SID Climb Gradient - B737 & other liners
 

Hello guys,

i tried already the search function but couldn't find much.

On departure procedures charts there are often published minimum climb gradients (in percentage%) to be respected in order to satisfy the vertical profile/obstacle clearance of that specific SID. If none are specificed, we assume 3.3% as minimum PDG but often non standard higher gradients are published.

- How do you calculate prior dispatch if your aircraft is capable to satisfy a particular climb gradient of a specific SID? (2 ENG of course)

I know ...... i should not be much concerned about it because the performance department of the operator does all the calculations prior starting service in that airport; i also know that the B737 and other liners usually have no problems with climb gradients using all engines. I'm just curious.

The Perf. Dept. of an airline uses the Boeing performance tool (or manufacturer equivalent tool) to calculate 2ENG climb gradients, where are those opt performance data coming from? because I don't know where to look for to find these performance values on paper.

Regarding the B737, I checked the FCOM v1 Performance Dispatch/Inflight section and i did not find a single table regarding 2 ENG climb gradients or limiting weights.
There is a table named "TakeOff Field/Climb limit weights" but does not specify which gradients are assured within those weights if any. I also checked the explanation of the tables into the text section and found no reference.

If tomorrow i wanna fly a BBJ for a private owner without any OPT/RTOW's or specific airline RWY tables how do i calculate my 2ENG climb gradients just by using the FCOM?

I am already aware of the formula ROC(ft/m)/GS(kts)= CLB gradient (%) but let's be realistic, it's too much of a guess to calculate the rate of climb and ground speed with so much weight and elevation difference for every departure.

I mentioned the B737 but any example for any airliner manufacturer is appreciated, i just wanna know if pilots can get a concrete value of their 2ENG climb gradients before departure if they want to, thanks a million guys.

the performance department of the operator does all the calculations prior starting service in that airport

Normally the ops eng folk provide OEI data. The crew flight operating manual (by whatever name known) should have AEO data lifted from the OEM AFM.

where are those opt performance data coming from? because I don't know where to look for to find these performance values on paper.

The OEM AFM/FCOM should have AEO data.

table named "TakeOff Field/Climb limit weights" but does not specify which gradients are assured within those weights if any.

These will be the WAT-limiting weights. Gradients depend on the number of engines and are specified in the Design Standards .. eg the second segment WAT limit for a twin is 2.4% gross.

pilots can get a concrete value of their 2ENG climb gradients before departure

A few years since I crawled over a 737 FCOM/AFM .. plenty of data there for folk to read.

Thanks for your reply,

although i had an extensive look to my AFM, i'm still unable to find the 2ENG climb gradient performance data. I'll try again page by page

Then, perhaps, have a delve into the OEM FCOM or similar.