Continental 737 Off Runway at DEN

[Mark in CA]

Reports just coming in about a Continental Airlines 737 flight 1404 off the runway at DEN during takeoff this eveninig. About 140 on board, about 36 injuries, no fatalities, all evacuated. Conditions cold, but dry.

[JET2LBIA]

737-500 - En route to IAH it seems. Any further news?

[PlatinumFlyer]

Follow-up comments from a report:

Garrod says after the aircraft was evacuated, the fire spread inside the aircraft, and crews had to go inside to extinguish it.

One of passengers, Maria Trejos, tells 9NEWS the plane was trying to take off, got into the air for a few seconds and then slammed back down into the ground into a ravine off the runway. At that point there was some sort of explosion on the right side of the plane and she saw a big ball of flames.

She says the plane then skidded to a halt after it went off the runway. Passengers were then evacuated to emergency exits and also the slides

[Jofm5]

Source: FAA: Plane goes off Denver runway, catches fire - USATODAY.com (http://www.usatoday.com/travel/flights/2008-12-20-denver-runway_N.htm?csp=34)

USA today quoting FAA (uncomfirmed) 7 injured during evacuation.

[PlatinumFlyer]

Continental Airlines Statement Regarding Flight 1404
HOUSTON, Dec. 20 /PRNewswire-FirstCall/ -- Continental Airlines (NYSE: CAL) tonight confirmed that flight 1404, a Boeing 737-500 aircraft carrying 107 customers and five crew members, exited the runway at Denver International Airport following a scheduled 6 p.m. MST departure to Houston Bush Intercontinental Airport. Continental and Denver International Airport are providing assistance to the passengers at this time. A number of injuries have been reported and authorities are transporting passengers and crew to area medical facilities as necessary.

The company is in the process of collecting additional information and will communicate additional information once it is known.

SOURCE Continental Airlines

[visibility3miles]

Nearly 40 people were hurt when a Continental Airlines jet taking off from Denver left the runway and caught fire, officials have said.

All 107 passengers and five crew members had to exit the Boeing 737 using emergency chutes.
BBC NEWS | Americas | Injuries as US jet leaves runway (http://news.bbc.co.uk/2/hi/americas/7794239.stm)

So, why? Why no takeoff? Weather?

Sleet, snow etc.

[Enderby-Browne]

I just wish the proper authorities would stop building runways alongside ravines.

[act700]

I really wish a/c manufacturers would stop building airplanes that catch fire.

No wait, what I really wish is for people to stop getting hit by busses crossing the street.
:mad:

[radeng]

From the San Diego Union Tribune

"Emily Pellegrini, a 21-year-old student at the University of Colorado at Colorado Springs, was on her way to Houston to see her parents. She left her cell phone and all her personal items behind in the rush to get off the plane.

"There was a fire after the crash, and I just went with the flow off the plane," she told The Denver Post. "That seemed like the thing to do." "

Are they suggesting that people did stop to grab personal belongings? Maybe Emily actually LISTENED to the safety briefing and did the right thing.

MORAL: listen and watch the CC when they do the safety briefing. It could save your life...

[LHR_777]

The aircraft involved was B737-524 ship number 611.

Reg - N18611
First flight 31st May 1994
First registered 14th June 1994
MSN - 27324
LN- 2621

[PlatinumFlyer]

News continues to dribble in. Apparently pretty serious:

"The blaze went on to cause significant fire damage inside the cabin with overhead luggage compartments melting and dripping onto the seats."

"Debris remained on the runway, with the plane about 200 yards away and its landing gear shorn off, Hynes said. The plane's left engine was also shorn off, FAA spokesman Ian Gregor said."

"The plane veered off course about 2,000 feet from the end of the runway and did not appear to be airborne, said Kim Day, manager of aviation for Denver International Airport." Many other reports that the aircraft had begun to rotate. Of note is the fact that the runway in use was 34R and 12,000 feet long.

[Glonass]

METAR around time of the accident (18:18 LT / 01:18 UTC); winds tend to pick up with gusty conditions.

KDEN 210053Z 28011KT 10SM FEW040 SCT100 M06/M16 A2997 RMK AO2 PK WND 29027/0000 SLP202 T10561161

KDEN 210134Z 29024G32KT 10SM FEW040 SCT100 M04/M18 A2998 RMK AO2 PK WND 28036/0123

KDEN 210153Z 30018G28KT 10SM FEW040 SCT100 M05/M17 A3000 RMK AO2 PK WND 28036/0123 SLP202 T10501172

KDEN 210253Z 29018KT 10SM FEW040 BKN100 M05/M18 A3002 RMK AO2 SLP205 T10501178 51027

[captplaystation]

Hope this one doesn't have shades of Spanair.
De-iced therefore didn't put flaps down at normal point.
Missed it on check-list
Oh & the TOWS would have to be U/S . . wouldn't it ? ?:ooh:

[Airbubba]

Hope this one doesn't have shades of Spanair.

Shhhh... don't even think it. The other scenario is abort after Vr. We'll see...

[frankpgh]

************************************************************

NTSB SENDS GO TEAM TO DENVER TO
INVESTIGATE 737 TAKEOFF ACCIDENT

************************************************************

The National Transportation Safety Board has dispatched a Go Team to Denver, Colorado to investigate the crash of an airliner on takeoff last night.

At 6:18 p.m., Mountain Standard Time, Continental Airlines flight 1404, a Boeing 737-500 (N18611), suffered an accident while on its takeoff roll for a scheduled flight to Houston, Texas. Although there have been injuries, no fatalities have been reported. Regional NTSB investigators were on the scene of the accident within hours.

NTSB Senior Air Safety Investigator Bill English is the Investigator-in-Charge for the team of approximately a dozen investigators. NTSB Member Robert Sumwalt is accompanying the team and will serve as principal spokesman for the on-scene investigation. Terry Williams is the team's press officer.

The Go Team is expected to arrive in Denver later this morning. At that time, Mr. Williams may be reached on his
cell phone at 202-557-1350.

[captainspeaking]

My thoughts as ever at this difficult time are with the insurers. Happily my Lloyds syndicate doesn't handle aviation.

[Longtimer]

Here is the go to to a slideshow of the aircraft. Note the left engine lying ahead of the wing. Flaps clearly deployed.


9NEWS.com | Colorado's Online News Leader | 9Slideshows Gallery | Continental1404 (http://www.9news.com/9slideshows/gallery.aspx?slideshowname=Continental1404&N=8)

[FlyingConsultant]

reasonably good posting here (http://www.thedenverchannel.com/news/18327329/detail.html#-). Journalism, obviously, but at least they quote an Ex-NTSB guy saying that just because passengers say that the plane was in flight doesn't make it so. Injuries mainly because a chute did not go all the way to the ground (no reason why that's the case but I am sure that will come out)

Personally, I am impressed with both the evacuation and the emergency crews/firefighters. If all is true, this gives me comfort that crews and large airports are well prepared for bad events.

Well done all for the evacuation

[captplaystation]

Longtimer
One potentialy very embarrasing cause discounted at least.

[belhavenrocks]

of course it still isnt known when the flaps were deployed...i hope it was long before the evac

[Continuous Ignition]

Looks like the LE devices were down meaning at least some degree of Flaps were deployed.

Have a look at 9NEWS.com | Colorado's Online News Leader | 9Slideshows Gallery | Continental1404 (http://www.9news.com/9slideshows/gallery.aspx?slideshowname=Continental1404&N=10)

For any of you 737 drivers out there, what is the crosswind limit for the 737-500? I'm not 100% sure but with winglets (which this 500 was fitted with) decreases the Max crosswind limit.

AeroPlanner.com (http://www.aeroplanner.com/calculators/avcalcdrift.cfm)

How that plays into the accident, who knows.. Lets wait to see what the NTSB says... Should be interesting none the less..

[xxgunnerxx]

The media is reporting that the airplane did takeoff for a few seconds, maybe they had an engine failure during Vr, started to just leave the ground and caught wind gust which pushed it down to the ground? :ugh:

[HighLow]

The fact the leading edges appear to be down in the picture, does not mean that the flaps were deployed for TakeOff.

Flying the 737 on the line, as part of the evacuation drill, we select FLAPS to assist with the evacuation.

Watch this space, think there is something more to this story,
Crew forgetting to set the flaps NOT to be ruled out yet.

HighLow

[Green-dot]

De-iced therefore didn't put flaps down at normal point.


Viewing the published pictures sofar it seems flaps and slats were selected.

But what is that crud on the fuselage and wings? Residue of a fire extinguishing agent, overnight frost or . . . . snow and ice not properly removed during de-icing?

[A310driver]

Pix on slide-show link show definite damage to right horiz stab apparently in-line wth right main gear. Catastrophic tire failure(s)?

[Hiflyer1757]

Looking at the DEN airport diagram
http://204.108.4.16/d-tpp/0813/09077AD.PDF

The aircraft was using 34R....video from a local tv station this morning shows a skid trail starting between F3 and F4 exiting to the left, crossing WC just east of Fire Station #4 and ending up just beyond. That distance, at first glance, would not be enough to attain V1 with a fully loaded 735 fueled for a decent length trip to IAH with the altitude impairment that KDEN has. If that is actually the case then flap settings/deployment may not be an issue.

