Method for inserting a segment of flight plan in a flight plan

Abstract

The invention relates to a method for inserting a segment (Tins) of flight plan into an initial flight plan (Pini) of an aircraft, performed by a flight management system (FMS) of the said aircraft, the initial flight plan (Pini) comprising an ordered series of initial legs (Sini), the said fixed initial legs being indexed with an index i that varies from 1 to n, the method comprising the steps involving: identifying (110), using a first iterative calculation on the index i, in the segment to be inserted (Tins), the fixed legs to be inserted that have a position identical to the position of the leg of index i Sini(i)),
the said legs thus determined being referred to as occurrences of the leg of index i, the said occurrences (O1, O2) being ordered by rank k varying from 1 to m, as a function of their position in the segment that is to be inserted (Tins), and searching, among the identified occurrences, for the occurrence of lowest index i and lowest rank k (O.sub.i0(k.sub.0)) that has a type and attribute values identical to the segment of index i, referred to as equivalent point, when the said equivalent point exists, inserting the segment that is to be inserted (Tins) from the said equivalent point, otherwise, inserting the segment that is to be inserted (Tins) from the identified occurrence of lowest index i and lowest rank k (O.sub.i1(k.sub.1)) referred to as a pseudo equivalent point, when the said pseudo equivalent point exists.

Claims

1. A method for inserting a segment (Tins) of flight plan into an initial flight plan (Pini) of an aircraft, performed by a flight management system (FMS) of said aircraft, the initial flight plan (Pini) comprising an ordered series of initial legs (Sini), the segment to be inserted (Tins) comprising an ordered series of legs to be inserted (Sins), a leg corresponding to an instruction for calculating an elementary trajectory and being defined by an aeronautical standard that defines a set of leg types, each type being characterized by at least one attribute corresponding to a type of data item needed for calculating the said elementary trajectory, a subset of the said set of types having an attribute (Fix) corresponding to a position (WPT) defined by geographical latitude and longitudinal coordinates, a leg the type of which belongs to the said subset being referred to as a fixed leg and having an associated position, the said initial fixed legs being indexed by an index i that varies from 1 to n, the method comprising the steps involving: identifying, using a first iterative calculation on the index i, in the segment to be inserted (Tins), the fixed legs to be inserted that have a position identical to the position of the leg of index i Sini(i)), the said legs thus determined being referred to as occurrences of the leg of index i, the said occurrences (O1, O2) being ordered by rank k varying from 1 to m, as a function of their position in the segment that is to be inserted (Tins), and searching, among the identified occurrences, for the occurrence of lower index i and lowest rank k (O.sub.i0(k.sub.0)) that has a type and attribute values identical to the segment of index i, referred to as equivalent point, when the said equivalent point exists, inserting the segment that is to be inserted (Tins) from the said equivalent point, otherwise, inserting the segment that is to be inserted (Tins) from the identified occurrence of lower index i and lowest rank k (O.sub.i1(k.sub.1)) referred to as a pseudo equivalent point, when the said pseudo equivalent point exists.

2. The method according to claim 1, in which the said first iterative calculation stops as soon as the said equivalent point is identified.

3. The method according to claim 1, in which the said pseudo equivalent point and the associated fixed initial leg are stored in memory while the first iterative calculation is being run.

4. The method according to claim 1, in which the aeronautical standard is the standard ARINC 424.

5. The method according to claim 4 in which the said set of types comprises 19 types of leg: initial fix (IF) fixed on the ground; course to a fix (CF); direct to a fix (DF); track to a fix (TF) between two fixes on a great circle; arc to a fix (AF) about a DME beacon; radius to a fix (RF) in a constant-radius turn between two fixes; fix to an altitude (FA) following a course from a fix to a specified altitude; fix to a manual termination (FM) from a fixed point until manually terminated; course to an altitude (CA) following a course to a specified altitude; course to a specified DME distance (CD); course to a radial termination (CR); heading to a specified altitude (VA); heading to a DME distance termination (VD); heading to a manual termination (VM); heading to a radial termination (VR); procedure turn (PI) following a course starting from a fix then making a one hundred and eighty degree turn; racetrack course with hold to an altitude (HA); racetrack course with a single turn holding to a fix (HF); manual racetrack course holding to a manual termination (HM).

