Thanks Tribekey for the explanation.
About the noise I don't see what the problem is over the New Forest. It's sparsely populated and the 737s and Airbuses that mainly operate out of the airport make little noise, my house is directly under the flightpath when aircraft are doing circuits and pretty close to the flightpath when aircraft are taking off on 26 to head toward the Southampton VOR. With double glazing It's a job to hear any significant noise.