Winds were reported off the left wing gusting to 32kt and the aircraft had been retrofitted with vertical wing tips. (A question I have is do these retrofit wingtips change crosswind ability on the aircraft?)

The debris field starts on the runway per reports...both turbines are at the aircraft with #1 offwing just ahead of the left wingtip and #2 still onwing but very beat up. The landing gear has been sheered off and is reported upstream in the debris field...one report said on the runway and another implied on taxiway WC. Aircraft is a writeoff with the fusealge having cracked open just aft of the wingbox.

[pattern_is_full]

We were pax on a flight that touched down at 6:10. Tower gave weather confirming the winds someone listed above - 220 @ 20 gusting high 30s.

For the main rways 35 L/R and 34 L/R that's a quartering tailwind.

The weather was mostly clear but there were obvious ice patches on the taxiways as we taxied in about 90 minutes after local sunset.

We were not aware that anything had happened until we left the airport by cab 25 minutes later and saw emergency equipment lights rolling on access roads and taxiways.

We were a United flight, so I was following the cockpit communications during approach on the cabin audio (ch. 9), and at least one other Frontier flight ahead of us requested rway 26 because "the winds are over our limits" for X-wind landing.

OTOH we had a smooth touchdown (757) on 35L a mile east of the accident rway and there was a Saab turboprop on a parallel approach with us to 35R that also landed OK at the same time.

Reports here all seem to point to a starboard engine/wing fire or explosion AFTER the plane had already veered and/or dropped, so it sounds like it may have been an aftereffect rather than the cause - but clearly it is way too early to rule much in or out.

Does sound like an inopportune wind gust will be one of several suspects.

Reports say the craft had traveled 2000 feet down the rway (corresponds to the diagram and analysis above) - would a 737 at 5,400 feet elev. have reached Vr and rotated in that distance? Seems short. OTOH a low speed would account for the relatively low number of casualties.

[kiwi1]

Girls/Guys , the a/c has winglets, so a 737-700 or greater, ie a NG, according to the 9NEWS.com | Colorado's Online News Leader | 9Slideshows Gallery | Continental1404 (http://www.9news.com/9slideshows/gallery.aspx?slideshowname=Continental1404&N=10) pix from the affiliate in DEN.

This is from a B777/A320 (ex) driver, so I stand to be corrected.

Hope the injured crew/passengers are OK, at at least in hospital with the right people looking after them.

Kiwi1

[Hiflyer1757]

CO says it is a classic 735....they are retrofitting them with winglets....it has confused a lot of folks but it is a 735. :8

Here is their statement
Continental Airlines Responds to Flight 1404 Accident: Financial News - Yahoo! Finance (http://biz.yahoo.com/prnews/081221/clsu908.html?.v=1)

HOUSTON, Dec. 21 /PRNewswire-FirstCall/ Continental Airlines (NYSE: CAL (http://finance.yahoo.com/q?s=cal&d=t) - News (http://finance.yahoo.com/q/h?s=cal)) tonight confirmed that flight 1404, a Boeing 737-500 aircraft carrying 110 customers and five crew members, went off the runway at Denver International Airport following a scheduled 6 p.m. MST departure to Houston Bush Intercontinental Airport

snip....

[captplaystation]

No it's a 500 all right (winglets retrofitted an increasingly common mod to save a bit of gas)
Older guys (300/400/500) had pitot probes under FD no 2 window where they would catch your b@lls during evacuation, the NG moved them forward to a more pilot friendly location.
Taxying behind it, the NG is the female version ( two holes below the fin for APU) the Classic is only blessed with one.
There you go simple guide to 737 model recognition. :rolleyes:

[Hiflyer1757]

They moved them...to save Pilot's privates??? Dang...all this time I thought it was because the jetway jockeys kept smashing them....the sensors I mean...grin

[pattern_is_full]

737 drivers (or equivalents): What are the dynamics of a twin-jet during acceleration in the early part of a TO roll?

I know the Guppies have a honking big rudder, but how does its effectiveness build up as speed increases? Is there a vulnerable point to a gust at moderate speeds (40-70kts) where the wing is starting to develop some lift and reduce tire contact ("light on its wheels") but not enough airflow for the rudder to be fully effective?

I'd guess if there is, then that is calculated in in certifying the X-wind limits, but that an overlimit gust at just that moment could make for a bad day.

[PJ2]

Highlow;
The fact the leading edges appear to be down in the picture, does not mean that the flaps were deployed for TakeOff.
Some observations and a question..

Extension of the slats alone would bring the stall speed down significantly. While the flaps can't be seen in the available photos, the fact that the slats are extended perhaps lends credence to correct extension of the flaps even given your helpful comment re evac procedures and extension of flaps, an interesting if not unfamiliar procedure, and my question is at what point in the Passenger Evacuation Checklist (QRH) is that checked/done and what setting is used? Additional question...are there any WAT circumstances in which a slats-only takeoff is made? - I ask because on the DC9, slats-only takeoffs were employed at high gross weights, (which this flight would certainly not have been). Just curious - not suggesting anything. The recorders will be in good shape.

We can see that the wind, as posted above anyway, was from the aircraft's left (west) side with a crosswind component of between 13kts, (sin50deg x 18kts) to (sin50deg x 38kts) 24kts on the gusts yet, (not particularly significant or unusual in and of itself), from the photos thus far available, the aircraft appears off the west side of 34R. No overhead photos seem to be available to confirm the site. One report stated that the aircraft was near WC when it departed the runway environment. WC is about 3800+ft from the threshold of 34R. I should think a typical takeoff run would be in the neighbourhood of 4500ft given WAT conditions and headwind.

[Mark in CA]

Am I imagining things, or do the photos we have so far show a rip around the circumference of the fuselage aft of the wings, wider at the top than on the sides? Makes me think the tail section of the plane almost came off. Would mean some pretty powerful downward force, no?

[pattern_is_full]

@Mark: Yep, big ol' crack. In the News9 slide show linked to on this thread above, the first slide shows the plane skipped over a ridge or dam across the ravine, topped by an access road (too skinny to be a taxiway/runway) - likely the one marked WC on the airport diagram. That thump (or the flop after it) probably cracked the hull and took the left engine off.

Airport officials who've been on the scene report the plane veered off the RIGHT side of the runway, BTW. That skinny ridge-top road I mentioned above, that is about 150 feet behind the tail, is not the runway.

But it's early, so I'm open to being corrected (or correcting myself) if I see better imagery.

[PJ2]

Mark in CA;
Would mean some pretty powerful downward force, no?
Yes, it is a crack. No it does not necessarily mean "downward" - the crack extends from the right side of the fuselage, across the top but does not appear on the left side of the fuselage. I don't know the 737 but that may be a joint where the rear fuselage section joins the over-wing section. That would be more consistent with stronger lateral forces than vertical forces although rough terrain will present a complex mixture of such forces, of course.

Note that the track of the aircraft curves very slightly left, and that the heading of the aircraft is pointing slightly left (about 10 to 15 degrees) of the track taken.

[LHR_777]

originally posed by kiwi1:
Girls/Guys , the a/c has winglets, so a 737-700 or greater, ie a NG, according to the 9NEWS.com | Colorado's Online News Leader | 9Slideshows Gallery | Continental1404 pix from the affiliate in DEN.

This is from a B777/A320 (ex) driver, so I stand to be corrected.

I'll correct you - I posted the aircraft type/registration/MSN and LN on the first page of this thread - post 11.

This is from a CO employee - me. Our classic 737's are retrofitted with winglets, as well as our NG 737 fleet.

[PJ2]

pattern is full;
That skinny ridge-top road I mentioned above, that is about 150 feet behind the tail, is not the runway.
Yes, knew that, it's just a service road.
Airport officials who've been on the scene report the plane veered off the RIGHT side of the runway, BTW.
Yes, it probably was the "right" side - looking south! The frame of reference needs to be enlarged from someone's "handedness" to a north-east-west-south grid! :}

Seriously...a right side departure doesn't correlate with the photos.

The shadows of the aircraft and service road taken as they are in morning sun, show that the aircraft maintained a northwesterly track as it left the runway. A left (west) side departure fits the available photographs. Going off the right side of 34R would mean that the aircraft "reversed course" to maintain the relationship it has with the service road - not possible! Take a look at the angle between the aircraft track and the service roads in the following diagram to see why:


http://img49.imageshack.us/img49/5618/aircrafttrackandpositioyg8.jpg

[hbiwe]

Conti Checklists on the 737 call for a Flap check several times, also on "Before Takeoff", they also have a Takeoff Config Warning Switch incorporated on all 737's. They have some of the best procedures on the 737 i have ever seen, contribution to flight safety due to training and standards is very high at CAL - i wonder what happened there... :ouch:

[PJ2]

hbiwe;
They have some of the best procedures on the 737 i have ever seen, contribution to flight safety due to training and standards is very high at CAL
I couldn't agree with you more strongly. We've had some excellent contact with your safety people - a great safety and operational culture, a full embracing of FOQA and ASAP programs - yes, it will be interesting to know what happened.

