# JASC 2781: Leading Edge Slat Position Indicating System

- Type: JASC system/component code (FAA)
- ATA chapter: 27 Flight Controls
- Title in the code table: LE SLAT POSITION IND. SYSTEM
- Service difficulty reports: 1,398
- FAA code table: https://www.faa.gov/sites/faa.gov/files/JASC_Code.pdf#page=27
- Page: https://openairdocs.org/jasc/2781

## What it covers

The transmitter, indicator, warning lamps, and associated circuitry providing relative position information of wing leading edge devices to the flight crew.

## Service difficulty reports (1,398, newest 50)

- [SDR ABXA20260922428](https://openairdocs.org/sdr/ABXA20260922428), Sep 22, 2026: Boeing 767281. PROXIMITY SENSOR. DEFECTIVE. LE SLAT ASSYM APPEARED ON ARRIVAL. CREW DECLARED EMERGENCY (EDC) & LANDED WITHOUT INCIDENT. PERFORMED PSEU BITE TEST IAW (N767AX)
- [SDR IPXA2026092264312](https://openairdocs.org/sdr/IPXA2026092264312), Sep 22, 2026: Boeing 76734AF. WARNING MESSAGE. FALSE ACTIVATION. EMERGENCY DECLARED ON APPROACH TO LANDING. FLAPS 25 SELECTED AND LE-SLAT DISAGREE EICAS CAME ON. TROUBLESHOT IAW FIM 27- (N322UP)
- [SDR DALA2026091605168](https://openairdocs.org/sdr/DALA2026091605168), Sep 13, 2026: Boeing 757351. FSEU. FAULTED. CREW DECLARED EMERGENCY ON APPROACH DUE TO LE ASSYM MESSAGE OCCURRING AFTER TAKEOFF AS FLAPS/SLATS WERE RETRACTED. FLIGH (N583NW)
- [SDR DALA2026090805021](https://openairdocs.org/sdr/DALA2026090805021), Aug 30, 2026: Boeing 767332. PSEU. FAULTED. FCTL, GO AROUND DURING APPROACH INTO HNL DUE TO LE ASSYM EICAS MESSAGE. QRH C/W AND A/C LANDED WITHOUT COMPLICATION. R & (N194DN)
- [SDR AALA202608262383](https://openairdocs.org/sdr/AALA202608262383), Aug 24, 2026: Boeing 737823. PROXIMITY SENSOR. FAULTED. AIRCRAFT WAS GROUNDED: IMMEDIATELY AFTER TAKEOFF RECEIVED LE EDGE FLAP TRANSIT LIGHT. HIGH SPEED AND LOW SPEED AWARENESS (N920AN)
- [SDR DALA2026082504820](https://openairdocs.org/sdr/DALA2026082504820), Aug 22, 2026: Boeing 737932ER. PROXIMITY SENSOR. FAULTED. ATO- APPROX 110KTS DUE TO TAKEOFF WARNING AND LEADING EDGE FLAP TRANSIT ANNUNCIATION. : REPLACED #4 SLAT O/B PROX SENSOR (N929DZ)
- [SDR FDEA202608141125](https://openairdocs.org/sdr/FDEA202608141125), Aug 14, 2026: Boeing 75728A. SLAT SYSTEM. ASYMETRIC. LE SLAT ASYM. COMPLIED WITH THE QRH. EMERGENCY DECLARED. TROUBLSHOT THE LE SLAT SYSTEM AND FOUND A SINGLE TORQUE TUBE CO (N912FD)
- [SDR CALA2026080718349](https://openairdocs.org/sdr/CALA2026080718349), Aug 6, 2026: Boeing 7379. PROXIMITY SENSOR. FAULTED. LE FLAPS TRANSIT LIGHT AT FL37000 AND SMOOTH WOULD NOT CLEAR POST NON NORMAL CHKLIST CHECKED INBOUND FLT DECK EFFECTS, F (N17467)
- [SDR DALA2026080604564](https://openairdocs.org/sdr/DALA2026080604564), Aug 5, 2026: Boeing 737832. PROXIMITY SENSOR. FAULTED. EMERGENCY DECLARED & DIVERTED TO JFK FOR LONGER RUNWAY DUE TO LEADING EDGE IN TRANSIT LIGHT ON APPROACH TO LGA. REPLACED (N371DA)
- [SDR CALA2026080418257](https://openairdocs.org/sdr/CALA2026080418257), Aug 3, 2026: Boeing 7379. WARNING MESSAGE. FALSE ACTIVATION. LE EDGE FLAP TRANS LGT APX 14000FT. 271KTS STAYED ON UNTIL BELOW 220KTS. ONE LIGHT ON. LATCHED MSG: 27-81220; LE FLAP 3  (N17467)
- [SDR AALA202608038448](https://openairdocs.org/sdr/AALA202608038448), Jul 31, 2026: Airbus A321231. PICKUP. FAULTED. AIRCRAFT WAS GROUNDED: AN EMEREGENCY WAS DECLARED AND THE AIRCRAFT DIVERTED TO DEN DUE TO THE FLIGHT CREW REPORTING THAT (N576UW)
