climb gradient

[trot]

hi,

reading through different literature regarding min climb gradient at various stages on take-off and landing.
but different books mention different values for same stages and for same #of engines.

eg.
1st seg= positive gradient or .3%

2nd seg= 2eng 2.4%
3eng 2.7%
4eng 3.0%
other books just 2.4% for all
another book 2.0%

3rd seg= 2eng 1.2%
3eng 1.5%
4eng 1.7%
other books 1.5% for 3rd seg no matter #of engines

4th seg= 1.5% for all
another book 1.2%

missed approach= 2.5% for all #of eng.

landing climb gradient(all eng working)= 3.2%
approach climb gradient (OEI)= 2eng 2.1%
3eng 2.4%
4eng 2.7%

do i get confused between gross and net and different authorities require different values?

thanks trot

[Bigmosquito]

Don't you hate those numbers? Used to confuse me a lot...
Be extremely carefull on literatures. They sometimes confuse different rules and regulations.
An example is airplane of more than 12,500 lbs (5.700 kgs) MTOW are certified under FAR/JAR 25, while airplanes less than 12,500 lbs are certitied under FAR 23.
This cover only airplane certitied under FAR/JAR 25. The FAR/JAR 25.121 subpart B gives:
First segment
Twin - 0%
Quad - 0.5%
Second segment
Twin - 2.4%
Quad - 3.0%
Third segment
Twin - none
Quad - none
4th segment
Twin - 1.2%
Quad - 1.7%
I did not put 3 engines as they become less frequent, except maybe in business jets.
Segments mentioned are gross segments. Net segment are reduced by a penalty of 0.8% (2 engines) and 1.0% (4 engines).
The net flight path as to clear all obstacles by at least 35 feet.
Sometimes FAR and JAR differ. An example is obstacle during turns. The FAR regulation does not consider any additional vertical margin during turns, as the bank is limited to 15°. The following rule is then purely JAR-OPS (operation).
JAR-OPS 1.495 subpart G says;
"any part of the net takeoff flight path in which the aeroplane is banked by more than 15° must clear all obstacles... by a vertical distance of at least 50 ft."
In conclusion, always refer to regulations in which the airplane has been certified.
Hope it covers part of the puzzle.
Happy reading.

[Igor37]

Minimum climb gradients :
-Take off :
-First segment : -2eng : positive
-3eng : 0.3%
-4eng : 0.5%
-Second segment : -2eng : 2.4%
-3eng : 2.7%
-4eng : 3.0%
-Third /fouth : -2eng : 1.2%
-3eng : 1.5%
-4eng : 1.7%
-Approach climb : -2eng : 2.1%
-3eng : 2.4%
-4eng : 2.7%
-Landing climb : -2/3 & 4 eng : 3.2%

I.

[Bigmosquito]

Yes, it is true. However the third segment can be transformed into an acceleration capability in level flight. That's why I did not put anything for the third segment.

Furhter correction to my previous post. I was refering to JAR 25.121. Well, actually JAR has changed to EASA CS 25.121 since 2003, I think.

But thanks for the correction.

[trot]

fellas,

great replies,
many thanks

trot