Cubsrule From United States of America, joined May 2004, 21246 posts, RR: 19 Posted (4 years 7 months 2 days 3 hours ago) and read 3214 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
Liedetectors From United States of America, joined Jul 2005, 357 posts, RR: 0 Reply 1, posted (4 years 7 months 1 day 21 hours ago) and read 3125 times:
Cubsrule From United States of America, joined May 2004, 21246 posts, RR: 19 Reply 2, posted (4 years 7 months 1 day 14 hours ago) and read 3071 times:
CosmicCruiser From United States of America, joined Feb 2005, 2214 posts, RR: 16 Reply 3, posted (4 years 7 months 1 day 13 hours ago) and read 3046 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.
EMBQA From United States of America, joined Oct 2003, 9292 posts, RR: 13 Reply 6, posted (4 years 7 months 1 day 8 hours ago) and read 2936 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"
Cubsrule From United States of America, joined May 2004, 21246 posts, RR: 19 Reply 7, posted (4 years 7 months 1 day 8 hours ago) and read 2934 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.
Starlionblue From Hong Kong, joined Feb 2004, 15873 posts, RR: 66 Reply 8, posted (4 years 7 months 1 day 2 hours ago) and read 2815 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." - from Citadel by John Ringo
CosmicCruiser From United States of America, joined Feb 2005, 2214 posts, RR: 16 Reply 9, posted (4 years 7 months 1 day ago) and read 2762 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.
AA737-823 From United States of America, joined Mar 2000, 5344 posts, RR: 11 Reply 10, posted (4 years 7 months 19 hours ago) and read 2702 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!!
CosmicCruiser From United States of America, joined Feb 2005, 2214 posts, RR: 16 Reply 11, posted (4 years 7 months 13 hours ago) and read 2654 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.
PhilSquares From , joined Dec 1969, posts, RR: Reply 12, posted (4 years 7 months 13 hours ago) and read 2647 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.
Cubsrule From United States of America, joined May 2004, 21246 posts, RR: 19 Reply 13, posted (4 years 7 months 11 hours ago) and read 2603 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
Kimberlyrj From United Kingdom, joined Mar 2008, 385 posts, RR: 1 Reply 14, posted (4 years 7 months 8 hours ago) and read 2560 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.
PGNCS From United States of America, joined Apr 2007, 2516 posts, RR: 45 Reply 15, posted (4 years 6 months 3 weeks 4 days 4 hours ago) and read 2268 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.
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