757 LNAV/VNAV Plus v1.2.36

757 LNAV/VNAV Plus v1.2.36

Hold handover and reqVS audit updates.

v1.2.36 — HOLD detection matches the real FF757 display

• The FF757 puts the hold direction on the course line (HOLD LEFT /
  HOLD RIGHT) with the fix on the next row:
  HOLD LEFT
  WX205
  1.2.35 looked for WX205 LEFT plus a standalone HOLD line, so this
  format was not detected. The parser now marks any leg whose course line
  contains HOLD (either direction), and still handles a standalone HOLD
  continuation line without creating a duplicate waypoint.
• On a hold leg guidance reports HOLD PASS and
  HOLD at WX205: FF757 owns the hold, stays inactive, and the flight loop
  clears override_nav_heading and the roll augmentation so the FF757 flies
  the hold. A one-shot log line marks the transition:
  LNAV HOLD handover: HOLD at WX205: FF757 owns the hold; nav override released.
  Lateral guidance resumes automatically when the FMS leaves the hold leg.

v1.2.35 — explicit HOLD handover

• Added RouteLeg::hold, propagated from the CDU cache into the route
  snapshot, plus the HOLD PASS source and the handover log line. The flight
  loop releases the nav override on a hold instead of continuing to command
  roll.

v1.2.34 — reqVS audit fields

• The VNAV profile note now prints the current altitude, groundspeed and
  target delta next to the target and distance, e.g.
  VNAV profile to FF24, 43.9 NM, 1970 ft | alt=9020 gs=327 delta=-7050.
  Every reqVS can be checked directly in the status window and log
  (reqVS ≈ delta / (NM / GS)).

Verification

• guidance 188 checks, CDU 48, CIFP 21 — 0 failures.
• CDU hold test uses the real HOLD LEFT / WX205 page format.
• VNAV 1.2.33 MCP-below fix (3000 selected no longer dives through 8625)
  and the 1.2.32 rescan-hitch fix are included.

Download

757LVNAVPlus-win.zip
SHA256 BC31CC371280CB9E7616B4009EDC3E8AA98922CDF9139C667C029CFD4E874349

Close X-Plane, replace Aircraft/.../plugins/757LVNAVPlus/64/win.xpl (or
unzip over the plugin folder), restart. The plugin does not modify SASL or
the aircraft files.

中文摘要

本版新增等待航线（HOLD）显式移交：识别 HOLD LEFT / HOLD RIGHT 页面格式，
进入等待时释放 override_nav_heading 和滚转增稳，由 FF757 飞等待，日志写
LNAV HOLD handover；退出等待后自动恢复。VNAV 状态新增 alt/gs/delta
字段，reqVS 可直接核算。

757 LNAV/VNAV Plus v1.2.29

757 LNAV/VNAV Plus v1.2.29

LNAV tracking, turn anticipation and parser-stability fixes since v1.2.22.

v1.2.29 — long-leg cross-track

• When the route and the FMS agree on a leg's course, the FMS CDI course was
  treated as the leg's initial bearing and the course line was rebuilt behind
  the fix. On long legs the CDI course is the LOCAL great-circle track at the
  aircraft, so the rebuild rotated the leg by its convergence. Live LH -> GYA
  (130 NM): xtk=-1.12 to -1.36 NM in ROUTE mode while the CDI stayed at
  ~0.05 NM, which commanded an unnecessary correction and raised NAV UNABLE RNP (ANP 2.76 > RNP 2.0). Legs longer than 30 NM now use the FMS
  cross-track directly; shorter legs keep the line rebuild.

v1.2.28 — turn anticipation

• Added lnav_turn_bank_deg (default 16°, range 5–35°) for fly-by corner
  anticipation only. lnav_max_bank_deg (25°) remains the RF-arc bank limit.
  Live Haikou SID: a 54° right turn at 408 KT cut 0.36 NM inside the new
  course and then overshot the next corner by 0.75 NM; the observed bank was
  ~15° (radius ~9 NM) while the plugin assumed 25° (5.6 NM) and started the
  turn ~1.7 NM early.

