WILCO737 From Greenland, joined Jun 2004, 8770 posts, RR: 77 Reply 1, posted (5 years 5 months 2 weeks 1 day 21 hours ago) and read 3285 times:
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Quoting HAWK21M (Thread starter): Anyone aware of Auto roll out under Cat 3C function.
Presume its connected to the rudder steering system,thus limited to 7 deg average.
Yes, many airplanes have that function. Not only autoland, it included ROLL OUT as well. The autopilot is able to steer within the 7° you mentioned. And he keeps it on the runway with that. You have low crosswind limits during CAT III (10 knots). So the AP will be able to compensate that - even on ground and safely roll out on the centerline.
At taxi speed you disconnect the AP and then you can taxi with the normal tiller.
TristarSteve From Sweden, joined Nov 2005, 3858 posts, RR: 34 Reply 3, posted (5 years 5 months 2 weeks 1 day 17 hours ago) and read 3213 times:
Most British Airways aircraft starting with the Trident in 1964 have a system called PVD, Para Visual Director. There is a small bar in the coaming in front of each pilot which rotates and is controlled by the localiser via the ILS receiver. On the Trident it was a rotating rod, on later aircraft a light. Watching it as you landed in low viz it was instinctive to follow it and keep the aircraft on the centreline manually. It was part of the BA Cat3B system for over 30years.
HAWK21M From India, joined Jan 2001, 31457 posts, RR: 57 Reply 4, posted (5 years 5 months 2 weeks 1 day 8 hours ago) and read 3125 times:
An add on query.After landing on Cat 3C conditions,How is taxing to gate/bay accomplished in bad visibility.Are there certain assistance on the Taxipath.
Practically We don't have Cat3C out here so not aware.
TristarSteve From Sweden, joined Nov 2005, 3858 posts, RR: 34 Reply 5, posted (5 years 5 months 2 weeks 1 day 7 hours ago) and read 3122 times:
When the Trident was designed to Cat 3C, the intention was that the taxiways at LHR would have sensors in them that the localiser could pick up to guide the aircraft. It was never introduced and in the end a landing visibility limit was used so that the aircraft could taxi. To help this the taxiway lighting at LHR is set by the ground controller so the aircraft only has to follow the green lights.
Cat 3C has never been used operationally.
Buzz From United States of America, joined Nov 1999, 697 posts, RR: 23 Reply 6, posted (5 years 5 months 2 weeks 5 hours ago) and read 2974 times:
Hi MEL, Buzz here. Sounds like the "roll out guidance servo" question has been answered. I had to explain to a couple guys that the part that showed up (rudder PCU) was not the same as the auto pilot roll out guidance servo... you access them by the hatch just forward of the APU compartment. Rudder PCU's are halfway up the tail.
Here at PDX, next to the Columbia River we sometimes get genuine Cat 3B fog. At most US airports, at the runway / taxiway junction there are curved yellow lines that you can follow to lead you to a taxiway. Very handy at night in a small airplane - you shouldn't simply steer for a gap in between a couple runway lights (grin)
And at PDX as you roll out in Cat 3 weather, the tower's Ground Surveillance Radar would permit the "nice guys in the glass house" to steer you down the correct taxi way. And there are "pink dots" with labels, so you can report in: "Holding at Mike Echo"
I don't think I've seen Cat 3C weather here. 3B is kind of rare, Cat 2 happens every so often. And to tell a secret... it doesn't rain all the time in the Pacific North West (grin).
How's the weather where you are? Much rain and low clouds?
MD11Engineer From Germany, joined Oct 2003, 13614 posts, RR: 63 Reply 9, posted (5 years 5 months 1 week 6 days 20 hours ago) and read 2878 times:
Quoting HAWK21M (Thread starter): Presume its connected to the rudder steering system,thus limited to 7 deg average.
Can anyone explain.
You are talking about the B757, correct?
With the 757, during rollout steering, the NLG is controlled backwards through the normal rudder feedback by the rudder PCU's through the linkage between the rudder pedals and the NLG tiller (the one, which disconnects as soon as the NLG scissor is being extended).
Since the rudder pedal authority for nose wheel steering is limited to 7 degrees left or right, NLG control during rollout is limited to the same value, basically just to keep the plane on the runway centerline until the captain takes over with the tiller (which has control authority up to 65 degrees). The B757 is at maximum certified for CAT 3B operations, this means there must still be enough visibility for the captain to find his way to the gate. Auto-taxi is not included.