Balanced/Unbalanced field length
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Balanced/Unbalanced field length
I have searched the forums but cannot find any direct answer to my question. When you have worked out the V-speeds for a runway e.g. Vmcg 110, V1 130 Vr 135 V2 140, can you change the V1 speed up to 130 and down to 110 to make the field length unbalanced? If this is correct, is it left down to the pilots to alter the V1 speed, as I believe all speeds calculated from charts and FMC are balanced anyway? How far do you usually change the V speeds?
In the example I have used, if the rwy is very long and not ASD limited can you choose to increase the V1 up to 130 to lengthen the time on the ground incase of an emergency. Am I right in believing increasing the V1 you shorten the TOD, so this helps you clear any obstacles after approach in case of an engine failure.
Thanks for all your help.
Kristian
In the example I have used, if the rwy is very long and not ASD limited can you choose to increase the V1 up to 130 to lengthen the time on the ground incase of an emergency. Am I right in believing increasing the V1 you shorten the TOD, so this helps you clear any obstacles after approach in case of an engine failure.
Thanks for all your help.
Kristian
Last edited by Kristian17; 17th Jan 2006 at 19:27.
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Re: Balanced/Inbalanced field length
If you reduce the V1 to Vmcg at high weights you will probably not get off the ground! A balanced field means (if I have it right) that at V1 you can just stop or go and you will only have one V1. At a field that is longer (ie not balanced - I think the term "unbalanced" is incorrect) you may have a range of V1s but this will be shown as Vmcg 110, V1 125 130, Vr 137, V2 140, which means that your V1 range is between 125 and 130. Vmcg just tells you the min speed for keeping directional control.
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Re: Balanced/Inbalanced field length
Originally Posted by Kristian17
I have searched the forums but cannot find any direct answer to my question. When you have worked out the V-speeds for a runway e.g. Vmcg 110, V1 130 Vr 135 V2 140, can you change the V1 speed up to 130 and down to 110 to make the field length inbalanced? If this is correct, is it left down to the pilots to alter the V1 speed, as I believe all speeds calculated from charts and FMC are balanced anyway? How far do you usually change the V speeds?
Not all performance chart data are 'balanced', for example. So using that as a starting assumption is not wise.
Additionally, there are margins between e.g. Vmcg and V1 in the regs - Vef not less than Vmcg, V1 not less than Vef plus margin - so you can't just set V1 to Vmcg anyway.
Re: Balanced/Inbalanced field length
Two different things are being confused here.
A "balanced field" is a runway which had the "stop" distance equal to the "go" distance. The stop distance is the runway length plus any paved stopway; the go distance is the runway length plus any clearway (inb essence a distance from the departure end of the runway guaranteed free of obstacles higher than the runway).
If the take-off mass is the maximum that the runway and weather conditions allow, then there is only one value of V1. If the mass is less, then a range of V1 speeds is possible, and for each type of aircraft there is a way of calculating that range of speeds.
So, you don't unbalance the runway by changing the speeds.
A "balanced field" is a runway which had the "stop" distance equal to the "go" distance. The stop distance is the runway length plus any paved stopway; the go distance is the runway length plus any clearway (inb essence a distance from the departure end of the runway guaranteed free of obstacles higher than the runway).
If the take-off mass is the maximum that the runway and weather conditions allow, then there is only one value of V1. If the mass is less, then a range of V1 speeds is possible, and for each type of aircraft there is a way of calculating that range of speeds.
So, you don't unbalance the runway by changing the speeds.
I think you will find that is UNbalanced
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Re: Balanced/Inbalanced field length
K,KenP hit it on the head.In your original question I think you meant can you increase your V1 to'135'as opposed to '130'as stipulated-YES if the braking will stop you on the runway upon a reject at 135..
One normally takes the V speeds for the actual weight-then go into the charts and see the gross weight V1(to provide the Acc/stop)..You can now see the variance between the speeds..BUT the discipline
is to reject at YOUR vef prior to VI..
When we first acquired the Airbus 320 we had rediculous V1's (about 112knots-light weights)..we raised the issue with the company that they expected one to reject at failure below V1 on an 11000 foot runway-the firm got back to Airbus who stipulated that due to the braking efficiency the V1 speeds could be just below VR,and still stop in the 'required/weight distance'.
This simplied all the calculations and that is why the 2 V speeds are close tegether except in the gross weight case.
