Sponsor Message:
Aviation Technical / Operations Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
Strange DC-9 Problem (NW 1749 10/26)  
User currently offlineCubsrule From United States of America, joined May 2004, 22864 posts, RR: 20
Posted (5 years 9 months 4 weeks 1 day 12 hours ago) and read 3713 times:

My wife asked me to try to get to the bottom of what happened on her NW flight, so I'm going to give it a shot...

She said they were descending normally when the f/as secured the cabin very quickly and then briefed the pax in the exit row. Despite the winds being relatively calm, she reported a lot of lateral motion on approach (like what happens on the ERJ, but worse) and then a very hard landing. They then taxied normally to the gate and deplaned; she didn't see any emergency equipment. She asked me what had happened and, based on what she reported, I didn't have a clue. I figured I'd at least take a stab at it here.


I can't decide whether I miss the tulip or the bowling shoe more
15 replies: All unread, jump to last
 
User currently offlineLiedetectors From United States of America, joined Jul 2005, 360 posts, RR: 0
Reply 1, posted (5 years 9 months 4 weeks 1 day 6 hours ago) and read 3624 times:

Yaw damper failure on approach perhaps?


If it was said by us, then it must be true.
User currently offlineCubsrule From United States of America, joined May 2004, 22864 posts, RR: 20
Reply 2, posted (5 years 9 months 4 weeks 23 hours ago) and read 3570 times:



Quoting Liedetectors (Reply 1):
Yaw damper failure on approach perhaps?

That was the first thing that popped into my mind too; I wonder if that is serious enough to brief the exit row passengers.



I can't decide whether I miss the tulip or the bowling shoe more
User currently offlineCosmicCruiser From United States of America, joined Feb 2005, 2255 posts, RR: 15
Reply 3, posted (5 years 9 months 4 weeks 22 hours ago) and read 3545 times:

Maybe someone who has flown a DC-9 can comment but in the 727 I don't remember it being an issue at low altitudes. I had only one yaw damp failure and at altitude there was some dutch roll but descending to a slightly lower alt toook care of that and we completed the flight.

User currently offlineCrimsonNL From Netherlands, joined Dec 2007, 1858 posts, RR: 42
Reply 4, posted (5 years 9 months 4 weeks 20 hours ago) and read 3507 times:
AIRLINERS.NET CREW
CHAT OPERATOR

Pardon for asking, but what effect does it have once the Yaw-Dampers fail?


Nothing's worse then flying the same registration twice, except flying it 4 times..
User currently offlineEMBQA From United States of America, joined Oct 2003, 9364 posts, RR: 11
Reply 5, posted (5 years 9 months 4 weeks 17 hours ago) and read 3439 times:



Quoting Cubsrule (Thread starter):
Despite the winds being relatively calm,

According to who...?Sounds like gusty conditions to me. Often you will get layers of winds. At 20,000ft it's calm, at 15,000ft it's gusty



"It's not the size of the dog in the fight, but the size of the fight in the dog"
User currently offlineEMBQA From United States of America, joined Oct 2003, 9364 posts, RR: 11
Reply 6, posted (5 years 9 months 4 weeks 17 hours ago) and read 3435 times:



Quoting Cubsrule (Reply 2):
I wonder if that is serious enough to brief the exit row passengers

Briefing the exit row passengers is very common on many airlines before landing. It's just to remind them of their conditions for sitting in that row and what they might be called on to do.



"It's not the size of the dog in the fight, but the size of the fight in the dog"
User currently offlineCubsrule From United States of America, joined May 2004, 22864 posts, RR: 20
Reply 7, posted (5 years 9 months 4 weeks 17 hours ago) and read 3433 times:



Quoting EMBQA (Reply 5):
According to who...?Sounds like gusty conditions to me. Often you will get layers of winds. At 20,000ft it's calm, at 15,000ft it's gusty

She said the yaw issue occurred on final, so the METAR should be pretty close to what the conditions were.