- [SDR IPXA2026071787701](https://openairdocs.org/sdr/IPXA2026071787701), Jul 16, 2026: Boeing 76734AF. WARNING MESSAGE. FALSE ACTIVATION. EMERGENCY DECLARED AFTER LANDING UPON FLAP/SLAT RETRACTION RECEIVED LE SLAT DISAGREE EICAS AND LE SLAT SHUTDOWN STATUS M (N327UP)
- [SDR CALA2026072017892](https://openairdocs.org/sdr/CALA2026072017892), Jul 15, 2026: Boeing 737824. SENSOR. FAULTED. CREW REPORTS LEADING EDGE FLAP TRANSIT LIGHT AFTER TAKEOFF. OVERHEAD INDICATOR FOR NR 3 LEADING EDGE FLAP INDICATING NOT (N73251)
- [SDR AALA202607179851](https://openairdocs.org/sdr/AALA202607179851), Jul 15, 2026: Boeing 7378. FLAP SYSTEM. FAULT MESSAGE. AIRCRAFT WAS GROUNDED: LE FLAPS TRANSIT AMBER LIGHT ILLUMINATED UPON SELECTION OF 30 FLAPS. COMPLETED QRH PROCEDURE AND  (N341TR)
- [SDR CALA2026070617558](https://openairdocs.org/sdr/CALA2026070617558), Jul 2, 2026: Boeing 737824. SENSOR. FAULTED. LE FLAPS TRANSIT NO.4 LE DEVICE IN TRANSIT. PERFORMED FSEU BITE. GOT MESSAGE FOR MOST RECENT FLIGHT F4 PROX RETRACT MM 2 (N37290)
- [SDR DALA2026062903833](https://openairdocs.org/sdr/DALA2026062903833), Jun 27, 2026: Boeing 757232. ACTUATOR. FAULTY. DE- DUE TO SLAT DISAGREE ON APPROACH. TROUBLESHOT, R & R L/E SLAT ROTARY ACTUATORS NR 5, 10, 20. (8433306) AIRCRAFT WAS  (N67171)
- [SDR IPXA2026060263875](https://openairdocs.org/sdr/IPXA2026060263875), Jun 2, 2026: Boeing 767300. SLAT SYSTEM. WARNING MESSAGE. EMERGENCY DECLARED, LE SLAT DISAGREE EICAS MESSAGE WHEN FLAPS SELECTED ON APPROACH TO 25. PERFORMED QRH PROCEDURE ACCOMP (N371UP)
- [SDR DALA2026060203356](https://openairdocs.org/sdr/DALA2026060203356), Jun 2, 2026: Boeing 737832. FSEU. FAULTED. -FCNT/DE- DECLARED EMERGENCY DUE TO #1 LEADING EDGE TRANSIT LIGHT ILLUMINATED AT FLAPS 5. FSEU FAULT CODE 27-81201 (SL1  (N379DA)
- [SDR ABXA20260525223](https://openairdocs.org/sdr/ABXA20260525223), May 25, 2026: Boeing 767316. SENSOR. OUT OF ADJUST. EICAS MSG LE FLAP ASYM FLAP INDICATOR STOPPED BETWEEN 1 AND UP. A/C THEN PERFORMED AIR TURN BACK (ATB) TO FIELD AND LAND (N227CY)
- [SDR DALA2026052503146](https://openairdocs.org/sdr/DALA2026052503146), May 23, 2026: Boeing 757232. CONTROL UNIT. FAULTED. FCNT/DE - DUE TO L/E SLAT ASYM MESSAGE. R & R FSEU AND R & R BROKEN TORQUE TUBE. (8673898) AIRCRAFT WAS GROUNDED (N688DL)
- [SDR DALA2026051903082](https://openairdocs.org/sdr/DALA2026051903082), May 16, 2026: Boeing 757232. SWITCH. MALFUNCTIONED. ATB/DE- DUE TO L/E SLAT ASYM DURING FLAP RETRACTION AFTER TAKEOFF. REPLACED LEFT OUTBOARD SLAT LOSS SWITCH AND CORRECTED (N686DA)
- [SDR CALA2026042415686](https://openairdocs.org/sdr/CALA2026042415686), Apr 23, 2026: Boeing 7379. PROXIMITY SENSOR. FAULTED. LEADING EDGE FLAP TRANSIT LT W/ FLAPS 30 SELECTED. REPEAT GRIPE . LOCKING FOR POSITIVE REPAIR LATCHED MESSAGE. CHECKED F (N17405)
- [SDR IXXA20260421036](https://openairdocs.org/sdr/IXXA20260421036), Apr 21, 2026: Boeing 767338. WARNING MESSAGE. FALSE ACTIVATION. LEADING EDGE SLAT DISAGREE EICAS MESSAGE IN THE AIR AFTER MOVING FLAP LEVER TO 1. AIR TRAFFIC CONTROL DECLARED EMERGENCY (N311AZ)
- [SDR AALA202604086577](https://openairdocs.org/sdr/AALA202604086577), Apr 7, 2026: Boeing 737823. INDICATOR. FAULTED. AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED DUE TO: DURING APPROACH ATTEMPTED TO EXTEND FLAPS TO 5 DEGREES, HOWEVER (N914AN)