Reducing the V1 only applies in the WET runway case in conjunction with the reduced screen height(15')..whereas one can stop a little(sometimes 10knots)sooner on the wet surface,BUT one also has to accept the fact one will cross the screen lower(than dry) in the continued takeoff case..
One normally takes the V speeds for the actual weight-then go into the charts and see the gross weight V1(to provide the Acc/stop)..You can now see the variance between the speeds..BUT the discipline
is to reject at YOUR vef prior to VI..When we first acquired the Airbus 320 we had rediculous V1's (about 112knots-light weights)..we raised the issue with the company that they expected one to reject at failure below V1 on an 11000 foot runway-the firm got back to Airbus who stipulated that due to the braking efficiency the V1 speeds could be just below VR,and still stop in the 'required/weight distance'.
This simplied all the calculations and that is why the 2 V speeds are close tegether except in the gross weight case.
Reducing the V1 only applies in the WET runway case in conjunction with the reduced screen height(15')..whereas one can stop a little(sometimes 10knots)sooner on the wet surface,BUT one also has to accept the fact one will cross the screen lower(than dry) in the continued takeoff case..
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Re: Balanced/Inbalanced field length
I need to reread this then, my undestanding was that a balanced field had nothing to do with the stop distance and "go" distance being the same but to do with operating at max wt for that field (or at max derate), thus giving you just a single V1
Re: Balanced/Inbalanced field length
Balanced field means stop and go distances are the same, as I said in my previous post. And, again, if the mass is the max for the runway and the conditions, there is only one V1, because if you go from there (in the engine-out case)you will clear the screen by the requisite amount (just) and if you stop, you will stop at the end(just) if everything has been calculated correctly.
In the real world, balanced fields (runways) are rare - usually the Go distance is greater than the Stop distance, as most runways have some declared clearway.
You will find much more detail in textbooks for Group "A" performance - but it's a complex subject and easy to get yourself bogged down. Even with lectures from experts it's easy to get confused!
(Edited to clarify that I'm talking about the engine-out case: when all engines behave as advertised there is not a problem!)
In the real world, balanced fields (runways) are rare - usually the Go distance is greater than the Stop distance, as most runways have some declared clearway.
You will find much more detail in textbooks for Group "A" performance - but it's a complex subject and easy to get yourself bogged down. Even with lectures from experts it's easy to get confused!
(Edited to clarify that I'm talking about the engine-out case: when all engines behave as advertised there is not a problem!)
Last edited by kenparry; 17th Jan 2006 at 10:08.
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Re: Balanced/Inbalanced field length
I would like to thankyou all (kenparry, mad (flt) scientist, foxmoth and oldebloke) for your kind help in this complex subject and quick replies. Your answers have made things much clearer.
Kristian
P.S. Mr Bernoulli, thanks for spotting my error, I was not thinking correctly
Kristian
P.S. Mr Bernoulli, thanks for spotting my error, I was not thinking correctly
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Re: Balanced/Inbalanced field length
Kenparry, I agree with most of what you have written, but I am of the impression that you may indeed "unbalance" the runway by changing speeds.
You have a balanced T/O when TOD=ASD. If your GW is not runway limited you may alter this TOD/ASD relationship by changing the speeds (of course staying within the "band" of safe speeds). Increasing V1 will decrease the TOD because you will have a higher speed when the engine fails, but ASD will increase because you need more runway to decellarate from the higher V1.
As I see it, one will rarely have a balanced T/O, and thus one will have a range/band of speeds applicable for the current weight and conditions, and the RTOW's or the computer gives us the speeds for the optimum relationship between TOD/ASD by "balancing" the T/O as much as possible.
You have a balanced T/O when TOD=ASD. If your GW is not runway limited you may alter this TOD/ASD relationship by changing the speeds (of course staying within the "band" of safe speeds). Increasing V1 will decrease the TOD because you will have a higher speed when the engine fails, but ASD will increase because you need more runway to decellarate from the higher V1.
As I see it, one will rarely have a balanced T/O, and thus one will have a range/band of speeds applicable for the current weight and conditions, and the RTOW's or the computer gives us the speeds for the optimum relationship between TOD/ASD by "balancing" the T/O as much as possible.
Re: Balanced/Inbalanced field length
No, 738 jockey, you don't unbalance the field. Being a balanced field is simply a characteristic of the runway, the ASDA(accelerate stop distance available) being equal to the TODA(take off distance available). Which is another way of saying that stopway and clearway are equal.
