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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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2 instructors on a practice instrument refresher training flight in actual IMC conditions returned to land after the aircraft light icing was encountered and the engine would only run under reduced power after pulling on alternate engine air.
| Attributes | |
| ACN | 458743 |
| Time | |
| Date | 199912 |
| Day | Tue |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| State Reference | MT |
| Altitude | msl single value : 11000 |
| Environment | |
| Flight Conditions | IMC |
| Weather Elements | Snow Ice |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zlc.artcc |
| Operator | Other |
| Make Model Name | Skyhawk 172/Cutlass 172 |
| Operating Under FAR Part | Part 91 |
| Flight Phase | cruise : level |
| Route In Use | enroute airway : v86.airway |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | other |
| Function | flight crew : single pilot |
| Qualification | pilot : cfi pilot : commercial pilot : instrument pilot : multi engine |
| Experience | flight time last 90 days : 100 flight time total : 3700 flight time type : 500 |
| ASRS Report | 458743 |
| Person 2 | |
| Affiliation | other |
| Function | instruction : instructor |
| Qualification | pilot : cfi pilot : atp |
| Experience | flight time last 90 days : 65 flight time total : 5900 flight time type : 300 |
| ASRS Report | 458394 |
| Events | |
| Anomaly | aircraft equipment problem : critical altitude deviation : excursion from assigned altitude inflight encounter : weather other anomaly |
| Independent Detector | aircraft equipment other aircraft equipment : engine roughness other flight crewa other flight crewb |
| Resolutory Action | flight crew : regained aircraft control flight crew : exited adverse environment flight crew : landed as precaution other |
| Consequence | Other |
| Supplementary | |
| Problem Areas | Weather |
| Primary Problem | Weather |
Narrative:
Customer departed with rental aircraft on IFR training flight in IMC. Encountered light icing, upon reaching clearance altitude of 11000 ft MSL. Detected momentary engine roughness and requested return to bzn. ATC held aircraft at 11000 ft (MEA 10400 ft). At this altitude aircraft continued to pick up ice. Engine showed some reduced RPM but automatic alternate air kept the fuel-injected engine operating. Upon passing zubli turn point (over gallatin valley) aircraft could not maintain altitude and pilot elected to accept 100-200 FPM descent (pilot and CFI very familiar with area). Crew had intermittent ground visibility but IMC with zero forward visibility. Upon reaching bzn VOR, aircraft drifted to 9200-9300 ft. Crew requested and received VOR approach and landed without further complications. ATC controller at ZLC panicked with aircraft's below-MEA altitude and instructed bzn tower to roll crash trucks and ambulance -- unbeknownst to aircraft crew. This created an emergency environment at the airport which the crew was unaware of until several days later. ATC emergency call could have also triggered FAA inquiry despite pilot not requesting crash fire rescue equipment. Crew was aware of position at all times and aware of terrain separation. ATC in this non radar environment believed them to be mi away. ATC seems unaware of area terrain and valleys. ATC action seems to have extended beyond prudence to borderline panic.
Original NASA ASRS Text
Title: 2 INSTRUCTORS ON A PRACTICE INST REFRESHER TRAINING FLT IN ACTUAL IMC CONDITIONS RETURNED TO LAND AFTER THE ACFT LIGHT ICING WAS ENCOUNTERED AND THE ENG WOULD ONLY RUN UNDER REDUCED PWR AFTER PULLING ON ALTERNATE ENG AIR.
Narrative: CUSTOMER DEPARTED WITH RENTAL ACFT ON IFR TRAINING FLT IN IMC. ENCOUNTERED LIGHT ICING, UPON REACHING CLRNC ALT OF 11000 FT MSL. DETECTED MOMENTARY ENG ROUGHNESS AND REQUESTED RETURN TO BZN. ATC HELD ACFT AT 11000 FT (MEA 10400 FT). AT THIS ALT ACFT CONTINUED TO PICK UP ICE. ENG SHOWED SOME REDUCED RPM BUT AUTOMATIC ALTERNATE AIR KEPT THE FUEL-INJECTED ENG OPERATING. UPON PASSING ZUBLI TURN POINT (OVER GALLATIN VALLEY) ACFT COULD NOT MAINTAIN ALT AND PLT ELECTED TO ACCEPT 100-200 FPM DSCNT (PLT AND CFI VERY FAMILIAR WITH AREA). CREW HAD INTERMITTENT GND VISIBILITY BUT IMC WITH ZERO FORWARD VISIBILITY. UPON REACHING BZN VOR, ACFT DRIFTED TO 9200-9300 FT. CREW REQUESTED AND RECEIVED VOR APCH AND LANDED WITHOUT FURTHER COMPLICATIONS. ATC CTLR AT ZLC PANICKED WITH ACFT'S BELOW-MEA ALT AND INSTRUCTED BZN TWR TO ROLL CRASH TRUCKS AND AMBULANCE -- UNBEKNOWNST TO ACFT CREW. THIS CREATED AN EMER ENVIRONMENT AT THE ARPT WHICH THE CREW WAS UNAWARE OF UNTIL SEVERAL DAYS LATER. ATC EMER CALL COULD HAVE ALSO TRIGGERED FAA INQUIRY DESPITE PLT NOT REQUESTING CFR. CREW WAS AWARE OF POS AT ALL TIMES AND AWARE OF TERRAIN SEPARATION. ATC IN THIS NON RADAR ENVIRONMENT BELIEVED THEM TO BE MI AWAY. ATC SEEMS UNAWARE OF AREA TERRAIN AND VALLEYS. ATC ACTION SEEMS TO HAVE EXTENDED BEYOND PRUDENCE TO BORDERLINE PANIC.
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.