- [SDR SIMA20260305001](https://openairdocs.org/sdr/SIMA20260305001), Mar 5, 2026: Emb ERJ170200LR. SENSOR. FAULTED. SLAT FAIL INDICATION ON APPROACH. FOLLOWED QRH, FLAP FAIL INDICATION REMAINED "TRANSFERRED TO NRWC 099-DFW-03224 ITEM-1" (N299JJ)
- [SDR DALA2026030501540](https://openairdocs.org/sdr/DALA2026030501540), Mar 4, 2026: Boeing 767332. SENSOR. OUT OF ADJUST. GO AROUND DURING APPROACH INTO LAX DUE TO LE ASSYM EICAS MESSAGE. QRH C/W AND A/C LANDED WITHOUT COMPLICATION. ADJUSTED  (N192DN)
- [SDR IPXA2026030567301](https://openairdocs.org/sdr/IPXA2026030567301), Feb 24, 2026: Boeing 7478F. INDICATOR. DAMAGED. NUMBER 17 LEFI DAMAGED. GVI CHECKED FLAP ADJUSTMENT IAW AMM 27-81-00-825-012, ALL CLEARANCES WITHIN LIMITS COMPLETED INS (N631UP)
- [SDR ABXA20260221076](https://openairdocs.org/sdr/ABXA20260221076), Feb 21, 2026: Boeing 767328. WARNING MESSAGE. FALSE ACTIVATION. LE SLAT DISAGREE EICAS CAUTION AND LIGHT ON GO AROUND DUE TO HIGH WINDS ACFT THEN LANDED WITH NO OTHER COMPLICATIONS MTX (N1499A)
- [SDR CALA2026020313531](https://openairdocs.org/sdr/CALA2026020313531), Jan 31, 2026: Boeing 737924ER. SENSOR. FAULTY. PER CREW VERBAL: NR 3 SLAT IND INTERMITTANT, BOTH OVERHEAD & FWD PANEL LIGHTS. CREW DEBRIEF, LANDING WEIGHT WITHIN LIMIT (N68834)
- [SDR ABXA20260120021](https://openairdocs.org/sdr/ABXA20260120021), Jan 20, 2026: Boeing 7673P6. TARGET. OUT OF ADJUST. DURING TAXI OUT, LE SLAT ASYM EICAS MESSAGE ILLUMINATED. A/C RETURNED TO BLOCKS (BTB). MEG CHECKED AND VERIFIED INDUCTAN (N764CK)
- [SDR DALA2026010700132](https://openairdocs.org/sdr/DALA2026010700132), Jan 4, 2026: Boeing 767432ER. WARNING MESSAGE. ILLUMINATED. FCTL- MISSED APPROACH WITH GO AROUND INTO MAD DUE TO LE DISAGREE EICAS MESSAGE. CREW C/W QRH AND LANDED WITHOUT INCIDENT (N842MH)
- [SDR SCNA20260105006](https://openairdocs.org/sdr/SCNA20260105006), Jan 3, 2026: Boeing 737800*. PROXIMITY SENSOR. MALFUNCTIONED. RED TAKEOFF CONFIG LIGHT AND TAKE OFF WARNING DURING TLCC WITH FLAPS 5 AND CONFIGURED FOR TAKEOFF NR 1 LEADING EDGE FLAP (N5237A)
- [SDR DALA2026010200003](https://openairdocs.org/sdr/DALA2026010200003), Jan 1, 2026: Airbus A320212. WARNING MESSAGE. FALSE ACTIVATION. DIVERTED TO PSM DUE TO A SLATS SYS 2 FAULT WITH A SLATS LOCKED MESSAGE ON APPROACH TO BOS. SLATS HAD JUST STARTED TO EXT (N340NW)
- [SDR DALA2025123109543](https://openairdocs.org/sdr/DALA2025123109543), Dec 31, 2025: Boeing 757232. ACTUATOR. TRIPPED. FCNT/DE- DUE TO LEADING EDGE DISAGREE ON APPROACH. CORRECTIVE ACTION: #6 INBOARD AND OUTBOARD SLAT ROTARY ACTUATOR FOUND (N698DL)
- [SDR CALA2025123012550](https://openairdocs.org/sdr/CALA2025123012550), Dec 28, 2025: Boeing 7378. SENSOR. FAULTED. LE FLAPS AMBER LIGHT INTERMITENTLY ON AND OFF IN CRUISE FL 340 MACH .7 90 CREW ADV DID NOT LAND OVERWEIGHT. REMOVED ACCE (N47293)
- [SDR AALA202512175969](https://openairdocs.org/sdr/AALA202512175969), Dec 16, 2025: Boeing 737823. SENSOR. FAULTY. AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED DUE TO: AFTER TAKEOFF WHEN FLAPS WERE RETRACTED THE LEADING EDGE FLAPS  (N955AN)
- [SDR ABXA20251214334](https://openairdocs.org/sdr/ABXA20251214334), Dec 14, 2025: Boeing 767383. WARNING MESSAGE. FALSE ACTIVATION. LE SLAT DISAGREE CAUTION MESSAGE ON SHORT FINAL , AFTER LANDING MTX .PERFOMED L.E.S OPERATIONAL CHECK WITH HYDS. AND ELE (N219CY)