If you are not performance limited, you can, as you say, use a range of V1 speeds, but that does not change ASDA or TODA. It just means you don't need all the available length - which always is a comfort. When you are performance limited, there is no room for error - so that decision at V1 is really critical on those occasions.
If you are not performance limited, you can, as you say, use a range of V1 speeds, but that does not change ASDA or TODA. It just means you don't need all the available length - which always is a comfort. When you are performance limited, there is no room for error - so that decision at V1 is really critical on those occasions.
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"(Edited to clarify that I'm talking about the engine-out case: when all engines behave as advertised there is not a problem!)"
Not always the case.
Keep in mind that the AEO case has a fudge factor included and may become limiting especially at lighter weights, lower Hp, lower OAT etc.
Not always the case.
Keep in mind that the AEO case has a fudge factor included and may become limiting especially at lighter weights, lower Hp, lower OAT etc.
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Kenparry: I think we are not on the same page here..I did not imply that I want to unbalance my T/O, my point being; it is possible to alter your speeds. Balanced field is not very relevant, because then we are talking about the TOD available versus ASD available. What the term balanced T/O refers to is of much higher relevance. Here we compare our actual TOD versus our actual ASD with the current GW and conditions. And it is here we can get the advantage of having a balanced T/O, which in essence means that we have the optimum relationship between TOD/ASD and therefore giving us equally "excess" distance in both the GO case, and the STOP case.
What we are after here is to be allowed to have the highest possible GW and at the same time being safe.
What we are after here is to be allowed to have the highest possible GW and at the same time being safe.
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Try a copy of PJ.Swatton's book "aircraft performance theory for pilots(2000)'.
It covers the Performance Area quite well(JAA rules)but is pretty well aligned with the FAR's(US)now..
'Flying the wing' doesn't cover the 'wet' ops as well as the JAA rules(reduced V1/lower screen height)as the FAR's only cover 'new' equipement(B777),or
Performance 'B'(JAA rules)customers..Canadair have Certified to the JAA rules.
cheers
It covers the Performance Area quite well(JAA rules)but is pretty well aligned with the FAR's(US)now..
'Flying the wing' doesn't cover the 'wet' ops as well as the JAA rules(reduced V1/lower screen height)as the FAR's only cover 'new' equipement(B777),or
Performance 'B'(JAA rules)customers..Canadair have Certified to the JAA rules.
cheers
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Very easy to get bogged down in semantics here.
Generally, BFL refers to the aircraft AFM takeoff calculations, ie if TODR=ASDR then the operation is defined as BFL and, in this case, TODR refers to whichever case is limiting in the calculation.
I guess you can talk about the term in relation to the physical runway environs but it doesn't really make much sense to do so.
For whatever reason, BFL sometimes acquires some mystical significance .. which is not really justified. BFL calculations usually give the quickest RTOW calculation answer. However, in general, the BFL answer won't be the maximum RTOW for the situation. Therefore, if the operator so chooses (and the AFM provides the data - and not all do) the extra effort involved in running an unbalanced calc can be done.
It is NOT acceptable to juggle the speeds arbitrarily for longer runways unless sufficient calculations have been done to ensure that such variation is justified by formal calculation. In EACH AND EVERY case, the set of AFM calculations MUST be run to ensure that ALL the required certification things are addressed .. to do otherwise is to invite considerable embarrassment at the Enquiry and potential liability .. big time bad news.
Generally, BFL refers to the aircraft AFM takeoff calculations, ie if TODR=ASDR then the operation is defined as BFL and, in this case, TODR refers to whichever case is limiting in the calculation.
I guess you can talk about the term in relation to the physical runway environs but it doesn't really make much sense to do so.
For whatever reason, BFL sometimes acquires some mystical significance .. which is not really justified. BFL calculations usually give the quickest RTOW calculation answer. However, in general, the BFL answer won't be the maximum RTOW for the situation. Therefore, if the operator so chooses (and the AFM provides the data - and not all do) the extra effort involved in running an unbalanced calc can be done.
It is NOT acceptable to juggle the speeds arbitrarily for longer runways unless sufficient calculations have been done to ensure that such variation is justified by formal calculation. In EACH AND EVERY case, the set of AFM calculations MUST be run to ensure that ALL the required certification things are addressed .. to do otherwise is to invite considerable embarrassment at the Enquiry and potential liability .. big time bad news.
