Hoping someone can clarify some performance issues for in regards to both dispatch and inflight calculations. I know I am basing it on EU ops but I believe there is similarities with these sort of regualtions worldwide as a result of ICAO so any people more familiar with FAA regs, please do add any info you have as I think it may help.
Right as part of our Dispatch legal requirements we are required to check a number of things in relation to the aircraft. I am taking in relation to a 737 but this would be similar to any jet transport operating commercially.
1. Expected aircraft Mass at time of arrival should not be over our dispatch limits using Cert data (CS25/FAR25) for either DRY/WET/CONTAMINATED depending on what the expected weather conditons are at time of arrival +/- hour of ETA
2. If missed approach is greater than 2.5% then check expected mass is ok to achieve this.
3. (Only EU Ops I believe) but if expecting to carry out a CAT 2/3 with a DA below 200ft we need to check that a G/A can be achieved of 2.5%
4. We check the approach climb limit weight (2.1% for two engine aircraft)
Of course when inflight the regs basically say a commander has to be satisfied that a safe approach/missed approach/landing can be achieved using actual weight and conditions.
My question is in regards to the approach climb limit weight which is my understanding has come from certification standards (CS25) and the standard missed approach unless otherwise stated is 2.5% which has come from PANS OPS/FAA/EU OPS regs. Why is there a mismatch between the two? Has no one ever asked why we are checking one for dispatch ie the 2.1% when a standard missed is always 2.5%. Also on that why is that we are never required to check a 2.5% missed approach unless the DA is below 200ft.
Any help or info would be greatly appreciated. I have been told that the reason for the differences is because the info is coming from three different areas namely certification, regulations and operational rules.
I would have thought something quite important like this would match up from all areas.