757 - selection of autopilot before vertical mode
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selection of autopilot before vertical mode
Hi,
Can somebody please confirm the FMA annunciations upon selecting autopilot, in the climb out, after having hit the HDG select but before selecting climb thrust and FLCHG/VNAV (ie at about 700ft AGL).
I have a feeling it will give VS at the rate at time of AP selection and obviously if this is a high rate then there will be very little in way of speed protection.
Any help appreciated,
Many thanks
Can somebody please confirm the FMA annunciations upon selecting autopilot, in the climb out, after having hit the HDG select but before selecting climb thrust and FLCHG/VNAV (ie at about 700ft AGL).
I have a feeling it will give VS at the rate at time of AP selection and obviously if this is a high rate then there will be very little in way of speed protection.
Any help appreciated,
Many thanks
Last edited by tom24; 24th Jan 2007 at 11:09.
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You are indeed correct. The default modes of the AP are HDG HOLD and V/S.
On a departure, typical selection is LNAV/ HDG SEL above 200ft (absolute min) then CLB thrust and FLCH or VNAV above 1000ft AAL and then Centre CMD.
On a departure, typical selection is LNAV/ HDG SEL above 200ft (absolute min) then CLB thrust and FLCH or VNAV above 1000ft AAL and then Centre CMD.
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The default of V/S is somewhat strange since there is no protection at all in that mode on the 757. Very strange indeed.
I rather try to avoid this selection but engage autopilot only after punching Vnav.
I rather try to avoid this selection but engage autopilot only after punching Vnav.
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The 757/767 AFDS will revert to the current modes when A/P is selected on if a flight director is on, except when in TO or GA modes. In these modes, it will revert to HDG Hold and V/S.
This fact if often missed, as it isn't obviously stated in the manual. It is there, however, it requires a second look.
Cheers
This fact if often missed, as it isn't obviously stated in the manual. It is there, however, it requires a second look.
Cheers
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It might have something to do with One Eng INOP profile ,say if you miss it on T/O : no action below 400 (only Positive CLB / Gear UP) fly the acft , 400 HDG or LNAV (memo items and APU on if aplicable), 1000ft VS 200, Bug UP ,Retract Flaps on Schedule,Cln ACFT and MCSPD ,MCT ADJUST,FLCH, NNC QRH, Norm CHKLIST.The selection of VS 200 allows the ACT to ACCELERATE to MCSPD safely.If you disconnect A/p then your flying Manually so you have to monitor carefully SPD and ATT.Normal procedure calls for 400 LNAV or HDG, 1000 VNAV or FLCH (in some ACFT you need to select CLB THR before selecting any pitch mode on the MCP).Be always ahead of FLT director he´s not 100% reliable.I remember once in JFK we los all AUTOFLT capability no AUTO THR ,no A/P,no FLT DIRECTOR it was actually frozen in HDG and VS at 2000´it was comanding 28 degrees of pitch
wich obviously we didn´t follow.
Fly Safe guys/girls!!
no AUTO THR ,no A/P,no FLT DIRECTOR it was actually frozen in HDG and VS at 2000´it was comanding 28 degrees of pitch wich obviously we didn´t follow.Fly Safe guys/girls!!
