AAPalmTree
Well-Known Member
Better forget all that when you're flying your 737 outta LAX!
Boeing teases the 797
- Thread starter RDoug
- Start date
Better forget all that when you're flying your 737 outta LAX!
Cherokee_Cruiser
Bronteroc
Cherokee_Cruiser
Bronteroc
Ahh ok. Makes sense. We had the 80 ft limitation in 2012. Then removed about 2014. Then added back this year.
AP off by 80 ft AGL when CATII or CATIII displayed. (which is usually almost always the case)
jtrain609
Antisocial Monster
Ain't no way, son. I'll "bid down" as soon as the opportunity presents itself.
Cptnchia
Dissatisfied Customer
So help a Boeing/McD pilot out. Y'all are saying that the AP has to be off by 80 feet on a CATII/III? How do you auto land?
Nark
Macho Superpilot
Nope, you have it backwards. If CAT II or CAT III is NOT displayed(on the FMA), you can't autoland.
So what we're saying, a plane-jane (see what I did there..) cat I approach the autopilot has to be off at 80/160' agl.
There is a host of other restrictions which I'm too lazy to look up as well.
Cptnchia
Dissatisfied Customer
So you cannot autoland from a CATI? Hell, even the MD88 can do that.
Nark
Macho Superpilot
Yup, it can autoland to a CAT I.
The limitation has to do with the FMA and what it's telling you.
Cherokee_Cruiser
Bronteroc
No, real CAT II and CAT III are all autolands.
If you're manually landing, the AP has to be off by 80 AGL if CATII/CATIII is displayed on FMA. Or 160AGL is CAT 1 is displayed on FMA.
Confusion is what's on FMA versus real approach you're doing. As long as all equipment working, you should always get a CATIII on FMA for an ILS. That means AP can stay on til 80AGL on a visual approach, backed up ILS.
If you're doing a real CATII or CATIII, that's a regular autoland.
Cherokee_Cruiser
Bronteroc
The confusion is what the FMA shows is your limitation. As long as everything is working, on an ILS approach once you arm, it'll get you CATIII Single. Arm 2nd autopilot, you get CATIII Dual on FMA. That's our standard op for all ILS.
Now..... "downgrade" situations. You take the authotrust OFF. CATIII on FMA will degrade to CATII. That's your new limitation. Still can do autoland, but need higher RVR per CATII requirements versus CATIII.
If the AP fails, both of them, in the FMA, CATIII switches to CATI. This FMA column simply shows approach *capability* , NOT what you are actually doing. Obviously you can't autoland with no AP.
SO....... for standard ops, in an ILS, you arm approach mode and arm 2nd autopilot. and capture LOC and GS. Your FMA shows capability as CATIII-Dual. Now since you're visual, you take autopilot off, the plane senses a degradation of systems, mainly, no AP. Since both AP were on, and simultaneously both were turned off with pilot pushing the red disconnect button, FMA initially shows "CATIII-Single" as it registers one AP off. A second later it senses both AP are off, and FMA displays "CATI". That's just approach capability on FMA. Since both AP are off, you are approach limited capability to non-autoland.
You can autoland to a CATI. But on that approach, your *capability* on the FMA will still show CATIII.
The FMA is showing your capability to do the highest level approach. As things fail, it automatically shows next degradation level.
So engine out, boom, instant CATIII-Sigle mode. That's Fail-Passive. The Fail-Active is CATIII-Dual, which is best case scenario and a failure of one shouldn't degrade your autoland ability below 400 feet.
If you're flying along and arm approach to capture ILS, and only CAT1 shows on FMA, you've had a failure or degradation somewhere. Most likely a systems issue or some fault which you're aware of. But with capability showing as CATI on FMA, you must take off the AP by 160AGL.
No degradations, FMA will show CATIII on FMA, and you must take AP off by 80AGL if non-autoland.
I hope that clarifies it
