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A fractional flight crew reported that a recent FMS software revision allowed VOR autotuning after takeoff which caused this flight to lose the departure airport DME for a required turn. The solution is to manually tune the VOR.
| Attributes | |
| ACN | 1179496 |
| Time | |
| Date | 201406 |
| Local Time Of Day | 0601-1200 |
| Place | |
| Locale Reference | SJC.Airport |
| State Reference | CA |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | Medium Transport Low Wing 2 Turbojet Eng |
| Operating Under FAR Part | Part 91 |
| Flight Phase | Initial Climb |
| Route In Use | SID LOUPE TWO |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | FMS/FMC |
| Person 1 | |
| Function | First Officer Pilot Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 60 Flight Crew Total 9500 Flight Crew Type 2000 |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Deviation - Procedural Published Material / Policy |
Narrative:
Following the loupe 2 SID; we were required to turn to a heading at 1.8 DME from the sjc VOR. As we climbed out of 3;600 feet; I lost the DME signal on my side; I then asked the pilot not flying to call my turn; but he lost his DME signal about the same time. As we checked on with norcal on 121.3; I stated; 'please call my turn; we lost the DME signal.' he asked us to identify; and gave us the required turn. He then asked what happened; and the pilot not flying replied; 'our FMS autotuned and we lost the DME signal momentarily.'on the taxi out for takeoff; we both displayed the sjc VOR along with the DME; and we had this during the takeoff and initial climb. What we hadn't noticed was that the VOR on power up went to autotune; apparently a new feature with the new software revision loaded in the FMS. As we climbed out; the autotune feature went to the lin VOR as it got the signal; and dropped the sjc VOR. As we followed the ATC given turn; the not flying pilot manually tuned in the sjc VOR and we got our DME back. This can be prevented by the following actions: more information on the subtle changes in the FMS when new software is loaded. Always manually tune the VOR for a vector departure. On subsequent trips that week on the same aircraft we noticed that on every power up; the VOR went to autotune. There was no deviations of altitude and airspeed; or TCAS event during the departure.
Original NASA ASRS Text
Title: A fractional flight crew reported that a recent FMS software revision allowed VOR autotuning after takeoff which caused this flight to lose the departure airport DME for a required turn. The solution is to manually tune the VOR.
Narrative: Following the Loupe 2 SID; we were required to turn to a heading at 1.8 DME from the SJC VOR. As we climbed out of 3;600 feet; I lost the DME signal on my side; I then asked the pilot not flying to call my turn; but he lost his DME signal about the same time. As we checked on with NORCAL on 121.3; I stated; 'Please call my turn; we lost the DME signal.' He asked us to IDENT; and gave us the required turn. He then asked what happened; and the pilot not flying replied; 'Our FMS autotuned and we lost the DME signal momentarily.'On the taxi out for takeoff; we both displayed the SJC VOR along with the DME; and we had this during the takeoff and initial climb. What we hadn't noticed was that the VOR on power up went to autotune; apparently a new feature with the new software revision loaded in the FMS. As we climbed out; the autotune feature went to the LIN VOR as it got the signal; and dropped the SJC VOR. As we followed the ATC given turn; the not flying pilot manually tuned in the SJC VOR and we got our DME back. This can be prevented by the following actions: More information on the subtle changes in the FMS when new software is loaded. Always manually tune the VOR for a vector departure. On subsequent trips that week on the same aircraft we noticed that on every power up; the VOR went to autotune. There was no deviations of altitude and airspeed; or TCAS event during the departure.
Data retrieved from NASA's ASRS site 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.