ATPL Performance Question
Thread Starter
Joined: Jul 2006
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From: Ireland
ATPL Performance Question
Taken from an Italian question bank. Could someone explain how you get to this answer? Only one I've found which a few of us can't arrive at happily.
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An airfield has a TORA of 3,000m with the first obstacle (that protrudes above an upward slope of 1.25% from the end of the runway) 6,560ft away. What would the TODA be for an aircraft with 3 turbojet engines?
a) 4500ft
b) 5000ft
c) 14760ft *
d) 16400ft
* Answer is C. How?
Spotted the obvious trap of 3000m needing to go to feet but don't know which factor to apply to the distances to arrive at C.
Something similar on Bristol question bank too with no explaination apparantly.
Appreciate the help.
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An airfield has a TORA of 3,000m with the first obstacle (that protrudes above an upward slope of 1.25% from the end of the runway) 6,560ft away. What would the TODA be for an aircraft with 3 turbojet engines?
a) 4500ft
b) 5000ft
c) 14760ft *
d) 16400ft
* Answer is C. How?
Spotted the obvious trap of 3000m needing to go to feet but don't know which factor to apply to the distances to arrive at C.
Something similar on Bristol question bank too with no explaination apparantly.
Appreciate the help.
Joined: Aug 2001
Posts: 775
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From: Dorset
ZYOX
Your Oxford notes probably tell you it in an indirect way.
Such as:
a. The TODA = TORA plus Clearway
b. The maximum allowable clearway = 50% of TORA.
Putting these two together gives you maximum TODA = 1.5 x TORA.
Your Oxford notes probably tell you it in an indirect way.
Such as:
a. The TODA = TORA plus Clearway
b. The maximum allowable clearway = 50% of TORA.
Putting these two together gives you maximum TODA = 1.5 x TORA.
Thread Starter
Joined: Jul 2006
Posts: 81
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From: Ireland
Ah yes. Found it on page 13-3 taken directly from JAR-OPS 1.490
"Take-off Distance required must not exceed the Take-Off Distance available, with a clearway distance not exceeding half of the Take off Run available"
Well deduced Keith, cheers Feckin' sneaky one though. They don't elaborate or cover it anywhere else and it's come up a few times in questions. Had it on some ground school notes though, with a side note nicely pointing out that it's 1.25 x TORA (if there's no clearway of course) for Single Engine Pistons.
I'd give anything to be back in the days of only have to remember which was bigger, Vx or Vx >_<
"Take-off Distance required must not exceed the Take-Off Distance available, with a clearway distance not exceeding half of the Take off Run available"
Well deduced Keith, cheers
Feckin' sneaky one though. They don't elaborate or cover it anywhere else and it's come up a few times in questions. Had it on some ground school notes though, with a side note nicely pointing out that it's 1.25 x TORA (if there's no clearway of course) for Single Engine Pistons.I'd give anything to be back in the days of only have to remember which was bigger, Vx or Vx >_<
Joined: Aug 2001
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From: Dorset
I think that you need to take care in reading your notes.
The 1.25 factor is not relevant to the question that you have asked. It does not apply to the TODA, but to the Take-Off Distance or TOD. If there is no stopway and no clearway you multiply the TOD by 1.25 to get the TODR, which must not be greater than the TODA (which with no stopway and no clearway is equal to the TORA).
The TODA is the Take-off Distance Available.
The figure that comes out of the take-off graphs is called the Graphical Distance.
The TOD is the Graphical Distance increased by the surface and condition factors.
When you then increase this by the Regulatoty factor you get the TODR. This must not be greater than the TODA.
The 1.25 regulatory factor (paragraph 2.1.1 (a) in the CAP 698) applies only when their is no Stopway and no Clearway.
If a Stopway or a Clearway exist then you must use the other factors listed in paragraph 2.1.1 (b)
These factors also apply to multi engine aircaft.
The 1.25 factor is not relevant to the question that you have asked. It does not apply to the TODA, but to the Take-Off Distance or TOD. If there is no stopway and no clearway you multiply the TOD by 1.25 to get the TODR, which must not be greater than the TODA (which with no stopway and no clearway is equal to the TORA).
The TODA is the Take-off Distance Available.
The figure that comes out of the take-off graphs is called the Graphical Distance.
The TOD is the Graphical Distance increased by the surface and condition factors.
When you then increase this by the Regulatoty factor you get the TODR. This must not be greater than the TODA.
The 1.25 regulatory factor (paragraph 2.1.1 (a) in the CAP 698) applies only when their is no Stopway and no Clearway.
If a Stopway or a Clearway exist then you must use the other factors listed in paragraph 2.1.1 (b)
These factors also apply to multi engine aircaft.
Thread Starter
Joined: Jul 2006
Posts: 81
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From: Ireland
Hmmm no I took that figure from a consolidation course where they told us that, or obviously weren't clear enough on what exactly it was.
Time to go over these distances in a little more detail I think...
Time to go over these distances in a little more detail I think...