6. The method according to claim 5, in which the said subset of types comprises 16 types of fixed leg: initial fix (IF) fixed on the ground; course to a fix (CF); direct to a fix (DF); track to a fix (TF) between two fixes on a great circle; arc to a fix (AF) about a DME beacon; radius to a fix (RF) in a constant-radius turn between two fixes; fix to an altitude (FA) following a course from a fix to a specified altitude; fix to a manual termination (FM) from a fixed point until manually terminated; course to a specified DME distance (CD); course to a radial termination (CR); heading to a DME distance termination (VD); heading to a radial termination (VR); procedure turn (PI) following a course starting from a fix then making a one hundred and eighty degree turn; racetrack course with hold to an altitude (HA); racetrack course with a single turn holding to a fix (HF); manual racetrack course holding to a manual termination (HM).

7. The method according to claim 1, in which one or more attribute(s) are chosen from a list comprising: a turn direction (TD), a heading (course), an altitude (Alt), a distance (di), a radial (R), a maximum excursion in terms of time or in terms of distance (tex, dex).

8. The method according to claim 1, in which when the pseudo equivalent point does not exist, the segment to be inserted (Tins) is inserted in the initial flight plan (Pini) after the last initial leg.

9. The method according to claim 1 further comprising, when the pseudo equivalent point does not exist, a step consisting in: identifying using a second iterative calculation on the index i, in the segment that is to be inserted (Tins), a fixed leg that is to be inserted that is of lower index i and lowest rank k (P1) having a position (WPT1) situated at a distance (d) from the position (WPT.sub.(i2)) of the leg of index i (S.sub.ini(i.sub.2)) that is less than a predefined distance (Dist) and referred to as a close leg, if the said close leg exists, inserting the segment that is to be inserted (Tins) from the close leg, if the close leg does not exist, inserting the segment that is to be inserted (Tins) in the initial flight plan (Pini) after the last initial leg.

10. A device for inserting a segment (Tins) of flight plan in an initial flight plan (Pini) of an aircraft, the device being configured to perform the steps of the method according to claim 1.

11. The flight management system (FMS) comprising the device according to claim 10.

12. A non-transitory computer readable storage medium having code instructions stored therein, that, when executed by a computer, carry out the method according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further features, objects and advantages of the present invention will become apparent from reading the detailed description which will follow and from studying the attached drawings given by way of nonlimiting examples and in which:

(2) FIG. 1 already mentioned depicts the various components of a flight management system according to the prior art.

(3) FIGS. 2a-2c already mentioned illustrate the method of inserting a segment using an FMS according to the prior art.

(4) FIGS. 3a-3c already mentioned illustrate a disadvantage of the method of insertion according to the prior art.

(5) FIGS. 4a-4b already mentioned illustrate another disadvantage of the method of insertion according to the prior art.

(6) FIG. 5 illustrates a method according to the invention.

(7) FIG. 6 illustrates an advantage of the method according to the invention to be compared with the disadvantage illustrated in FIGS. 3a-3c.

(8) FIG. 7 illustrates a first embodiment of the method according to the invention.

(9) FIG. 8 describes one example of an algorithm for implementing the invention according to the first embodiment.

(10) FIG. 9 illustrates a second embodiment of the method according to the invention.

(11) FIG. 10 illustrates one advantage of the second embodiment of the method according to the invention.

DETAILED DESCRIPTION

(12) FIG. 5 illustrates the method 100 according to the invention for inserting a segment Tins of flight plan into an initial flight plan Pini of an aircraft. The method according to the invention is implemented by the flight management system (FMS) of the aircraft.

(13) The initial flight plan Pini comprises an ordered series of initial legs Sini(i), with i varying from 1 to n, and the segment that is to be inserted Tins also comprises an ordered series of legs that are to be inserted Sins(j), with j varying from 1 to m.

(14) A leg corresponds to an instruction to calculate an elementary trajectory and is defined by an aeronautical standard that defines a set of leg types, each type being characterized by at least one attribute corresponding to a type of data needed for calculating the elementary trajectory.

(15) For preference, the aeronautical standard is the international standard ARINC 424 which applies to commercial navigation.

(16) Of the various types, a subset SEF of the set of types has an attribute that we shall refer to as fix, corresponding to a position WPT, namely to a navigation fix defined by geographical coordinates of latitude and longitude. In order to define unambiguously the elementary trajectory corresponding to a leg it is in fact often necessary to use a fixed point in space which is listed in the navigation database 103 or input by the pilot.

