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Maniac59

No VNAV aloft

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When you say "Speed cannot be set," what do you mean? You've got 253kts set in LVL CHG.


Matt Cee

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You guys don't miss much. You really should do the tutorial again Mark.


Alex Cadle

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I cannot make out from the photo what it says in the scratchpad though.
I had closer look at the screenshot and it looks like the "UNABLE YYY KNOTS AT XXXXX" message. FCOM2 says:
When the speed profile causes an anticipated violation of a waypoint speed constraint, the FMC displays the CDU scratchpad message UNABLE YYY KNOTS AT XXXXX, where speed is YYY and waypoint is XXXXX. When a waypoint speed constraint greater than 10 kts above the predicted speed at the waypoint exists, the FMC displays the CDU scratchpad message DRAG REQUIRED AFTER XXXXX where waypoint is XXXXX.
Basically it means that the distance between two waypoints is too small for the VNAV mode to make the necessary change in speed in time to meet the programmed restriction. Enter a more conservative speed restriction for the next waypoint, delete the restriction altogether if possible (you would have to check with ATC in a real situation, I suppose) or manually and more aggressively adjust your speed to make the restriction after all.

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You never press the SPEED button. You are in LVL CHG pitch mode with a MCP speed set to 253 knots. Note the 'N1' and 'MCP SPD' modes shown in your PFD - this means that whilst the A/T is maintaining CLB thrust (N1), LVL CHG will control the pitch of the aircraft at whatever angle is required to maintain 253 knots airspeed. If you manually decrease the airspeed on the MCP you'll note that the climb angle will increase and vice verca. Another example is when you are descending in LVL CHG and suddenly decrease the MCP speed, you'll find the aircraft will stop descending to allow the airspeed to decrease and then descend at a slower speed in order to maintain the MCP speed.


CRAIG MACPHEE • Core i5 4690K • GTX 460 1GB

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