Mastropiero From Spain, joined Dec 2005, 120 posts, RR: 0 Posted (3 years 6 months 5 days 18 hours ago) and read 6769 times:
Hi everyone!
I have come on many ocasions across this, without ever understanding what do you talk about when you refer to either "normal law" or "direct law". I have done some research but, alas, no useful results so far.
Would you mind explaining what do you mean when you refer to it?
I hope it is not something as simple as to make me blush with shame for not being able to figure it out myself....
WILCO737 From Greenland, joined Jun 2004, 8006 posts, RR: 83 Reply 2, posted (3 years 6 months 5 days 18 hours ago) and read 6746 times:
AIRLINERS.NET CREW FORUM MODERATOR
Quoting Mastropiero (Thread starter): I have come on many ocasions across this, without ever understanding what do you talk about when you refer to either "normal law" or "direct law". I have done some research but, alas, no useful results so far.
The "normal law" is the normal way or controlling Airbus Aircrafts. like 320s or 340s. Then the airplane trims on its own and maintains the bank and pitch etc etc. With the "direct law" the Airbus flies like a boeing.
I don't know too much about it, as I am flying MDs. But I am sure the Airbus pilots will explain it to you more detailed.
Jetlagged From United Kingdom, joined Jan 2005, 2371 posts, RR: 15 Reply 4, posted (3 years 6 months 5 days 17 hours ago) and read 6718 times:
Normal and direct law are levels of control provided by the FBW system
Normal Law provides envelope protection (which prevents stalls, overspeed, excessive g, etc). It also provides autotrim so the aircraft stays in the attitude it was put when the control was released (within limits).
Direct Law provides no envelope protection and the sidestick moves the control surfaces in proportion to the control input. The stabilizer trim has to be moved manually by the pilot, there is no electric trim.
In between these two there is Alternate Law, which provides much reduced protection and speed stability. Pitch trim is automatic, as with Normal Law.
Degredation from Normal to Alternate or Direct Law is automatic, depending on system failures.
TristarSteve From Sweden, joined Nov 2005, 3489 posts, RR: 36 Reply 5, posted (3 years 6 months 5 days 14 hours ago) and read 6656 times:
Quoting Jetlagged (Reply 4): Degredation from Normal to Alternate or Direct Law is automatic, depending on system failures.
In 20 years on the A320, I have only once encountered Direct Law in flight. An A320 had a double failure of an elevator posn transmitter, and went into direct law. Saw the words direct law on the PFR.
One and only time.
Tdscanuck From Canada, joined Jan 2006, 11028 posts, RR: 72 Reply 7, posted (3 years 6 months 5 days 10 hours ago) and read 6610 times:
Quoting WILCO737 (Reply 2): With the "direct law" the Airbus flies like a boeing.
That's not true for FBW Boeing's (i.e. the 777). A 777 has normal, secondary (equivalent to Airbus' "alternate"), and direct (same as Airbus' "direct").
Jetlagged From United Kingdom, joined Jan 2005, 2371 posts, RR: 15 Reply 9, posted (3 years 6 months 4 days 22 hours ago) and read 6553 times:
Quoting TristarSteve (Reply 5): In 20 years on the A320, I have only once encountered Direct Law in flight. An A320 had a double failure of an elevator posn transmitter, and went into direct law. Saw the words direct law on the PFR.
One and only time.
I suspect most pilots only ever see it in the simulator. My experience of trying Direct Law out in the sim is that it is pretty ugly, certainly worse than hand flying a non FBW aircraft.
The glass isn't half empty, or half full, it's twice as big as it needs to be.
Sponsor Message: 
From Spain, joined Dec 2005, 120 posts, 
From India, joined Jul 2005, 1403 posts, 
From Greenland, joined Jun 2004, 8006 posts, 
From United Kingdom, joined Jan 2005, 2371 posts, 
From Sweden, joined Nov 2005, 3489 posts, 
From Canada, joined Jan 2006, 11028 posts, 
From United States of America, joined Apr 2007, 2443 posts, 
Sponsor Message: 
Printer friendly format