(17) A leg the type of which belongs to the subset SEF is referred to as fixed leg, and to each fixed leg there corresponds to an associated position.

(18) The fixed initial legs of Pini are suffixed by an index i, i varying from 1 to n.

(19) The method 100 according to the invention comprises a step 110 which consists on the one hand in identifying, using a first iterative calculation on the index i, in the segment that is to be inserted Tins, the fixed legs that are to be inserted that have a position identical to the position of the leg of index i, Sini(i).

(20) The segments of Tins thus determined are referred to as occurrences of the leg of index i and are ordered Ok(i) by rank k varying from 1 to m, O1(i), O2(i), . . . , according to their position in the segment that is to be inserted Tins.

(21) For example, the leg of index 2 of PiniSini(2)has 2 occurrences, m=2 and the occurrences are O1(2) and O2(2).

(22) On the other hand, the step 110 searches the identified occurrences for the occurrence of lowest rank k that has a type and attribute values that are identical to the leg of index i considered: O.sub.i0(k.sub.0). This identified occurrence which has an identical type and identical attributes is referred to as an equivalent point.

(23) Thus, the iterative calculation identifies the occurrences and compares them in terms of type and attribute i by i, starting with Sini(1) then Sini(2).

(24) The equivalent point is the first occurrence encountered during the iterative calculation, that has the lowest index i0 of all the occurrences and, for this index i.sub.0, the lowest rank k that has the property of having an identical type and identical attributes. So, if several occurrences Ok.sub.0, Ok.sub.1, Ok.sub.2 of the same type and with identical attribute values exist for the one same index i.sub.0, with k.sub.0<k.sub.1<k.sub.2, it is the occurrence Ok.sub.0 of lowest rank k that is chosen.

(25) Next, when the equivalent point O.sub.i0(k.sub.0) exists, the method 100 inserts the segment that is to be inserted Tins from the equivalent point.

(26) Once the equivalent point O.sub.i0(k.sub.0) and the associated leg Sini(i.sub.0) have been identified, the insertion of Tins takes place in the conventional way, as explained in the prior art: the part of Tins from O.sub.i0(k.sub.0) onwards inclusive replaces the part of Pini from Sini(i.sub.0) onwards, Sini(i.sub.0) being replaced by O.sub.i0(k.sub.0). Insertion is performed in the conventional way.

(27) If the equivalent point does not exist, the method 100 inserts the segment that is to be inserted Tins from the identified occurrence of lower index i and lowest rank k O.sub.i1(k.sub.1) referred to as pseudo equivalent point, if such a pseudo equivalent point exists. The pseudo equivalent point is the first occurrence encountered when running the iterative calculation with no consideration of type or attribute. It corresponds to the occurrence searched for in the prior art.

(28) The pseudo equivalent point is used only if the iterative calculation comes to an end, i.e. up to i=n, without having been able to identify an equivalent point.

(29) For preference, the first occurrence encountered (pseudo equivalent point) is stored in memory while the calculation is being done, as is the corresponding leg Sini, namely the corresponding index in case no equivalent point can be identified.

(30) If an equivalent point is identified later, for an index i.sub.1 higher than i.sub.0, the pseudo equivalent point is not used.

(31) Table 1 at the end of the document explains, according to one example, the attributes that are to be compared for leg types according to standard ARINC 424.

(32) The fixed legs, of type IF, CF, DF, TF, RF, AF, VD,VR, FA, FM, CD,CR, HA, HF and HM, PI have the attribute Fix as described hereinabove.

(33) The IF leg has just one attribute, Fix, the value of which is the latitude and longitude of the associated waypoint.

(34) The TF leg has two attributes, the Fix attribute and the turn direction attribute, which describes the direction in which the aircraft must turn. This attribute may adopt two values, left or right.

(35) The CF leg has three attributes: Fix, Turn Direction and Course; the course attribute corresponds to a heading with which the aircraft must comply and its value is an angle identifying this heading, typically a value in degrees comprised between 0 and 360 and identified with respect to north.

(36) Certain types of leg have other attributes, for example an altitude (values expressed in m or in feet), a distance, a time.