- [SDR DALA2025120408860](https://openairdocs.org/sdr/DALA2025120408860), Dec 3, 2025: Boeing 737832. SENSOR. INOPERATIVE. DECLARED EMERGENCY INTO ORD DUE TO LEADING EDGE TRANSIT INDICATION. REPLACED FSEU AND CHECKED PERFORMED WIRING CHECKS. O (N3746H)
- [SDR IPXA2025120337341](https://openairdocs.org/sdr/IPXA2025120337341), Dec 3, 2025: Boeing 76734AF. WARNING MESSAGE. FALSE ACTIVATION. EMERGENCY DECLARED, LE SLAT ASYM AT FL 340 FOUND LE SLAT ASYM EICAS MSG AND LEADING EDGE LIGHT ON, PERFORMED PSEU BITE I (N308UP)
- [SDR SWAA2025120140303](https://openairdocs.org/sdr/SWAA2025120140303), Nov 27, 2025: Boeing 7378H4. PROXIMITY SENSOR. FAULTED. LEADING EDGE DEVICE EXTENDED ON ITS OWN AT FL 370 MACH .79. PERFORMED LEADING EDGE FLAP/SLAT OPS TEST IAW 27-88-00-700-8 (N8513F)
- [SDR K11A2025112500360](https://openairdocs.org/sdr/K11A2025112500360), Nov 25, 2025: Boeing 7373Y0. WARNING LIGHT. FALSE ACTIVATION. LEADING EDGE FLAPS TRANSIT LIGHT WOULD NOT EXTINGUISH IN FLIGHT. PERFORMED OPS CHECK OF LEADING EDGE FLAP AND SLAT POSIT (N335CK)
- [SDR SWAA2025102727936](https://openairdocs.org/sdr/SWAA2025102727936), Oct 23, 2025: Boeing 7377H4. SENSOR. FAULTY. LE FLAPS TRANSIT AT FLAPS 10 AND BEYOND. ALL LE DEVICES APPEARED EXTENDED; NO ASYMMETRY WAS DETECTED NOR ANY SKEW. PERFO (N263WN)
- [SDR DALA2025101307472](https://openairdocs.org/sdr/DALA2025101307472), Oct 12, 2025: Boeing 737932ER. ECU. INOPERATIVE. FCNT/DE- DECLARED EMERGENCY DUE TO LEADING EDGE FLAP TRANSIT LIGHT. FLAPS LOCKED OUT. PERFORMED FLAPS UP LANDING. PERFOR (N824DN)
- [SDR SCNA20251010404](https://openairdocs.org/sdr/SCNA20251010404), Oct 9, 2025: Boeing 73783N. FLAP SYSTEM. FAULTED. DURING APRROCH THE LE FLAP TRANSIT LIGHT STAYED AMBER WITH FLPAS SET TO 5 LE DEVICE IDIACTION ON OVERHEAD REMAINED GREEN (N5153)
- [SDR FDEA202510031878](https://openairdocs.org/sdr/FDEA202510031878), Oct 3, 2025: Boeing 7673S2F. SENSOR. ILLUMINATED. LE SLAT ASYM EICAS, LEADING EDGE LIGHT. ON APPROACH AT 160 KTS SELECTING FLAPS 30 FOR LANDING. G/A TO COMPLETE QRH. LAND (N168FE)
- [SDR SWAA2025092417727](https://openairdocs.org/sdr/SWAA2025092417727), Sep 24, 2025: Boeing 7377H4. PROXIMITY SENSOR. FAULTED. FL370 LE FLAPS TRANIT LIGHT ILLUMINATED #2 SLAT POSITION PERFORMED QRH PROCEDURE BELOW FL200. LIGHT STAYED ON; PERFORMED (N431WN)
- [SDR CALA2025091508918](https://openairdocs.org/sdr/CALA2025091508918), Sep 11, 2025: Boeing 737824. PROXIMITY SENSOR. FAULTED. LE FLAPS TRANSIT LIGHT CAME ON SELECTING FLAPS TO 30. FAULT CODES CHECKED. REMOVED AND REPLACED SLAT NR 1 INBD PROXIMITY (N78509)
- [SDR AALA202508259181](https://openairdocs.org/sdr/AALA202508259181), Aug 17, 2025: Boeing 737823. TARGET. DAMAGED. AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED DUE TO: LEADING EDGE FLAPS WERE RAISED BUT THE FLAPS TRANSIT LIGHT REMA (N950AN)
- [SDR AALA202508256316](https://openairdocs.org/sdr/AALA202508256316), Aug 17, 2025: Boeing 737823. SENSOR. FAULTED. AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED DUE TO: LEADING EDGE FLAPS WERE RAISED BUT THE FLAPS TRANSIT LIGHT REMA (N950AN)
- [SDR AALA202508117635](https://openairdocs.org/sdr/AALA202508117635), Aug 8, 2025: Boeing 737823. PROXIMITY SENSOR. FAILED. AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED DUE TO: AFTER TAKEOFF AND FLAPS COMING UP, LEADING EDGE FLAPS TRANSIT L (N928AN)