From an aerial video sequence, it appears that the a/c left the runway well before taxiway WC:

http://img514.imageshack.us/img514/4615/aerialview2008122113120gl7.jpg

[PlatinumFlyer]

Wall Street Journal -Crew comment. Appears to be an RTO followed by brake problem:
Braking Problem May Have Caused Denver Runway Accident - WSJ.com (http://online.wsj.com/article/SB122984038314824361.html)

[pattern_is_full]

PJ2 - yeah I'll buy your map/photo interpretation for now. Photos, esp. older ones seems confusing becasue 34L was a recent addition so not all web pix are up-to-date (e.g. they show WC ending just past rway 34R and the firehouse is missing on some maps/photos)

Trying to work up a set of captions for our newspaper's website right now - from nothing but video stills that show very little context. Glad to have Prrune as an image resource/cross-reference (no quotes - I promise!)

[seacue]

Message #42 looks as though they didn't miss a building (the fire station??) by very much.

[ZAGORFLY]

Nice evaquation?

I would say that: why the slides are detached?
have the crew secures the slide to the floor as procedures require?
Any injury occures becasue the pax had to jump out in the frozen ground?

[Machaca]

http://i337.photobucket.com/albums/n385/motidog/CO1404DEN1.jpg


http://i337.photobucket.com/albums/n385/motidog/CO1404DEN2.jpg

[Rapid D]

Nice first thought Captain - isn't "pilot error" enough of a knee-jerk outside of our profession??

[Airflight69]

Taking in consideration airport elevation, wind direction, and the distance the a/c traveled i highly doubt they reached Vr.
It looks like a good jolt from that ridge just after WC. I`m surprised no casualties considering a/c had a considerate amount of fuel on board.

[MNBluestater]

Nice evaquation?

I would say that: why the slides are detached?
have the crew secures the slide to the floor as procedures require?
Any injury occures becasue the pax had to jump out in the frozen ground ?

You're viewing photos from the next morning. The slides were obviously detached, probably by the fire department in order to facilitate getting into the aircraft to put out fire or by the safety team to obtain the data recorders. There is a ladder by L1.

From the photos it appears slides L1, R1 and the left window exit would have been used--since fire would have been on right side of a/c.

BTW, slides are armed prior to pushback from the gate on departure and upon arrival at the gate. Standard operating procedure.

[MNBluestater]

the photo above makes much more sense

[MNBluestater]

Message #42 looks as though they didn't miss a building (the fire station??) by very much.

Seems like a stupid idea to me to put a fire station between parallel runways....

[RatherBeFlying]

... firefighters train daily for situations like this one, but none of them had experienced it... They knew what to do: One group attacks the fire, another assists injured passengers, and another climbs inside the plane to search for survivors.

Cole, 37, clambered up the slide, which was already slick with foam that other firefighters sprayed on the plane, and he braced himself.

"I was expecting the worst," he said.

So was Benton, 55, who entered after Cole. "I took a little pause. I thought, 'This is going to be terrible.' "

It was black within. Cole, breathing through an oxygen tank, started down the aisle on his knees, groping with gloved hands for anything that felt human. Outside, firefighters aimed foam at the plane, and the spray blasted through the skin of the aircraft, dousing Cole in the face.

An obstacle blocked the aisle, so he started climbing over the seats, running his hands over cushions, patting luggage. What he feared most, he said, was that a child was unconscious under a seat.

Benton followed holding a thermal imager, a device that looks like a camcorder and detects body heat. He pointed it down each row of seats. Nothing.

"I was overjoyed," he said later. "Not a soul was on that plane."On a Denver runway, a nightmare and a miracle - Los Angeles Times (http://www.latimes.com/news/nationworld/nation/la-na-denver-airport22-2008dec22,0,7514876.story)

[BreezyDC]

Message #42 looks as though they didn't miss a building (the fire station??) by very much.

Seems like a stupid idea to me to put a fire station between parallel runways....

On the other hand, how many passengers owe their lives to the rapid response of firefighters who didn't have to drive from the terminal area?

The fire station appears to be in the middle of the runways, not the ends. And who knows whether those earthen berms were intended to offer some protection from even a low risk mid runway event. Based on a risk/benefit analysis, probably low risk, high benefit. And in this case, even higher benefit with firefighters literally right there.

[Jofm5]

Seems like a stupid idea to me to put a fire station between parallel runways....

The postioning could have made all the difference in this instance given possible response times (although that would be speculating the fire station was manned at the time and the services departed from said building). I am not educated enough in airport/runway dynamics so will not comment further on that.

From the wsj article linked above it was suggested an aborted takeoff with brake problems - whilst this is speculatory and no indication was given as to why abort the takeoff - how severe a brake problem would need to occur for the plane to deviate in such a manner (considering one would expect the flight crew to do their best to counter any effects of a brake problem). Is the article just speculating and claiming to cite the pilots or is this indeed a possibility ?

[alph2z]

According to Reuters


Brakes looked at in Continental runway incident: report

They mean locked :E

Brakes looked at in Continental runway incident: report | U.S. | Reuters (http://www.reuters.com/article/newsOne/idUSN2146567620081222)

NEW YORK (Reuters) - Braking problems may be to blame for a Continental Airlines flight running off a runway in Denver this week-end, according to an online report in the Wall Street Journal on Sunday.

On Saturday, a Continental-operated Boeing 737 failed to take off from Denver en route to Houston. The airplane subsequently ran off the runway, dramatically catching on fire, and leaving many of those on board with injuries.

The Journal, citing people familiar with early data gathered by investigators, said preliminary indications point to a braking malfunction..........
.

[newarksmells]

the problem started when the plane hit something on the runway which caused it to bounce up in the air and come back down...It looks like somebody took a blow torch to the right side of the plane right behind the wing.

These are the 1st pictures I've seen pf the right side pf the plane...

Denver plane skids off runway - Yahoo! News Photos (http://news.yahoo.com/nphotos/Preston-Gannaway/photo//081222/480/0f7602ba90f248fbaf76e3a5d719ba42//s:/ap/20081222/ap_on_re_us/airport_accidentctures) here..

[PEI_3721]

Pure speculation, but worth thinking about for everyday operations:-
Rejected take off due to engine malfunction, asymmetric reverse, directional control problems in a strong crosswind.
Or
Reject due to ‘bang’ - tyre failure, resulting in braking difficulties and control problems in a strong crosswind.
Runway conditon - blowing snow?

[TheMessenger]

Assuming the Right engine failed prior to V1;

The Left engine still producing thrust would have caused the plane to yaw to the RIGHT requiring left rudder and possibly left brake to compensate.

As the pilot applied reverse thrust during the abort, the operating left engine would now produce a yaw to the LEFT.

If the pilot did not then apply RIGHT rudder and/or the RIGHT brake, the result would be the aircraft departing the runway to the left.

If the Pilot applied the right brake and it failed, it would have the same result.

[visibility3miles]

At the risk of thread drift (or irritating people who know far more than I do...)

Cabin crew does wonders at briefing passengers who bother to listen. They CLEARLY helped get everyone out of the plane before part of it was burning.

Many of the facts seem to be lacking...

Please don't rip my head off if I ask if Cabin Crew can go above and beyond the standard emergency chute departure routine by asking a few healthy muscular passengers to catch fellow passengers as they reach the end of the emergency slide?

I assume most of the injuries and "broken bones" happened when people hit the ground trying to get away from the plane.

Looking at a few people with a steely-eyed gaze and telling them to make sure you assist these people exit safely by standing at the end of the slide to slow their fall (but run away if needed) might reduce injuries and give people hero moments to remember for years.

[chase888]

The wheel tracks in the snow are too close together to be main undercarriage legs.
Maybe a big tyre blow, and wheel rim drag tore off a leg?

[SASless]

Let's slow down for a moment and think about the Fire crews entering a burning aircraft to rescue people!:ok:

I for one....tip my hat to those guys!:D:D

[pattern_is_full]

Update from the newsroom:

>> The reports that the plane swerved off the right side were just - incorrect - as the photos have long since revealed.

>> Some reports now that perhaps there WAS fire visible on one engine or another before the first swerve, so a powerplant failure (stall, ingestion, etc.) is still a possibility.

>> yes that is a fire station just off the skid path, (No. 4 on the diagram)and yes it was manned, and yes it responded within seconds due to the proximity. That plus the fact that the plane was well below V-speeds gets credit for the low number and severity of injuries.

[misd-agin]

TheMessenger (http://www.pprune.org/members/196524-themessenger)

Join Date: Oct 2007
Location: Las Vegas
Posts: 8


Assuming the Right engine failed prior to V1;

The Left engine still producing thrust would have caused the plane to yaw to the RIGHT requiring left rudder and possibly left brake to compensate.

As the pilot applied reverse thrust during the abort, the operating left engine would now produce a yaw to the LEFT.

If the pilot did not then apply RIGHT rudder and/or the RIGHT brake, the result would be the aircraft departing the runway to the left.

If the Pilot applied the right brake and it failed, it would have the same result.