• lnav_rollout_lead_deg default raised 3° -> 4°.

v1.2.27 — CDU leg course

• The LEGS page course line ( 336 14NM) is now parsed into
  CduLeg::legCourseDeg. Unresolved DME-arc / altitude pseudo-fixes
  (D323P, D331W, (500)) are synthesised from that leg's own CDU course
  and distance instead of the single active desired track, so their positions
  no longer rotate on every rescan.

v1.2.26 — startup crash

• Fixed a crash inside Trim (win.xpl +0x2b445, 0xc0000005). Blank lines
  and one-field rows such as a bare RF give a single-element vector, and an
  unguarded p[1] read ran off the end of ParseFfProcLines. The guard is
  now marked as protected. Verified against all 7,321 Proc files
  (3,625 RF arcs, 0 unreadable).

v1.2.25 — active-waypoint sequencing

• CDU LEGS page 1 is the highest-priority active-index source while displayed;
  rescans keep its waypoint, and a page showing an already-passed fix cannot
  rewind the index. Removes the repeated 2 (DM) -> 0 (LXA) tug-of-war and
  the resulting route distance disagrees with CDI fallbacks.

v1.2.24 — route re-sync fly-off

• Active sync no longer rewinds across coincident fixes ((INTC) on top of
  UGOVA).

• Exit-only CIFP RF matching is limited to procedures within 40 NM of the exit
  fix, and an RF lead-in without an entry fix must agree with the FMS course
  within 30°. Stops a borrowed LS987 -> (INTC) arc (145.7°) from replacing
  the 091.6° leg (12.8 NM phantom cross-track, intercept saturated at 30°).

• GPS CDI dot-sign calibration is frozen after a trusted route cross-track
  confirms it and disabled under lnav_force_cdi; it also needs aligned track
  plus ~2 s of disagreement. Stops the sign flipping during a recovery turn
  (xtk +0.97 -> -0.89, corr -3.46 -> +3.41).

v1.2.23 — source switch and diagnostics

• LNAV source: GPS CDI (menu, lnav_force_cdi=1, command
  757lvnv/toggle_cdi_source) ignores the parsed route and tracks the FF757
  CDI directly.

• Throttled LNAV servo diagnostic every 5 s: source, track, base/desired
  course, xtk, distance, correction, nav_steer command/readback, damping,
  L1 term and CDI dot.

Verification

• guidance 181 checks, CDU 42, CIFP 21 — 0 failures.

• All 7,321 FF757 Proc files parse without a crash.

• Live log after the fix: GPS CDI xtk ~0.05 NM; ROUTE agrees instead of a
  phantom -1.36 NM; long legs no longer command a correction.

Download

757LVNAVPlus-win.zip
SHA256 215B2AFEBCED3702EACFB00F13E66F23DF249453A73C7CB8A497BD55A26A19A0

Close X-Plane, replace Aircraft/.../plugins/757LVNAVPlus/64/win.xpl (or
unzip over the plugin folder), restart. The plugin does not modify SASL or
the aircraft files.

中文摘要

本版集中修复 LNAV 直线跟踪与转弯：长航段 ROUTE 模式不再出现 1.1–1.4 NM 的
假偏航距（改用 FMS CDI 偏航距）；飞越转弯按实际 16° 坡度预测切点，出弯提前
4° 锁定，减少切弯和过冲；CDU 伪航点按各航段自身航道合成；修复 Proc 文件解析
启动崩溃；CDU 页面 1 作为活动航段最高优先级，消除索引来回拉扯。

757 LNAV/VNAV Plus v1.2.25

757 LNAV/VNAV Plus v1.2.25

LNAV sequencing and fly-off fixes. VNAV is unchanged in this build.

