sxmarbury33
Posts: 405
Joined: Fri Oct 20, 2000 5:41 am

Autoland Wind Restriction

Fri May 31, 2002 8:35 am

Ok from what i have read the autoland restriction is xwind 10 knots. First question what happenes if a pilot initiates an autoland with a crosswind of 7 knots but sometime during the approach it gets up to 15. Does the pilot have to execute a missed or can he take over control manually. Second are pilots allowed to go manual after DH or to they have to hit the TOGA to go around?
 
AJ
Posts: 2295
Joined: Wed Nov 03, 1999 3:54 pm

RE: Autoland Wind Restriction

Fri May 31, 2002 9:22 am

The 767s autoland crosswind capability is 25kts, except on a contaminated runway, where it is 12kts, or very low visibility (<1200m/<600m) where it is lower (15kts/10kts respectively).
The autopilot will still attempt the autoland if wind speeds exceed these limits, but Mr. Boeing cannot guarantee that it will be successful. Once the runway alignment process takes place the autopilot will go to the limits of yaw and roll to try maintain localiser, if the wind is stronger than it allows for then the aircraft will fly out of tolerance and a go-around would have to be initiated. The same applies on the runway, however a wet runway could allow the aircraft to slide off the side, thus the lower limit.
The go-around is initiated if below Cat 1 minima and the aircraft is outside tolerance, normally autocoupled. If at or above Cat 1 minima and the crew becomes visual the autopilot may be disengaged and the approach flown manually. This is known as reversion and allows up to 33kts (+5kt gusts) of crosswind.
Depending on the airline's procedures use of the go around switch is required for a missed approach to apply thrust to GA limits and provide pitch and roll guidance to the flight directors. Not activating the TOGA switches was cited as one of the causes for the QF1 accident at Bangkok:

View Large View Medium
Click here for bigger photo!

Photo © K W Chui

http://www.atsb.gov.au/aviation/acci/ojh/index.cfm
Whether or not the autopilot is engaged is another matter. The MA can be flown manually, but as it is a relatively high workload period the AP relieves some pressure!
Hope this helps.
 
sxmarbury33
Posts: 405
Joined: Fri Oct 20, 2000 5:41 am

RE: Autoland Wind Restriction

Fri May 31, 2002 11:05 am

Sorry i worded that second question bad. Lets say the wind is 25 knots at lets say a 200agl DH and right after the minimas call the wind increases to 27. Is the pilot alowed to disengage and handfly or would he have to go around since he is below minimums.
 
Rick767
Posts: 2613
Joined: Sun Jan 30, 2000 8:11 pm

RE: Autoland Wind Restriction

Fri May 31, 2002 12:09 pm

For the 757/767 (Britannia Airways):

Max Headwind: 25kt
Max Crosswind: 25kt
Max Tailwind: 15kt

Company policy if RVR < 100m, Max Crosswind reduced to 10kt.
No reduction for a "wet" runway, autoland not permitted on a "slippery" runway.

"Lets say the wind is 25 knots at lets say a 200agl DH and right after the minimas call the wind increases to 27. Is the pilot alowed to disengage and handfly or would he have to go around since he is below minimums."

For the sake of 2 knots no problem, would be difficult to notice and while the non-flying pilot is monitoring the flight instruments during the approach and landing phase he would not normally announce such a small issue.

If it was a more sudden gust to a higher level then provided the approach can be continued under Cat 1 minima, the AP can be disconnected and a manual landing flown, otherwise a go-around can still be made if the flying pilot sees that as the safest course of action.

Rick.
I used to love the smell of Jet-A in the morning...
 
411A
Posts: 1788
Joined: Mon Nov 12, 2001 10:34 am

RE: Autoland Wind Restriction

Fri May 31, 2002 3:38 pm

The Lockheed L1011 (standard long body aeroplane) was certified to land with 35 knots direct crosswind. Most airlines (or their regulatory authority) limit the crosswind component, especially in low visibility or wet runways.

Who is online

Users browsing this forum: No registered users and 20 guests