IT SEEMED to be flying at a very low speed. Like I said I thought it had mechanical problems. Propeller planes can kinda glide where a jet goes straight down basically if it loses power.
This is not at all true. Once the power is out, the source of thrust doesn't matter so much as the aerodynamic properties of the plane do, and a lot of jets have surprisingly good glide ratios. In 1983,
Air Canada 143 managed a 12:1 glide ratio while making an unpowered landing at what turned out to be a car track with a race in progress.
The C-130 has an official stall speed rating of 114 miles per hour (slower than the airliners that I know of), but upon Googling I've found some pilots claiming speeds as low as 85 mph in ones they've flown, and conflicting claims of glide ratios up to 9:1.
As for the illusion of hovering, it's important to remember that your eyes don't see anything in a linear matter, they see everything in angles (99% of what we "see" is really post production trickery your brain does, and it isn't exactly running on Michael Bay's effects budget):
Excuse my terrible MSPaint diagram, but here you see yourself heading one direction on a road, while a plane heads in the opposite direction in the air. Between you is a stationary building. Since you're moving, the building has an apparent angular speed to your eyes.
If the ratio of your distance to the building and the plane's distance to the building is close to the ratio of your relative speeds (in the simplified version you and the plane are roughly equidistant at roughly the same speed because I'm bad at diagrams), the angular speed of the plane and the building will be the same, even though one is moving and one is stationary.
Your brain is really bad at solving this type of conflict - if the plane was over a clear horizon, it wouldn't appear to be stationary to you, but with the building, your perceptions are messed up. Normally your brain is pretty good at sorting out what it thinks everything you see should be doing, and you perceive them as doing those things. But any time things you see create a conflict - like a stationary object and a moving one right next to each other with the same angular speed - it just throws up its hands and you get this sort of illusion instead.
Fundamentally, it's the same thing as the
hollow face illusion. Just another one of those little ways our brains betray us because we're subjecting them to situations and stimuli that evolution never had a chance to prepare them for.