v1.2.25 — active-waypoint sequencing

• The CDU LEGS page 1 waypoint is now the highest-priority active-index
  source while the page is displayed. Rescans keep that waypoint instead of
  resetting the index to 0, and the geometric fallback / Airnav distance
  heuristic may catch up to it but not run ahead of it.
• A CDU page that still shows a waypoint the aircraft has already passed is
  treated as stale and may not rewind the index.
• Removes the repeated live log lines CDU active from page 1: 2 (DM) -> 0 (LXA) (every few seconds) and the resulting route distance disagrees with CDI (sustained) GPS CDI fallbacks around dynamic pseudo-fixes.

v1.2.24 — straight-leg fly-off after a route re-sync

• Active sync no longer rewinds across coincident fixes. The FF757 computes
  pseudo-fixes such as (INTC) on top of an existing waypoint; matching
  distance/bearing picked the lowest index and moved the active leg from
  UGOVA back to (INTC). Near-tied candidates now keep the one closest to
  the current active index.
• Exit-only CIFP RF matching is limited to procedures whose airport is within
  40 NM of the exit fix. The rewind had borrowed the ZULS arc LS987 -> (INTC)
  for an enroute leg 67 NM away: its 145.7° entry tangent replaced the 091.6°
  leg and produced a 12.8 NM phantom cross-track with the intercept saturated
  at 30° while the FF757 CDI was centered.
• Second guard: an RF lead-in whose entry fix is missing from the route cache
  must agree with the FMS course within 30°. Genuine pair matches with the
  entry fix in the route stay purely geometric (RNP segments unaffected).
• The GPS CDI dot-sign bootstrap is frozen once a trusted route cross-track
  confirms it, disabled while lnav_force_cdi is on, and needs aligned track
  plus ~2 s of continuous disagreement. Live case: during a recovery turn
  xtk flipped +0.97 -> -0.89 and corr -3.46 -> +3.41 while the aircraft
  stayed right of course.

v1.2.23 — source switch and diagnostics

• LNAV source: GPS CDI in Plugins -> 757 LNAV/VNAV Plus (config
  lnav_force_cdi=1, command 757lvnv/toggle_cdi_source). While enabled the
  parsed route is ignored and the FF757 GPS CDI is tracked directly; the status
  window shows src=GPS CDI and the note GPS CDI source (forced).
• Throttled LNAV servo diagnostic (every 5 s): source, track, base and
  desired course, xtk, distance, correction, nav_steer command and
  previous-frame readback, damping, L1 term and CDI dot.

Verification

• guidance 177 checks, CDU 39, CIFP 18 — 0 failures.
• Live log after the fix: xtk within ±0.05 NM on straight legs; corrections
  exceed a few degrees only inside 1 NM of a fix (normal near-fix homing).

Download

757LVNAVPlus-win.zip
SHA256 8A2B3C93B73BB6949D1ECA990CFB40D8173738AD9172F346978CC788DFE6786A

Close X-Plane, replace Aircraft/.../plugins/757LVNAVPlus/64/win.xpl (or unzip
over the plugin folder), then restart. The plugin does not modify SASL or the
aircraft files.

中文摘要

本版修复 LNAV 直线段飞偏与航段索引抖动：航路重同步不再因重合伪航点（(INTC)）
回退 active 航段；RF 弧只接受 40 NM 内机场的程序并要求与 FMS 航道一致；GPS CDI
符号在航路验证后冻结，不再在恢复转弯时反转；CDU 页面 1 在显示期间为 active 航段
的最高优先级，已飞过的航点不再把索引拉回。VNAV 无改动。

