping 670 ft in the first round, or after dropping 1,150 ft on any round thereafter). Presumably, if you only have a land-based movement speed, you would not be able to actually move, but you would get a move action, as well as swift and standard actions, as usual. Because of the abstractions present in the rules, this means that for shorter falls, if you fall during your own move action you can land and still make your Standard action afterwards. In theory, maybe some or all of that is actually going on during the fall but the game does not model that.

Personally, if this was any thing like a major part of a campaign I was running, I would houserule some way to move as a move action while in free fall—even without any kind of equipment you can aim yourself in a long fall, though I’d have to do some research on how much.

1. _{See the comments for dlras2’s calculation. Using real-world physics and a lot of estimation, and assuming you take 20d6 damage, i.e. 200 ft., to be the point at which you hit terminal velocity, you would move 470 ft. in the first round and 660 ft. per round thereafter.}

Answer 2

The rules for falling don't make any special allowances for actions while falling, though immediate actions (such as casting Feather Fall) can be used immediately at the beginning or during any point of the fall.

If you're looking to add a houserule to your 3.5 game, Pathfinder rules adds that if a character is falling more than 500 feet they can cast a spell with a concentration check. It would be sensible to allow a character falling more than 500 feet any single standard action rather than just a spell casting, tho it make take some sort of additional check — a character falling less than 500 feet simply doesn't have the time to do anything that can't be done as an immediate action.

Answer 3

The rules are not clear on this question, but they do provide some guidelines. Based on those guidelines, I think we can draw some reasonable conclusions that provide an outside boundary. From those outside bounds, I then make one suggestion for a relatively simple house rule.

Certain: If you're prepared to act, and start falling from more than 670 feet, you can definitely take a full round's worth of action

This is based on the following text:

(PHB 138): Each round represents 6 seconds in the game world. At the table, a round presents an opportunity for each character involved in a combat situation to take an action. Anything a person could reasonably do in 6 seconds, your character can do in 1 round.

and

(DMG2 47): That means a character falls roughly 670 feet in the first round. After that, a character falls about 1,150 feet each round.

From that solid information, we can draw some conclusions:

Very Reasonable: If you're falling from more than 335 feet, you can take a move action

A round takes six seconds, and we know you can take two move actions in a round. Therefore, it's reasonable to conclude that a move action takes a maximum of 3 seconds. It may take less time than that, but by reason it couldn't be more.

A Continuation: If you're falling from more than 168 feet, you can take a move action

According to this excerpt (and the laws of physics) speed is not constant — falling creatures accelerate until they reach terminal velocity.

(DMG2 47): A falling character reaches terminal velocity (roughly 130 miles per hour, or nearly 200 feet per second) within the first round of a long fall. That means a character falls roughly 670 feet in the first round. After that, a character falls about 1,150 feet each round.

This follows the laws of gravity — we accelerate as we fall.

The distance, \$d\$, fallen in a time \$t\$, given an acceleration \$a\$, follows this formula:

$$d = \tfrac{1}{2} \times a \times t \times t$$

Physicists refer to the particular acceleration imparted by gravity as \$g\$, which on Earth is approximately \$g_\text{Earth} \approx 9.8\tfrac{\text{m}}{\text{s}^2} \approx 32.2\tfrac{\text{ft}}{\text{s}^2}\$.

We can't use Earth's acceleration due to gravity, because we're not on Earth, but we can easily calculate the gravity constant used in the DMG2 using the same formula and solving for \$g_\text{D&D}\$ (from now on, just \$g\$):

\begin{align} 670\text{ ft} &= \tfrac{1}{2} \times g \times 6\text{ s} \times 6\text{ s} \\ 670\text{ ft} &= \tfrac{1}{2} \times g \times 36\text{ s}^2 \\ 670\text{ ft} &= 18\text{ s}^2 \times g \\ \tfrac{670\text{ ft}}{18\text{ s}^2} &= g \\ 37.22\tfrac{\text{ft}}{\text{s}^2} &= g \\ \end{align}

Now that we have the \$g\$ for the D&D Universe, we now re-solve for \$t=3\text{ s}\$

\begin{align} d &= \tfrac{1}{2} \times 37.22\tfrac{\text{ft}}{\text{s}^2} \times 3\text{ s} \times 3\text{ s} \\ d &= 167.5\text{ ft} \\ \end{align}

Therefore, based on the information and rules provided, we can reasonably conclude that if you're falling from at least 168 feet, you can take a move action.

