Hi everyone,
Firstly I know this forum is about GA and sorry for the weird title, but I was wondering if someone with ATPL knowledge could answer my question about how to operate a Class B aircraft (single piston or twin piston for example) for commercial purposes. I had a discussion with my ATPL instructor and he couldn’t really answer my question and didn’t find any info elsewhere. Here is my problem:
EASA says:
Takeoff Field Length Requirements – SEP and MEP
a) When no stopway or clearway is available the take-off distance when multiplied by 1.25 must not exceed TORA.
b) When a stopway and/or clearway is available the take-off distance must:
1)not exceed TORA
2) when multiplied by 1.3, not exceed ASDA; or
3) when multiplied by 1.15, not exceed TODA
My issue is with the “and/or” part and when to apply the i), ii), iii). If I take for example the airport of Beziers in south of France LFMU, the declared distances are:
TORA = 2000m
ASDA = 2050m
TODA = 2050m
In this case, I assume that b) is applicable because there is a stopway. BUT, b) has 3 conditions:
i) not exceed TORA
ii) when multiplied by 1.3, not exceed ASDA; or
iii) when multiplied by 1.15, not exceed TODA
So if we do the calculation, we will have:
TORA 2000/1 = 2000m
ASDA 2050/1.3 = 1576m
TODA 1800/1.15 = 1 782m
Therefore, the limiting distance will be 1576m.
Now, WHY then airport operators bother creating and declaring stopways ? Because let’s say the 50 more meters placed after the TORA would have been just plain grass, this would have been considered as clearway only, right ? And then the aircraft operator would only need to divide the distance by 1.15 and as a consequence, the new limiting distance would have been 1 782m which means that the aircraft operator could take more payload for example. So why are stopways useful in this situation ?
Am I wrong to think like this or is there something I am missing ? My instructor answer was like “yes, it makes no sense, but this is just the way it is…”. Well..
Thank you very much 😉
S.
The balanced field concept (ASDA=TODA) is a Performance A concept for aircraft which can continue the take off with an engine failure at V1, and typically ASDA will be limiting. Performance B operate in a Net Take Off Flight Path environment and the engine failure scenario is when they enter the cloud base. By definition Performance B, do not have a V1 concept, and are not required to even publish ASDA tables, and some manufacturers of Performance B do not publish them. However, if the AFM has ASDA tables then it would potentially be the limiting factor.
I think the issue is trying to shoehorn Performance A concepts into the Performance B world.
Are you sure ASDA=TODA? typically TODA includes the airborne segment to 50(?)ft.
Yes am sure
Hi and thanks @RobertL18C for your contribution.
I think the issue is trying to shoehorn Performance A concepts into the Performance B world.
But this is the way we are taught in ground school. So this is just an EASA mistake ?
I am wondering how performance B operators are approaching this, the likes of Pilatus and Caravan operators or twin pistons aero taxis.
Seb
seb64 wrote:
Am I wrong to think like this or is there something I am missing ?
My understanding of the rule (CAT.POL.A.305) is that you have a choice between conditions ii) and iii). So in your example, the limiting distance will be 1782 m, which is better than the 1600 m without the stopway. But it is weird that 50 m of stopway would give an effective 182 m increase in available unfactored take-off distance. But the other interpretation – that all three conditions have to be met – is just as weird as the additional 50 m would give a decrease in available unfactored take-off distance.
Most PC-12 operations are either flown on behalf of owners, or fractional schemes, both using Part 91 type regulations. In any event TODR and ASDR are similar at around 3000 feet around ISA SL and 10,000 lbs.
An AOC MEP would need to calculate a NTOFP with factors applied to the multi and OEI climb gradient, this would tend to be more limiting than runway requirements.
Airborne_Again wrote:
My understanding of the rule (CAT.POL.A.305) is that you have a choice between conditions ii) and iii).
Me too.
But it looks like its not the case according to ATO and questions from database. Anyway, maybe I am overthinking this too much in the end ;)
Thanks
In this question, they even use the 1.3 factor rule for ASDA even though there is no stopway, just a clearway…. and because the ASDA is the same as TORA, the limiting distance is 1400 FT because 1820/1.3 = 1400 FT
Now lets imagine the same runway with TORA=TODA=ASDA = 1820 ft, the only rule that would apply would be 1820/1.25 = 1456 ft !!!!! Which gives a bigger number ! So more payload for the same TORA. So why bother with clearway and stowaways !?
I don’t get it. I am lost with this rule lol.
