Can an airplane skid off the runway upon landing if the brakes are engaged? I have an uncle who knows a lot about planes because he was a pilot. If you have any answers, I would very much like to hear from you.
Once again, you've got a great website.
No, the plane would not skid off the runway because of the anti-skid systems. The systems keep the plane from skidding by ensuring that the wheel continues to turn when it senses the plane is skidding. It is similar to the ABS (anti-lock brake systems) in your car as it prevents the brakes from locking up and allows the car to steer in any direction that you want to go while applying hard braking.
The ABS in a car pumps the brakes many times per second (much faster than a human can), thus preventing wheel lockup and helping to maintain steering control. Basically, the system measures the rotational speed of the wheels to determine if a skid is occurring and then releases the appropriate brake to prevent directional control problems. This means that when that car suddenly stops in front of you, you can brake hard and still steer over to the shoulder if you won't stop fast enough to avoid an accident.
If the anti-skids are not working in a plane, what would be the result if brakes are applied hard during landing? Well, from the simulator, it has been shown that the tires would burst but the plane is likely to maintain the direction along the runway.
See the rejected take off videos of a Boeing 777, a brake test on an Airbus A380 and another rejected take off on an Airbus A340 below: