FMC / MCDU Messages — Complete List
Everything the flight computer can tell you: the message, what it means and what to do. Scratchpad messages clear with CLR — but clearing is not fixing.
Boeing 737 FMC — All Operational Messages BOEING
| Message | Meaning | Your Action |
|---|---|---|
| STANDBY ONE | FMC is busy computing. | Wait a moment; don't re-press. |
| INVALID ENTRY | Input format invalid for this field. | Check the format (speed vs waypoint mix-up). |
| INVALID DELETE | This field cannot be deleted. | Overwrite with a new value instead. |
| NOT IN DATABASE | Waypoint/procedure not in nav database. | Check spelling; update your AIRAC. |
| NOT ON INTERCEPT HEADING | LNAV armed but you won't intercept the route. | Turn toward the route with HDG, then LNAV. |
| VERIFY POSITION | IRS/GPS/radio positions disagree. | Compare on POS REF; realign if needed. |
| ENTER IRS POSITION | IRS waiting for coordinates to align. | Enter GPS/airport position on POS INIT. |
| IRS ALIGN MODE | IRS still aligning. | Don't move the aircraft; wait ~7-10 min. |
| UNABLE REQD NAV PERF-RNP | Nav accuracy can't meet required RNP. | Crosscheck raw data; question RNP approach. |
| UNABLE NEXT ALT | Next altitude constraint unreachable. | Climb/descend earlier or request revision. |
| UNABLE CRZ ALT | Too heavy for that cruise level. | Enter a lower FL; step climb later. |
| DRAG REQUIRED | Above the descent path — excess energy. | Speedbrake; consider early flap. |
| THRUST REQUIRED | Speed decaying below target. | Add thrust / check A/T. |
| INSUFFICIENT FUEL | Computed fuel won't reach destination. | Review route/level; plan a divert. |
| USING RSV FUEL | You're into reserve fuel. | Assess fuel state; request priority if needed. |
| TAKEOFF SPEEDS DELETED | A change invalidated V-speeds. | Re-enter V1/VR/V2 on TAKEOFF REF. |
| V SPEEDS UNAVAILABLE | FMC can't compute V-speeds. | Complete PERF & weights; or enter manually. |
| PERF/VNAV UNAVAILABLE | Performance data missing. | Fill PERF INIT (ZFW, fuel, CI, CRZ ALT). |
| DESCENT PATH DELETED | Descent profile was erased. | Check LEGS constraints; rebuild. |
| END OF ROUTE | Active route finished. | HDG SEL if on vectors; else extend route. |
| ROUTE DISCONTINUITY | Gap in the route (boxed line on LEGS). | Close it by moving the next waypoint up. |
| RESET MCP ALT | MCP altitude window needs updating. | Set the newly cleared altitude. |
| CHECK ALT TGT | VNAV target conflicts with MCP. | Reconcile MCP/constraints. |
| CYCLE FMC POWER | FMC software fault. | Power-cycle the FMC / reload aircraft. |
| SINGLE FMC OPERATION | Second FMC offline. | Informational; continue on one. |
| DES PATH UNACHIEVABLE | Path can't be met from here. | Speedbrake/vectors; recapture profile. |
| RW/ILS FREQ ERROR | Runway and ILS frequency mismatch. | Match DEP/ARR and NAV RAD pages. |
| TIMEOUT-RESELECT | Datalink request timed out. | Send the request again. |
Airbus A320 MCDU — All Operational Messages AIRBUS
| Message | Meaning | Your Action |
|---|---|---|
| INITIALIZE IRS / ALIGN IRS | ADIRS awaiting alignment. | Enter FROM/TO on INIT A; ADIRS to NAV. |
| IRS IN ALIGN > 7 MN | Alignment will take over 7 minutes. | Wait; keep the aircraft still. |
| F-PLN DISCONTINUITY | Gap in the plan — NAV stops there. | Clear it with CLR. |
| NOT IN DATA BASE | Point/procedure not found. | Check spelling & AIRAC cycle. |
| FORMAT ERROR | Wrong input format. | Use the field's format (e.g. 12.5 tonnes). |
| ENTRY OUT OF RANGE | Value outside limits. | Enter a sensible value. |
| NOT ALLOWED | Action not permitted on this page/phase. | Try the correct page or phase. |
| CHECK TAKE OFF DATA | Takeoff data needs re-confirmation. | Review PERF TO; confirm again. |
| T.O SPEEDS TOO LOW | Entered V-speeds too low for weight. | Recompute/re-enter speeds. |
| V1/VR/V2 DISAGREE | Speed order illogical (V1>VR etc.). | Correct the values. |
| GPS PRIMARY | GPS is primary — high accuracy. | Informational; CLR to remove. |
| GPS PRIMARY LOST | GPS source lost. | Monitor accuracy on PROG; crosscheck radios. |
| NAV ACCUR DOWNGRAD | Navigation accuracy degraded. | Raw-data check; care with RNP ops. |
| DEST EFOB BELOW MIN | Arrival fuel below minimum. | Review plan; consider alternate. |
| NEW CRZ ALT: FLxxx | New cruise selected on FCU. | Informational — confirm it's intended. |
| STEP DELETED | Step climb point invalidated. | Re-enter a step if needed. |
| USING COST INDEX xx | CI loaded with company route. | Informational; change on INIT A if desired. |
| CSTR DEL ABOVE CRZ | Constraints above cruise deleted. | Informational. |
| SPD LIM EXCEEDED | Exceeding speed limit below 10,000 ft. | Slow below 250 kt. |
| TOO STEEP PATH AHEAD | Upcoming descent segment too steep. | Descend early or request track miles. |
| MORE DRAG | PFD cue: above profile. | Extend speedbrakes. |
| DECELERATE | Past the approach decel point. | Managed speed / slow down. |
| SET MANAGED SPEED | System expects managed speed. | Push the FCU speed knob. |
| SET GREEN DOT SPEED | Fly best clean speed. | Set green dot. |
| ENTER DEST DATA | Arrival QNH/wind/temp missing. | Fill the PERF APPR page. |
| RWY/ILS MISMATCH | Runway vs tuned ILS mismatch. | Fix RAD NAV / ARRIVAL selection. |
Route Planning — SimBrief to Cockpit
The complete dispatch flow: build the plan on SimBrief → read the OFP → load it into the FMC/MCDU (automatically or by hand). Example flight: LTFM → LTAI.
Step A — Building the Plan on SimBrief SIMBRIEF
Create a free account at dispatch.simbrief.com → New Flight.
ORIGIN LTFM, DEST LTAI, ALTN LTBS; AIRLINE GKT, your FLT NBR; AIRCRAFT B738 (pick your fleet type).
Hit Auto-Generate in the ROUTE box — SimBrief builds a valid route on the current AIRAC (e.g. ASMA1C ASMA UL851 ERGUN BADAP DIDRU1A). Use Analyze to compare alternatives.
Generate Flight → your OFP is ready. Key lines: ROUTE (the string you'll load), CI, FL, BLOCK FUEL, ZFW, TOW.
Step B — Loading the Route (Automatic)
| Aircraft | Method |
|---|---|
| PMDG 737 | Export the OFP in PMDG format via SimBrief Downloader → on the FMC RTE page enter the plan name (e.g. LTFMLTAI01) in CO ROUTE — full route loads. |
| Fenix / FBW A320 | MCDU INIT A → INIT REQUEST* on the CO RTE line — route, CI and FL download straight from SimBrief (Fenix also via EFB). |
| Zibo 737 | FMC → RTE → type the SimBrief name in CO ROUTE, or import via EFB. |
| ToLiss | ISCS menu → Import SimBrief. |
Step C — Manual Entry: Boeing 737 FMC/CDU
POS INIT — INIT REF → REF AIRPORT LTFM; copy the GPS position to SET IRS POS; IRS switches to NAV and aligns.
RTE — ORIGIN/DEST/FLT NO; then fill VIA/TO from the OFP: VIA UL851 TO ERGUN... For a direct leg, enter only the TO waypoint.
DEP/ARR — LTFM: runway 35L + SID ASMA1C. LTAI: STAR DIDRU1A + approach ILS 36C. Pick transitions per the OFP.
LEGS — Scroll the whole route: does every waypoint match the OFP? Close all ROUTE DISCONTINUITY lines; verify speed/altitude constraints (like 250/8000).
PERF INIT — from the OFP: ZFW 58.4, RESERVES 2.5, CI 35, CRZ ALT FL340. TRANS ALT 10000 (Turkiye).
