ATPL PERF QUESTION

[powdermonkey]

Hi Guys, can you clarify this for me?

Field length requirements:
a. When no stopway or clearway is available the take off distance must not exceed 1.25 x TORA...I presume that means clearing the 50ft obstacle clearance within 1.25 the TORA?

b. When you have a stopway or clearway, take off distance must not exceed
1. Tora
2. 1.3 x ASDA
3. 1.15 the TODA

What on earth does no. 3 mean? How can your take off distance be within a limit of 1,15 times the TODA???? If the TODA is assumed to be the distance from the start of the ground roll to the nearest obstacle in the direction of take off, then when calculating your required TOD, how can you go beyond it?

This always confuses me , any help out there???
Thank you

[Old Smokey]

Actually powdermonkey, most things in your post are confusing me, but seeing as you're addressing Item No. 3....................

Perhaps you're confusing this with the rule that for an All Engines Takeoff, the TODA must be at least 1.15 times the TODR. This rule applies whether you have a Stopway, a Clearway, both, or none at all. No such margin applies for the OEI Takeoff.

Regards,

Old Smokey

[powdermonkey]

Indeed I am a very confused person, but think this was a type error in the manual.
For the MEP take off requirements it states:
1.When no stopway or clearway is available the take off distance x 1.25 must not exceed the TORA
2. When stopway or clearway is available the take off distance must:
a. not exceed TORA
b. When multiplied by 1.3 not exceed the ASDA
c. When multiplied by 1.15 not exceed TODA
THAT MAKES PERFECT SENSE, but for the SEP, it was worded completely differently:
Field length requirements:
a. When no stopway or clearway is available the take off distance must not exceed 1.25 x TORA
b. When you have a stopway or clearway, take off distance must not exceed
1. Tora
2. 1.3 x ASDA
3. 1.15 the TODA
Which makes no sense at all; perhaps what they ment, like for the MEP is that the take off distance when multiplied by 1.25 must not exceed the TORA. That then makes perfect sense.....
Sorry to confuse you Old Smokey, but I hope you can see that the wording in the Cap 698 makes sense in the MEP section but not the SEP, hence both our confusion!!!

Thank you for your reply nonetheless
Cheers

[john_tullamarine]

Like OS, I find your post a tad confusing. Perhaps you can put a link to the relevant manual or whatever source the words came from and it might make a bit more sense to us in context.

[powdermonkey]

Sorry guys,
Forget my first post, I confused myself wriying it!!
Look at the second one, and it is in relation to performance for the SEP and MEP with field length limited TOM. Anyway, I have it sorted, it was an error in the manual. But thank you for taking the trouble.
Cheers
PM