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Balanced vs. unbalanced field length
Dear Kristian17 & others interested in this thread,
I have just done some research for the subject and can perhaps contribute the following:
The most useful definition of "Balanced Field Length"(BFL) which I have found this far is:
the distance obtained by determining the decision speed (V1) at which the take-off distance and the accelerate-stop distance are equal. In other words the V1 is moved around (between 1.05 VMCG and VR) until those 2 distances are equal. No factors such as wet, etc. are taken into account.
In other words, the aircraft manufacturer will simply determine, for a given weight, which decision speed will result in the same distance to reject and stop the plane as to achieve the 35' screen height at the required point. This is a general performance calculation which does not care on which runway, or at which temperature your take-off is taking place. (The calculation also assumes dry, sea-level conditions).
This is how the good old "speed booklet" for each weight is produced. Obviously, the speedbooklet does not "know" from which runway you happen to be taking-off. The advantage of the BFL calculation, as you stated quite rightly in your thread, is twofold:
Firstly, it allows a decision speed as close as possible to flying speed (Vr). This leaves you with the "comfortable" option of rejecting take-off right up until you are practically airborne. (Being forced to wait from an early (unbalanced) V1 until Vr while accelerating with a broken airplane must be a rather unpleasant experience indeed...)
Secondly, as you again stated quite rightly, the later V1 will ensure maximum performance in the first and second segments, as no potential energy (distance) will be lost accelerating with an engine out from V1 to Vr. Either you have a failure right up to Vr and you stop safely, or your engine fails practically at Vr and you are ready to go with your "optimal" one engine inoperative flight profile.
UNbalancing the take-off (ie adjusting V1 within the allowed limits of 1.05 VMCG and Vr) is, in any case, a runway-specific procedure which must take into account all relevant factors. (Also referred to as "scheduled" distance or "factored" distances). Multiple factors must be included in the calculation. They include:
runway condition: wet, contaminated, head/tailwind, temperature (to be determined by the pilot)
and
1st, 2nd segment obstacle clearance requirements (predetermined by the operator, in rare cases by NOTAM (eg. crane, etc.))
ONLY runway, temperature, obstacle, etc.-specific information will allow an adjusted (earlier) V1. As correctly pointed out in several related threads, it is not foreseen that the pilot be more or less arbitrarily shifting around the V1! There will be a very specific V1 for each particular runway and each particular set of weather conditions. Now all this begs the question: Why an UNbalanced field length, or take-off?
The answer is simple: You can play around with the V1 as much as you like, the aircraft Vr for a specific weight(or to be more precise Vmu) will not change. In other words, the aircraft will not be ready to actually fly any earlier because you need it to on that day! So if your 35' screen height (dry runway) is limiting, bad luck. However, if the Accelerate-stop distance (ASDA) is limiting (which it often will be in less than ideal runway conditions), then there is some room to play:
let' say that, on a particularly wet day, you decide (incorrectly) to go with a BFL calculation. An engine fails just before V1. You apply full brakes (no reverse is assumed). You may be lucky and stop before the physical end of the runway. But the ASD you just needed would be greater than the continued one-engine out take off distance to a screen height of 15' (wet) ie the take-off is unbalanced. So to right the wrong, we would have to reduce the aircraft RTOW until both distances match again. Bummer. Lots of angry offloaded people. Provided ASD is your limit today, we could also move the V1 earlier in order to achieve the same distance in case of a rejected take-off, as that required for a continued, one engine inoperative take-off to a 15' screen height. And now we see the advantage of an unbalanced take-off (which, by the way, the BCAR (British Civil Aviation Requirements) first allowed for in 1965).
Long-winded indeed, but hopefully helpful.
Cheers.
I have just done some research for the subject and can perhaps contribute the following:
The most useful definition of "Balanced Field Length"(BFL) which I have found this far is:
the distance obtained by determining the decision speed (V1) at which the take-off distance and the accelerate-stop distance are equal. In other words the V1 is moved around (between 1.05 VMCG and VR) until those 2 distances are equal. No factors such as wet, etc. are taken into account.
In other words, the aircraft manufacturer will simply determine, for a given weight, which decision speed will result in the same distance to reject and stop the plane as to achieve the 35' screen height at the required point. This is a general performance calculation which does not care on which runway, or at which temperature your take-off is taking place. (The calculation also assumes dry, sea-level conditions).
