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TODA

  • John.Heddles
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John.Heddles replied the topic: TODA

Have another look at 5.2.2.1.(b) - the stopway, necessarily, HAS to be included in the bit between the TORA head (end of the runway, generally) and EOS. Pity the question overlooked the EOS bit !

Then, 6.2.17.1 should add to your confusion, somewhat.

Then, many years down the track, you will end up thoroughly confused and become an acknowledged expert !

Engineering specialist in aircraft performance and weight control.
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Stew bond replied the topic: TODA

Well....let's just hope I don't get this question again....although I think it's narrowed down to just one answer now!
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Carello replied the topic: TODA

Have another look at 5.2.2.1.(b) - the stopway, necessarily, HAS to be included in the bit between the TORA head (end of the runway, generally) and EOS. Pity the question overlooked the EOS bit !


That is what logic would dictate, but the last sentence of that same paragraph goes on to say, " Any stopway is not involved".

Good luck Stew


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John.Heddles replied the topic: TODA

but the last sentence of that same paragraph goes on to say

One could write a book identifying all the inconsistencies in the regulatory documents. Just part of the flying game's entertainment value, I suggest. The stopway reference doesn't make a great deal of sense, does it ?

Engineering specialist in aircraft performance and weight control.
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Carello replied the topic: TODA

The stopway reference doesn't make a great deal of sense, does it ?

Agreed!
It becomes more convoluted when you consider that 5.2.2.1 b is an Australian practice registered with ICAO. From that I would guess that 5.2.2.1 b is not an international standard.
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Stuart Tait replied the topic: TODA

Carello

Your profile picture is very apt regarding this subject

Cheers
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Carello replied the topic: TODA

G'day Stuart

I had to stop thinking about it - I beginning to get a headache!

Do you or Bob have any pearls of wisdom on this question? Does TODA include or exclude a stopway when there is NO clearway? The Aerodrome MoS looks to has a bob each way on this question - excuse the pun!

Cheers
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Stuart Tait replied the topic: TODA

Carello this is what we have in the book and I'll stick with it

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Carello replied the topic: TODA

Does not help a lot - but I know what you aren't saying !
Cheers
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John.Heddles replied the topic: TODA

[The legislation links are not working at the moment so I'm having to rely on memory, so there may be some minor details to change ..]

(a) MOS 139 covers most aerodromes and ERSA will be compliant with the MOS requirements ie, the MOS calls the shots in most situations.

(b) the EOS local rule means that a stopway will be in the TODA for MOS 139 complying aerodromes.

(c) TORA is a confusing one for light aircraft pilots as it is of no certification relevance to small aeroplanes. Rather it only plays a part in heavy aircraft performance. CAO 20.7.1b refers in the local context although that is another story altogether ...

TORA is definitely NOT there to provide a lift off point at the end of the TORA. In any case, the light aircraft POH doesn't provide any information to allow the calculation of such a procedure.

For heavy aircraft, the initial part of the takeoff flare to screen height (normally 35 ft in lieu of 50 ft for lighties) has to be over the TORA and the latter part may be over the clearway. Depending on the rules, the ratio normally is 1:1 but, for older UK rules, it may be 1:2. That is to say, the TORA/TODA setup provides that the aircraft, barring major problems, will be airborne some distance prior to the end of the declared TORA and at/above screen height by the end TODA. The whole of the clearway distance may not be usable by a given aircraft performance requirement.

So how should one try to resolve the problems ?

(a) first, it is manifestly and potentially hazardous just to blindly use the declared TODA for a light aircraft if there is a significant declared clearway. This is due to the comparatively short air distance to screen for a light aircraft. Typically, AEO, the lightie should be doing better than 6% which suggests an air distance somewhat less than 1000 ft. Hence, if you have an unsuitable set of data, you could find yourself still on the ground in the clearway .. and that could be rather less than nice. It is unfortunate that the light aircraft rules don't think about this at all.

(b) my practice is to know the expected performance numbers and make sure that I am not trying to use more than, say, 150 metres of nominal clearway. For most runways where TORA is declared, this won't be a problem as the TODR will be less than the TORA. However, do be careful as there is the possibility that you can bite yourself and badly if you don't think a bit about what you are doing.

So far as transient obstructions are concerned, the clearway will be under the control of the aerodrome authority.

The often seen 60m difference between TORA and TODA covers the RESA requirement under the old standards. These are in the midst of a long term change but it will be a while before the new standards prevail generally. In the meantime, 60m is a savings clause letout.

In general, aerodromes stuff is the material of airports experts and we pilots (even if in the guise of performance engineers) are often likely to get the finer details of the aerodrome design rules mixed up to some degree.

Engineering specialist in aircraft performance and weight control.
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