View Full Version : Do any APs "crab" in a crosswind?
I understand that most APs don't have rudder authority so at some point, say on approach, you'd have to take over but are there any APs that can hold an approach like this? Will an AP disconnect if you handle the rudder to keep the plane aligned on the localizer?
Intruder
30th Jan 2021, 23:16
The 747-400 and -8, when in Autoland mode with all 3 Autopilots engaged, will both crab and induce wing-down and top-rudder sideslip, as needed for crosswind. AFAIK, there is no Autopilot disconnect when attempting to use the rudder pedals.
Denti
31st Jan 2021, 08:43
The 737NG in fail operational dual channel (LAND2/3) operation crab, it will induce wing low as needed to a certain extent as well during the final stages of the approach. At least in the simulator you cannot disconnect the AP by using the rudder pedals.
Uplinker
31st Jan 2021, 10:07
Airbus FBW auto-pilots do have 3 axis control, i.e. including rudder control, (and control of nose-wheel steering).
So for an auto-land the auto-pilot(s) does fly a crabbed approach (at max 20 kts cross-wind), and decrabs on touch-down. Then it steers along the RWY centreline until the auto-pilot is disconnected.
Intruder
As I recall it the 777 does something similar.