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GA small aircraft had a blocked pitot-static system that was discovered at cruise altitude on a cross-country training flight.
| Attributes | |
| ACN | 143071 |
| Time | |
| Date | 199004 |
| Day | Sat |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : vuz |
| State Reference | AL |
| Altitude | msl bound lower : 6000 msl bound upper : 6000 |
| Environment | |
| Flight Conditions | Marginal |
| Light | Dusk |
| Aircraft 1 | |
| Operator | general aviation : instructional |
| Make Model Name | Small Aircraft, High Wing, 1 Eng, Fixed Gear |
| Flight Phase | cruise other |
| Route In Use | enroute airway : v168 |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | Other |
| Function | instruction : instructor |
| Qualification | pilot : cfi pilot : commercial pilot : instrument |
| Experience | flight time last 90 days : 110 flight time total : 600 flight time type : 340 |
| ASRS Report | 143071 |
| Person 2 | |
| Affiliation | Other |
| Function | instruction : trainee |
| Qualification | pilot : student |
| Events | |
| Anomaly | aircraft equipment problem : critical altitude deviation : excursion from assigned altitude |
| Independent Detector | other flight crewa |
| Resolutory Action | none taken : unable other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | other |
Narrative:
The occurrence took place while on a routine training flight from auo to bhm. While en route, I noticed vsi erratically moving between +500' and -500'. Shortly afterwards, the student noticed the airspeed indicating 80 KIAS (normally 105 at cruise power). After a few moments, airspeed indicated '0' KIAS and I advised ATC of my situation and requested an immediate 180 degree turn back to auo. Shortly thereafter, the altimeter showed a rapid descent, but vacuum instruments indicated straight and level. Birmingham approach assigned me to maintain 6000', but with a pitot-static system failure, relying on the altimeter to maintain altitude would be pointless. Possibly approach did not understand the situation fully or did not understand what was meant by pitot-static system. It is for this reason that I am filing this report. Approach suggested a diversion to sylacauga, and the landing was uneventful. After a thorough check on the pitot-static system by an authority/authorized inspector, an insect was flushed from the system.
Original NASA ASRS Text
Title: GA SMA HAD A BLOCKED PITOT-STATIC SYSTEM THAT WAS DISCOVERED AT CRUISE ALT ON A CROSS-COUNTRY TRAINING FLT.
Narrative: THE OCCURRENCE TOOK PLACE WHILE ON A ROUTINE TRNING FLT FROM AUO TO BHM. WHILE ENRTE, I NOTICED VSI ERRATICALLY MOVING BTWN +500' AND -500'. SHORTLY AFTERWARDS, THE STUDENT NOTICED THE AIRSPD INDICATING 80 KIAS (NORMALLY 105 AT CRUISE PWR). AFTER A FEW MOMENTS, AIRSPD INDICATED '0' KIAS AND I ADVISED ATC OF MY SITUATION AND REQUESTED AN IMMEDIATE 180 DEG TURN BACK TO AUO. SHORTLY THEREAFTER, THE ALTIMETER SHOWED A RAPID DSNT, BUT VACUUM INSTRUMENTS INDICATED STRAIGHT AND LEVEL. BIRMINGHAM APCH ASSIGNED ME TO MAINTAIN 6000', BUT WITH A PITOT-STATIC SYS FAILURE, RELYING ON THE ALTIMETER TO MAINTAIN ALT WOULD BE POINTLESS. POSSIBLY APCH DID NOT UNDERSTAND THE SITUATION FULLY OR DID NOT UNDERSTAND WHAT WAS MEANT BY PITOT-STATIC SYS. IT IS FOR THIS REASON THAT I AM FILING THIS RPT. APCH SUGGESTED A DIVERSION TO SYLACAUGA, AND THE LNDG WAS UNEVENTFUL. AFTER A THOROUGH CHK ON THE PITOT-STATIC SYS BY AN AUTH INSPECTOR, AN INSECT WAS FLUSHED FROM THE SYS.
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.