v1.2.22 — VNAV 剖面跟随、响应速度与稳定性修复

v1.2.22

本次集中修复 VNAV 下降不跟剖面、响应偏慢，以及两处稳定性问题。

VNAV 剖面跟随

• CDU 高度限定符：FL157A = at or above，6890B = at or below，无后缀 = at。
  旧版丢弃 A/B 后缀，把 at-or-above 下限当成“必须精确到达”，在 FL340、距限制点
  43 NM 时要求约 4000 fpm，把飞机压离 FMC 剖面并与机模 VNAV 抢俯仰。现在已满足的
  at-or-above 下限不再作为下降目标。
• 下限坡度保护：跳过下限后，下降率仍限制为“恰好在该点达到下限高度”，不会提前
  跌破；状态窗备注显示 at-or-above floor kept。
• 俯仰权限迟滞：接管需 |vsError| > 200 fpm 或路径偏差 > 250 ft，释放需
  |vsError| < 80 fpm 且偏差 < 120 ft。旧版在 150 fpm 死区立即交权，机模以更浅
  速率接管后再被抢回，导致飞机长期高于剖面（实测 1630 ft）。
• 路径偏差积分：新增 pathErrorFt，持续偏离时保持修正，不被单帧小误差洗掉。
• before TOD 只在平飞时成立：已经开始下降时不再停在 ROUTE HOLD / PTH STBY
  透传，而是按实时路径计算 reqVS。
• 进近阶段交还俯仰：检测到 servos=0 或 override_artstab=1 约 1 秒即释放权限
  并清空 override，不再与机模抢俯仰。

VNAV 响应与稳健性

• 增益调整：默认 vnav_vs_gain 0.8 → 1.2，vnav_smoothing_tau_s 0.12 → 0.10。
  实测 945 fpm 误差曾只给 +0.75°（约 450 fpm，不到误差一半）；1.2°/1000 fpm 约为
  物理反推的 85%（400 KT 时 1° ≈ 707 fpm）。
• 拒绝假航点：同名导航点距当前航路超过 500 NM 时不采用；VNAV 高度/速度目标累计
  距离超过 500 NM 时停止搜索。修复了 FI07 在 2241.8 NM 外导致
  reqVS=-43 fpm 的错误。
• 自动 250 KT / 10000 ft：只在进入减速窗口后激活，不再巡航时显示
  250 kt @ 106 NM。

稳定性

• 修复读取 Custom Data/STSFF/navdata/Proc/<ICAO>.txt 时的越界崩溃。Proc 文件用空行
  分隔程序块，SplitComma("") 仍返回 1 个元素，旧代码随后读取 p[1] 越界，损坏的
  std::string 在 Trim 中触发访问违规（ZSPD/ZSNJ 航路必现）。空行/短行现在按块
  结束处理。

诊断

• 飞行中每 5 秒写入一条 VNAV servo 日志：corr、FD 俯仰写入/回读、override、
  AP/伺服状态、override_artstab、vs/req/pathErr/held，便于定位俯仰归属。

升级说明

1. 完全退出 X-Plane（不是最小化）。
2. 用压缩包内 64/win.xpl 覆盖到
   ...\plugins\757LVNAVPlus\64\win.xpl。
3. 旧配置文件 Output/preferences/757LVNAVPlus.cfg 里若仍是
   vnav_vs_gain=0.8，新版不会自动改它。想获得新的响应速度，请改为 1.2
   （或删除该文件恢复默认）；1.0 更柔和，1.4 更灵敏。
4. 启动后日志应出现 [757LVNAV+] 757 LNAV/VNAV Plus v1.2.22 starting。

校验

• 757LVNAVPlus-win.zip — 513,198 字节
  SHA256 AD89474D2DA62228978F7705663C44EBCD90DC46AE4A9B2B8D5BAE9EE9D553D8
• 64/win.xpl — 1,116,672 字节
  SHA256 194FD04D6E09C6F128A9D2DFFC0D25D953C6EF81BC68E0754BAF1066A225AE22

已知问题

• 个别航路的程序航点若在 FF757 navdata 中无同名近距点（如某些 ZSNJ 进近点），
  坐标仍可能被错误合成，或把 (660) 之类字段当成航点 ident；已加 500 NM 过滤，
  但 CDU 伪 ident 解析仍在单独修复。
• 本次未改动 LNAV / RF 算法。

v1.2.21 – 修复部分机器加载失败与 CDU 扫描崩溃

757 LNAV/VNAV Plus v1.2.21

面向 FlightFactor 757/767 的独立 LNAV/VNAV 增强插件（不修改 SASL、不改机模文件）。Windows x64，X-Plane 12 / 11。

