Have you ever read a book with sentences like these?

Sailing through the air, Reese landed in the sand.

Lumbering away from us, Fergus lay down on the hardwood floor.

Stopping the car, Philip rushed through the front door.

Slamming her beer down on the table, Simone left the restaurant.

These are examples of forced simultaneity, an extremely common error. We love to use the -ing forms of verbs in our opening clauses, perhaps in order to vary sentence structure or because we simply like how it sounds.

But as authors, we need to be aware of whether the two actions represented in sentences like these can truly be performed at the same time.

*Here's a fun trick to use to check: Flip the order of the clauses. For example #1 above, that would be: Reese landed in the sand, sailing through the air. Seems pretty obvious when you read it that way, doesn't it? She definitely can't perform both actions at the same instant.

Sequence is often best used over simultaneity

I have to give a shout-out to writing coach Kim Lozano for tuning me in to this issue. (Yes, copyediting courses also discuss sequce versus simultaneity, but Kim's the one who really opened my eyes to it, and now I can't unsee it when I notice errors.)

Reread the examples above and you'll see what I mean. Our long jumper can't literally sail through the air and land in the sand simultaneously. Neither can Philip both stop the car and rush through the door simultaneously. And no matter how angry Simone is, she can't actually leave the restaurant at the same moment she's slamming the drink down.

Whether you're writing, revising, or editing, you can bring precision to the work by paying attention to structures like these. Sentences beginning with a gerund don't automatically contort your characters into impossible positions, but it's a good place to start.

What you want to strive for in your writing is precision, which means that many of the times you're tempted to use simultaneity, what you really need is sequence.

Things tend to happen in order.

Inaccurate: Sailing through the air, Reese landed in the sand.

Correction: Reese sailed through the air and then landed in the sand.

Inaccurate: Lumbering away from us, Fergus lay down on the hardwood floor.

Correction: After lumbering away from us, Fergus lay down on the hardwood floor.

or: Fergus lumbered away from us and lay down on the hardwood floor.

Inaccurate: Stopping the car, Philip rushed through the front door.

Correction: After stopping the car, Philip rushed through the front door.

or: Philip stopped the car and rushed through the front door.

Inaccurate: Slamming her beer down on the table, Simone left the restaurant.

Correction: Simone slammed her beer down on the table before leaving the restaurant.

However, there are certainly verbs that work well with simultaneity. Actions like think, look, listen, wonder, etc. that are more internal are some to consider.

Simultaneity examples

Listening to the strains of Vivaldi's Four Seasons, she craned her neck to peer out the window.

Watching carefully for hummingbirds, the cat moved over next to the patio door.

Thinking about the mess he'd made of his life, he waded into the water up to his knees.

The above examples show that simultaneity is possible, but not always. Be sure you're not subjecting your characters to actions that are physically impossible. In those cases, a revision that makes things happen sequentially is necessary.