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SID MNM CLIMB%, but until when ???

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SID MNM CLIMB%, but until when ???

Old 5th Feb 2021, 15:53
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PAG
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SID MNM CLIMB%, but until when ???

Hello everyone,

Question under EASA regulation

Reading company Ipad to stay current with this covid, looking at SID plates, and looking at these departures with different minimum climb gradient, 5,6% ,4.3%, etc, and then I wonder, but until when ? I know MNM CLIMB starts at DER but when is it non longer required ? some say until 400ft, some say MSA, some say it's an average until the end of the SID and some say until SID STOP ALTITUDE.

I've been looking for it in EASA documentation but nothing shows up

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Old 5th Feb 2021, 22:03
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The answer is in ICAO Pans Ops Doc 8168. The design criteria is for 3.3% up until the SID finishes.
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Old 5th Feb 2021, 22:34
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PANSOPS VOL1 states that where a gradient greater than 3.3% is specified, the altitude or fix to which it extends shall be promulgated. Eg "gradient 4.4% to 1200' thence 3.3%". It is not necessarily the end of the SID but a point from where the standard 3.3% will provide MOC. Obviously if you have a stop altitude in the SID you comply with that but the procedure design is such that you will already have obstruction clearance in that case.


some say until 400ft, some say MSA, some say it's an average until the end of the SID and some say until SID STOP ALTITUDE
400' figure probably comes from min height for intial turn (or maybe 2nd segment). The gradient is definitely not "an average until the end of the SID" but a minimum to be maintained at all times (in normal ops). The answer to the question remains that the minimum gradient extends to the altitude or fix promulgated and the reference is PANSOPS VOL1.

Last edited by oggers; 6th Feb 2021 at 01:03.
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Old 6th Feb 2021, 10:12
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Hi,

as mentioned above by other forumers. Ref. PANS OPS VOL 1

1.5.5 Gradient specification
1.5.5.1 Published gradients are specified to an altitude/height after which the minimum gradient of 3.3 per cent is considered to prevail.
1.5.5.2 The final PDG continues until obstacle clearance is ensured for the next phase of flight (i.e. en-route, holding or approach). At this point, the departure procedure ends and is marked by a significant point.
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Old 6th Feb 2021, 12:54
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PAG
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Thank you for your answers guys, but sometimes there isn't any fix or altitude promulgated, have a look at this plate

On CNA5P dep, we do have 4.8% to maintain until 666ft that's clearly stated, but then 8.6% as a minimum for the entire SID? well when we accelerate to retract flaps we are well below 8.6%. Could it be airpace related and not obstacle related ?


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Old 6th Feb 2021, 13:46
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Originally Posted by PAG View Post
but then 8.6% as a minimum for the entire SID? well when we accelerate to retract flaps we are well below 8.6%. Could it be airpace related and not obstacle related ?
It's 8.6% until the stop altitude, which is FL70. Flap retraction isn't an issue, as your climb gradient does not need to be 8.6% or greater during the entire SID.

Let's say on a normal takeoff, your V2+20 (or whatever the initial climb speed on takeoff is for your type), will typically result in less than 200kts GS on an average takeoff with a narrowbody aircraft. If your rate of climb then is say 2,500 ft/min at 200kt GS, your initial climb gradient will be around 12.5% at that point, so you will be flying well above the minimum gradient. While you retract the flaps, your flight path will be shallow and your margin from the minimum gradient will reduce, but once they are retracted, your climb performance will again greatly exceed the minimum required gradient.
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Old 6th Feb 2021, 16:05
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Originally Posted by PAG View Post
Thank you for your answers guys, but sometimes there isn't any fix or altitude promulgated, have a look at this plate

On CNA5P dep, we do have 4.8% to maintain until 666ft that's clearly stated, but then 8.6% as a minimum for the entire SID? well when we accelerate to retract flaps we are well below 8.6%. Could it be airpace related and not obstacle related ?
Check your chart provider’s explanation. (Called Legend and Tables for LIDO charts.)
This is LIDO’s explanation (not necessarily the same for your charts, but the text in bold should apply as well for your charts):

Minimum climb gradient
Procedure climb gradients of more than 3.3% are displayed. A minimum climb
gradient without an associated altitude applies until the SID termination point
. If the reason for a non-standard climb gradient is known, then the reason is given as a ball note. Climb restrictions applicable for SIDs after their termination point are displayed as ball flag notes.



During acceleration, your climb gradient will be less. But prior to accelerating, it would have been much higher. Your average gradient is still higher than required and your vertical profile will always stay above the imaginary line drawn from DER up to the required altitude or point. If in doubt, calculate by converting your gradient to ft/NM and verify your FMS predictions. If there are no altitude constraints on the SID and in the FMS, you can always create them yourself with your ft/NM calculation, or keep them on a scratchpad.

(Also, don’t believe everything you are being told. Different persons will give you different contradicting answers. Only what’s actually published somewhere is correct. So always try to find the answer somewhere or ask for a reference.)
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