“That assumes that the drone knows the exact altitude at which the aircraft will cross over a given point on the ground, and that it will not drift sideways from the runway centerline after takeoff.”
If you read down into the blog this issue is extensively discussed.
On each airframe, such as a 747-400, each engine is mounted at a known distance to the left or right of the centerline and at a predictable altitude from the runway surface during takeoff (allowing for wing lift of the outer engines).
If you go onto Google Earth, for example, you can find any airport and hover your pointer at each end of any runway centerline to obtain the GPS coordinates for latitude, longitude and altitude. Knowing the three-dimensional coordinates for each end of the runway centerline and the known distance that each engine is from the airframe centerline, say of a 747-400, allows the individual linear path down the runway that each engine will follow.
This allows each engine of that specific airframe to be targeted by terrorists.
“This allows each engine of that specific airframe to be targeted by terrorists.”
Not really Load weight determines the speed of acceleration and a terrorist would need to know the weight and takeoff performance of the aircraft to know when the aircraft will be at a specific point and the terrorist would need to know the acceleration and performance characteristics of their weapon to get the weapon and the engine to be at the same place at the same time. Sorry, but implausible.