G5 Autothrottle question

[fokkerjet]

Let's just say, the auto-throttles work as advertised. I just don't like the commercial.


(Kind of like that dorky SWA commercial with the F/O and a guitar...)

What commercial? It's an aircraft system, like PlaneView, you just need to understand how it works, so you can get the most out of your airplane.

 

[X-rated]

I can't speak for the G, but the auto-throttles in XRS are great. Unless it's gusty, they hold the speed within a knot and bring the throttles back at 50 ft. I am curious, if the auto-throttles work as advertised, why are guys floating so much? What do you do differently than the auto throttles? Do you fly slower than ref or pull the power off before 50 feet? What am I missing?

I'm not really a big fan for takeoff unless we want to flex though. On long runways, I prefer to bring the power in smoothly and at a more controlled pace. But, at 400 ft the flaps come up and the auto throttles come on. I rarely turn them off; I just let them disengage after they retard on landing. Oh, and then I let the auto-breaks do their thing too.

Now for that thing taking up the headroom above the left seat, I haven't used it as much as I should. But, I just did a 5 day recurrent and used it the entire time. I'm going to try to use it all the time for a while and see how it goes. I doubt I'll trust the flare que for a while though... baby steps

 

[G3G4]

The EGPWS (call outs) and the A/T system both use the Rad Alt, but the EGPWS does not tell the A/T system to pull back to idle. If the a/c detects landing config than the RAD ALT is whats telling the A/Ts to pull back so I would suspect the RAD ALT system. You can test them both and make sure they go to 100 ft + - 5 ft ( they should be at -5 ft on the ground) also I think that the A/T system is using the RAD ALT that is selected on the pilots Display controller so you could try flying with #2 RAD ALT selected. If that does not work try Boxing the #2 A/T computer. Has for the 5000 ft runway I don't understand how that would effect it. I hope this helps.

Thanks that's basically the answer I was looking for.. Will check out the rad alt

 

[G3G4]

I don't understand whynpeople are floating aswell using the auto throttles. Auto retard at 50 ft is the same as you manually bringing throttles back at 50 ft. So the guys floating 1500 ft has nothing to do with the auto throttles but more like landing technique and trying to grease it on all the time.

 

[fokkerjet]

I don't understand whynpeople are floating aswell using the auto throttles. Auto retard at 50 ft is the same as you manually bringing throttles back at 50 ft. So the guys floating 1500 ft has nothing to do with the auto throttles but more like landing technique and trying to grease it on all the time.

IMHO, if your holding your Vref + wind correction speed to 50' (for the G550, that's Vref +20), it's going to float.

During takeoff, I advance the throttles almost to the desired EPR, then engage AT, that way I can control the engine acceleration and still get the desired power setting.

On approach and landing, I'm guarding the throttles all the way down to touchdown. If I have wind correction added, I start bleeding off the excess speed around 200', manually (disengaging the AT) works better for me, verses clicking off manual speed and switching to autospeed. If while on AT, I enter a shear, I correct by overriding the autothrottles and push/pull the throttles as necessary. At 50', if I'm happy with my speed (and trend) I let the throttles do their thing; to fast, I pull power early, slow, I hold the power in. This works for me just fine.

 

[gulfstreameric]

IMHO, if your holding your Vref + wind correction speed to 50' (for the G550, that's Vref +20), it's going to float.

During takeoff, I advance the throttles almost to the desired EPR, then engage AT, that way I can control the engine acceleration and still get the desired power setting.

On approach and landing, I'm guarding the throttles all the way down to touchdown. If I have wind correction added, I start bleeding off the excess speed around 200', manually (disengaging the AT) works better for me, verses clicking off manual speed and switching to autospeed. If while on AT, I enter a shear, I correct by overriding the autothrottles and push/pull the throttles as necessary. At 50', if I'm happy with my speed (and trend) I let the throttles do their thing; to fast, I pull power early, slow, I hold the power in. This works for me just fine.

thank you

 

[Ty Webb]

What sort of approach were you flying? Was it a GPS approach with a FMC-generated Glide-path?

The reason I ask is that when shooting GPS IAN approaches to some runways, there is an anomaly where the 737NG Flight Director will take you down to 50' RA and just level off there, and the A/T will subtly increase to maintain bugged speed and 50' RA, like the airplane doesn't realize you are landing on that runway . . .

 

[AA717driver]

Never used AT to touchdown. The float problem is less of a concern than them going to idle and getting a big sinker and not responding. I saw that once at EWR. Had to have my fillings replaced (and, no, I wasn't flying...). I've seen that scenario numerous times (with less dramatic results) on other full-time AT's. My butt and other body parts are apparently better at detecting sinkers than the avionics are.

I just hate to get in the habit of letting the automation work when I could do the job.

TC

 

[91er]

The system is only as good as its operator. Like the autopilot, never trust the automation when close to the ground, which means that one had is always on the yoke, and the other hand on the throttle (in our SOP) anytime the RA is active. Also, know what mode you’re in, how the automation will comply, and what you’re actually trying to do. Seen people command a descent, while on autopilot, click off the autopilot and level off. All the computers know, is that you want to descend, hence the power is reduced (or at idle), aircraft is level and the pilot is wondering why the throttle aren’t reacting. I always get rid of the flight director when maneuvering visually, say on a visual approach, with no lateral or vertical commands left in the guidance panel, other than speed. Works great, and haven’t been surprised.

Agreed. I've had this thing in the 550 for 5+ years and use it only occasionally on on something like an 8,000 ft runway on a nice day just to stay proficient with it. It's important to know the limitations of it, which have all pretty much been mentioned above. We fly into 5,000 feet almost every day and I (personally) would not use it on such a runway. Get it down and get it stopped, because it can float and you can't afford 'to go the extra mile'.

The only RA issues I can remember in recent memory were sitting on the ramp while the ramp itself was reflective / ice covered. The RA signal was confused because of the reflectivity and gave erroneous indications.

Good luck, and safe travels...