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Climb Gradient


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  • Deputy Sheriffs

Puuhbear, I think he's asking for the performance chart that shows the gradient for given temperature and pressure altitude so he can determine whether the aircraft meets the standard climb gradient (for missed approach segment, 200'/NM (about 3.3%) in the US) or as on the charts in your answer.

 

Volker, if I interpreted your question correctly, it looks like such a chart isn't included in the manuals supplied with the add-on. If you really want/need the info, you'll probably have to find it on the net.

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Thanks both of you !

Yes Herman, you interpreted correctly - thats what i am looking for, but i did not find anything on the net and, as you say, at the manuals.

 

Just to understand that "climb gradient" right:

it is NOT always the same gradient? (i thought, i can find somewhere a chart that say´s: CRJ 700 Climb Gradient :  4,5% - i am not a real pilot so i don´t know anything about climb gradient)

so it depends on the "environment" (weather) and differs every approach?

 

i asked because i want to read the correct MDA at LOWI - see attached chart...

 

 

 

LOWI_Approach_Instrument Approach Chart - LOC-DME East_18072019.pdf

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It varies with temperature, weight, airport pressure altitude and also airplane configuration etc. I checked our books and on average you will end up in between 4-5% at 31 tons landing weight (so above MLW) and 2000ft pressure altitude (since threshold elevation is 1894'). This is with APU off, anti ice off and packs on. 

 

Worst case at 31 tons is 2,4%, but that is at 4000ft pressure altitude and +40C OAT. In general the CRJ performs quite decent on single engine.

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On 5/13/2021 at 3:26 AM, Selberfliegenisttoll said:

Thanks both of you !

Yes Herman, you interpreted correctly - thats what i am looking for, but i did not find anything on the net and, as you say, at the manuals.

 

Just to understand that "climb gradient" right:

it is NOT always the same gradient? (i thought, i can find somewhere a chart that say´s: CRJ 700 Climb Gradient :  4,5% - i am not a real pilot so i don´t know anything about climb gradient)

so it depends on the "environment" (weather) and differs every approach?

 

i asked because i want to read the correct MDA at LOWI - see attached chart...

 

 

 

LOWI_Approach_Instrument Approach Chart - LOC-DME East_18072019.pdf 3.14 MB · 11 downloads

This FAA table will help.  It shows the FPM required at a given speed to achieve a given gradient

 

So if you want to go missed at D6.3 on the chart you posted, you would need a minimum gradient of 3.0%  If you look at the chart you will pick out your climb speed and then look for the FPM  rate next to the 3.0 gradient.  If you climb out at 180 kts a 3.0 gradient would be 956fpm, so any climb rate above 956 fpm would keep you safe along the published missed approach course.

 

ClimbDescent-Table-721x1024.jpg

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One thing to point out.  Weight and conditions have nothing to do with gradient calculations.  This is purely geometric and speed based.  However weight and conditions will decided if you able to comply with the speed and geometry. 

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Understood...  seems very logical, if i think about a little bit... :)

 

Thanks for the Climb/Descent Table !!!    saved it already at the desktop and will print it soon for the next approach :)

 

And again a bit closer to reality ...

 

 

Thanks again !

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5 hours ago, Selberfliegenisttoll said:

Understood...  seems very logical, if i think about a little bit... :)

 

Thanks for the Climb/Descent Table !!!    saved it already at the desktop and will print it soon for the next approach :)

 

Just a note that those tables don't tell you anything useful or relevant for deciding which minima to use. 

 

Yes, a gradient is simple geometry. The minimum required is set in regulations for procedures such as SIDS/STARS or missed approach procedures. Standard procedure design calls for a 2,5% climb gradient with one engine inoperative. However, the missed approach climb gradient that you base your choice of minima on, is the climb gradient that your aircraft can achieve should you have an engine failure. And that is very dependent on temperature, pressure altitude, landing weight, configuration. Operators will have a table for different landing weights, outside air temperature and pressure altitude of the airport. 

 

So just to reiterate, for your initial question about which minima to use in LOWI... 5% climb gradient on single engine should be achievable in most conditions so you could probably use the lowest minima. But if you want to play it safe you should go with the minima for 4%.

 

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On 20.5.2021 at 17:57, Crabby sagte:

This FAA table will help.  It shows the FPM required at a given speed to achieve a given gradient

 

So if you want to go missed at D6.3 on the chart you posted, you would need a minimum gradient of 3.0%  If you look at the chart you will pick out your climb speed and then look for the FPM  rate next to the 3.0 gradient.  If you climb out at 180 kts a 3.0 gradient would be 956fpm, so any climb rate above 956 fpm would keep you safe along the published missed approach course.

 

ClimbDescent-Table-721x1024.jpg

 

 

 

Okay thanks a lot - once again :)     i guess, thats what crabby means with: "However weight and conditions will decided if you able to comply with the speed and geometry. "    But this table is still missing at the documentation of the crj - or i did not find it :)

 

but - one question to the dlimb/descent table to crabby:

 

i am confused, because you say going missed at 6.3 dme with 3% gradient on my postet chart (LOWI) will be 956 feet/min at 180 knots ground speed.

But at the climb table you postet i have to use degrees - not percent... so if i change the 3% into degrees i will get an angle of 1,72 degrees. The table starts at 2 degrees - so i should be fine with a climb rate of 635 feet/min with a ground speed of 180 knots...

 

so who is right? :)

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  • Aerosoft

Yeah, it's fairly easy to confuse between degrees and percentage. So if the required climb gradient is 3 % it would mean around 550 feet/min with GS of 180 knots. if we do some quick math by changing 180 knots (nm/hr) to feet per minute by dividing by 60 and multiplying by 6076 we get 18228 feet/min lateral movement. Climb gradient is merely a value of the ratio between vertical distance covered per lateral distance covered. So we get a formula of climb gradient = vertical speed/lateral speed, where we can solve for the vertical speed so that vertical speed = climb gradient*lateral speed.

So for example, if we need to know if the aircraft is able to meet 5% climb gradient we would simply take the presumed ground speed at go around (lets say it's 160 knots). Do some unit conversions to get ground speed of 16202 feet/min and then plug it into the formula we get that we need vertical speed of at least 810 feet/min to meet the 5% gradient.

Now, pilots are not really required to do this math themselves in the aircraft and the takeoff/landing performance calculators will give them very accurate values when all the parameters are given. But usually pilots still have some ballpark values in their head for the aircraft type that they can use for quick decision making.
 

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On the approach is the wrong time to be doing anything this complicated.  As stated, during the arrival/approach brief the PIC and PM would go over any unusual go around items, such as you find in LOWI.  At that time they would determine what MAP point they will fly to based on their knowledge of the aircraft.  One thing to keep in mind, I seriously doubt you would find a MAP on any chart in the world that could not be flown by standard missed approach climb profiles in any civil passenger jet.  Maybe a military base, but even then they tend to be at least as safe as the civilian side since they don't like to lose multi million dollar aircraft to general dumbassery.

 

One of the most dangerous things in flying is thinkingtoomuchitis.

 

Also, I posted this elsewhere and it is not mine but wish it was.  "Every arrival should be planned as a missed approach.  Landing is just an acceptable outcome"

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okay - i understood the "principle" and can select the correct mapt now. bird strikes are not simulated in msfs and the rest of "failures" are turned to "off" - so i am fine at my next approaches :DDD

just doing some missed approaches for training - thats enough for me at the moment ;)

 

thanks so much to both of you for explaining !

 

 

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  • Deputy Sheriffs

Because we believe this topic has been answered we have closed it. If you have any more questions feel free to open a new topic.

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