Ads by Google
Continental Airways (http://static.internetbrands.com/partners/afc/ads.html?google_kw=Continental+Airways&google_rt=ChBJTxUaAAEKagoahwxNUndREhNDb250aW5lbnRhbCBBaXJ3YX lzGghqJuHZdXmafigBUhMIy-Dzna_TlwIVDSkaCh2sBO0Q&client=ca-ib-radlinks&channel=PPRune_ROS_Top_120x90,PPRune_URL&google_page_url=http%3A//www.pprune.org/rumours-news/355401-continental-737-off-runway-den-3.html&ad_border=000000&ad_title=0000FF&ad_bg=FFFFFF&ad_text=000000&ad_url=008000)Flight Test Aircraft (http://static.internetbrands.com/partners/afc/ads.html?google_kw=Flight+Test+Aircraft&google_rt=ChBJTxUaAAEKgwoahwxNUndREhRGbGlnaHQgVGVzdCBBaXJjcm FmdBoICXyoTgpz9kMoAVITCMvg852v05cCFQ0pGgodrATtEA&client=ca-ib-radlinks&channel=PPRune_ROS_Top_120x90,PPRune_URL&google_page_url=http%3A//www.pprune.org/rumours-news/355401-continental-737-off-runway-den-3.html&ad_border=000000&ad_title=0000FF&ad_bg=FFFFFF&ad_text=000000&ad_url=008000)Aircraft Runway (http://static.internetbrands.com/partners/afc/ads.html?google_kw=Aircraft+Runway&google_rt=ChBJTxUaAAEKiQoahwxNUndREg9BaXJjcmFmdCBSdW53YXkaCO 9Y3DbcAoeQKAFSEwjL4POdr9OXAhUNKRoKHawE7RA&client=ca-ib-radlinks&channel=PPRune_ROS_Top_120x90,PPRune_URL&google_page_url=http%3A//www.pprune.org/rumours-news/355401-continental-737-off-runway-den-3.html&ad_border=000000&ad_title=0000FF&ad_bg=FFFFFF&ad_text=000000&ad_url=008000)A380 Aircraft (http://static.internetbrands.com/partners/afc/ads.html?google_kw=A380+Aircraft&google_rt=ChBJTxUaAAEKjwoahwxNUndREg1BMzgwIEFpcmNyYWZ0Ggg2XL z7B3EwuygBUhMIy-Dzna_TlwIVDSkaCh2sBO0Q&client=ca-ib-radlinks&channel=PPRune_ROS_Top_120x90,PPRune_URL&google_page_url=http%3A//www.pprune.org/rumours-news/355401-continental-737-off-runway-den-3.html&ad_border=000000&ad_title=0000FF&ad_bg=FFFFFF&ad_text=000000&ad_url=008000)


http://static.pprune.org/images/statusicon/user_online.gif http://static.pprune.org/images/buttons/report.gif (http://www.pprune.org/report.php?p=4605575)


How about not assuming anything and letting the facts speak for themselves?

[jburke]

Lots of defensive PAX comments in the Newsweek thread regarding PAX taking their bags with them. Seems that's a definite safety hazard to me.

The Newsweek article, nicely written by the way.
A Flight 1404 Passenger Describes the Crash | Newsweek National News | Newsweek.com (http://www.newsweek.com/id/176611)

Comments, mostly about bags
A Flight 1404 Passenger Describes the Crash | Newsweek National News | Newsweek.com (http://www.newsweek.com/id/176611/output/comments)

[TheMessenger]

misd-agin

Isn’t the purpose of this forum to speculate about aircraft incidents?

Do you caution EVERYONE on PPRUNE against speculating?

You are right about one thing. I shouldn’t have used the word Assuming.

My post should have been:

Passengers onboard the aircraft told The Associated Press the aircraft's nose raised into the air, then dropped suddenly back down before the aircraft exited the runway, its right wing on fire.

If the RIGHT engine failed, the Left engine still producing thrust would have caused the plane to yaw to the RIGHT requiring left rudder and possibly left brake to compensate.

As the pilot applied reverse thrust during the abort, the operating left engine would now produce a yaw to the LEFT.

If the pilot did not then apply RIGHT rudder and/or the RIGHT brake, the result would be the aircraft departing the runway to the left.

[Mäx Reverse]

What is the dark area on the right-hand stabilizer? Can be seen on Pics #3/5 of the slideshow.

The sunlight is coming from behind the aircraft, so it doesn't seem to be the fin's shadow. Looks rather like something is protruding the upper surface of the stabilizer?

Season's Greetings, MAX

[OFSO]

As far as I can see nobody posted the answer to earlier queries on takeoff crosswind limitations. What I have is:

3/4/500

Runway

Dry 40kt

Wet 40kt

Snow - not melting 35kt

Standing water or slush 20kt

Ice - not melting 17kt

NG

Runway

Dry 36kt*

Wet 25kt

Snow - not melting 25kts

Standing water or slush 15kt

Ice - not melting 15kt


* reduced to 34kt with winglets

[kichwa ngumu]

No amount of rudder deflection can compensate for an opposite engine full thrust,with events happening in a matter of 1/1000 second.:=

[pulseair]

For those that are assuming that the flap were not extended for T/O, I raise the point "The crew should have heard the aural T/O Configugration Warning going blasting away" if the flap were not selected for T/O. Only a deaf and sucidal person would disregard such critical warning.

[Goffee]

This should become an interesting phenomena over time, as long as the writer is vaguely literate and rational:

http://www.alleyinsider.com/2008/12/twitter-holy-*******-****-i-was-just-in-denver-plane-crash

[hbiwe]

Could point into direction of power loss with rejected takeoff, aka engine failure with RTO brake application trouble. Only one side applied...from what i have "heard" so far.

[Mahatma Kote]

If you look at the aerial shot from Denver plane skids off runway - Yahoo! News Photos (http://news.yahoo.com/nphotos/Preston-Gannaway/photo//081222/480/0f7602ba90f248fbaf76e3a5d719ba42//s:/ap/20081222/ap_on_re_us/airport_accidentctures#photoViewer=/081221/480/15d9daf316e341668734a6ee413da9f2)

See image 14 of 34

http://d.yimg.com/us.yimg.com/p/ap/20081221/capt.15d9daf316e341668734a6ee413da9f2.airport_accident_coden 101.jpg?x=228&y=345&q=85&sig=QSrrvZjFYrW5NTgJW.RsgA--

You will notice some quite distinct phases of the incident.

At the start there is a linear departure from the runway. That is whatever caused the aircraft to depart to the left had occurred a way back on the runway. Whatever it was did not cause further deviation. The aircraft kept going in a straight line. (This would tend to reject theories about differential braking/thrust)

Shortly after leaving the runway the aircraft starts into a radius turn to the left. Causes for this could be as simple as higher drag on the left hand side - perhaps deeper snow on the left?

A little while later the aircraft crosses taxiway WC and possibly straightens up. Definitely a short while later it loses its undercarriage (note the widening of the track) and commences a straight run to its stopping point.

My theory is that a single catastrophic incident occurred on the runway causing an immediate turn left. There was no further dynamic effects until the aircraft encountered snow/terrain. At this stage either the crew started braking with faulty brakes or the differential drag from the terrain caused the curve. Finally, the undercarriage was sheared off and the aircraft continued in a straight line till it stopped.

[HotDog]

I assume most of the injuries and "broken bones" happened when people hit the ground trying to get away from the plane.

As the aircraft came to a stop, skidding on it's belly since the the landing gear sheared off, I doubt if the injuries occured as stated above. The slides would have been at an extremely shallow angle after deployment.

[no sponsor]

Max x-wind limit for a 737-300 is 35kts on a dry runway.

[cwatters]

I'm not really suggesting this but.. it almost looks like they aimed for the earth bank.

[Blip]

Just so people not flying the B737 know, the procedure for a passenger evacuation is to extend the flaps fully (Flap 40) so that any one escaping via the overwing exits can follow the arrows and slide down the back of the wing.

However I doubt that the crew would have been able to extend the flaps any more than they already were as neither engine would have been running so there would have been no hydraulic pumps working. In fact I'm sure the hydraulic systems would have been severed with total pressure loss.

Either way, the flaps were staying just as they were before the accident happened.

[Centaurus]

Just so people not flying the B737 know, the procedure for a passenger evacuation is to extend the flaps fully (Flap 40) so that any one escaping via the overwing exits can follow the arrows and slide down the back of the wing

With the all-cargo versions of the 737 with just two or three crew in the cockpit, they would evacuate using the escape ropes in the cockpit. In that configuration therefore, what is the purpose of selecting landing flap as part of the evacuation drill when there are no passengers to slide down the lowered flaps?

[grizzled]

Centaurus

Please tell me you don't really want an answer to that question . . .

[dvv]

Mahatma Kote (http://www.pprune.org/members/199670-mahatma-kote), just a little correction - the widening of the track happens after the aircraft crossed taxiway WC and jumped what seems to be a ditch. And after the service road, it seems to have plowed the snow completely on its belly.

