Resetting flight director on RNAV approach

[tuaapache]

Hi,
I am just curious why do we have to reset flight director when doing non precision approach such as RNAV.
1. what happens if we do not reset it.
2. if we set go around altitude before 300 feet below the missed approach altitude and before final approach fix, would the airplane start climbing.
3. if we do not reset flight director on RNAV approach and press toga, what would happen and what happens if we reset FD and press toga?
Cheers

[tuaapache]

any comments appreciated

[tubby linton]

Please specify the aircraft and avionics manufacturer.

[FlyingStone]

If I'm correct assuming this topic is regarding 737, the reason why you have to reset FDs on RNAV approach is standardization of SOP for all types of non-precision approaches.

[tuaapache]

Yes sir, it 737-800
Any 737 pilots out there, please enlighten me.
Cheers

[B737900er]

Read the FCOM 1&2 and FCTM and you will find your answer.

[mischo1990]

Well a little bit late but according to my knowledge (Pilot of a 737) they have to be recycled during the final phase of the circling approach because once you turn final and start descending towars the rwy the flight directors do not provide the wanted vertical and lateral profile comands (showing something different) -THIS IS A VISUAL SEGMENT. So if you recycle them they will be gone until if something gone wrong on the circl. app and you hit TO/GA they would pop out providing LAT and VERT info to guide you through the Missed approach. The same is in NPA flying LNAV/VNAV because before reaching FAF you set the MDH - 300ft below the Missed app alt you can set the actual missed approach altitude. If you kept the autopilot on down to MDH the FD would bring the plane to the Missed approach altitude.