Departure Instructions

[Guest nat2005]

"Cross Noise Monitoring Points not below 1196ft QNH (1000ft QFE) thereafter maintain minimum climb gradient of 4% to 3000ft to comply with Noise Abatement Procedures"It would be greatly appreciated if anyone could explain what this actually means, and if/what i have to enter into the FLAPS: 20/XXXXft in the FMC.Thanks in advance,Nat

[Tabs 2,790]

Hi Nat,Do you have the actual chart? What airport/SID is this for?

[Guest nat2005]

Hi Ryan,Yep it is for the KENET SID

[cowpatz 243]

Gidday Nat,These are fairly common requirements for some airfields. Normally a chart is available in the flight library (Jepp)that show where the noise monitoring stations are located. These stations take noise readings (db's). Operators who exceed the limits can be fined or have limitations placed upon them. I tried to look up the noise chart for EGKK but it wouldn't let me...said the file was corrupt. Any way the normal ICAO noise abatement techniques will work fine ie. TO thrust and flap configuration to 1500ft then CLB thrust and accelerate cleaning up flap as you go. What it is saying is that you have to cross the noise monitoring station above the height indicated and from then on fly at a gradient of 4.4%. Gradient is basically slope. It can be found from a chart or you can work it out. A 1% gradient is equal to 60 ft per nautical mile. So for a 4.4% gradient you need 4.4 x 60 = 264. In otherwords for every nautical mile you travel you need to have increased altitude by 264 ft.How do you know you are acchieving this gradient?There are 2 ways. Prior to departure the legs page will give you a distance to a particular waypoint in miles. Multiply this by 264. ie if the first fixed waypoint is 10 miles away then you know you need to be about 2700 ft crossing it. You could put a 10 mile range circle in around the airfield on the fix page as a crude measure to help visualize or you can work out a required rate of climb on the departure. You can do this by first of all determining what your groundspeed will be (this is also indicated on your ND during flight). Divide your groundspeed by 60 to get nautical miles per minute. ie a ground speed of 120 kts = 2 miles per minute. 180 = 3 miles per minute. From what you worked out before you know you need to acchieve 264 ft for every mile. Therefore if you are doing 180 kts (3 miles per minute you will need a Rate of climb of 264 x 3 = 792 ft per minute. Remember that this is an average rate of climb and there may be times, especially during flap retraction when heavy, that you will be less than that and at other times more than it. As you have probably seen flying the sim 800 ft/min is not too difficult to acchieve.I have attached a chart from the UK AIP that has easy to read gradients foir anyone who might need them.Hope this helps.CheersSteve

[Guest nat2005]

Thanks for the brilliant reply Steve, thats just what i was looking for!Thanks again,Nat