(37) For the CD, CR, VD and VR legs one attribute explains the fact that the leg is or is not derived from a combination of other legs.

(38) For example: procedure IF (point A)/FA (from point A to an altitude of 900 m on a heading of 130)/CF (heading of 140 towards point B)/CF (heading of 120 towards point C).

(39) Two legs of the same type of necessity have the same attributes and the method compares the values of these attributes with one another and keeps the occurrence found only if all the attributes have values identical to the values of the corresponding attributes of the current leg.

(40) For example:
Pini=Sini(1)=leg A/Sini(2)=leg CF(WPT B, course 100)/Sini(3)=leg CF(WPT C, course 130)/leg B
Tins=Tins(1)=lex X/Tins(2)=leg CF(WPT B, course 60)/Tins(3)=leg CF(WPT C, course 130)/leg Y

(41) During the iterative calculation, the method identifies first of all, for i=2, the leg Tins(2) that has the same position WPT B as the leg Sini(2). Tins(2) is the first occurrence that the method encounters and the only occurrence of i=2: Tins(2)=O1(2); Tins(2)=O1(2) is not the equivalent point because the values of the course attribute are different, it is the pseudo equivalent point. Tins(2) is stored in memory as is the value of i=2 and/or the corresponding leg Sini(2). The prior art considers this leg Tins(2) for the insertion.

(42) Then, for i=3, the method 100 according to the invention identifies the leg Tins(3) corresponding to O1(3) which has the same position WPT C as the leg Sini(3) and also the same type and same values of course attribute as Sini(3). The leg Tins(3) is the equivalent point.

(43) The iterative calculation stops and the part of Pini from Sini(3) inclusive is replaced by the part of Tins from Tins(3) inclusive:
Pm=leg A/Sini(2)=leg CF(WPT B, course 100)/Tini(3)=leg CF(WPT C, course 130)/leg Y

(44) Thus, the occurrence chosen as equivalent point is the one with the lowest rank in i and k which has the following characteristics: position, type, attributes identical to the current initial leg.

(45) It should be noted that in the method 100 according to the invention, the occurrence of the same type but that has different attribute values is not given preference, for insertion, over the pseudo equivalent point that has only the same position. It is a perfect comparison that is being sought, and no priority is given to the degraded cases.

(46) Furthermore, the segment Tins is inserted as such from the equivalent point onwards, which means to say with the fixed and nonfixed legs it contains, respecting the order.

(47) One advantage of the method according to the invention is that when there are at least two occurrences that exist, the implementation of the method allows the FMS to determine the best occurrence, avoiding unnecessary overflying and fuel consumption, thanks to the use of two criteria above and beyond those used in the prior art, namely the type and the attributes.

(48) This advantage is illustrated in FIG. 6 which reconsiders the scenario in FIGS. 3a-3c.
Pini=B/C.sub.alt1500/D/E/C.sub.alt150/F Fraction of Pini still to be flown: C.sub.alt150/F.
Tins=B/C.sub.alt1500/D/E/C.sub.alt150/M For the current segment S.sub.ini/cour=Sini(5) equal to the leg C.sub.alt150, for example of type FA the altitude of which is an attribute with value 150 m, the step 110 of identifying the occurrences identifies two: O1(5)=Tins(2)C.sub.alt1500 and O2(5)=Tins(5)=C.sub.alt150 assuming that the two legs C of Tins are also of type FA.

(49) A comparison of the attributes, in this instance the altitude, determines Ok.sub.0(5)=O2(5). Unlike an FMS according to the prior art, which stops at 01(5), the method allows the more relevant second occurrence O2 to be selected. Thus, Tins is inserted from C.sub.alt1500 onwards and not from C.sub.alt1500, thereby avoiding the aircraft making an unnecessary loop (flying back over points that have already been overflown) or pilot intervention: Part of Tins to be inserted: C.sub.alt1500/M
Pm=B/C.sub.alt1500/D/E/C.sub.alt150/M.

(50) Accounting for the current position of the aircraft between E and C, the fraction of Pm still to be flown Fmv is equal to:
Fmv=C.sub.alt150/M.

(51) An optimal insertion of Tins in Pini makes it possible to obtain an adequate modified flight plan and also avoids the pilot having to intervene to delete duplicates. In addition, the resultant trajectory corresponds to what air traffic control is expecting.

