PPRuNe Forums - View Single Post - Vnav does not engage on the ground B737NG
Old 17th May 2018, 08:46
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Skyjob
 
Join Date: Jan 2000
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Care needs to be taken when using VNAV for departures, as default values are used on TAKEOFF PAGE 2/2 and these may need adjusting, depending on departure profile NADP1 or NADP2 or a non-standard use of either (eg using 1500' instead of 1000' flap retraction altitude):
  • thrust reduction height
  • acceleration height
Both references are used as AGL, not altimeter.
Thus an airline changing over to these automated profile MUST ENSURE the heights are made available to crew, rather then the MFRA as an altimeter altitude only as likely was previously used by its crew.
If airline is using OPT a config setting can be adjusted to display both MFRA and MFRH (MFRH in lower smaller letters displayed underneath or next to MFRA to be set by crew on altimeter tape bug), this is a to do item for the EFB Admin team of the airline. The MFRH is then used by crew and entered into TAKEOFF PAGE 2/2 as ACCEL HT.
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