本版修复（1.2.21）

• 修复部分机器加载失败（错误 1114）：CDU 读取器的构造函数是全局静态对象，会在 DllMain / LoadLibrary 期间执行，而它之前调用了 XPLMFindDataRef / XPLMGetSystemPath。在 DllMain 里调用 XPLM 是未定义行为，部分机器会直接报 DLL initialization routine failed。现在改为懒绑定（首次飞行循环回调时才绑定），静态构造不再触碰 XPLM。
• 修复 CDU 扫描后的崩溃：故障偏移解析到路由重建阶段的字符串处理函数，根因是 CDU 屏幕读取缓冲按“当前行×列”分配；翻页瞬间行列 dataref 可能异常，自定义显示 accessor 若不遵守 inMaxLength 会写越界。现在始终按 32×64 分配，越界最多落在预留空间内。
• 制导逻辑与 1.2.20 完全一致，无行为变化。

尚未发布 1.2.19 / 1.2.20（直飞小偏差修正）

• 直飞段加入 L1 前视横向项（参考本人之前做的关于MK787fix的项目），0.15 NM 级偏差不再需要几分钟才能收回。
• lnav_l1_factor 默认 1.6：巡航速度下 0.15 NM 偏差约给 1° 修正，一分钟内收敛，不摆头；调大更柔，调小更强，0 关闭。
• 航向直写默认覆盖所有 LNAV 航段（lnav_heading_direct=1）；该模式不写 FD 滚转，保证只有一个横向控制器。

安装

1. 完全退出 X-Plane。
2. 解压到 <X-Plane>/Aircraft/<你的 757 机型>/plugins/757LVNAVPlus/，确认存在 .../757LVNAVPlus/64/win.xpl（不要多套一层同名文件夹）。
3. 启动后 Plugins 菜单应出现 757 LNAV/VNAV Plus；没有出现请检查是否 Windows x64、是否装在当前加载机型的 plugins 下、安装时模拟器是否关闭。

文件校验

• win.xpl 1,112,064 字节，SHA256 2635077380B82DD198E0DA2F1BE7606DBF84C17B605E06876B1FC850F9E6900D
• 757LVNAVPlus-win.zip 508,646 字节，SHA256 FD8E9F2E9C09A6062A46B4E0FC4FBE16EFBA7C6A25D2FFC96F8610BFA3983606

说明

• 仅 Windows x64 构建；macOS/Linux 可用 CI 产物或按源码构建。
• MIT 许可，转载/修改均可，但必须保留作者署名 JACKGONG。
• 实验性增强，建议先在可弃档试飞；报告问题时附状态窗截图与 Log.txt 中的 [757LVNAV+] 行。

---

English summary: v1.2.21 fixes two failures: (1) the CDU reader's global constructor called XPLM APIs inside DllMain, which some machines reject as DLL initialization routine failed (1114) - binding is now lazy; (2) the CDU screen buffer is always allocated for a full 32x64 screen, so a custom display accessor writing past inMaxLength can no longer corrupt the heap and crash the route rebuild. Guidance behaviour is unchanged. MIT; credit "JACKGONG" required.

v1.2.17 – RF 弧段、航路识别与 RNP 离场修复

757 LNAV/VNAV Plus v1.2.17（自 v1.2.4 以来的累计更新）

面向 FlightFactor 757/767 的独立 LNAV/VNAV 增强插件（不修改 SASL）。Windows x64，X-Plane 12 / 11。

