Sponsor Message:
Aviation Technical / Operations Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
No Slope Correction For Certain Autobrake Setting  
User currently offlinesmartt1982 From United Kingdom, joined Nov 2007, 225 posts, RR: 0
Posted (1 year 6 months 3 weeks 5 days 5 hours ago) and read 1654 times:

On the inflight landing calculations for the 737-800 for a Dry runway with Auto brake 3, there is no corrections to apply for the slope of the runway.

I believe we only accept 2% up/down on a runway but there are corrections for all the other auto brake settings, just wondering why nothing for AB3?

3 replies: All unread, jump to last
 
User currently offlineMax Q From United States of America, joined May 2001, 4435 posts, RR: 19
Reply 1, posted (1 year 6 months 3 weeks 4 days 21 hours ago) and read 1571 times:

Why would you need a slope correction for an autobrake setting ?


The Autobrakes provide a predetermined rate of deceleration for each setting not affected by slope.



The best contribution to safety is a competent Pilot.
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 2, posted (1 year 6 months 3 weeks 4 days 20 hours ago) and read 1556 times:

Quoting smartt1982 (Thread starter):
On the inflight landing calculations for the 737-800 for a Dry runway with Auto brake 3, there is no corrections to apply for the slope of the runway

Strictly speaking, there is a correction, it just happens to be zero for that particular combination. For the same slope on other runway surface conditions, it's non-zero.

Quoting Max Q (Reply 1):
Why would you need a slope correction for an autobrake setting ?

I was wondering that too, but I think it falls out of the way landing distances are calculated...they come off actual data and, with slope, if you cross the threshold at the correct height your touchdown point is going to move a little bit. The roll distance from the time the brakes come on shouldn't change with slope for autobrakes, but the distance from the threshold to the start of braking will change.

If you look at some of the data, there are obvious trend reversals, which wouldn't happen if you were doing analytic solutions but can happen if you're generating the data with actual performance landing data.

Tom.


User currently offlinevikkyvik From United States of America, joined Jul 2003, 9901 posts, RR: 26
Reply 3, posted (1 year 6 months 3 weeks 4 days 1 hour ago) and read 1435 times:
Support Airliners.net - become a First Class Member!

Quoting tdscanuck (Reply 2):
I was wondering that too, but I think it falls out of the way landing distances are calculated...they come off actual data and, with slope, if you cross the threshold at the correct height your touchdown point is going to move a little bit. The roll distance from the time the brakes come on shouldn't change with slope for autobrakes, but the distance from the threshold to the start of braking will change.

That's certainly true. For a standard 3 degree glide path, 50 foot TCH, and discounting flare, your touchdown point will move like so:

% upslope - touchdown point (feet from threshold)

0.0 - 954
0.1 - 936
0.2 - 919
0.3 - 902
0.4 - 886
0.5 - 871
1.0 - 801

(that's of course assuming the main gear is at 50 feet when crossing the threshold)

As far as autobrakes go, with a constant deceleration rate, the brakes simply won't have to work as hard if you're landing on an upslope. They'll have to work harder if you're landing on a downslope.

Is that the basic gist of it?



"Two and a Half Men" was filmed in front of a live ostrich.
Top Of Page
Forum Index

Reply To This Topic No Slope Correction For Certain Autobrake Setting
Username:
No username? Sign up now!
Password: 


Forgot Password? Be reminded.
Remember me on this computer (uses cookies)
  • Tech/Ops related posts only!
  • Not Tech/Ops related? Use the other forums
  • No adverts of any kind. This includes web pages.
  • No hostile language or criticizing of others.
  • Do not post copyright protected material.
  • Use relevant and describing topics.
  • Check if your post already been discussed.
  • Check your spelling!
  • DETAILED RULES
Add Images Add SmiliesPosting Help

Please check your spelling (press "Check Spelling" above)


Similar topics:More similar topics...
Why No Decompression Training For Civil Pilots? posted Tue May 22 2007 01:35:47 by Ukair
Why No Bigger CRJs For NWA Airlink? posted Wed Nov 30 2005 08:27:01 by AirWillie6475
Where To Find O&D Numbers For Certain Cities posted Thu Jul 28 2005 15:47:21 by DLKAPA
Why No C-130 Aircraft For Cargo Airlines? posted Fri Mar 18 2005 01:19:54 by PPVRA
Why No RPM Display For Big Jets? posted Sat Jan 5 2002 12:29:42 by Trent_800
Info Needed: How Much Runway For Certain A/C? posted Mon Oct 22 2001 20:27:04 by Airsicknessbag
No Varable Area Fan Nozzles For CSeries...Why? posted Thu Dec 20 2012 21:58:59 by JoeCanuck
Why No Winglets On Brand New 767 For JAL? posted Thu Nov 25 2010 14:01:25 by windshear
No ETOPS For GEnx And Trent 1000? posted Sun Apr 26 2009 09:31:33 by A342
Why No Winglets For Class B747? posted Thu Oct 2 2008 10:05:44 by Warren747sp

Sponsor Message:
Printer friendly format