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Md-11 captain reported that during cockpit setup crew noticed the tat indication was well above normal and the FMS would not calculate V speeds or EPR. Crew then realized ground personnel were using a tether from a larger aircraft that allowed the nose to rise enough that the flight/ground switch was activated.
| Attributes | |
| ACN | 1216102 |
| Time | |
| Date | 201411 |
| Local Time Of Day | 0001-0600 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Aircraft 1 | |
| Make Model Name | MD-11 |
| Flight Phase | Parked |
| Flight Plan | IFR |
| Person 1 | |
| Function | Captain Check Pilot |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Deviation - Procedural Published Material / Policy |
Narrative:
During preflight loading of the takeoff data; FMS would not calculate V speeds or EPR. Rfo noticed that the tat indication was well above normal. Eventually the tat started coming back down and soon the FMS calculated V speeds and EPR. While the captain student and myself were continuing with our preflight duties; the rfo deduced that the aircraft had sensed that it was airborne due to nose strut extension. I do recall during preflight feeling the nose rise up; but it was not dramatic.the aircraft had been tethered with a [larger aircraft] tether as opposed to an md-11 tether. The additional length allowed the nose wheel to lift off of the ground sufficiently for the ground shift to sense airborne.all 3 crew members checked that the aircraft was securely tethered prior to entering the aircraft. However we were not aware that there are different length tethers and that interchanging them could cause a problem.
Original NASA ASRS Text
Title: MD-11 Captain reported that during cockpit setup crew noticed the TAT indication was well above normal and the FMS would not calculate V speeds or EPR. Crew then realized ground personnel were using a tether from a larger aircraft that allowed the nose to rise enough that the flight/ground switch was activated.
Narrative: During preflight loading of the takeoff data; FMS would not calculate V speeds or EPR. RFO noticed that the TAT indication was well above normal. Eventually the TAT started coming back down and soon the FMS calculated V speeds and EPR. While the Captain student and myself were continuing with our preflight duties; the RFO deduced that the aircraft had sensed that it was airborne due to nose strut extension. I do recall during preflight feeling the nose rise up; but it was not dramatic.The aircraft had been tethered with a [larger aircraft] tether as opposed to an MD-11 tether. The additional length allowed the nose wheel to lift off of the ground sufficiently for the ground shift to sense airborne.All 3 crew members checked that the aircraft was securely tethered prior to entering the aircraft. However we were not aware that there are different length tethers and that interchanging them could cause a problem.
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.