KMEM 262053Z 31010KT 10SM FEW050 24/12 A3002 RMK AO2 SLP164 T02440117 55007



I can't decide whether I miss the tulip or the bowling shoe more
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17015 posts, RR: 67
Reply 8, posted (5 years 9 months 4 weeks 11 hours ago) and read 3314 times:



Quoting CrimsonNL (Reply 4):
Pardon for asking, but what effect does it have once the Yaw-Dampers fail?

As I understand it: The pilot flying has to coordinate turns himself (work the rudder) and in a swept wing jet this is not a trivial endeavor. You can thus get some fishtailing.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineCosmicCruiser From United States of America, joined Feb 2005, 2255 posts, RR: 15
Reply 9, posted (5 years 9 months 4 weeks 9 hours ago) and read 3261 times:

DUTCH ROLL DESCRIPTION
This section describes the procedures and techniques
used to familiarize the pilot with dutch roll recovery.
At high altitudes and high Mach number, dutch
roll may occur with both yaw dampers inoperative. At
low altitudes and low airspeed, the roll is dampened
sufficiently so that a no-yaw-damper approach and
landing presents no problem.
Dutch roll, as experienced in the B-727, differs from
that in other swept wing airplanes not only in speed of
occurrence, but in characteristics. The B-727 has
more side-slip per degree of bank angle and the bank
angle should not be allowed to exceed plus or minus
8° from the initial bank angle. Oscillations exceeding
the 8° limits impose excessive stress on the empennage
and could possibly cause structural damage.


User currently offlineAA737-823 From United States of America, joined Mar 2000, 5766 posts, RR: 11
Reply 10, posted (5 years 9 months 4 weeks 4 hours ago) and read 3201 times:



Quoting Starlionblue (Reply 8):
As I understand it: The pilot flying has to coordinate turns himself (work the rudder) and in a swept wing jet this is not a trivial endeavor. You can thus get some fishtailing.

This can get VERY ugly in a hurry. Especially for anyone seated aft of the wing- make sure those barf bags are in place!!!!! Lol.

It's hard for a pilot to coordinate his turns properly in this class of aircraft. I mean, granted, they're just pilots, but still- I'll give them some credit with this one!!


User currently offlineCosmicCruiser From United States of America, joined Feb 2005, 2255 posts, RR: 15
Reply 11, posted (5 years 9 months 3 weeks 6 days 22 hours ago) and read 3153 times:

As I posted IF you did have yaw damp fail you certainly would not be pushing on the rudders, at least not in the 727. The slightest input both aileron or rudder starts a yawing that is stabilized only thru opposite inputs of the aileron. As the description says above at high mach and alt you would stabilize the yaw and descend; at low alt it's not a factor. As I posted it happened to me only once CLT-MEM and the recovery was much easier than what we always saw in the sim. We went down a few flight levels and continued on. The recovery requires an aileron input opposite the direction of the bank/yaw followed by a quick small input in the other direction. Done right the yaw stops very quickly, done wrong and you will lose control.

User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 12, posted (5 years 9 months 3 weeks 6 days 22 hours ago) and read 3146 times:



Quoting Starlionblue (Reply 8):
As I understand it: The pilot flying has to coordinate turns himself (work the rudder) and in a swept wing jet this is not a trivial endeavor. You can thus get some fishtailing.



Quoting AA737-823 (Reply 10):
This can get VERY ugly in a hurry. Especially for anyone seated aft of the wing- make sure those barf bags are in place!!!!! Lol.

It's hard for a pilot to coordinate his turns properly in this class of aircraft. I mean, granted, they're just pilots, but still- I'll give them some credit with this one!!

I have to jump in here and back up what CosmicCruiser is saying. I have never flown the DC-9 series, but like CC have flown the 727. Down at lower altitudes failure of a yaw damper is a non event. The airspeeds are too slow to have any adverse yaw be strong enough to start the Dutch Roll process. I can't imagine the DC-9 being any worse than the 727.

As to what it was, who knows, perhaps an over zealous FA or some minor malfunction that the cockpit crew didn't have a chance to advise the passengers about. Either way, at the end of the day, the takeoffs and landings were the same and that's what counts.


