macdo
17th Mar 2012, 09:11
Couple of nights ago we were doing lazy 4 minute racetrack holds at FL 360 for about 45 mins. Although the FMGC had been set for the hold, the actual flying was done in HDG and SELECTED Mach., with the shape of the hold being used for situational awareness. All normal so far.
Upon setting off for home using a DCT TO a waypoint approx 100 miles away, with NAV engaged and Managed Speed, the Managed Speed Target set itself to 229 kts, 3 knots below Green Dot, but above Vls. This was seen and an appropriate Selected Mach was re-engaged.
We cannot work out why the Perf Page Cruise phase Managed speed was 229 and would not shift with changes of mode, cost index or FMGC Cruise FL.
In the end, we Activated Appr Phase (in Selected Speed) then reselected the Cruise FL in the FMGC and the Managed Cruise Speed corrected itself to .78.
We recently had FMS Rev 1A fitted which already has one anomaly which has been Flight Crew Noticed to us and wonder if this is another.
Upon setting off for home using a DCT TO a waypoint approx 100 miles away, with NAV engaged and Managed Speed, the Managed Speed Target set itself to 229 kts, 3 knots below Green Dot, but above Vls. This was seen and an appropriate Selected Mach was re-engaged.
We cannot work out why the Perf Page Cruise phase Managed speed was 229 and would not shift with changes of mode, cost index or FMGC Cruise FL.
In the end, we Activated Appr Phase (in Selected Speed) then reselected the Cruise FL in the FMGC and the Managed Cruise Speed corrected itself to .78.
We recently had FMS Rev 1A fitted which already has one anomaly which has been Flight Crew Noticed to us and wonder if this is another.