(Note the structure next to the taxiway - it's a fire station)

Another view of the locale:

http://busybee.dvv.org:8000/flying/KDEN-WC.jpg

[skyken]

From Patternisfull:

Landed in DEN 5 minutes before

--------------------------------------------------------------------------------

We were pax on a flight that touched down at 6:10. Tower gave weather confirming the winds someone listed above - 220 @ 20 gusting high 30s.

For the main rways 35 L/R and 34 L/R that's a quartering tailwind.

You're mistaken as to the winds. There wasn't a tailwind component.

KDEN 210053Z 28011KT 10SM FEW040 SCT100 M06/M16 A2997 RMK AO2 PK WND 29027/0000 SLP202 T10561161

KDEN 210134Z 29024G32KT 10SM FEW040 SCT100 M04/M18 A2998 RMK AO2 PK WND 28036/0123

[overthewing]

Is it possible that the curved part of the trail is where there's sloping ground? As in, the a/c was being pulled down a mild gradient?

[PEI_3721]

Re external fire damage: Can anyone recall / confirm that the damage pattern is similar to that seen during the initial stages of the MCT 737 accident many years ago.
Also note the dissimilarity in the success of the evacuation in the two accidents; and those briefings to stop facing into wind are of little value in this type.

[Murexway]

I remember a 737 accident at LGA back in 1989. Tried to get airborne with the rudder trim mis-set and ran off the left side of the runway into the water.

Any of you 737 drivers know if that's possible to do on a -500?

USAir Flight 5050 - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/USAir_Flight_5050)

[BOAC]

That is a nasty drop on the pic by dvv just after the taxiway and again after the road and there are shades of the Madrid off-runway 'terrain'. Little surpise the back broke, really.

[Dairn]

The 'widening of the track' has occured after the aircraft jumped and dropped down a significant embankment adjacent to the taxyway. Note the summer picture of the site as compared to the accident photo above. Therefore I believe the widening of the track is in fact both engines contacting the ground after this drop. The aircraft then crossed a small gully and has come to rest on the upslope opposite. I don't believe the apparent wider wheel track has been caused by the wheels, although the undercarriage clearly collapsed during the accident, I think it happened after this drop.

[dvv]

Or rather the aircraft hit the upslope leading to the service road with the undercarriage and engines (at least with #1), lost it when on or close to the pavement of the service road, and slid down the gully on the other side of the road behind the fire station, with the left engine careening alongside. Anyway, it's been an interesting exercise in interpreting the photos, but, of course, it will be much more interesting to know what happened onboard the aircraft leading to the crash. I'll just wait until NTSB's LISTSERV brings more news on that.

[Carbon Bootprint]

Thanks to jburke for posting the link to the Newsweek article. Unless I've missed it in an earlier post, the article is the first reference I've seen to the flight deck crew being injured. It states "the pilots" were the most seriously injured. Any word on their condition?

I have to take some issue with the survivor's account, particularly the section stating "The inside of the plane so orange with firelight that I could see the destruction—the overhead baggage compartments destroyed and pieces of plastic hanging down, wires everywhere and the acrid smell of burning plastic and jet fuel suddenly thick in the cabin."

I question his actually seeing this since by most accounts, the evac went smoothly and quickly, and interior fire damage was only reported by emergency crews. I suppose it's entirely possible that the survivor's lead paragraph may have been "massaged" by an editor, but unfortunately this apparently has the knock-on effect of being picked up by all the other media outlets -- such as the breathless CNN reporter who keeps repeating this almost verbatim. :=

[misd-agin]

Murexway (http://www.pprune.org/members/287612-murexway)
Probationary PPRuNer

Join Date: Dec 2008
Location: Florida
Posts: 1


Rudder Trim
I remember a 737 accident at LGA back in 1989. Tried to get airborne with the rudder trim mis-set and ran off the left side of the runway into the water.

Any of you 737 drivers know if that's possible to do on a -500?

USAir Flight 5050 - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/USAir_Flight_5050)

-----------------------------------------------------------------------

It did not go off the side of the runway. Departing runway 31 there is only pavement on the left side.

The plane went off the end of the runway, as wikipedia says it did, because they aborted too late. The rudder trim did not cause them to leave the side of the runway. That's a huge difference.

[misd-agin]

kichwa ngumu (http://www.pprune.org/members/287524-kichwa-ngumu)
Probationary PPRuNer

Join Date: Dec 2008
Location: north east
Posts: 2


No amount of rudder deflection can compensate for an opposite engine full thrust,with events happening in a matter of 1/1000 second.:=
http://static.pprune.org/images/statusicon/user_offline.gif http://static.pprune.org/images/buttons/report.gif (http://www.pprune.org/report.php?p=4605766)
-----------------------------------------------------------------------

No amount of rudder deflection can compensate for an opposite engine at full power? Are you a professional pilot?

Vmca. Vmcg. Either of those terms ring a bell?

[misd-agin]

TheMessenger (http://www.pprune.org/members/196524-themessenger)

Join Date: Oct 2007
Location: Las Vegas
Posts: 9


misd-agin

Isn’t the purpose of this forum to speculate about aircraft incidents?

---------------------------------------------------------------------

No. The amateurs might think the purpose is to speculate but the professionals hope to see what factual information, or observations, are presented.

Anyone can play the game of "let's speculate" or "let's assume" -

I heard the guy was born in the western portion of the U.S. and those people have noticeably lower left shoulders. It's from carrying surf boards instead of going to school. From a pilots perspective the danger is that his hand subconsciously sags on the rudder tiller and his pinky finger might have gotten caught on the tiller. During the subsequent abort he had the choice of amputating his finger or 'giving' and turning the tiller left, which resulted in the runway departure.

Now, you can't say for a fact that he didn't get his hand caught on the tiller, can you? So the possibility exists that the event did occur in this fashion.

Yeah, let's run with that scenario. :ugh:

[RobertS975]

Dairn (post #86) appears to right on about the "widening of the track" issue... instead of just the main gear creating tracks through the snow, the engines have now contacted the ground either because of a collapse of the gear or the changing slope of the terrain.

[Willie Everlearn]

misd-agin

Why would he get his hand caught in the tiller?

(is that part of your tongue-in-cheek)

[hbiwe]

After the US Air accident, the design of the rudder trim button had changed (accidental activation should not be possible anymore.

[SFFrequentFlyer]

CNN has just posted this article about the possibility of there having been a problem with the landing gear or tyres:

Source: Landing gear, wheels, brakes possible cause of crash - CNN.com (http://www.cnn.com/2008/US/12/22/colorado.plane.investigation/)

I do not work in the industry, so please excuse my posting here, but I did want to comment that I experienced a Continental flight this past summer from Newark to San Francisco, where there was *definitely* something very, very wrong with the landing gear tyres on the right hand side of the aircraft.

I was seated near the right wing and landing gear on a Continental 737 non-stop service from Newark to SFO this past August. We were delayed in taking off due to "mechanical problems", and while we landed in SFO, the right side landing gear made a jangling, loud noise that both myself and the passenger next to me noticed. The aircraft bounced a bit more on the right side, as well.

While we were taxing into the airport, the tyres/landing gear also made a super loud squealing and griding noise, so while I was disembarking the plane, I mentioned to one of the pilots that the right tyres were making a "racket". He seemed skeptical until other passengers echoed my sentiments. I have no idea what came of it, but I remember feeling like my comment wasn't taken very seriously by the crew. I'm sure they hear a lot of bizarre feedback, but really and truly, for several passengers to comment that the right side landing gear was grinding and squealing during our landing doesn't seem to be something that a pilot or crew member should just shrug off as crazy, jet lagged nonsense. I've flown countless times and up until that point, I had never heard landing gear make that kind of noise, so it was definitely unusual.

Anyway, I don't mean to bother folks on here, but I just thought I'd mention my experience for the record.

[Capt. Inop]

Why would he get his hand caught in the tiller?

Why would anyone keep his (or hers) hand on the tiller above walking speed on takeoff?

[pattern_is_full]

@SkyKen - you are correct, however I was basing my comments on the winds quoted by the approach controller (not ATIS or METARs) audible over the aircraft radio, which did have a TW component (220 @ 20) - but clearly the winds were shifting from moment to moment on a gusty evening.

(I've had winds swing 110 degrees from a quartering headwind to quartering tailwind in the time it takes to flare a Skyhawk).

Regarding the photos in posts #80 and #73: DIA's rways and taxiways are generally built up on berms from the surrounding terrain. So where the path curves after runway departure the plane was tipped to the left running down the runway berm at an angle, then across snowy field stubble, then it ran up a berm to taxiway WC, became briefly airborne shooting over that berm/taxiway, then touched down again and skidded across the firehouse road and into the ravine.

I.E. there would have been a couple of substantial jolts each time it crossed the paved areas after leaving the rway.

Which of course has little to do with the cause of the accident, but may clarify what fell off, or broke, and when during the ensuing "sleigh ride" through the snow.

[PJ2]

SFFrequentFlyer;

The noise was likely the brakes which can squeal and howl depending upon wear and temperature. The rattle could be the oleo movement over rougher areas of the taxiway/ramp area - also, brake shuttle valves (various purposes), on some installations make quite a strong clanking noise.