(52) For preference, the iterative calculation stops as soon as an occurrence that has an identical type and identical attributes has been identified. No unnecessary calculation is performed because the relevant occurrence is identified as quickly as possible, thereby optimizing calculation time.

(53) According to one preferred mode, a set of 19 types of leg from the ARINC aeronautical standard is considered: IF: Initial fix, fixed point on the ground; CF: Course to a fix; DF: Direct to a fix; TF: Track to a fix following a great circle between 2 fixes; AF: Arc to a fix about a DME beacon; RF: Radius to a fix between 2 fixes; FA: Fix to an altitudefollowing a course from a fix to a specified altitude; FM: Fix to a manual termination from a fixed point until manually terminated; CA: Course to an altitude following a course to a specified altitude; CD: Course to a specified DME distance; CR: Course to a radial termination; VA: Heading to a specified altitude; VD: Heading to a DME distance termination; VM: Heading to a manual termination; VR: Heading to a radial termination; PI: Procedure turn outbound from a fix then making a one hundred and eighty-degree turn; HA: Racetrack course with hold to an altitude; HF: Racetrack course with a single turn holding to a fix; HM: Racetrack with manual termination;

(54) Alternatively, the set is made up of the 23 types from the ARINC standard, namely types FC, FD, CI and VI in addition to the 19 above.

(55) According to a preferred embodiment, the subset SEF of fixed leg types is made up of 16 types: IF, CF, DF, TF, AF, RF, FA, FM, CD, CR, VD, VR, PI, HA, HF and HM.

(56) According to a preferred embodiment, the attribute or attributes are chosen from a list comprising: a turn direction TD, a heading Course, an altitude Alt, a distance di, a radial R, a maximum excursion in terms of time tex or in terms of distance, dex.

(57) For preference, the list also comprises an attribute relating to the stringing sequence when the set comprises the aforementioned 19 legs (see table 1).

(58) According to a first embodiment illustrated in FIG. 7, when the pseudo point does not exist, the segment that is to be inserted Tins is inserted into the initial flight plan Pini after the last initial leg Sini(n), and from the first leg Tins(1) to the last Tins(m), namely in its entirety.

(59) FIG. 8 describes one example of a flow diagram of the implementation of the invention, according to the first embodiment of the invention.

(60) In the algorithm 80 of FIG. 8, the initial flight plan Pini is referred to as the current procedure, and the segment that is to be inserted Tins is referred to as the procedure to be inserted.

(61) The fixed initial leg of current PiniSini(i)loaded for the iterative calculation is initialized with the active leg, which is the first leg ahead of the aircraft. The current leg is referred to as Valid_to_Leg.

(62) The algorithm 80 is split into three branches, no occurrence, one occurrence and more than one occurrence. The pseudo point is stored in memory during the iterative calculation and as soon as an equivalent point is identified the procedure Tins is inserted from this point. If during the course of iteration over the set of legs of Pini, no equivalent point is identified, the procedure Tins is inserted from the pseudo equivalent point stored in memory, if there is such a point.

(63) According to a second embodiment illustrated in FIG. 9, the method 100 according to the invention further comprises, when the pseudo equivalent point does not exist, the step 120 which consists in identifying, through a second iterative calculation on the index i, in the segment that is to be inserted Tins, a fixed leg to be inserted of lower index i.sub.2, and lowest rank k2, P having a position WPT.sub.P situated a distance d away from the position WPT.sub.(i2) of the leg of index i.sub.2S.sub.ini(i.sub.2)that is less than a predefined distance Dist. This leg P identified is referred to as close leg.

(64) If a close leg P exists, the FMS inserts the segment that is to be inserted Tins from the close leg.

(65) If the close leg P does not exist, the FMS inserts the segment that is to be inserted Tins into the initial flight plan Pini after the last initial leg.

(66) For preference, the second iterative calculation stops as soon as the close leg P is identified, in order to save on calculation time.

(67) Typically Dist=50 m, 100 m, 250 m, or 500 m or 1000 m, or 2000 m.

(68) In this embodiment, in the case where no occurrence has been identified (no pseudo equivalent point), the calculation is repeated for each fixed leg of Pini, looking for the leg of Tins of lowest order the associated position of which is close to the position associated with the leg of Pini considered. The leg of Tins of lowest order situated near to one of the legs of Pini is thus identified.

