Narrative:

Upon arrival at mli at XA00 my first officer proceeded to preflight the aircraft. No discrepancies were noted. I walked out to the aircraft at XA20 with my release in hand. I performed a visual check upon arrival at the aircraft and also noted no discrepancies. We completed the receiving checklist. Completed all additional checklists and started engines. We departed the gate on time and taxied out for takeoff. Engine tests, taxi and before takeoff checklist completed. No abnormalities noted. Level 2 takeoff was required due to low ceiling (500 ft overcast), visibility was good (4 mi with light mist), temperature was -1 degree C. The ceilings and visibility are to the best of my recollection. After 2 takeoffs, gear selected up, at acceleration ht I did the climb sequence and we began acceleration. Approximately 3000 ft now in VFR conditions, flaps 0 degrees and after takeoff checklist, I noted the gear was still down and locked. I informed my first officer that I was going to cycle the gear handle at that point. I cycled the landing gear handle, watched the hydraulic system and nothing happened, I proceeded to visually check the landing gear circuit breakers for any abnormalities. No circuit breakers were popped and everything appeared normal. I proceeded to comply with the landing gear retraction impossible checklist. After completion of the checklist, I verified for the second time that 3 landing gear pins were in the designated cockpit location. We decided that we would level off in VFR conditions, assess the problem and maintain VFR. I concluded that the landing gear non retraction was not an emergency. The checklist did not state to land as soon as possible or practical. It stated gear handle down, flight at 185 KTS or below (vlo). This situation is an abnormality/irregularity and safety would never be compromised. Making a mental note as to the possible causes of the gear non retraction being worst case scenario, I decided the best location in the event of a gear failure (crash) upon landing would be stl. Stl has a crash fire rescue equipment unit on field and several hospitals in the immediate vicinity. I have no knowledge of mli status or familiarity of adequate hospital facilities in the immediate area. We had plenty of fuel on board to compensate for the additional consumption both into stl and back to our alternate which was mli. Coincidentally, our assigned airspeed was 180 KTS due to a meter delay going into stl. We would also have to descend into icing no matter where we attempted to land. The length of time in icing would also be much less going into stl than into mli. The WX at stl had better ceilings (900 ft overcast) but slightly less visibility (3 mi) than mli. That also was a determining factor for proceeding into stl along with stl having a longer runway. After reaching level flight and out of sterile cockpit, I informed the #1 cabin attendant as to the landing gear non retraction and that we were proceeding into stl. I then had her enter the cockpit and visually verify that the 3 landing gear pins were in their holster. She did so and proceeded back to the cabin. On the ILS runway 30R approach into stl, we maintained VFR conditions until 2000 ft, continued the approach into IMC noting slight trace of ice, made visual contact with approach light system at 1000 ft and complete airport visual at 600 ft. Landing was smooth and uneventful and we taxied into the gate with no incident or accidents accountable to our airline. Callback conversation with reporter revealed the following information: reporter called back to state that the aircraft equipment problem was found to be a gear handle microswitch which maintenance replaced after aircraft's arrival in stl. The reporter stated that the delay in recognizing that the gear had not retracted leaving mli was that the gear sounds are quite minimal in the ATR72. The checklist is a good tool as a reminder he said. There have been other cases of this microswitch problem on the ATR72. There was 1 specific case he knew of that occurred a week later on a different aircraft. That PIC also made a decision to proceed on to stl. WX was not a factor in that event. The local FSDO, upon receiving the initial occurrence was slightly unhappy. On the second one he was very unhappy. The ATR72 has no performance criteria for gear extended, 1 engine inoperative. Aircraft performance versus weight in this case met or exceeded all considered requirements.

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Original NASA ASRS Text

Title: ATR72 FLC UNABLE TO RETRACT LNDG GEAR AFTER DEP FROM MLI, IL. PIC ELECTS TO CONTINUE TO DEST ARPT OF STL WITH GEAR DOWN.