N1 LIMIT / TAKEOFF REF — SEL TEMP for derate if desired; on TAKEOFF enter FLAPS 5 and CG → confirm V1/VR/V2 with the LSKs. Enter arrival QNH and winds on the DES FORECAST page. EXEC.
Step D — Manual Entry: Airbus A320 MCDU
INIT A — FROM/TO LTFM/LTAI, ALTN LTBS, FLT NBR, CI 35, CRZ FL FL340. Align the IRS.
F-PLN — LSK on LTFM → LAT REV → DEPARTURE: runway 35L + SID ASMA1C. For airways: LSK the exit fix → LAT REV → AIRWAYS: UL851 ending ERGUN. On LTAI → ARRIVAL: ILS36C + STAR.
Delete every F-PLN DISCONTINUITY with CLR; compare the plan line-by-line with the OFP.
INIT B — enter ZFW/ZFWCG and BLOCK fuel (from the OFP). EFOB predictions turn green.
PERF — TO: V1/VR/V2, FLAPS/THS 1+F, FLEX 52; APPR: arrival QNH, temp, wind, MINIMA (ILS: DH 200). Done — you're set for a fully managed flight.
ATC — From First Call to Shutdown
ATC (Air Traffic Control) is the chain of units that keeps aircraft separated on the ground and in the air. Below: every radio call of the LTFM→LTAI flight, phase by phase.
| Unit | Role | Typical Order |
|---|---|---|
| ATIS | Automated airport info (runway, wind, QNH) — listen only. | Before departure + before arrival |
| DELIVERY | Issues your IFR clearance. | 1 |
| GROUND | Pushback & taxi instructions. | 2 · last after landing |
| TOWER | The runway: takeoff & landing clearances. | 3 · 8 on arrival |
| DEPARTURE | Radar climb after takeoff. | 4 |
| CENTER / CONTROL | En-route control (cruise). | 5-6 |
| APPROACH | Descent, sequencing, approach clearance. | 7 |
| UNICOM 122.800 | Broadcast intentions when no ATC is online. | — |
ICAO Alphabet & Numbers
Numbers: 3=TREE 4=FOW-er 5=FIFE 9=NIN-er · point=DECIMAL · FL350 = "flight level tree fife zero"
PHASE 1 · Clearance (at the gate)
DELIVERY: GKT1MD, cleared to Antalya via ASMA1C departure, runway 35L, climb initially 5000 feet, squawk 2345.
GKT1MD: Cleared to Antalya via ASMA1C, runway 35L, initial 5000 feet, squawk 2345, GKT1MD.
Read the clearance back word for word — the readback is mandatory. DELIVERY: GKT1MD, readback correct, contact Ground 121.700 when ready for push.
PHASE 2 · Pushback & Taxi
GROUND: GKT1MD, pushback and start approved, facing south.
GKT1MD: Push and start approved facing south, GKT1MD.
GKT1MD: GKT1MD, request taxi.
GROUND: GKT1MD, taxi to holding point runway 35L via Alpha, Charlie 4, hold short runway 35L.
GKT1MD: Taxi holding point 35L via Alpha, Charlie 4, hold short 35L, GKT1MD.
"Hold short" means: do NOT enter the runway.
PHASE 3 · Takeoff
TOWER: GKT1MD, line up and wait runway 35L.
Enter the runway, line up — but wait for the takeoff clearance. TOWER: GKT1MD, wind 340 degrees 8 knots, runway 35L, cleared for takeoff.
GKT1MD: Cleared for takeoff 35L, GKT1MD.
TOWER: GKT1MD, airborne, contact Departure 120.500, good day.
PHASE 4 · Climb (Departure → Center)
DEPARTURE: GKT1MD, radar contact, climb FL240, direct ERGUN.
GKT1MD: Climb FL240 direct ERGUN, GKT1MD.
DEPARTURE: GKT1MD, contact Ankara Control 132.500.
GKT1MD: Ankara Control, GKT1MD, passing FL180 climbing FL240, direct ERGUN.
CONTROL: GKT1MD, identified, climb FL340.
PHASE 5 · Cruise & Top of Descent
GKT1MD: Descend FL240, expecting DIDRU1A, 36C, GKT1MD.
CONTROL: GKT1MD, descend FL120, contact Antalya Approach 128.300.
PHASE 6 · Approach
APPROACH: GKT1MD, descend 4000 feet, QNH 1015.
Note: no more flight levels — set QNH 1015 on the altimeter. GKT1MD: Descend 4000 feet QNH 1015, GKT1MD.
