It's under 2 1/2 hours drive from Manchester to Newcastle, and approx the same on the train.
Doesn't really make sense to fly unless the fares are competitive with other transport modes and door to door times are quicker. Flight time must be about 20-25 mins in a jet a/c, subject to routing, but the "check-in" to "out of the airport door" times must be similar to car/train times.
Don't know enough about potential pax loads on the route, but I'd certainly use it if the price was right.