Unless you are in a spin and in that case hopefully you are high. Lol
Correction. 20,000 ft
Easiest way for me to calculate a continous 3° GP is:
Top of Descent [NM] = (Altitude to lose/100)/3
Rate of descent = GS * 5 (adjusting it continously)
Descending from 12000ft to 3000ft --> TOD= (9000/100)/3 = 30NM
Straight and simple. Top of descent:
The height needed to lose, minus 3 000’s then times 3
Need to lose 20,000?
20 * 3 = 60. Start descent 60NM out, tho it is advisable to add a 5NM “buffer” to even it out
Need to lose 34,543?
34 * 3 = 102
107NM top of descent
Current ground speed * 5
400GS * 5 = 2000
Descend at 2000FPM
(Note, requires re calculating every 5 thousand feet or so)
Wow! I’d rather fly United and get dragged off a plane!
@SingaporeAirlines @larryb 😂😂😂😂✈️
I just roughly calculate it by looking at my flight plan and generally if the VS of my climb is 2 times of what I usually use for my decent in that type of plane then I roughly double the length of how long it took me to reach cruising ALT and apply it to the end of my FLP (roughly) and I descend around that calculation. And mostly its a little early but i would rather that than having to descend to rapidly.
also just use ILS or GPS. and if you don’t get you preferred runway on the little list, then just remember to ad the air port on your FLP (Flight Plan) and the runways should appear on your little ILS, GPS list.
also shout out to @SingaporeAirlines.
When 1 NM out, begin your decent by going into a 45 degree bank angle to the right. Pull as hard as you can which will slow you down as quick as you can. Ignore the 40G’s you pull. When at 2000ft, level out and line up with the runway. Put the gear down when you are below 220 knots. Once on the ground activate the reverse thrusters at 190 knots until you stop.
This is a joke
So your rate of descent is Ground Speed * 5.
So assume a theoratical maximum ground speed of approx 450 kts at cruise, your max decscent rate would be 450 * 5 = 2250 feet per minute.
And by the time you have reached 9,000 feet, doing 240 knots, your max descent rate would be 240 * 5 = 1200 feet per minute.
So with the descent rate being so variable and our rate if descent also being variable, how can you accurately determine when (how far out) you need to start descending?
I don’t know how but the 3 * altitude needed to lose will always work
As long as you recalculate the descent speed every few thousand feet
Unless terrain conditions dictate otherwise, I personally adhere to the
traffic pattern altitude for that particular airport which is usually
around 1,000’ AGL for light aircraft and 2,000’ AGL for larger airliners by
the time I intercept the localizer.
This topic sure has a lot of opinions being floated around.
You can use the same rule-of-thumb formula I wrote above ( (ALT to lose/100)/3 )
The ROD has to decrease with decreasing altitude because TAS (aswell as GS assuming constant wind) decreases as well. If you would maintain same ROD your descent angle would continiously increase because your losing more altitude than you cover distance over ground.
Did I answer your question?
I think it’s nice: Everyone can choose a rule of thumb that “fits them best”. I can’t get the other formulas in my head :p
Flightplandatabase.com usually is pretty good about giving ascent rates, descent rates, I have learned that it also adds in waypoints to navigate with
This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.