Aspiring Boeing + Airbus Pilot
Dec 28 2007, 11:15 AM
When I am flying along in my boeing 737 classic at FL300 I usually initiate my decent 80 miles from the threshold. There is a calculation you can use (which I use) to calculate my decent rate. Every so often I will re-calculate to make sure I am decending at the right rate.
I am sure loads of us finish up approaching too high in flight simulator. Sometimes I have to face this prob.
I usually do as the manual says, the tip in the lower page says "our Target airspeed/altitude will be 30 miles from the threshold at 10,000 feet AGL at 250kts... any approach can be completed if you pass through this window"
This is the rule of thumb to figure out a good decent:
1) take your present altitude (in my case 30,000ft)
2) Subtract the altitude you want to be (the threshold elevation or your next altitude over a certain VOR etc)
3) Multiply answer to above by 3
4) this is the number of miles needed to decend.
So If I am at FL300 and landing at Denver with an elevation of 5,000feet for example then we do 30 - 5 = 25
then 25x3= 75. So for this decent you will need 75 miles to make a good decent. And a little amout of space for error. Lets say 5 miles to round it to 80 miles.
Kep re doing this calculation in order to make sure you are decending.
It says in the book that this does not really matter in FS because the differences in pressure and air density, temp etc are not simulated, but to make sure you are ok at least do it a couple more times throughout the decent.
If you are to go to the FIX page in the CDU and select the landing airport, if you type /30 and enter it, it will show a green arc around 30 miles all around the threshold. This will help to guide you on the decent so you know when you should be at 10,000ft. Keep calculating so you don't end up too high or too low in proportion to the distance from threshold.
This is a little confusing at first but with help of the manual in fornt of me I get more farmilliar with this method each time. Keep reading over until you understand.