(69) The advantage with this second alternative form is illustrated in FIG. 10 which reconsiders the case of FIGS. 4a-4b.

(70) The desire is to insert the segment Tins=K/L/M/N/O into a flight plan Pini=A/B/C/D/E (see FIG. 4a).

(71) The position WPT.sub.M associated with M is not identical to the position WPT.sub.D associated with D, but is close, for example WPT.sub.M is situated at a distance d less than 1 km away from WPT.sub.D.

(72) For a predefined distance Dist equal to 1 km, the point M satisfies the proximity condition, M is the close leg and Tins is inserted from M. Fraction of Tins inserted: M/N/O, M replacing D in Pini:
Pm=A/B/C/M/N/O

(73) Accounting for the current position of the aircraft 20 between A and B, the fraction of Pm still to be flown is: B/C/M/N/O

(74) One advantage with this alternative form is that it avoids flying unnecessary points or manual intervention on the part of the pilot in order to delete them.

(75) This alternative form is preferably implemented during the cruising phase of the aircraft, on routes for which the aircraft position to within the distance Dist is non-critical.

(76) Operationally, if an airway (highway in the sky) made up of a list of fixes is modified or inserted during cruising flight, crossing points between airways, which are close to one another but noncoincident, may exist. Likewise, for a maritime patrol manoeuvre following mobile points (sonar buoys for example), the mission computer sends the FMS the procedure with the names of points corresponding to the position of the buoys. If the system wishes to modify the search procedure, new points are transmitted, corresponding to the new positions of buoys (which can move on the sea). A comparison of distances then becomes highly beneficial in order to allow the new list of legs to be incorporated efficiently into the existing flight plan as the points will have moved by only a few tens of metres.

(77) This alternative form needs to be adjusted in the terminal procedures when the aircraft is approaching the aircraft because the space is generally cluttered with other aircraft and the demands on the positional accuracy of the aircraft are more strict. The choice of distance value is therefore dependent on the zone in which the aircraft is operating (unless it is zero in zones in which position and trajectory are very tightly controlled, such as RNP AR approaches).

(78) Another aspect of the invention relates to a device for inserting a segment Tins of flight plan into an initial flight plan Pini of an aircraft, the device being configured to implement the steps of the method according to the invention. Another aspect of the invention is a flight management system FMS comprising the device according to the invention.

(79) A final aspect of the invention relates to a computer program product, the said computer program comprising code instructions to run the steps of the method according to the invention.

(80) TABLE-US-00002 TABLE 1 Tables of comparison attributes by leg type. Turn direction attribute Leg Type WP (left or Heading Attributes- combining English-language of leg attribute right) attribute other attribute definition of the leg IF Fix Initial fix TF Fix Turn_di- Track to a fix rection CF Fix Turn_di- Course Course to a fix rection DF Fix Turn_di- Direct to a fix rection FA Fix Turn_di- Course Altitude Fix to an altitude rection (target altitude) FM Fix Turn_di- Course From a fix to a manual rection termination CA Turn_di- Course Altitude Course to an altitude rection (target altitude) CD Fix Turn_di- Course Distance Is_CI_VI Course to a DME distance rection (target distance of the fix) CR Fix Turn_di- Course Radial (target Is_CI_VI Course to a radial rection radial of the termination fix) RF Fix (*2) Turn_di- Constant radius arc rection AF Fix (*2) Turn_di- Arc to a fix rection VA Turn_di- Course Altitude Heading to an altitude rection (target termination altitude) VD Fix Turn_di- Course Distance Is_CI_VI Heading to a DME rection (target distance termination distance of the fix) VM Turn_di- Course Heading to a manual rection termination VR Fix Turn_di- Course Radial (target Is_CI_VI Heading to a radial rection radial of the termination fix) PI Fix Turn_di- Course Max_excursion 045/180 procedure turn rection (maximum time or distance for making the one eighty turn) HA Fix Turn_di- Course Altitude Holding in lieu of rection (target Procedure Turn (Altitude altitude)- termination) distance (of hold) HF Fix (*2) Turn_di- Course Distance Holding in lieu of rection (distance of Procedure Turn (Single hold) circuit terminating at the fix) HM Fix Turn_di- Course Distance Holding in lieu of rection (distance of Procedure Turn (Manual hold) termination)