APPROACH: GKT1MD, turn left heading 010, cleared ILS approach runway 36C, report established.
GKT1MD: Left heading 010, cleared ILS 36C, wilco, GKT1MD.
GKT1MD: GKT1MD, established localizer 36C.
APPROACH: GKT1MD, contact Tower 119.400.
PHASE 7 · Landing & Taxi In
TOWER: GKT1MD, wind 010 degrees 6 knots, runway 36C, cleared to land.
GKT1MD: Cleared to land 36C, GKT1MD.
TOWER: GKT1MD, vacate right via Bravo 4, contact Ground 121.900.
GKT1MD: Vacating right Bravo 4, Ground 121.900, GKT1MD.
GKT1MD: Antalya Ground, GKT1MD, Bravo 4, request taxi to stand.
GROUND: GKT1MD, taxi to stand 12 via Bravo, Delta.
Engines off → END FLIGHT & FILE PIREP in ACARS. Good flight!
Emergency & Special Phrases
| Phrase | Meaning & Use |
|---|---|
| MAYDAY MAYDAY MAYDAY | Life-threatening emergency (fire, engine loss). Then: who, where, problem, intentions. |
| PAN-PAN PAN-PAN PAN-PAN | Urgency — not life-threatening (sick passenger, pressurization issue). |
| Unable | Cannot comply (state the reason). |
| Request vectors / direct ... | Ask for headings / direct routing. |
| Going around | Abandoning the landing — Tower will issue instructions. |
| Say again / Speak slower | Repeat / slow down. |
| Radio check | Signal test ("read you 5" = perfect). |
| Roger · Wilco · Affirm · Negative · Standby | Understood · will comply · yes · no · wait. |
GokturkACARS v4.5 — User Guide
⬇ Download GokturkACARS v4.5
Our official software: reads your flight live from the sim, records and scores your procedures, and files the PIREP. MSFS 2020/2024 · X-Plane 11/12 · P3D/FSX — same rules on every platform.
Tabs
| Tab | What It Does |
|---|---|
| Flight Info | Main screen: flight number, departure/arrival, cruise, aircraft selection, pax; start/end/PIREP buttons, live cards and the altitude profile. Drag cards to build your own layout. |
| Route | SimBrief integration: enter your username, fetch the OFP with one click — route, fuel, pax, level fill automatically. Departure/arrival METAR lookup lives here too. |
| Flight Log | Live event record: lights, phases, speeds, landing — this log is sent with your PIREP. |
| LogBook | Your past flights and their details. |
| Map | Live map: your position and route. |
| Checklist | Phase-by-phase checklist — shows which procedures have ticked; this is where your score comes from. |
| Network | VATSIM/IVAO verification: if you're online, [VATSIM ONLINE] / [IVAO ONLINE] is added to your PIREP automatically. |
| Landing | Landing analysis: touchdown point on the runway diagram, centerline deviation, distance from threshold, G-force, bounce, rollout, wind at touchdown. Replay your approach; Share copies the image (Ctrl+V into Discord). Opens automatically after landing. |
| Loadsheet | Auto weight & balance from the OFP: PAX, cargo, ZFW, fuel distribution, TOW/LDW/MTOW bar + plan-vs-sim fuel difference. |
| Guide | Built-in handbook: rules, features, sim info, aviation basics. |
| Settings | 6 themes (+auto day/night), sound/music, updates, language (TR/EN). |
A Flight, Start to Finish — 9 Steps
Sign in: Pilot ID (GKT0019) and your crew center password.
Plan: Fetch the OFP from SimBrief, or enter details manually in Flight Info.
Select aircraft: Pick from the Aircraft list — MANDATORY; the flight won't start without it (no auto-detect).
Connect: Choose your platform (MSFS/X-Plane/FSUIPC), hit Connect — SIM LED turns green.
START: At the gate, engines off, parking brake set — press it. The UI switches to flight mode; REC blinks.
Fly: Follow procedures; checkpoints tick themselves. Going around is allowed and never costs points.
Park: At the gate — parking brake, engines off, lights per procedure.
END FLIGHT: Score screen + Landing Analyser; the Landing tab opens by itself.
FILE PIREP: Send it → "PIREP sent" → check on the site. Approval happens in the Admin Center.