User currently offlineCubsrule From United States of America, joined May 2004, 22864 posts, RR: 20
Reply 13, posted (5 years 9 months 3 weeks 6 days 20 hours ago) and read 3102 times:



Quoting PhilSquares (Reply 12):
As to what it was, who knows, perhaps an over zealous FA or some minor malfunction that the cockpit crew didn't have a chance to advise the passengers about.

Based on the lack of emergency equipment (and the normal taxi), I'd say an overzealous f/a might be a good guess... still, I've probably flown close to 100 NW flights, and I've never seen them say anything to exit row pax prior to landing.



I can't decide whether I miss the tulip or the bowling shoe more
User currently offlineKimberlyrj From United Kingdom, joined Mar 2008, 385 posts, RR: 1
Reply 14, posted (5 years 9 months 3 weeks 6 days 17 hours ago) and read 3059 times:



Quoting EMBQA (Reply 6):
Briefing the exit row passengers is very common on many airlines before landing. It's just to remind them of their conditions for sitting in that row and what they might be called on to do.

Its something we are starting to do at British Airways on short haul flights and on long haul flights an announcement is made prior to landing asking passengers to remind themselves where their nearest exit is located.

On flights that are 11 hours plus the crew will point out the nearest exits to were passengers are seated.

Not sure what other airlines do though…

Kimberly.


User currently offlinePGNCS From United States of America, joined Apr 2007, 2821 posts, RR: 45
Reply 15, posted (5 years 9 months 3 weeks 1 day 13 hours ago) and read 2767 times:



Quoting AA737-823 (Reply 10):
Quoting Starlionblue (Reply 8):
As I understand it: The pilot flying has to coordinate turns himself (work the rudder) and in a swept wing jet this is not a trivial endeavor. You can thus get some fishtailing.

This can get VERY ugly in a hurry. Especially for anyone seated aft of the wing- make sure those barf bags are in place!!!!! Lol.

It's hard for a pilot to coordinate his turns properly in this class of aircraft. I mean, granted, they're just pilots, but still- I'll give them some credit with this one!!

It is not difficult in the DC-9.

Quoting PhilSquares (Reply 12):
I have to jump in here and back up what CosmicCruiser is saying. I have never flown the DC-9 series, but like CC have flown the 727. Down at lower altitudes failure of a yaw damper is a non event. The airspeeds are too slow to have any adverse yaw be strong enough to start the Dutch Roll process. I can't imagine the DC-9 being any worse than the 727.

You are right, Phil. The DC-9 series is much tamer than the 727 in this regard. Unlike the 727, it is a nonevent at any speed and altitude.

Quoting PhilSquares (Reply 12):
As to what it was, who knows, perhaps an over zealous FA or some minor malfunction that the cockpit crew didn't have a chance to advise the passengers about. Either way, at the end of the day, the takeoffs and landings were the same and that's what counts.

 checkmark 


Top Of Page
Forum Index

Reply To This Topic Strange DC-9 Problem (NW 1749 10/26)
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...
NW DC-10-40s Engines posted Wed Aug 29 2007 13:30:37 by OceansWorld
DC-10 Weight Change? posted Tue May 6 2008 12:15:33 by DC10student
Changes In Materials And Weight Of The DC-10 posted Sat May 3 2008 06:29:47 by DC10student
DC-10 Structure posted Fri May 2 2008 05:18:58 by DC10student
CF6-6 Engine On DC-10... Why The Weird Cone? posted Tue Mar 4 2008 08:11:31 by BR715-A1-30
DC-10 Fuel Fill Valves posted Tue Dec 4 2007 23:39:14 by HawaiianHobo
NW DC-9 "Late Acceleration" posted Mon Nov 5 2007 19:44:32 by NW747-400
"Broken" DC-10-30 posted Tue Sep 4 2007 19:07:16 by Fxfan
DC-8 And DC-10 Aileron Design posted Sat Sep 1 2007 03:19:18 by Blackbird
DC-10 Front Door Arm/disarm Handle Question posted Wed Aug 29 2007 21:47:07 by NWA320

Sponsor Message:
Printer friendly format