Climb gradient on go-around

[FLT86]

Hi All,

I am writing to you regarding net/gross climb gradient.

On books, I've read that the climb gradient on go-around for a turbo-propeller aircraft is 2.5%. Is it net or gross ?

At the same time, still on books, I've read the following for a turbo-prop:

G/A => One engine inop => Approach configuration => 2.1 % gross
G/A => All engine => Landing configuration => 3.2% gross

Should I take into account the 2.5% for a G/A or those mentioned before ?

Same for the penalty of climb gradient on cruise with one engine inop (turbo-prop) => 1.1%.
Should I know it ?

Thanks for your help.

[selfin]

FLT86,

The 2.5 percent is a recommendation for the nominal minimum missed approach climb gradient made in ICAO PANS-OPS for all aeroplane performance classes assuming normal operations. The approach chart may require a higher gradient.

The 2.1 and 3.2 percent figures are CS25/FAR25 certification requirements.

ICAO PANS-OPS V1 as of 2006-11-23:

6.1.7 Missed approach gradient

6.1.7.1 Normally procedures are based on a minimum missed approach climb gradient of 2.5 per cent. A gradient of 2 per cent may be used in the procedure construction if the necessary survey and safeguarding have been provided. With the approval of the appropriate authority, gradients of 3, 4 or 5 per cent may be used for aircraft whose climb performance permits an operational advantage to be thus obtained.

6.1.7.2 When a gradient other than 2.5 per cent is used, this is indicated on the instrument approach chart. In addition to the OCA/H for this gradient, the OCA/H applicable to the nominal gradient will also be shown.

6.1.7.3 Special conditions. It is emphasized that a missed approach procedure which is based on the nominal climb gradient of 2.5 per cent cannot be used by all aeroplanes when operating at or near maximum certificated gross mass and engine-out conditions. The operation of aeroplanes under these conditions needs special consideration at aerodromes which are critical due to obstacles on the missed approach area. This may result in a special procedure being established with a possible increase in the DA/H or MDA/H.

NB:

1.5 The design of procedures in accordance with PANS-OPS criteria assumes normal operations. It is the responsibility of the operator to provide contingency procedures for abnormal and emergency operations.

C.f. http://www.pprune.org/tech-log/445232-approach-climb-2-1-vs-macg-2-5-greater.html
and http://www.pprune.org/tech-log/9629-landing-climb-limit-approach-climb-limit.html
and http://www.pprune.org/tech-log/457743-missed-approach-climb-gradient-question.html
and http://home.scarlet.be/ppleducation/Perfo%20briefing%20737.ppt (powerpoint file - slide 43 et seq.)

[selfin]

FLT86,

Same for the penalty of climb gradient on cruise with one engine inop (turbo-prop) => 1.1%.
Should I know it ?

The deduction is already taken account of by the AFM so there's no point in committing the figure to memory. Planning a route based on drift down capabilities presented in the AFM, while observing CAT.POL.A.215 ENR OEI requirements, ensures that the design incident probability of a catastrophic outcome is preserved. The incident probability would increase unacceptably if the AFM did not make the deduction.

Here is a relevant Boeing slideshow from 2002, Operations in Mountainous Areas, for your pleasure: http://www.smartcockpit.com/download.php?path=docs/&file=Operations_In_Mountainous_Areas.pdf

If you're interested in the history of the 1.1 percent gradient you can find it in chapter 5 of the report developed by the 1953 ICAO Standing Committee on Performance. HathiTrust maintains an electronic copy here: Final report of the Standing Committee on Performance. ... . - Limited View | HathiTrust Digital Library | HathiTrust Digital Library (http://babel.hathitrust.org/cgi/pt?id=uc1.b5079799;view=1up;seq=208)