It’s like the mouth of a bass once the fan blades are spun up. It sucks in the air in front of it, creating a vacuum, with enough force to lift things off the ground and into the engine’s intake.
There’s a video out there of a jet preparing to be catapulted off a carrier deck. It’s on the verge of being launch when a deck hand gets ingested into one of the intakes. Some piece of metal on the deck hand’s gear gets hang up and his hands and arms strain on the rim of the intake at the force being generated, the fan blades just inches from his face. Even switched off, it takes some long, agonizing seconds before the force slacks off enough for the sailor to be pulled back out.
One of the Concords (supersonic airliner) was fatally disabled when a piece of metallic debris on the runway was ingested into its engines, initiating a catastrophic failure.
Airfields, runways, and career decks constantly have to be cleared and monitored for debris, birds and other animals, and vagrants.
“Even switched off, it takes some long, agonizing seconds before the force slacks off enough for the sailor to be pulled back out.”
Vactors (big sewer/mess cleaning vacuum trucks) are like that too. One getting attached to you is a very bad situation and it takes 10’s of seconds for them to wind down. 5000 cfm, 27 in/Hg. One sucked the Tyvek off a coworker once, and we heard of a competitor employee that had one catch him at the waist which left like a foot diameter hickey/bruise and made one of his testicles suck up inside him. it can apparently suck the blood out through your skin also. It’s like portable “outer space”.