There is a hydraulic pump in the A320 which makes a quick buzzing sound during single engine taxiing. It's pressurizing one of the two engine-driven hydraulic systems while that system's pump is not turning, (engine shut down during taxi to save fuel). A high-pitched whine/buzz is a hydraulic pump which pressurizes the hydraulics for the cargo doors.

Crews would take every comment made into consideration but most comments arise out of unfamiliarity with the aircraft and crews usually don't have a spare moment on the ground to explain the details. They might pass the comments on to maintenance to have a look. Doesn't mean comments shouldn't be made but don't expect the undivided attention of crews - domestic flying has really short turn-around times and often a crew is out the door quickly, sometimes before the passengers to get to their next aircraft. It's just the way it is and it works well. All the same, thanks for paying attention.

Tell me something as an aside - it you're heading to or from a sun-destination, are you in sandles and shorts if arriving or departing a place like Denver in the winter? Not being a smart-axx here but I've seen passengers wearing t-shirts, shorts and thongs (the kind that go on feet...) all excited of course but an evacuation like we've just seen with such unpreparedness can really add to injuries and hypothermia. Just curious - used to see it all the time and wondered if most know that they're in an airplane in winter... ;-)

[jackellis]

Tell me something as an aside - it you're heading to or from a sun-destination, are you in sandles and shorts if arriving or departing a place like Denver in the winter? Not being a smart-axx here but I've seen passengers wearing t-shirts, shorts and thongs (the kind that go on feet...) all excited of course but an evacuation like we've just seen with such unpreparedness can really add to injuries and hypothermia. Just curious - used to see it all the time and wondered if most know that they're in an airplane in winter... ;-)

Most passengers don't think about the prospects for an evacuation when they decide what to wear or not wear on an airplane. A few don't think at all. I've seen folks on flights from Florida to points north wearing sandals and either shorts or swimsuits without shirts (men and women in case you're curious).

[wings1011]

Well just to say it all depends what kind of brake problems. Just to give some examples.Quite some years back our company had an aircraft taking off from porto santo an military base just outside of canary island.The type of aircraft was an md83.The aircraft taxied out from the apron but appearently one brake did not release,the aircraft were fully loaded and heading norht toward sweden.During the long taxi out one of the brakes were locked and made an mile long black stripe along the apron and taxiway by the locked wheel.Nobody noticed this ,also the crew.Then the aircraft took off and around 80kts the light "wheel not turning" came on followed by (afew ? ) second/s later by a big bang when the exploded tire went thru the airintake and smashed one of the engine.At that time they were traveling around 120kts and they attemt to stop prior rotation-The weather were sunny and warm and they managed to stop on the rwy with some small fire coming from both tires exploaded and the aircraft came to rest at the end of the rwy limped down on one side and shafed all the way to the sliding member (wheel attachment) on one side.All crew and 167 passanger evacuated thru exits normally.But that were in a sunny day with dry surface.Another incident around 10 years later we had an fokker 100 landing in Italy were the crew had selected autobrake for landing as normal.The only problem at that time were that the brakes for some reason went to full RTO braking and did not release-Aircraft stoped rather fast.... and the crew could not release the brakes to taxi in.They were standing at the fist part of the RWY with smoking brakes and and after a couple of minutes all the tire bursts due to ovht and melt plugs melting,as is should be,Aircraft were later towed to the ramp for replacing of various components and wheels and brakes.Also this happened in good condition.This incident (continental) as far as I can see is in snowy conditions and any serious incident like this would make it hard or impossible to stay on rwy.But anyway my experience and opinion is that probably nothing happened during take-off with the brakes but rather the airctaft took off with the problem without knowing it maybe.? Just why should brakes fail when they are not used or applied ?? I meen probably no imputs were made to the brakes as for a normal take- off.just a thought

Regards 1011

[BreezyDC]

This isn't the only discussion of the accident with its share of speculation:
Wall Street Journal
[Excerpts] "Pilots of the jetliner that careened into a snowy ravine at Denver International Airport on Saturday apparently tried to execute what safety experts say can be one of the trickiest maneuvers in aviation: aborting takeoff once an aircraft has accelerated to high speed on the runway...."

"Based on eyewitness reports, skid marks and preliminary data gathered by investigators, the Boeing 737 may have been moving at more than 100 miles per hour when it veered off the strip in a stiff crosswind, according to people familiar with the details...."
Full article: Crash Probe Focuses on Risky Maneuver - WSJ.com (http://online.wsj.com/article/SB122996653028526701.html)

[pattern_is_full]

Notes from NTSB press conference Denver 04:00Z Tuesday:

first main gear marks on rway at 1,900 feet from threshold - nose gear marks at 2,000 feet.

approx 700 feet more before plane left runway

approx 2,000 feet more until plane came to standstill

Max speed achieved, 119 kts; last speed recorded (see below) 89 kts.

both CVR and FDR shut down at the point where the plane returned to earth after going slightly airborne when crossing taxiway WC - takes a 3g shock to shut off the recorders. Scene confirms that main gear did leave ground for about 100 feet as the plane shot over the berm north of WC.

Only two vocalizations on CVR - "Takeoff power" and a call for rejected takeoff. CVR records thumps and rumbles starting at 41 seconds after brake release until CVR shutdown.

slash mark on one tire, but could be impact damage

did not appear to be a brake failure - brakes tested OK

i.e. some data on the progress of the event, but not much yet on the primary cause, not surprisingly

--------

separately, CNN source reports captain was among the seriously injured and still hospitalized and not available to investigators.

[PJ2]

pif;
Interesting info.
takes a 3g shock to shut off the recorders.
Probably mis-heard that, because that is an incorrect and, if you think about it for half a second, an entirely illogical statement. The crash recorder (DFDR) is typically designed to withstand instantaneous 'g' forces in the neighbourhood of 3000g's, for obvious reasons.

The only time the recorder shuts off is when there's no more electricity on the AC (#1 on the 320, not sure on the 73') and possibly DC busses. The recorder likely quit when one or both of the engines quit either through cockpit actions, (fuel levers off -possible but not likely) or more likely, destruction of the engine upon hitting the berm, or separation of the left engine from the aircraft.

For me, unless it was a left brake that possibly seized, the brake theory alone doesn't explain the excursion. Neither does a failed engine - on it's own. These guys were almost certainly highly experienced, and the practising of engine failures in all kinds of conditions in the simulator is routine training. I know that a seized brake alone is controllable - (if I recall from some time ago, on takeoff I think) an A320 in LAS had a complete brake seizure and stayed right on the centerline, although I don't think there was a 24kt crosswind.

[pattern_is_full]

PJ2 - well I wondered about that too, but the NTSB guy speaking was very clear (if wrong) in saying that there was a G-load switch that would shut down the recorders (disk-drive protection?)... anyway...

EDIT: Actually - take a look at this hot-off-the-press AAIB report on a different crash which specifically refers to 3g switches on recorders (designed to stop them in the event of heavy shock to prevent data overwrites, but highly disapproved of by the AAIB...) on the bottom of pg 27 (pg 7 of the pdf document) and following:

http://www.aaib.dft.gov.uk/cms_resources/Bombardier%20BD700%20Global%20Express,%20VP-CRC%2012-08.pdf

[SFFrequentFlyer]

The NTSB is saying the landing gear, brakes and tyres are okay:
NTSB: Wheels, brakes didn't cause Continental accident - CNN.com (http://www.cnn.com/2008/US/12/23/ntsb.colorado.plane/)

[andrasz]

Good photo on airliners.net showing the vertical displacement from runway/taxiway level. It pretty much explains the fuselage and other damage.

Photos: Boeing 737-524 Aircraft Pictures | Airliners.net (http://www.airliners.net/photo/Continental-Airlines/Boeing-737-524/1452392&tbl=photo_info&photo_nr=1&sok=WHERE__%28datestamp_%3E_date_sub%28NOW%28%29%2C_INTERVAL _48_HOUR%29%29__twodays&sort=_order_by_views_desc_&prev_id=&next_id=1452053)

[philipat]

Investigators Confirm Continental Jet Crew Tried to Abort Takeoff - WSJ.com (http://online.wsj.com/article/SB123001946569629719.html?mod=googlenews_wsj)

[BOAC]

If you wish to keep your blood pressure down do NOT read Crash Probe Focuses on Risky Maneuver - WSJ.com (http://online.wsj.com/article/SB122996653028526701.html?mod=loomia&loomia_si=t0:a16:g12:r1:c0.441039:b0)

Where do they find them?:mad:

[Flaperon777]