This is how the good old "speed booklet" for each weight is produced. Obviously, the speedbooklet does not "know" from which runway you happen to be taking-off. The advantage of the BFL calculation, as you stated quite rightly in your thread, is twofold:
Firstly, it allows a decision speed as close as possible to flying speed (Vr). This leaves you with the "comfortable" option of rejecting take-off right up until you are practically airborne. (Being forced to wait from an early (unbalanced) V1 until Vr while accelerating with a broken airplane must be a rather unpleasant experience indeed...)
Secondly, as you again stated quite rightly, the later V1 will ensure maximum performance in the first and second segments, as no potential energy (distance) will be lost accelerating with an engine out from V1 to Vr. Either you have a failure right up to Vr and you stop safely, or your engine fails practically at Vr and you are ready to go with your "optimal" one engine inoperative flight profile.
UNbalancing the take-off (ie adjusting V1 within the allowed limits of 1.05 VMCG and Vr) is, in any case, a runway-specific procedure which must take into account all relevant factors. (Also referred to as "scheduled" distance or "factored" distances). Multiple factors must be included in the calculation. They include:
runway condition: wet, contaminated, head/tailwind, temperature (to be determined by the pilot)
and
1st, 2nd segment obstacle clearance requirements (predetermined by the operator, in rare cases by NOTAM (eg. crane, etc.))
ONLY runway, temperature, obstacle, etc.-specific information will allow an adjusted (earlier) V1. As correctly pointed out in several related threads, it is not foreseen that the pilot be more or less arbitrarily shifting around the V1! There will be a very specific V1 for each particular runway and each particular set of weather conditions. Now all this begs the question: Why an UNbalanced field length, or take-off?
The answer is simple: You can play around with the V1 as much as you like, the aircraft Vr for a specific weight(or to be more precise Vmu) will not change. In other words, the aircraft will not be ready to actually fly any earlier because you need it to on that day! So if your 35' screen height (dry runway) is limiting, bad luck. However, if the Accelerate-stop distance (ASDA) is limiting (which it often will be in less than ideal runway conditions), then there is some room to play:
let' say that, on a particularly wet day, you decide (incorrectly) to go with a BFL calculation. An engine fails just before V1. You apply full brakes (no reverse is assumed). You may be lucky and stop before the physical end of the runway. But the ASD you just needed would be greater than the continued one-engine out take off distance to a screen height of 15' (wet) ie the take-off is unbalanced. So to right the wrong, we would have to reduce the aircraft RTOW until both distances match again. Bummer. Lots of angry offloaded people. Provided ASD is your limit today, we could also move the V1 earlier in order to achieve the same distance in case of a rejected take-off, as that required for a continued, one engine inoperative take-off to a 15' screen height. And now we see the advantage of an unbalanced take-off (which, by the way, the BCAR (British Civil Aviation Requirements) first allowed for in 1965).
Long-winded indeed, but hopefully helpful.
Cheers.
Moderator
Flyboy 136,
Welcome to the PPRuNe Tech Log sandpit .. just a few comments on your post ..
the take-off distance and the accelerate-stop distance are equal.
Might be better to read "limiting takeoff distance ...[/i]"
No factors such as wet, etc. are taken into account.
It is appropriate to take into consideration whatever factors are relevant to the particular takeoff .. ie, the intent is to balance the particular takeoff .. it is not a generic thing.
This is a general performance calculation which does not care on which runway, or at which temperature your take-off is taking place. (The calculation also assumes dry, sea-level conditions).
I think a quick look at the typical AFM will indicate a dependence on Hp and OAT. Certainly not limited to SL conditions and not a general (ie generic) calculation. I can only presume that you have misread some guidance material along the way somewhere ?
UNbalancing the take-off (ie adjusting V1 within the allowed limits of 1.05 VMCG and Vr) is, in any case, a runway-specific procedure which must take into account all relevant factors. (Also referred to as "scheduled" distance or "factored" distances).
Distance and other factors apply equally whether we are looking at a balanced or unbalanced calculation .. both calculations are made using the same AFM data (although, often, there will be a simplified cut-down chart specifically for BFL calculations .. still based on the main AFM data, though.
