is a term of art in the early space industry and we asked this court to give stability margin its ordinary in cost america meaning which is the meaning that the term would have to a person of ordinary skill in the art in a think the issue is the way i'm wrong is whether or not you have to do we whether requires a calculation and it it that is the issue your honor and if we construe stability margin if we give it meaning you have to do a calculus calculation you have to make a determination because the industry standard definition for stability margin is you have this on a famine map a stability limit line and then stability margin is defined as the pressure ratio on the stability limit line down to the fram pressure ratio at the operating point and because that's indeed one of the board's errors in particularly with respect to claim fifteen we could submit they they rewrote the claim quoting the board it says quote the claims are similarly devoid of any expressed language requiring that a stability margin be numerically calculated is not true the claims themselves don't literally say it needs to be numerically calculated if we construe stability margin though consistent with the specification it does need to be numerically calculated but then the board went on to say rather they simply require detecting conditions that may lead to instability are present we submit your honour's is they're not exactly what the claim says i mean it it says detect from these four different things at least one of which doesn't require any kind of calculation and then determine the un's desired margin from that the testing stuff i mean if if you're determining the desired margin from that detecting stop then several of those don't require calculation if if you take from that detecting step which says detecting at least one of a tribe or family pressure ratio los full speed airflow direction and throttle position and that's inclusive it needs to have one of those to meet the st part of the method claim limitation here in detecting but just using that information alone you can't determine what the stability margin is whatsoever indeed both x spurts when they were asked or weighted what does it mean i mean maybe i'm looking at the wrong site doesn't the determining step me say determining the end desired stability margin from the detected step so you would the only answer to how do you determine it claim fifteen alone and to meet that specific limitation you would need one of those but you have to look at the specification to to give this meaning the reason that those parameters there in the  step of claim fifteen are important and why one of those might affect your stability margin is they're going to move your operating point and what your operating point is is where that fan is in flight and so we submit your honor focusing soley on just claim fifteen that it doesn't mean that based on one of those conditions alone aha you would have stability margin indeed we asked each of the experts here if you simply know air flow direction just air flow direction do you know what the stability margin is and the answer is no you're right no idea what the stability margin is so you can think plane fifteen ains the determining step in the determining from the detecting step or from other information not  at the detecting step the st thing is the trigger a fan pressure ratio and so if if you know the chirp of fram pressure ratio and you combine it with looking at the fam map that shown in figure three in the specification then you can walk exactly where your operating point is you can look at it in relation to the stability limit line and you can calculate your stability margin fair enough i mean i'm not going to  n a map but the plane says detecting at least one so that's one but that's not required by the happenings right it could be any of the four it could be and it could be any of the four limited it by any means to exactly what stability margin means because it's shown very consistently with what's an industry standard definition in figure three with that vertical line that fan stability  so when the person of ordinary skill has that understanding and knows full well what stability margin is when that person reads claim fifteen not reading it literally as we're reading it right now from the detecting step alon that doesn't alter the definition to a question of ordinary skill they understand that what the controller's doing is using one of those parameters in its calculation of the stability margin along with what else is required to determine what is stability margin is so if we look at claim fifteen simply end of vacuum i understand your honour's questions of why from the detecting step could literally mean just one of these things but again that's why we asked the x for true knew full well exactly what stability margin means consistent with the specification as well as they know one of those if you will the pattern is clear that you have these sensors you have a throttle position sensor you have a low speed spool sensor and so those parameters they are in claim fifteen that's feeding information into back control or the controller also has other information and therefore using all of that information it can go ahead and calculate a stability margin the other part of claim fifty we should also look at claim fifteen we were focused solely on from the detecting step but what's important as well is the following limitations that come after from the operating line to increase your stability margin that's a correcting step there and what is the correcting for it's determined you have an undesired stability margin and then the claim goes on and corrects for it well you have to do a calculation in order to make the correction as the patten explains these turbo fans operate with which you're talking about the lowering portion of it yes your honor that yes you're saying you can't do this without a calculation correct your honor because what you've determined in that nd step is an undesired stability margin then what the controller is going to do is tell the nozzle laxity area go ahead an increase release the fact pressure on the fran and what that will do was lower the turbofan operating line increasing the turbofan stability margin so which restoring the stability margin so that it's sufficient the way these pans work in flight they're obviously highly sophisticated instruments you have supersonic airflow coming into the fan fundamentally you have to know where that operating point is venue calculate a stability margin if you determine it's undesired the rest of claim fifteen goes through and says make that correction and we submit that when this controllers making such a correction it's doing quite precisely it's not doing it simply i detected a condition that may lead to see instability and i simply react and have still know how to correct and it's very precise you're saying  calculates that difference between the pressure ratio of the fans ability to limit line and the true sure ratio at the fan operating point you know sort of you're saying has to be done has to be done fundamentally and then if it is straight if you have an undesired or insufficient stability margin it's going to correct for side slee that would have been easy enough to write into the patent wouldn't we submit your honor at least in figure three the specification it's it's clearly shown and the person of ordinary skill new york would understand exactly that lowering that fan operating line you lowered your operating point your restoring your stability margin i see that i'm in side thank you think your honour's and may it please the court ryan ferguson for general electric the entire argument that u t c is making is based on a nonexistent claim there is no claim there is no claim language that requires calculating a stability margin if there was this would be a different