Narrative: UPON ARR AT MLI AT XA00 MY FO PROCEEDED TO PREFLT THE ACFT. NO DISCREPANCIES WERE NOTED. I WALKED OUT TO THE ACFT AT XA20 WITH MY RELEASE IN HAND. I PERFORMED A VISUAL CHK UPON ARR AT THE ACFT AND ALSO NOTED NO DISCREPANCIES. WE COMPLETED THE RECEIVING CHKLIST. COMPLETED ALL ADDITIONAL CHKLISTS AND STARTED ENGS. WE DEPARTED THE GATE ON TIME AND TAXIED OUT FOR TKOF. ENG TESTS, TAXI AND BEFORE TKOF CHKLIST COMPLETED. NO ABNORMALITIES NOTED. LEVEL 2 TKOF WAS REQUIRED DUE TO LOW CEILING (500 FT OVCST), VISIBILITY WAS GOOD (4 MI WITH LIGHT MIST), TEMP WAS -1 DEG C. THE CEILINGS AND VISIBILITY ARE TO THE BEST OF MY RECOLLECTION. AFTER 2 TKOFS, GEAR SELECTED UP, AT ACCELERATION HT I DID THE CLB SEQUENCE AND WE BEGAN ACCELERATION. APPROX 3000 FT NOW IN VFR CONDITIONS, FLAPS 0 DEGS AND AFTER TKOF CHKLIST, I NOTED THE GEAR WAS STILL DOWN AND LOCKED. I INFORMED MY FO THAT I WAS GOING TO CYCLE THE GEAR HANDLE AT THAT POINT. I CYCLED THE LNDG GEAR HANDLE, WATCHED THE HYD SYS AND NOTHING HAPPENED, I PROCEEDED TO VISUALLY CHK THE LNDG GEAR CIRCUIT BREAKERS FOR ANY ABNORMALITIES. NO CIRCUIT BREAKERS WERE POPPED AND EVERYTHING APPEARED NORMAL. I PROCEEDED TO COMPLY WITH THE LNDG GEAR RETRACTION IMPOSSIBLE CHKLIST. AFTER COMPLETION OF THE CHKLIST, I VERIFIED FOR THE SECOND TIME THAT 3 LNDG GEAR PINS WERE IN THE DESIGNATED COCKPIT LOCATION. WE DECIDED THAT WE WOULD LEVEL OFF IN VFR CONDITIONS, ASSESS THE PROB AND MAINTAIN VFR. I CONCLUDED THAT THE LNDG GEAR NON RETRACTION WAS NOT AN EMER. THE CHKLIST DID NOT STATE TO LAND ASAP OR PRACTICAL. IT STATED GEAR HANDLE DOWN, FLT AT 185 KTS OR BELOW (VLO). THIS SIT IS AN ABNORMALITY/IRREGULARITY AND SAFETY WOULD NEVER BE COMPROMISED. MAKING A MENTAL NOTE AS TO THE POSSIBLE CAUSES OF THE GEAR NON RETRACTION BEING WORST CASE SCENARIO, I DECIDED THE BEST LOCATION IN THE EVENT OF A GEAR FAILURE (CRASH) UPON LNDG WOULD BE STL. STL HAS A CFR UNIT ON FIELD AND SEVERAL HOSPITALS IN THE IMMEDIATE VICINITY. I HAVE NO KNOWLEDGE OF MLI STATUS OR FAMILIARITY OF ADEQUATE HOSPITAL FACILITIES IN THE IMMEDIATE AREA. WE HAD PLENTY OF FUEL ON BOARD TO COMPENSATE FOR THE ADDITIONAL CONSUMPTION BOTH INTO STL AND BACK TO OUR ALTERNATE WHICH WAS MLI. COINCIDENTALLY, OUR ASSIGNED AIRSPD WAS 180 KTS DUE TO A METER DELAY GOING INTO STL. WE WOULD ALSO HAVE TO DSND INTO ICING NO MATTER WHERE WE ATTEMPTED TO LAND. THE LENGTH OF TIME IN ICING WOULD ALSO BE MUCH LESS GOING INTO STL THAN INTO MLI. THE WX AT STL HAD BETTER CEILINGS (900 FT OVCST) BUT SLIGHTLY LESS VISIBILITY (3 MI) THAN MLI. THAT ALSO WAS A DETERMINING FACTOR FOR PROCEEDING INTO STL ALONG WITH STL HAVING A LONGER RWY. AFTER REACHING LEVEL FLT AND OUT OF STERILE COCKPIT, I INFORMED THE #1 CABIN ATTENDANT AS TO THE LNDG GEAR NON RETRACTION AND THAT WE WERE PROCEEDING INTO STL. I THEN HAD HER ENTER THE COCKPIT AND VISUALLY VERIFY THAT THE 3 LNDG GEAR PINS WERE IN THEIR HOLSTER. SHE DID SO AND PROCEEDED BACK TO THE CABIN. ON THE ILS RWY 30R APCH INTO STL, WE MAINTAINED VFR CONDITIONS UNTIL 2000 FT, CONTINUED THE APCH INTO IMC NOTING SLIGHT TRACE OF ICE, MADE VISUAL CONTACT WITH APCH LIGHT SYSTEM AT 1000 FT AND COMPLETE ARPT VISUAL AT 600 FT. LNDG WAS SMOOTH AND UNEVENTFUL AND WE TAXIED INTO THE GATE WITH NO INCIDENT OR ACCIDENTS ACCOUNTABLE TO OUR AIRLINE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR CALLED BACK TO STATE THAT THE ACFT EQUIP PROB WAS FOUND TO BE A GEAR HANDLE MICROSWITCH WHICH MAINT REPLACED AFTER ACFT'S ARR IN STL. THE RPTR STATED THAT THE DELAY IN RECOGNIZING THAT THE GEAR HAD NOT RETRACTED LEAVING MLI WAS THAT THE GEAR SOUNDS ARE QUITE MINIMAL IN THE ATR72. THE CHKLIST IS A GOOD TOOL AS A REMINDER HE SAID. THERE HAVE BEEN OTHER CASES OF THIS MICROSWITCH PROB ON THE ATR72. THERE WAS 1 SPECIFIC CASE HE KNEW OF THAT OCCURRED A WK LATER ON A DIFFERENT ACFT. THAT PIC ALSO MADE A DECISION TO PROCEED ON TO STL. WX WAS NOT A FACTOR IN THAT EVENT. THE LCL FSDO, UPON RECEIVING THE INITIAL OCCURRENCE WAS SLIGHTLY UNHAPPY. ON THE SECOND ONE HE WAS VERY UNHAPPY. THE ATR72 HAS NO PERFORMANCE CRITERIA FOR GEAR EXTENDED, 1 ENG INOP. ACFT PERFORMANCE VERSUS WT IN THIS CASE MET OR EXCEEDED ALL CONSIDERED REQUIREMENTS.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.