Another note — Reaction

While you may have time to make a move action in your first 168 feet, that assumes you are ready to act immediately and have great reflexes. It could be that it takes you a few seconds to figure out what's happening to you, and by the time you figure it out, you've already gone *SPLAT* against the hard ground.

A Practical Suggestion (i.e. An Informed House Rule)

Based on the information above, if this issue arose in a campaign I was running, I would use the following rule, which is based on the above information but uses simplified and round numbers:

1. Roll a dexterity check, representing your ability to react quickly
2. Multiply that check by 10 ft

Then:

• If you want to take a full round action, subtract that resultant number from 750 feet. That's how far you will fall before you complete your full round action.

• If you want to take a standard action, subtract the resultant number from 300 feet. That's how far you will fall before you complete your standard action.

• If you want to take a move action, subtract the resultant number from 200 feet. That's how long you fall before you are able to take a move action.

• If you want to take a swift action, subtract the resultant number from 100 feet. That's how long you fall before you are able to take a swift action.

Obviously, this is a suggestion for a house rule, and it may present its own problems if extended to more complex situations (i.e. what if you want to take two swift actions, or a swift and immediate action, or a swift and a move action?). That being said, it is a single roll with a simple look up table that provides a reasonable set of rules for the first round of falling. I also think the general principles are extendable for all reasonable cases of a single round of action.

Answer 4

I'm going to crunch the numbers in feet and seconds. What we're missing in this example is how much distance is between the height from which the character falls and the ground. I'm going to assume it's a cataclysmic 1,000' drop.

Terminal velocity of a parachutist is about 150 mph.

This is 220 feet per second (fps).

Acceleration of Earth's gravity is 9.8 m/s². Or 32.167 fps².

Acceleration distance = v²/(2a)

Acceleration distance = 220²/ (2x32.167)

Acceleration distance = 48400 / 64.334

Acceleration distance = 752'

Player Character plummeting to Earth reaches terminal velocity in the first 752' of falling.

Time to accelerate = v/a

Time to accelerate = 220 fps/32.167fps²

Time to accelerate = 6.839 seconds

The rest of the fall occurs at vt = d, because he's plummeting at a constant speed. The question becomes, "How far does he have to fall?" That will determine how much time he has to execute any other maneuvers, but bear in mind he's now traveling at 220 fps.

But your specific question seems to be at what point can the character try to do something about the fall. Let's assume for maximum character survivability that the character is a very quick thinker and can immediately react to what's happening. He still has to deal with normal reaction time, which is about 0.2 seconds.

Based on our earlier numbers, time to accelerate = 0.2 s.

t = v/a

v = t/a

v = 0.2/32.167

v = 0.006 fps

Acceleration distance = v²/(2a)

d_accel = 0.006²/(2x32.167)

d_accel = 0.000036 / 64.334

d_accel = 0.000000559' or 0.0000067" of travel.

I'd say the character has barely begun to move by the time he's reacting to his fall. If the ring of teleportation works instantaneously, he's fine. Oof!

If it takes more time to activate, he's in for a bigger jolt. Depends on how much time the ring takes, or whatever else the character is trying to do to save himself. Also depends on how far he can fall before the Party Wizard will need a Wet/Dry Vacuuming spell to slurp the remains into a bag of holding.

Answer 5

Timing

The rules for falling are quite explicit in how long it takes to fall. If you crack open the Dungeon Master's Guide 2, in the section on fighting in exotic locations, the rules state that you fall 670 feet in the first round of combat and 1150 every subsequent round.

I am away from my books at the moment, so I can't tell you during what phase of the initiative track this happens, but I will be able to check this evening and give a more detailed answer. I should at least hope to save people from doing more algebra.