Topic: | Re:Re:Re:Re:3rd runway noise in Chiswick | |
Posted by: | Richard Jennings | |
Date/Time: | 02/02/08 12:03:00 |
"why do they fly so low over Chiswick when Heathrow is 10 miles or so away?" The runways are about 7 miles away. Nearly all major airports have their landing aids (Instrument Landing Systems, etc.) set to a 3º approach path, which works out at a descent rate of about 300 ft per mile. This is effectively the international standard, to which aircraft manufacturers optimise their designs. So the planes are roughly 2000 ft above us in Chiswick. Why couldn't everyone standardise on a steeper slope? To quote an answer on the subject from the PPRUNE pilots' forum: "A 3 degree slope for most types [of aircraft] gives you a lowish power setting but not such a low setting that the engine is running so slowly it takes a long time to power up should you need it. Flying anything much steeper means flying the approach with the power back at or near idle and gives a high rate of descent near the ground (especially on the heavy jets with highish approach speeds)." So safety would be compromised. London City airport has a 5.5º slope because of all the high buildings around it, but only takes small aircraft. |