1st, 2nd segment obstacle clearance requirements (predetermined by the operator, in rare cases by NOTAM (eg. crane, etc.))
The minimum clearance requirements are specified by regulation. The operator may impose a more conservative clearance profile although most would not for commercial reasons. NOTAM regularly advise changed or temporary obstacle data which must be plugged into the calculations ...
ONLY runway, temperature, obstacle, etc.-specific information will allow an adjusted (earlier) V1
For a specific takeoff on any given runway, there will be a range of usable V1. The lower end will be TOD/Vmcg limited, the higher either ASD/BE limited. You pick which suits your operating philosophy and needs on the day. One of these V1 values will result in a BFL situation if that is important to you. Depending on the runway, the day, and the takeoff weight, the calculated BFL data may or may not be limiting for the particular runway.
I suggest that BFL is only of much value for simplification of data .. general TO charts, typical on board computers etc .. For maximum RTOW, one normally needs to go unbalanced. Some AFMs, of course, don't give you the option, only scheduling balanced data, ... but that's another story.
Welcome to the PPRuNe Tech Log sandpit .. just a few comments on your post ..
the take-off distance and the accelerate-stop distance are equal.
Might be better to read "limiting takeoff distance ...[/i]"
No factors such as wet, etc. are taken into account.
It is appropriate to take into consideration whatever factors are relevant to the particular takeoff .. ie, the intent is to balance the particular takeoff .. it is not a generic thing.
This is a general performance calculation which does not care on which runway, or at which temperature your take-off is taking place. (The calculation also assumes dry, sea-level conditions).
I think a quick look at the typical AFM will indicate a dependence on Hp and OAT. Certainly not limited to SL conditions and not a general (ie generic) calculation. I can only presume that you have misread some guidance material along the way somewhere ?
UNbalancing the take-off (ie adjusting V1 within the allowed limits of 1.05 VMCG and Vr) is, in any case, a runway-specific procedure which must take into account all relevant factors. (Also referred to as "scheduled" distance or "factored" distances).
Distance and other factors apply equally whether we are looking at a balanced or unbalanced calculation .. both calculations are made using the same AFM data (although, often, there will be a simplified cut-down chart specifically for BFL calculations .. still based on the main AFM data, though.
1st, 2nd segment obstacle clearance requirements (predetermined by the operator, in rare cases by NOTAM (eg. crane, etc.))
The minimum clearance requirements are specified by regulation. The operator may impose a more conservative clearance profile although most would not for commercial reasons. NOTAM regularly advise changed or temporary obstacle data which must be plugged into the calculations ...
ONLY runway, temperature, obstacle, etc.-specific information will allow an adjusted (earlier) V1
For a specific takeoff on any given runway, there will be a range of usable V1. The lower end will be TOD/Vmcg limited, the higher either ASD/BE limited. You pick which suits your operating philosophy and needs on the day. One of these V1 values will result in a BFL situation if that is important to you. Depending on the runway, the day, and the takeoff weight, the calculated BFL data may or may not be limiting for the particular runway.
I suggest that BFL is only of much value for simplification of data .. general TO charts, typical on board computers etc .. For maximum RTOW, one normally needs to go unbalanced. Some AFMs, of course, don't give you the option, only scheduling balanced data, ... but that's another story.
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It might be worth pointing out that there are two definitions of balanced field. One, essentially American, has TODR = ASDR the other, of British origin, is that ASDA = TODA. It comes to almost the same thing in the end but the approach and semantics are different.
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.. not wanting to be difficult but, as a practitioner (both in the sharp end and as an ops engineer), TODA=ASDA is, in effect, a useless definition.
TODA=ASDA has some significance to the civil engineer designing a runway .. I will refer this to Overrun to get his view ... but is of little interest to the pilot or ops engineer
TODR=ASDR is very pertinent to the operation.
As to whether the two definitions relate to each other will depend on the relative criticality of the runway to the aircraft. So, for instance, a 737 out of a 15000ft strip is not going to be interested .. whereas the 744 might be ..
TODA=ASDA has some significance to the civil engineer designing a runway .. I will refer this to Overrun to get his view ... but is of little interest to the pilot or ops engineer
TODR=ASDR is very pertinent to the operation.
As to whether the two definitions relate to each other will depend on the relative criticality of the runway to the aircraft. So, for instance, a 737 out of a 15000ft strip is not going to be interested .. whereas the 744 might be ..