本版重点

• RF 定半径弧段：从 FF757 自己的 Proc/<ICAO>.txt 解析真实圆弧（圆心/半径/转向），整段由插件带飞：入弧前按入弧航道飞向入弧点，弧上按切线 + 径向修正跟踪；RF 段不参考机模 FMS 航路。
• RF 航向直写（默认）：弧段每帧维持 override_nav_heading=1 并写 nav_steer_deg_mag，按 787 参考脚本做"航迹→航向"换算（风补角 hdg-trk + 航迹阻尼）；该模式不写 FD 滚转，避免双控制器争夺。可用 lnav_rf_nav_override=0 退回 ±4° 滚转修正。
• 航点识别：以 CDU LEGS 第 1 页第 1 行为"下一个航点"，双向校正；几何回退改为沿航迹投影，不再在密集短航段上连跳。
• 修复误识别为 RF：仅当快照完全没有入口航点时，才按"终点匹配"找弧，避免把其他 SID 的弧套到直飞段（ZULS LS516→LS428、LS612→LS819 已修复）。
• VNAV：DES 时插件锁定俯仰优先权（vnav_priority），消除与机模 VNAV 的逐帧夺权；250 KT / 10000 ft 硬限制与减速提前量按 1 NM/10 KT 计算。
• 性能：navdata 改为内存索引（只建一次，约 6–10 MB），修复 1.2.0 的掉帧；ANP(trk) 为航迹保持误差代理量，仅提示。

完整逐条记录见仓库 CHANGELOG.md。

安装

1. 完全退出 X-Plane。
2. 解压 757LVNAVPlus-win.zip 到：
   <X-Plane>/Aircraft/<你的 757 机型目录>/plugins/757LVNAVPlus/
   确保存在 .../plugins/757LVNAVPlus/64/win.xpl（不要多套一层同名文件夹）。
3. 启动 X-Plane，Plugins 菜单应出现 757 LNAV/VNAV Plus。

若菜单没有出现：确认是 Windows 64 位、装在当前加载机型的 plugins 下、且安装时模拟器已关闭。

文件校验

• win.xpl 1,111,552 字节，SHA256 3538E6E750D20B0A3E649405D9A312658148DCCB18F27303617E585F190CAFD2
• 757LVNAVPlus-win.zip 500,439 字节，SHA256 98E2F8D7BAAE96F21F8A0A490C5F5C3A281395AEBBEFDA8E9272FA65FFB21E4E

说明

• 仅提供 Windows x64 构建。
• 不修改机模 SASL；所有增强均通过标准 X-Plane dataref 完成。
• 许可证 MIT，转载/修改/商用均可，但必须保留作者署名 JACKGONG。

---

English summary: Independent LNAV/VNAV augmentation for the FlightFactor 757/767 (no SASL changes), Windows x64. Since v1.2.4: true RF arc tracking (FF757 procedure data first, plugin-flown lead-in, heading-direct guidance with wind correction and damping), CDU page-1 authoritative active waypoint and safer sequencing, straight legs no longer mis-annotated as RF, VNAV pitch-priority latch, and an in-memory navdata index (FPS fix). See CHANGELOG.md for details. MIT; credit "JACKGONG" required.

v1.2.4 — RF legs, VNAV speed limits, stable turns, descent authority

Highlights

RF (constant-radius-to-fix) legs — the FF757 flies them as a polygon chain;
the plugin now resolves the real arc from X-Plane's CIFP database (centre fix,
radius, turn direction) and tracks the circle: tangent course plus a bounded
radial correction, unwrapped progress so arcs beyond 180° cannot wrap, and a
roll-out lead so it levels on the exit course. Computed centres such as CFBRK
fall back to earth_fix.dat; if that fails the centre is reconstructed from
the entry fix, inbound course and radius.

VNAV speed limits — FAR 250 KT below 10000 ft and CDU DECEL points, with
the 757 rule of 1 NM of deceleration per 10 KT of slowdown. The lead softens
the descent VS so the speed is met at the fix instead of on short final.

