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flightsimmer747

737 procedure question when landing

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HiI was doing a dual ILS approach when touching down on this approach should the A/T be turned off before or after disengaging the autopilot, before idle and reversers?

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Hi Joe,The autothrottle will reduce thrust to idle during the flare and will disconnect when the main gear compresses upon contact with the runway so that reverse thrust can be manually applied. The autopilot can be turned off once you're firmly on the ground if doing a full autoland since the 737NG has no centerline guidance like the 744 and you'll need to point the aircraft down the runway during the rollout phase of the landing.Jim Karnhttp://www.precisionmanuals.com/images/forum/pmdg_pf.jpg


Jim Karn

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On the 737NG and most aircraft the AT and AP are exclusive to some degree.If AT is armed when main wheels touch it will disable on the 737NG. The throttles will go to idle and you can apply reverse thrust. This happens whether or not the A/P is engaged. I do not recall if the A/P needs to be engaged specific to the 737 for AT MCP speed control as it does for vertical and horizontal control by the MCP or VNAV/LNAV. VNAV of course takes over speed control and AT must be armed for that.Anyway if you are going to disengage AP do it early on final and if you want to disengage AT do it early as well so you are at the correct power and configuration for the descent and speed you wish. You can cut power once over the threshold at 100 feet or so AGL and after the flare and nose drops apply reverse thrust if necessary.My procedure is to let AT stay on until contact so Vref + 10 or so is maintained, my throttle control set at 0 but my hand on it should a go-around be required in the last stages. Pushing the throttles high will overide AT and your MCP speed setting indicating you are executing a go-around/missed approach and applying full N1 thrust for an immediate climb power. As I recall in the event of that AP disengages and when ready you can reengage it using MCP control or if desired LNAV for the missed approach if you have placed an approach in the FMC. If you have AP enabled and AT enabled and you hit TO/GA, then the aircraft reverts to the N1 speed and MCP heading mode (heading being set on the inbound bearing during the approach), MCP speed taking effect when you reduce the throttles and hit the speed button.Many airlines require both the PF and PNF be ready to exert manual throttle control at the PF's request especially on the few dual throttle control aircraft. The PFs view in the last stage is directed outside the windscreen at the runway for visual contact and the PNF is focused on manipulating some of the controls if the PF removes his hand from the throttle.More than you asked about but it influences the procedure as you can see.Some airlines say everything goes manual at 400 AGL and others at 1000 and others yet more.I do not believe autoland is used except in very low visibility CAT III certified landings where pilot response time might not be quick enough.


Ron Ginsberg
KMSP Minnesota, Land of 10,000 Puddles
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