story but i gather that their argument is that this is the only way possible to do any of that it's legal to do that calculation and went throughout when they're talking about the controller and the various inputs and things like that it necessarily means when you're talking about him under his wearable stability of margin that it relies on a calculator to get there the problem wrong with that are you the problem w that argument your honor is that that is not what is taught in the patent itself the pattern and very clearly teaches that undesired stability margins can occur simply from the result of air entering the engine at an angle that is not in line with the engine axis this is so i don't how do they know that that angle of air will create an undesirable stability margin without knowing what the desired one is and then calculating the difference that is exactly what this pattern is attempting to overcome is that it was known in the art as taught in the background of the invention it was known in the art that if the air comes into the engine at an undesirable angle it causes on wanted pressure gradients on the fan and that alone can cause an undesired stability margin so there is an embodiment in this pattern that teaches all you do all you need to do is detect that the air is coming into the engine along absolutely your honor we're there there are several spots in the  pattern but i will start with column one at line twenty four and this says one of the important performance limitations for the fan is the loss in fan stability margin that occurs during aircraft maneuvers in cross wind operating conditions during those maneuvers or cross wind conditions the inlet flow that's the in the flow the air approaches the aircraft in a direction it's not in line with the axis of the engine that can cause pressure gradients that result in significant pressure distortion entering the fan that right there talks about this problem of air entering the engine at a direction that is not in line with the access which can cause pressure gradients on the fan which causes loss in fan stability margin then in the summer the invention they say this is how we're going to solve this problem and this is o engine creates this destabilizing pressure ingredient gradient air comes into the engine in a direction that is not parallel the access it causes pressure gradients on the fan that results in an undesired stability margin all you need to do is to detect that and then open the nozzle which automatically increases your stability margin what about that your three certainly your honor and i figure three first of all is the board correctly found figure three shows no it's not it's not quantitative in any sense there is nothing in this patent there's nothing in figure three that says how much of a margin is required in order to maintain a sufficient stability margin and when we see it when you look at figures it shows an operating point yes but nowhere does the specification ever state that in order to determine an undesired stability margin you have to st calculate the fan operating point because what shown here in figure three is that the nominal fan operating line which was the one in the middle of the graph the operating line moves downward when the nozzle area is increased the whole line moves not just a point and that's the whole point of this is that when that air is coming in into the engine at that undesired angle your you want to better safe than sorry situation if you know the air is coming in at a point at an angle that's not in line you want to automatically open the nozzle because  releases the back pressure and lowers that entire line not just the point and when you lower that operating line you necessarily increase the stability margin because that is determined by the fan stability limit line which is the line at which the fan should never operate above so your here air is coming this is your stability limit line the one on top this is your your fan operating line where the fan is you determine the air is coming into the engine at a wrong angle oh my stability margin can now will will be decreased so i better off open the nozzle and lower this line you think that what you're talking about that's exactly what it teaches it teaches that in fact if you look to claim if you look at figure three your honor at the upper right of figure three it says that the fan stability limit decreases with increasing inlet flow distortion in reduces the stability much well that that is increasing in lift flow distortion is what's caused by the airflow interim the engine at an improper direction all you need to do is detect that when that is detected you know that the stability margin has now lessened because of the pressure gradient on the fan so you just open up the nozzle release the back pressure down goes  engine relative to the access to the sensing devices located on the airframe and is used by the controller determine the angle of attack so i type so that's only detecting that the air that's coming into the engine is out an improper it's not calculating a fan operating point it doesn't need to do that that's the whole point of the invention they want to cover the situation where it's better safe than sorry if you know the air is coming in the engine at an improper angle you don't need to take those precious milliseconds to then calculate what the actual operating point is determine if your stability margin isn't off and only then open up the nozzle to increase the margin you just detective yours coming in at the wrong angle we're in a situation that could cause unstable operating conditions so we're going to lower the line here claim fifteen says specifically that you detect these one the until you detect the undesired stability margin from the detecting step determinant from the detection step so undesired stability margin is determined by detecting at least one of in that list those four things and one of those things is the air flow direction so as the board properly said the plain language of this claim but the way that this claim is written if they have with they were asserting this claim in all they would need to show is that somebody was determining or detecting the airflow direction and then opening the nozzle to two increases to billy martin that would infringe that claim well then they're also stuck with that will be proven invalid that claim if we can show in the prior art that such a such an invention already existed and that's that you teach series claim fifteen is to rewrite it by requiring st calculate in a stability margin based on at least one of those and according to my colleague perhaps more things but that's not the way claim fifteen is i want to pick up exactly where counsel left off in g e wrote this in their brief they framed the question quote in other words do the claims require determining the fan operating point and calculating as stability chervil fan stability margin you have to make that determination we're left at a claim construction and an argument that is tantamount to if you don't know what the stability margin is how can you determine that it's undesired because in their construction no one's ever even determined or calculated what the stability margin is the nd and last point i want to address is this argument that the board used as purposes for their construction that g e makes here which is simply basing claim fifteen inches to terminations on airflow direction alone in council said if the airflow is coming in not parallel to the in line access you have an undesired stability margin they frame this in their brief simply as these if then scenarios and that simply can't be the case when an airplane is device that as as counsel said at the bottom of column three top of column for that goes into the controller the controller makes a calculation it's a computer it calculates stability marg