Stable turns — the leg course is now anchored on the FMS/CDI course when
both agree. Our course is derived from resolved coordinates and could sit a
degree off; over a 60 NM leg that became a ~1 NM phantom cross-track, which at
400 KT turned into a 21° intercept and a visible S-turn. Small offsets now home
direct to the fix; the constant 30° capture only applies beyond
lnav_xtk_blend_nm.

VNAV pitch authority — the FF757's VNAV and the plugin write the same FD
pitch dataref. The plugin now latches pitch priority while its vertical path is
valid and releases only after ~2 s of inactivity, so the two controllers no
longer alternate frame by frame in DES.

Performance — the navdata is indexed once per session (~390,000 fixes,
~6 MB, hard cap 600,000 records) instead of a ~340 ms full rescan on every route
rebuild; CIFP RF lookups are negative-cached. Fixes the frame-rate dropwith 1.2.0.

Status window

• ANP is labelled ANP(trk) because it is track-keeping error against the
  active path, not the FMS's 95% position-error estimate.
• Notes show course from FMS when the course was re-anchored, and
  plugin pitch priority while the plugin owns pitch in the descent.

Config

New keys (all default to the new behaviour):
lnav_rf_enabled, vnav_speed_limits_enabled,
vnav_speed_decel_factor_nm_per_10kt, vnav_hard_250_below_ft,
vnav_priority.

Removed (no longer used): lnav_intercept_distance_nm,
lnav_capture_distance_nm. Unknown keys in an existing config file are ignored.

Verified

guidance 131 · cifp 10 · cdu 35 checks — all passing.

Files

• 757LVNAVPlus-win.zip — SHA256
  FF08DFE9F0E27D47671ABD6A527994F005F806FAF18129CAF488A98583E45753
• 64/win.xpl — 1,097,728 bytes, SHA256
  2E139DCE70250B4521AF50252CAA948EDDFCFC1E30F6B24F4D071E680CE04747

Install

Copy 64/win.xpl into
X-Plane 12/Aircraft/Laminar Research/Boeing757-Full/plugins/757LVNAVPlus/64/.
The log at Output/757LVNAVPlus.log starts with v1.2.4.

中文摘要

• RF 定半径弧段：从 X-Plane CIFP 解析真实圆心/半径/转向，按圆弧平滑跟踪。
• VNAV 速度限制：250 KT/10000 ft 与 DECEL 点，按 1 NM/10 KT 计算减速提前量。
• 转弯修复：航向锚定 FMS，小偏航距改为直接向心飞，消除远端 21° 甩摆。
• 下降时插件独占俯仰，不再与机模 VNAV 夺权（可用 vnav_priority=0 关闭）。
• 导航数据一次性建索引，修复帧数下跌。

Free to redistribute, original or modified, including commercial use.
Author credit "JACKGONG" is required. MIT, (c) 2026 JACKGONG.

757LVNAVPlus v1.1.1

757 LNAV/VNAV Plus v1.1.1

FlightFactor 757/767 的独立 LNAV/VNAV 增强插件，不修改 SASL、不改飞机文件。
Standalone LNAV/VNAV enhancement for the FlightFactor 757/767. SASL and aircraft files untouched.

本次更新 / Changes

• 转弯改为真正的 fly-by 切线弧：圆心置于切点内侧 R，修复"切弯过多"。
• 转弯进度改用圆心方位角，横向偏差不再被误判为"已转半圈"。
• 起弯判定改用沿航段剩余距离，去掉 0.5 NM 提前量。
• lnav_intercept_distance_nm 默认 1.5 NM。
• 状态窗按 PFD FMA 显示 VNAV 子模式 SPD / PTH，未介入时显示 STBY。

安装 / Install

解压到 X-Plane 12/Aircraft/Laminar Research/Boeing757-Full/plugins/757LVNAVPlus/，确认存在 64/win.xpl。
见 docs/USAGE.md（中英双语）。

许可证 / License

Free to redistribute, including commercially, with credit to JACKGONG. MIT.