An airplane has just before liftoff, when it is building up to an incredible speed and you feel like you are on a roller coaster that’s about to fly? Now imagine what would happen if the pilot had to slam on the brakes at that moment right before liftoff because another plane, which had just landed, crossed directly in front of him on an active runway.That’s what happened to my flight – Delta Flight 873 from Atlanta to Miami – at 10:30 a.m. Wednesday. Because of what the pilot later told us over the loudspeakers was an “administrative mistake” made by air traffic controllers, we had to hit the brakes to avoid another Delta plane. More than 100 of us passengers were jolted forward and then back – shaken and surprised, but with no apparent injuries that I saw. It was an aborted takeoff, or as a Delta spokesman would later term it, a “high-speed slowdown.”A few hours later, I asked the pilots how fast we had been going at the time they had to hit the brakes. They said “120 knots,” which translates into about 140 mph. Jets normally take off at a speed of 150-180 mph, so we were very close to getting airborne