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Thread: LNAV/VNAV
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Old 23rd Mar 2017, 12:16
  #20 (permalink)  
oggers
 
Join Date: Nov 2005
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toseg

First i would like to thank you all very much for your answers . At FCTM is written the following : "Boeing airplanes have uncompensated Baro-VNAV systems and are prohibited from using LNAV/VNAV minima on approach charts when operating outside of published temperature restriction limits. However, if cold temperature altitude corrections are applied as described in the Cold Temperature Operations Supplementary Procedures chapter of the FCOM, descent to the corrected LNAV (MDA) minima is allowed." It says for minima not for VNAV mode.
Is mentioning to descent to LNAV minima but does not clarify if you can use VNAV mode. At the part C of my company, if you are above -15 C you correct the FAF altitude and the DA only by 10% .Not all the altitudes between. Bellow -15 C you correct all the altitudes and the MDA from the classic table. In the FMS you don't insert new points. Just correct the altitude of the existed ones in the FMS.
Your company rules seem to be compliant with the regs. In your example, due to the temperature restriction you must use the LNAV minima (and apply temperature correction to it). But as a commercial operator you must make a CDFA so what vertical mode you use depends on your particular system and SOPs.

However, if you had WAAS (or equivalent type of SBAS) you CAN still use the LNAV/VNAV minima (and apply temperature correction to it).
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