Scoring & Rules
| Rule | Detail |
|---|---|
| Valid landing range | 0 to −400 fpm. Harder than −400 = REJECT. |
| Greaser zone | −50 … −200 fpm scores highest (your target: −150). |
| Landing Analyser — 6 metrics | Landing rate · G-force · bounce · approach stability · rollout · fuel efficiency — each scored separately. |
| Landing Light | Climb: OFF between 7,000–14,000 ft; Descent: ON below 14,000 ft. |
| Speed limit | Stay within 250–270 kt IAS below 10,000 ft. |
| Taxi Light & Beacon | Taxi light: on after vacating, off at the gate. Beacon: on before engine start, off after shutdown. |
| Post-landing ticks | Light/flap ticks keep processing until you park — no rush. |
REJECT Reasons
| ✕ Total score below 70% | ✕ Landing harder than −400 fpm |
| ✕ Slew mode / teleporting | ✕ Time compression |
| ✕ Mid-air refueling | ✕ Repeated overspeed violations |
Tips & Troubleshooting
Aviation Rules — A to Z
First the twelve phases of a flight and the core operating rules; then an alphabetical glossary of every concept a Gokturk pilot should know.
Phases of Flight
| Phase | Meaning |
|---|---|
| BOARDING / PREFLIGHT | Passengers board; FMC setup, fuel, checklists. |
| PUSHBACK | Tug pushes you off the gate; engines start. |
| TAXI | Rolling to the runway — ~20-25 kt straight, ~10 kt in turns. |
| TAKEOFF | The roll: V1 (decision speed) → VR (rotate) → V2 (safe climb). |
| INITIAL CLIMB | Flap retraction, acceleration altitude, SID tracking. |
| CLIMB | Up to cruise — max 250 kt below 10,000 ft. |
| CRUISE | The long leg; fuel/route monitoring, step climbs. |
| DESCENT | Starts at TOD; aim for a steady, economical profile. |
| APPROACH | Sequencing via STAR/vectors; speed & configuration. |
| FINAL / LANDING | Stabilized final; target touchdown ≈ −150 fpm. |
| ROLLOUT & TAXI IN | Decelerate, vacate, taxi to stand. |
| SHUTDOWN | Engines off, parking brake → PIREP ✈ |
Core Operating Rules
| Rule | Explanation |
|---|---|
| 250 kt / 10,000 ft | IAS ≤ 250 kt below 10,000 ft (unless ATC lifts it). |
| Transition Alt / Level | Above TA set STD 1013 and fly Flight Levels; below TL on descent set QNH. In Turkiye TA is usually 10,000 ft. |
| Semicircular Rule | IFR cruise: eastbound (000-179°) ODD levels; westbound (180-359°) EVEN levels. |
| Stabilized Approach | By 1000 ft AGL: configured, Vref+5/-0, ≤1000 fpm, checklist done — otherwise GO AROUND. |
| Sterile Cockpit | Below 10,000 ft: flight-related talk and actions only. |
| Squawk 7500/7600/7700 | Hijack / radio failure / emergency. |
| Landing Lights | ON below 10,000 ft (ACARS: below 14,000 on descent). |
| Fuel Policy | Trip + alternate + 5% contingency + 30-min final reserve. |
| Tail Strike Awareness | Don't rush the rotation — limits vary by type (777-300ER ≈ 9°! See the Fleet page). |
| Wake Turbulence | Extra spacing behind heavies: 2-3 min / 4-6 NM. |
Aviation Glossary A–Z
Top 5 Most Realistic Airliners
Across all simulators, ranked by systems depth, flight model and community support:
PMDG 737 (600/700/800/900)
The gold standard of study-level Boeings: every circuit breaker, every failure scenario, true-to-life FMC logic. The best school for the 737-800 — the backbone of our fleet.
Fenix A320
The summit of Airbus systems simulation: real-aircraft performance data, a flawless MCDU, live hydraulic/electric schematics. Learn the Airbus philosophy here, from FLEX to managed descent.
FlyByWire A32NX
An open-source miracle — free, yet deeper than most payware. Constantly updated; a zero-cost, fully capable Airbus starting point.
ToLiss A321 / A340-600
X-Plane's Airbus master: detailed FMGS, a realistic failure system, and those famous XP flight dynamics. Also home for quad-jet lovers with the A340.
Zibo 737-800
The most legendary freeware in sim history — a community project that lifts the default XP 737 to study level. No budget is no excuse.