PJ2,
Yes it does take a vertical impact as little as 3G's to shut down both the recorders.The key word here being "shut down".
Having said that, yes,both recorders can withstand G's as high as 3,900g's.Keep in mind these high g's are tested for a maximum of 1/1000th of a second.That is to say for the moment of impact.Therefore it would be incorrect that these recorders can "withstand upto say 3,900g's".That statment would definitely not be true.
More importantly is another fact i'm making.The boxes cant make an impact of upto 3900g's AND KEEP RUNNING! They would've shut off on the first impact exceeding 3g's.BUT the design of the boxes is such that the data within would be completely retrievable even after 'momentary' g forces as high as 3,900 g's.Therefore making them "indestructible".
I would'nt want to live so long as to be able to see the day when a harddrive continues to function even after a 3,000+ G-shock....!! Cause I never will!!
Then there is the 'switch off logic'.Which requires the boxes to stop recording when the power cord is pulled or a 3g+ impact.In both cases the logic assumes that a crash has taken place and therefore there would be nothing more to record! This in my personal opinion is a design fault and needs to be rectified.As has been proven time and again when critical data was'nt available due recorders shutdown.For example dual engine failure on older airplanes.Or complete electrical loss on the same.OR,for that matter,a runway excursion such as this one,followed by a low G impact.Of course modern jets have worked around the problem by having an alternate sourceof power(such as RAT) to power critical systems,but I for one would much rather have a recorder which continues to run at least for a minute or so,on its own power,after the shut down logic has taken over.
Unless of course........(we could go on here).
What was the braking coefficient reported(if any).Because,a port engine failure at takeoff,coupled with a gusty wind from the port(weathercock effect) along with a marginally slippery runway and maybe less than perfect handling of it all, could well result in a runway excursion such as this one.
My two cents worth......
Now onto the real facts......:rolleyes:

[TheShadow]

= rolling with one main-mount tire on the port bogey deflated/underinflated/deflating - yet undetected and causing detectable vibration only latterly (once at high-speed), as it flailed, broke up and provoked a subsequent directional control issue - causing the abort (GETS MY VOTE FOR LIKELIHOOD).

This would also explain the ensuing divergence and departure from the runway.
.

[BOAC]

Because,a port engine failure at takeoff,coupled with a gusty wind from the starboard along with a marginally slippery runway and maybe less than perfect handling of it all, could well result in a runway excursion such as this one.

Met reports ('real facts'?) indicate wind from the left

For TheShadow -from the papers, quote from NSTB man:

"The brakes showed no leaks, no locked brakes," Sumwalt told reporters late Monday, adding that the brake pads "looked good."
He said tire marks indicate that all four main landing gear were inflated."

Next?!

[PJ2]

Flaperon777;
Well, that's a new one on me and I've been doing this for a long time now! ;-) - I have seen landings greater than 3g's in the data and the recorders (DFDR/FDIU and QAR) kept running so there must be more to this than a simple shutdown. Your clarifications are appreciated - now my curiosity's up!

Fully concur with your views on keeping recorders running. The Swissair 111 accident was a case in point. Once the main AC busses quit, the recordings stop - I should have thought it entirely logical to have a back up to keep both going for, say, between 15 and 30 minutes but even today, nothing has been done to advance this obvious need.

On the braking, the runway was reported as bare-and-dry. The crosswind component was around 24kts (using the METARS provided earlier in the thread) and gusty conditions (in this case, from port), aren't normally a problem to control. A port engine failure and a strong port wind would tend to swing the airplane to port but again, we practise this kind of scenario in the simulator all the time - it isn't a problem providing you get on it immediately.

That said, the A320 WILL, without fail, take a dirty dart for the weeds with an engine failure below about 72kts and one has to be very fast and very aggressive to keep the airplane on the runway...in zero wind at that.

pattern-is-full;
Thanks for the link to the Global Express pdf file - again very interesting. I certainly agree with the AAIB's remarks! That said, detecting when a crash has occurred such that the recorders need to be shut down. As the report states, there aren't many (if any) circumstances where the recorders have been able to function after the accident...

[ATPMBA]

I hope they resolve this quickly.

Did they ever have a solid reason why the B-737 would roll over and head straight down?

[forget]

From pattern_is_full link.

The system included an ‘impact’ or ‘g’ switch interlock, designed to cut the power to the CVR in the event of a significant crash impact. The switch operates by sensing acceleration and removing the power supply to the CVR in the event of the acceleration exceeding 3G. The switch was mounted in the rear section of the aircraft, at a 45 degree incline to the longitudinal axis. The 3G threshold was therefore a combination of the aircraft’s normal and longitudinal accelerations.

[BenThere]

Did they ever have a solid reason why the B-737 would roll over and head straight down?

The rudder hardover problem on the 737 was supposedly fixed, and to my knowledge there haven't been any recent occurrences.

I was thinking, though, that a rudder event, either hardover or manual reversion in a 24 knot crosswind at or about rotation might be cause for one of those "aircraft incapable of flight" decisions after V1 to keep it on the ground.

Not implying anything of the sort happened in Denver, I'm a wait for the facts type, but the scenario would make sense as a possibility.

[PJ2]

forget;
Also from the link, the following recommendation (of a few):
Safety Recommendation 2008-074
It is recommended that the Federal Aviation Administration and the European Aviation Safety Agency review the certification requirements for automatically stopping flight recorders within 10 minutes after a crash impact, with a view to including a specific reference prohibiting the use of ‘g’ switches as a means of compliance as recommended in ED112 issued by EUROCAE Working Group 50.
As I say, the presence of a 'g' switch was a surprise to me, although I can see the reason (but perhaps not the need) for same. This is, as your quote from the report states, not a 'g' force normal to one plane either - it is 45deg to the vertical/longitudinal axiis and is the sum of 'g' forces in these two axiis. I can see the reason for the AAIB's concern.

Darn poor day when you don't learn something...

[TheShadow]

Perhaps add to the previous conjecture that a section of loose (but not yet detached) tread on any tire can cause the sort of bumping and rattling (i.e. rotational asymmetry) that was noted during the take-off [and caused them to abort from 119kts].
.
What Sumwalt actually said was (more completely):
.
"Mr. Sumwalt said the bumping and rattling sound was first heard 41 seconds after the plane started down the runway, according to the Associated Press. Four seconds later, one of the crew members called for the takeoff to be aborted. Mr. Sumwalt said investigators have found no problems with the plane's engines, tires or brakes, but aren't ruling anything out. Investigators found that the plane's flight control surfaces -- including flaps, slats and speed brakes -- were in proper position. And there was no indication of locked brakes."

[Finn47]

If I remember it right, the FAA has been demanding enhanced flight recorders since 2005, and GE has a new model out for the 787. One of the demands the FAA made in the new regulations was an independent power source for at least 10 minutes for the boxes.

GE Aviation to commence delivery of flight recorders for Boeing 787. | Transportation > Transportation Navigation & Tracking Systems from AllBusiness.com (http://www.allbusiness.com/energy-utilities/utilities-industry-electric-power/11428784-1.html)

[PlatinumFlyer]

I know there are a lot of photos, but this one is a little clearer and sharper.

http://extras.mnginteractive.com/live/media/site36/2008/1222/20081222_120721_CD22CRASH_GRAPH.pdf

[Airflight69]

Lucky that no a/c was holding on WC as it would have been wiped out by the 735 as it crosses WC just before holding point. Imagine the tragedy in that case!

[coolbeans202]

Denver crash baffles aviation experts - USATODAY.com (http://www.usatoday.com/travel/flights/2008-12-22-denver-air-accident_N.htm)

Not much in this article that hasn't already been stated. However this comment in particular jumped out at me:

"Interviews by the NTSB shed new light on actions by Continental employees in the hectic moments after the impact. One off-duty pilot who was flying on the jet went inside the burning wreckage three times to help passengers escape, [Robert] Sumwalt [a member of the National Transportation Safety Board (NTSB)] said."

Truly outstanding! :D

[Pugilistic Animus]

Regarding this incident and the AF A330 crash

Thank God for the work done by NASA et al. in order to keep the fire away from the interior, also for the evacuation criteria it has already saved many lives---I can't wait until the final report on this!

YouTube - boeing 720 crash test (http://www.youtube.com/watch?v=VYp2aWo4TUM)

PA

[Green-dot]

41 seconds after brake release. Had the aircraft been sitting idle for a little while between brake release and take-off power? Seems quite long, a 41 second take-off roll before the noises began and not yet at rotation speed at that time?

Another obervation from the picture of the tracks in the snow, where is the nose gear track? I see the 2 mains, abruptly terminating where the engines dig in and a smal spot approximately in the center at the start of and between the engine tracks which may have been the nose gear contacting the ground at that location but no other signs the nose gear had made contact the moment the aircraft veered off the runway. Unless the nose gear was bearing a light load, not enough to create a track, it appears as if the aircraft might have been nose high, in other words, rotation had commenced?

[thcrozier]

I haven't been an active pilot for 15 years, but isn't 3 g's a mighty low threshold to shut down any system in an aircraft?

[Mark in CA]

Green-Dot - perhaps the plane was in a skid and the nose wheel track is coincident with the port main gear? To me, there seems to be signs of snow being shot off to the right, as if the plane was carving like a skier through the turn.

[theron]

green-dot, are these marks made by the nose gear? or maybe im seeing something that isnt really there

http://p91vcw.bay.livefilestore.com/y1pT-HdajTDxG-V6Z6Lfke8vsnx03CNFMge4KBbLP8xw4HmqCQrY3X5pmPCLut-PYBlh-6oZSDaeTO1APV_DnLKag/nose%20gear2.jpg

[jackellis]

If you wish to keep your blood pressure down do NOT read Crash Probe Focuses on Risky Maneuver - WSJ.com (http://online.wsj.com/article/SB122996653028526701.html?mod=loomia&loomia_si=t0:a16:g12:r1:c0.441039:b0)

Where do they find them?