All 1,398: https://openairdocs.org/jasc/2781/reports.md

## Other codes in chapter 27

- [JASC 2700](https://openairdocs.org/jasc/2700): Flight Control System (1,742 reports)
- [JASC 2701](https://openairdocs.org/jasc/2701): Control Column Section (510 reports)
- [JASC 2710](https://openairdocs.org/jasc/2710): Aileron Control System (2,967 reports)
- [JASC 2711](https://openairdocs.org/jasc/2711): Aileron Tab Control System (415 reports)
- [JASC 2720](https://openairdocs.org/jasc/2720): Rudder Control System (3,130 reports)
- [JASC 2721](https://openairdocs.org/jasc/2721): Rudder Tab Control System (686 reports)
- [JASC 2722](https://openairdocs.org/jasc/2722): Rudder Actuator (284 reports)
- [JASC 2730](https://openairdocs.org/jasc/2730): Elevator Control System (2,647 reports)
- [JASC 2731](https://openairdocs.org/jasc/2731): Elevator Tab Control System (1,295 reports)
- [JASC 2740](https://openairdocs.org/jasc/2740): Stabilizer Control System (2,126 reports)
- [JASC 2741](https://openairdocs.org/jasc/2741): Stabilizer Position Indicating (889 reports)
- [JASC 2742](https://openairdocs.org/jasc/2742): Stabilizer Actuator (610 reports)
- [JASC 2750](https://openairdocs.org/jasc/2750): Trailing Edge Flap Control System (10,186 reports)
- [JASC 2751](https://openairdocs.org/jasc/2751): Trailing Flap Position Indicating System (3,078 reports)
- [JASC 2752](https://openairdocs.org/jasc/2752): Trailing Edge Flap Actuator (1,978 reports)
- [JASC 2760](https://openairdocs.org/jasc/2760): Drag Control System (3,502 reports)
- [JASC 2761](https://openairdocs.org/jasc/2761): Drag Control Actuator (1,070 reports)
- [JASC 2770](https://openairdocs.org/jasc/2770): Gust Lock Damper System (90 reports)
- [JASC 2780](https://openairdocs.org/jasc/2780): Leading Edge Slat Control System (2,157 reports)
- [JASC 2782](https://openairdocs.org/jasc/2782): Leading Edge Slat Actuator (1,225 reports)
- [JASC 2797](https://openairdocs.org/jasc/2797): Flight Control System Wiring (919 reports)

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