When can a receiver go down field to block after a running back catches a swing pass behind the line of scrimmage?

If a quarterback throws the football behind the line of scrimmage and the receiver does not catch it is it a fumble?

That depends on the angle the ball travelled. If the receiver is behind or exactly to the side of the quarterback and the ball travels at an angle parallel to or away from the line of scrimmage, the throw is considered a lateral and would be a fumble if the receiver did not catch it. If the receiver is in front of the quarterback and the ball travels at an angle towards the line of scrimmage, the throw is considered a forward pass and would be an incomplete pass.

Is a pass behind the line of scrimmage a run or pass?

It depends on where the quarterback is standing in relation to the receiver. If the pass is forward, it is still a pass even if the receiver is behind the line of scrimmage. If the pass is backwards, it is considered a lateral and therefore a run.

What is sacking the quarterback?

A sack is when the quarterback is tackled behind the line of scrimmage before he can throw a forward pass/lateral. Tackling the quarterback behind the lime of scrimmage on a running play is not considered a sack.

Who is allowed to throw a forward pass in football?

Wrong choice of terminology - a Forward Pass must be made behind or in the neutral zone (the width of the ball where it is spotted for the Down) by the passer to be legal, and be caught by an eligible receiver to be complete. It can, however, be caught by an eligible receiver anywhere on the field of play, even behind the line of scrimmage.

Is tackle of running back who receives direct snap behind line of scrimmage a sack?

yes

Can a quarterback go for a pass after handing the ball off to a running back or wide receiver?

If a quarterback and the entire ball are in front of the line of scrimmage then a forward pass can no longer be thrown but a lateral is still a legal play. However, by the act of crossing the line of scrimmage, the quarterback does not lose the right to throw a forward pass as long as after crossing the line scrimmage, the ball returns behind and is thrown from behind the line scrimmage.

Explain a screen pass and why it's called a screen?

The term screen comes from the play's design which has several blockers in front of the pass receiver at the time of the catch, creating a 'screen' in front of the receiver. The two general types of screen pass are those that are thrown to a running back and to a wide receiver. A screen pass to a wide receiver is a quick developing play. The quarterback will drop back, usually three steps, and throw the ball laterally or a yard or two forward, to the wide receiver who is behind the line of scrimmage. While this is going on a couple of offensive lineman run out to the side and get in front of the receiver. There might also be another wide receiver or tight end lined up on that side so there would be three blockers in front of the receiver when he catches the ball and begins running upfield. A screen pass to a running back is a slow developing play. The quarterback will drop back normally as if he is looking to throw the ball downfield. The running back will stay in the backfield as if he is going to block for the quarterback. Then the running back will move into an area, behind the line of scrimmage, to catch a pass while two or three of the offensive lineman and maybe the tight end, who have been blocking defensive lineman, will peel off and get in front of him. The quarterback will throw him the ball and he will have several blockers ahead of him. This type of screen pass can also be thrown to a tight end. The tight end will line up on the line of scrimmage next to an offensive tackle and start the play as a blocker. He will then peel off the block and the quarterback will get him the ball while some of the offensive lineman also peel off their blocks and get into position to block for the receiver.

What does the running back do?

the running back is a pretty vital position. his job is to carry the football up the field on offense by taking either a hand off or a toss from the quarterback behind the line of scrimmage. He offers an alternative to passing. Notable examples include Ladanian Tomlinson, Adrian Peterson, Brandon Jacobs, Deuce McAlister, etc. The running back also can be sent out on passing routes as a receiver, or can stay back to block any defenders that may try to get the QB or as a blocker for the fullback/recievers.

Does the running back snap the ball to the quarterback?

He can do either. He can run with the ball, hand it off, or (as long as he's behind the line of scrimmage) pass it.

What position does FL stand for in football?

FL usually refers to the flanker, which is a wide receiver who lines up behind the line of scrimmage.

Illegal receiver downfield?

"Legal" receivers are elligable to catch a pass. Players who start a play on the end of the line or in the backfield are elligable. Linemen can't cross the line of scrimmage before a foreward pass crosses the line or they are considered to be downfield illegally unless the pass is caught behind the line of scrimmage.

Is a pass illegal if it is thrown from behind the line of scrimage in football?

No! A pass is only legal if it is thrown from behind the line of scrimmage. A pass is illegal if it is thrown from in front of the line of scrimmage.