737-700 model question.....
- Thread starter Stomp16
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mtsu_av8er
Well-Known Member
What does "lunging forward and backward" have to do with auto throttles?
PeanuckleCRJ
Poodle Wrangler
As in, WHOOPS! getting behind on speed.
Poorly managed autothrottles will do the same thing... they wake up and go, "IM SLOW! MAX POWER, SCOTTY!" We call them throttle bursts. The 767-300 with the non-fadec engines and the MD-88 are very susceptible.
We don't really measure things as in CAT III a b or c. We just go to our lowest approved RVR for the runway- which in the 757 we're legal for 500 RVR. Most runways are only good to 600, so that's where it stops.
The DAL 737's are HGS CAT III manual land approved, as well as autopilot approved. I'd have to dig into our ops specs to see the lowest RVR capable. 300 comes to mind....
Cptnchia
Dissatisfied Customer
You need to go read this:
http://www.faa.gov/about/office_org/headquarters_offices/avs/offices/afs/afs400/afs410/smgcs/media/FAA%20SMGCS%20Broc%20300%2071102.pdf. If the runway is CAT III, then the airport has the appropriate SMGCS program.
Edit: Don't ask me why part of it is upside down. It's an FAA document. Nuff said.
Cptnchia
Dissatisfied Customer
I've flown them at DAL.
mtsu_av8er
Well-Known Member
LOL - I kinda knew that's what he meant, but I was trying to get him to see that auto-throttles do the same thing . . .
PeanuckleCRJ
Poodle Wrangler
I had a passenger come up to me after a flight on the CRJ and say "those have got to be the smoothest autothrottles on any airplane.
I raised up my right hand and said "you're looking at the entire system right here."
mtsu_av8er
Well-Known Member
Niiice!
You know, I fly with some guys that freak out of I turn the autopilots off for 30 seconds (like to slow from M.78 to M.75, etc) to keep it smooth. In my airplane, George WILL go almost to idle just for that change . . . silliness!!
BobDDuck
Island Bus Driver
I have yet to see a SMGCS system that is good for anything below 600RVR. I still say that you could be stuck on the runway after landing from a IIIc approach.
Where have you shot a IIIc before? I knew AMS was approved, but other than that I've never seen one before. The lowest I've seen is a 300RVR IIIb to 9L (I think) in Atlanta.
PeanuckleCRJ
Poodle Wrangler
Oh, lord. The MD-88 is like "we're a knot too fast!" (LO LIM) to "we're a knot too slow!" (full throttle)!
I rode the MD-88 throttles just like I was flying a plane that didn't have them....
PeanuckleCRJ
Poodle Wrangler
That shows total automation dependence, which is a bad thing. It's a very typical thing for me in the 757/767 to turn off the AP and FD on any visual approach... I turn off the autothrottles at opportune times when I know they will go to extremes and I can do it smoother.
Oh, the huge manatee....
That means that you were a good maddog pilot.
Hell, I still "follow through" on the autothrottles on the 757/767 too.
PeanuckleCRJ
Poodle Wrangler
Oh, you assume much.
I do the exact same on the 75/76... Doesn't feel right if I'm not connected. Plus, I am so twitchy about the N1's being out of synch. I fly with a lot of captains that can't seem to hear the "womp womp womp." Just wait for them to look away to bump the offending TL....
mtsu_av8er
Well-Known Member
Brings up a GREAT question!
So, on the 170/175, if you override the autothrottles, you'll get the appropriate annunciation, which is fine. But, the autothrottles will ALSO fight you (not much, but enough that you can feel/hear them). Once you remove your pressure, they will go in the other direction. So, you're slowing to 150 from 190. The autothrottles don't go quite to idle, and you override them. The speed gets down to about 155, you release the pressure. The throttles may go full power, and bump the speed to 170, and THEN go to idle to play catch-up.
I just turn them off, slow, and then re-engage them if that's the scenario . . .
It's a Sierra Nevada inspired scenario, though. YMMV.
PeanuckleCRJ
Poodle Wrangler
Brings up a GREAT question!
So, on the 170/175, if you override the autothrottles, you'll get the appropriate annunciation, which is fine. But, the autothrottles will ALSO fight you (not much, but enough that you can feel/hear them). Once you remove your pressure, they will go in the other direction. So, you're slowing to 150 from 190. The autothrottles don't go quite to idle, and you override them. The speed gets down to about 155, you release the pressure. The throttles may go full power, and bump the speed to 170, and THEN go to idle to play catch-up.
I just turn them off, slow, and then re-engage them if that's the scenario . . .
It's a Sierra Nevada inspired scenario, though. YMMV.
That is true on the 88 and 75/76.... minus the annunciation. I "ride" them and ensure they do what I want them to do. If it is a big enough difference between what I want and what they are going to do, I just turn them off until I get them stabilized and then reselect the mode I would like them in.
mtsu_av8er
Well-Known Member
So, can you turn the autothrottles off without turning the AP off? All this techno-wizardry is beyond me.
Yeah, it's pretty sweet, huh? The autothrottles are a completely different component!
PeanuckleCRJ
Poodle Wrangler
So, can you turn the autothrottles off without turning the AP off? All this techno-wizardry is beyond me.
Yep, they are 2 independent systems.
You can have any combination of on or off with AT and AP.
The 757 really likes idle and 180 at idle and flaps 5 or 15 on the glideslope. I'll typically capture and click off the AT and let her coast down if it's a long straight in.
Cptnchia
Dissatisfied Customer
While you are right that ATL only goes to IIIb, there is a chart for less than 600 RVR, so you could still taxi in. Plus, there's always the "Follow Me" truck.
9R in ATL. And my bad, I was talking about CAT III, not IIIc specifically.