757 G/A question
Thread Starter
757 G/A question
Been driving them for 9 years. We couldn't work out last night (3rd deep night) what would happen in landing mode if you applied G/A through the thrust lever switches whilst still above the missed approach alt in the MCP window. Instinctively you'll push the levers forwards and achieve some entertaining results.
To get a full perspective, can some knowledgeable soul give FULL chapter and verse on the mode changes, FD bar movement and flight path?
Ta
To get a full perspective, can some knowledgeable soul give FULL chapter and verse on the mode changes, FD bar movement and flight path?
Ta
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It will climb...and climb, and climb,
"The GA pitch mode initially commands a go-around attitude and then transitions to speed as the rate of climb increases. This speed is normally between command speed and command speed + 25 knots."
My take on it is that you will never capture the altitude in the MCP window because it is below you.
When you select GA, as stated in the quote above (from the FCTM page 4.51), the pitch mode is GA. With AT armed or engaged, the AT mode is GA. The jet will pitch toward GA attitude, and operate with the AT toward achieving a 2,000 fpm climb. If you do nothing other than select GA in these conditions, you will continue climbing until you decide to select something else on the MCP.
My take on it is that you will never capture the altitude in the MCP window because it is below you.
When you select GA, as stated in the quote above (from the FCTM page 4.51), the pitch mode is GA. With AT armed or engaged, the AT mode is GA. The jet will pitch toward GA attitude, and operate with the AT toward achieving a 2,000 fpm climb. If you do nothing other than select GA in these conditions, you will continue climbing until you decide to select something else on the MCP.
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"None" is quite right - I think! Its been a while since I flew 757 but the SOPs catered for a GA from above Missed Approach Alt in the following way if memory serves correctly:
PM Calls "Above Flap Retract Altitude"
PF Calls (Assuming manual flight) "Set Speed Vref 30 +80, Climb Thrust."
You can then select Fl Ch, Hdg Sel, LNav etc as appropriate to comply with the revised clearance.
Modes should all go to GA initially. Thrust for 2000 fpm ROC. FD directs elevators to fly Speed and Ailerons to maintain ground track. Since Elevators are flying speed and Thrust is set for 2000 fpm climb, you will never get an alt cap unless you reset the mcp alt window to above your current altitude or select another pitch mode such as Alt Hold.
Standing by to be corrected.
Now, as to what happens on an early GA when you use VNav for acceleration and there is still an active waypoint such as the OM with an alt constraint (below you) between you and the rwy - well thats another story. Later software mods can remove this problem.
PM Calls "Above Flap Retract Altitude"
PF Calls (Assuming manual flight) "Set Speed Vref 30 +80, Climb Thrust."
You can then select Fl Ch, Hdg Sel, LNav etc as appropriate to comply with the revised clearance.
Modes should all go to GA initially. Thrust for 2000 fpm ROC. FD directs elevators to fly Speed and Ailerons to maintain ground track. Since Elevators are flying speed and Thrust is set for 2000 fpm climb, you will never get an alt cap unless you reset the mcp alt window to above your current altitude or select another pitch mode such as Alt Hold.
Standing by to be corrected.
Now, as to what happens on an early GA when you use VNav for acceleration and there is still an active waypoint such as the OM with an alt constraint (below you) between you and the rwy - well thats another story. Later software mods can remove this problem.
Thread Starter
Our SOPs don't have a specific for G/A above G/A altitude. Having never tried it (and was too tired to deal with any extra excitement one the last flight) I wasn't sure if the transition to G/A would command a pitch down. It does say "G/A attitude" and not upward pitch, doesn't it? The assumption is that it will ALWAYS be a pitch up.
Our SOPs call for a call of "1000 -check-speed plus 80, climb power" when passing 1000 above threshold altitude and so it is possible to miss this if we do a G/A from higher alt.
Hmmmmm. Methinks a call to the Tng Dept is called for.
Thanks
Our SOPs call for a call of "1000 -check-speed plus 80, climb power" when passing 1000 above threshold altitude and so it is possible to miss this if we do a G/A from higher alt.
Hmmmmm. Methinks a call to the Tng Dept is called for.
Thanks
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None is spot on. We asked Boeing this question a couple of years ago and got the same answer. Also, the G/A switches don't work until the flaps are out of the up position or you have glideslope capture.
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I've tried it!
On an empty positioning flight with a company trainer recently..we tried it.
The result is exactly as described by None I would hasten to add it was when we were given an enroute climb to a higher level 
The result is exactly as described by None
I would hasten to add it was when we were given an enroute climb to a higher level
