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Compass error after departure results in apparent loss of separation.
| Attributes | |
| ACN | 131297 |
| Time | |
| Date | 198912 |
| Day | Wed |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : ord |
| State Reference | IL |
| Altitude | msl bound lower : 1100 msl bound upper : 5000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : ord |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Navigation In Use | Other |
| Flight Phase | climbout : initial climbout : intermediate altitude |
| Route In Use | departure other enroute : on vectors |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : commercial pilot : atp |
| Experience | flight time last 90 days : 200 flight time total : 20000 flight time type : 1500 |
| ASRS Report | 131297 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : private pilot : atp pilot : instrument |
| Experience | flight time last 90 days : 210 flight time total : 8000 flight time type : 2200 |
| ASRS Report | 131303 |
| Events | |
| Anomaly | aircraft equipment problem : less severe conflict : airborne less severe non adherence : clearance other spatial deviation |
| Independent Detector | other controllera other flight crewa |
| Resolutory Action | flight crew : overcame equipment problem flight crew : returned to intended course or assigned course other |
| Consequence | faa : investigated |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
We were cleared for takeoff on runway 27L ord. Told to maintain runway heading. First officer was flying. On liftoff first officer observed and mentioned problem with headings. We switched to O'hare departure control. They asked what headings we were assigned. I was clearing departure path. We then checked our headings with standby compass (no easy feat in medium large transport) and determined that captain system was correct. We also confirmed our new headings as assigned by departure were tracking us correctly. We slaved our compass systems and they appeared accurate and remained so remainder of 4 hour flight. The problem from this event is that we found out later that we did not have the prescribed separation from other departing aircraft. This was due to our heading problem. At no time did departure control indicate to us that we were too close to other aircraft. What I would have done differently would be to tell departure control immediately of heading problem and I believe they should have given us more urgent vectors if we were indeed close to other aircraft. Supplemental information from acn 131303: at 300' AGL, I armed the heading select on the flight director which was set to 270 degree. Initially the command bars indicated a left turn then disappeared from view. My HSI heading indicated 300 degree and my RMI indicated 270 degree.
Original NASA ASRS Text
Title: COMPASS ERROR AFTER DEP RESULTS IN APPARENT LOSS OF SEPARATION.
Narrative: WE WERE CLRED FOR TKOF ON RWY 27L ORD. TOLD TO MAINTAIN RWY HDG. F/O WAS FLYING. ON LIFTOFF F/O OBSERVED AND MENTIONED PROBLEM WITH HDGS. WE SWITCHED TO O'HARE DEP CTL. THEY ASKED WHAT HDGS WE WERE ASSIGNED. I WAS CLEARING DEP PATH. WE THEN CHECKED OUR HDGS WITH STANDBY COMPASS (NO EASY FEAT IN MLG) AND DETERMINED THAT CAPT SYSTEM WAS CORRECT. WE ALSO CONFIRMED OUR NEW HDGS AS ASSIGNED BY DEP WERE TRACKING US CORRECTLY. WE SLAVED OUR COMPASS SYSTEMS AND THEY APPEARED ACCURATE AND REMAINED SO REMAINDER OF 4 HR FLT. THE PROBLEM FROM THIS EVENT IS THAT WE FOUND OUT LATER THAT WE DID NOT HAVE THE PRESCRIBED SEPARATION FROM OTHER DEPARTING ACFT. THIS WAS DUE TO OUR HDG PROBLEM. AT NO TIME DID DEP CTL INDICATE TO US THAT WE WERE TOO CLOSE TO OTHER ACFT. WHAT I WOULD HAVE DONE DIFFERENTLY WOULD BE TO TELL DEP CTL IMMEDIATELY OF HDG PROBLEM AND I BELIEVE THEY SHOULD HAVE GIVEN US MORE URGENT VECTORS IF WE WERE INDEED CLOSE TO OTHER ACFT. SUPPLEMENTAL INFORMATION FROM ACN 131303: AT 300' AGL, I ARMED THE HDG SELECT ON THE FLT DIRECTOR WHICH WAS SET TO 270 DEG. INITIALLY THE COMMAND BARS INDICATED A LEFT TURN THEN DISAPPEARED FROM VIEW. MY HSI HDG INDICATED 300 DEG AND MY RMI INDICATED 270 DEG.
Data retrieved from NASA's ASRS site as of August 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.