IMHO this article borders on being irresponsible. On what basis does the reporter conclude "two experienced pilots ... allowed the plane to stray off the runway's centerline in clear weather, and then tried to stop suddenly and lost control as the jet barreled toward its projected takeoff point"?

[newarksmells]

if they find the cause to be the aircraft striking an animal and the events going downhill from there.

For those who don't know DIA, it's closer to Kansas than Denver meaning it's not situated in the mountains, it's on rolling flatland about 25 miles northeast of Denver. When the construction started, one of the biggest problems was removing grass snakes and various squirrels, chipmunks, ferrets etc before they could even flatten the land to build the runways.

The airport was was their natural habitat and continues to be so it would come as no great shock if one of these varmints made an excursion to the runway and got caught up in the wheels. It would certainly explain the "bounce" the passengers felt prior to takeoff as well as the rattling and thumping on the CVR...

Having said that, 41 seconds does seem like a long time to be on a takeoff roll unless he held for traffic ahead of him to clear to his satisfaction and avoid any wake turbulance conditions. Anybody what type plane took off immediately before the CAL 737?

[theron]

the same marks seem to fade in and out further along?

http://p91vcw.bay.livefilestore.com/y1pVTafxEzdRhCSsTG5lCpxAvIh9BhKaUFjxQhlEF72tzVVVzITfBi7IcoY4 Ioivxhunl6ZI2G_qHU/nose%20gear.jpg

[forget]

3 g's? I haven't been an active pilot for 15 years, but isn't 3 g's a mighty low threshold to shut down any system in an aircraft?

The switch is mounted in the rear section of the aircraft, at a 45 degree incline to the longitudinal axis. The 3G threshold is therefore a combination of the aircraft’s normal and longitudinal accelerations.

45 degree incline to the longitudinal axis. Doesn't this mean the switch needs 6G vertical and horizontally to trip?

[paulthornton]

45 degree incline to the longitudinal axis. Doesn't this mean the switch needs 6G vertical and horizontally to trip?

Looking at what others have said here, I would expect that it would require around 4.25G in either axis alone to trigger the switch (4.25 sin 45 = 4.25 cos 45 = 3).
Think of it like a crosswind at 45 degrees to the runway - you'll have a headwind/crosswind component of 0.707 * windspeed.

Paul.

[overthewing]

Does anyone know what that object is, that's to the right of the track just as they leave the runway?

Is it an airport-related structure, or could it be part of the a/c?

[etesting2000]

Back about 1980 I saw the results of a turboprop twin HP-137, encountering about a 120 lb doe with #1 at V1. Bent prop, tweaked shaft but enough went through to tear of the main gear door and brake lines. They got it stopped and back to the gate. I'd have to say you would need something bigger than a bear to deflect a 737.

[dl3daz]

Looking at what others have said here, I would expect that it would require around 4.25G in either axis alone to trigger the switch (4.25 sin 45 = 4.25 cos 45 = 3).Referring to G-forces alone is quite useless. You need one more figure, i.e. duration.
The above mentioned 3.900G for 1/1000sec. would mean a change in speed from of 38m/s. 38m/s for 1ms will have the box travel the distance of 38mm or less than two inches.

Let it drop to concrete floor from 2m altitude and parts of it will be exposed to 3000G easily.

3900G for one second would result in 38.000m/s, or 100.000ft/s.

Just my 2¢,
Falk

[vapilot2004]

The G switch on the data recorders refers to older types that had an actual recording medium. These recorders were manufactured prior to the 1990s and have since been replaced with DFDRs, which have few moving parts and data is recorded direct to memory modules.

The old FDRs and CVRs had moving parts with heads and recording medium...stylus/drum, transducer/wire and later tape/head types. A high G shock could indeed cause the mechanism to jump to another track or lose it's place which could damage recently written data.


Good job crew, getting passengers out before the inferno breached the cabin!

[ankh]

Good job all around.

Someone mentioned being glad no aircraft was on that taxiway -- would aircraft ever hold at the takeoff end location, say immediately after having landed? I'd expect aircraft would be holding at the other end.

What struck me looking at the picture was -- if the aircraft had left the runway very slightly earlier, almost as fast, it looks like it could have hit that fire station. Anyone know what the ground contours are? Looks like the fire station is on landfill, up at runway height?

[capeverde2008]

Bringing a bit more IT technobabble to the 'Black Box' recording scenario....having not seen the inner workings of this model or type of drive used (if in fact a HDD is used).

Following might be helpful.

Yes, a 'parked' drive platter head is able to withstand huge 'G' forces, however, in use and recording, this is a hard parameter to determine before the platter head touches the disk platter in use.

For example, the disk head in use has a 'flying speed' over the platter from up to about 15,000rpm and is 'flying' mere microns above the drive platter - based on air pressure inertia of the spinning platter. (That's why Hard Drives have a 'breathing hole' of approx. .5mm in them). That 'balances' the hinged arm of the platter read head at micronic levels based on platter spin speed.

Under probably relatively low 'G' force (in use) the platter head can contact the hard drive platter (which it's not meant to) and this causes 'thermal asperity', i.e. a heating of the magnetised platter and damages the magnetic data to a greater or lesser extent depending on how long the head is in contact with the platter. This could render the data unreadable permanently or due to the physics laws of 'sticktion' be recoverable and read on 'forensic-type' equipment. i.e. sometimes data is available after initially being unreadable.

As a useable example, if one accidentally knocks off an external HDD (built to similar specs to an a/c HDD Black-Box recorder) from a surface as low as a couple of feet even onto a carpeted surface while it is in use - it can be rendered unuseable. If the drive was off at the time....in all probability it would be unharmed. It's all to do with whether the platter head is 'parked' safely off the drive platters that it can withstand tested levels of thousands of 'G' per microsecond.

'In use' drive heads are largely untested (as far as I'm aware, after many years in the IT tech field) for 'G' resistancy other than purely and relatively small lateral or longitudinal shocks (not a combination of complex lateral/longitudinal forces combined). A pre-determined (unknown to me) level of 'G' shock will produce an electronic command for the drive head to 'park' itself in a 'locked' secure place at the side of the platter. This speed of action varies from drive to drive and is relational to temperature and air pressure (drive head 'flying speed'). It is only a matter of microseconds for this 'park' status to occur (if triggered correctly), however, it can relatively easily cause the drive to stop working/recording data under loads of a few 'G'.

Hope this is helpful and not too IT 'nerdy' :8

[etesting2000]

I just took a look at Google Earth and it shows that only the paved areas are flat. Everything else is drainage, ravines and rolling low hills. Older image as 34L is under construction

[Green-dot]

@ theron,

green-dot, are these marks made by the nose gear? or maybe im seeing something that isnt really there

the same marks seem to fade in and out further along?


Those marks may or may not be from the nose gear. Such marks exist adjacent to eachother as well along the track. For instance, in the second picture you posted, to the left of your marked areas just below the red encircled 2 where the tracks are about to cross taxiway WC, you can distinguish several of such marks splitting up into seperate tracks adjacent to eachother. On the other side of taxiway no such tracks at all. Maybe they are just a pattern in the frozen soil.

I would have expected the nose gear track to have stood out more pronounced as the aircraft was decelerating to some degree (putting at least some load on the nose gear) since the NTSB mentioned use of thrust reversers.

Mark in CA,
With the (aircraft) nose gear in a sideslip and being covered by the left main gear track, wouldn't that have resulted in nose gear skid marks when the aircraft crossed taxiway WC?

[TonyWilliams]

I know there are a lot of photos, but this one is a little clearer and sharper.

http://extras.mnginteractive.com/liv...RASH_GRAPH.pdf


Look at the debri/snow pattern after the wheels past through... direct 90 degree crosswind.... with peak wind reported at 36 knots 4 minutes after the accident.

As has been reported, the -500 model with winglets has a 34 knot x-wind published speed. Certainly not the cause, but more likely a mitigating circumstance than I previously thought.

[edmundronald]

As an electronics engineer who hasn't been active for years, I do find 3g shutdowns by design a bit strange.

It's pretty easy these days to design a device which can stand much more; in fact I'd be willing to bet that your average flash-RAM ipod packed in a few inches of polystyrene would stand a LOT more. Of course a more heat-resistant shock absorber might be preferable for airplane use.

But then, the good thing about a non-working flight recorder is one can blame the aircrew :)


Edmund

[Swedish Steve]

A 100,000+lb aircraft bouncing on a squirl? Perhaps.

I pushed back a B777 in the summer and we forgot to remove a rubber chock behind the mainwheel.
We didn't notice it until we passed it in the tug!

[PJ2]

But then, the good thing about a non-working flight recorder is one can blame the aircrew
...or exonerate them.

[snowfalcon2]

I know there are a lot of photos, but this one is a little clearer and sharper.
http://extras.mnginteractive.com/liv...RASH_GRAPH.pdf

To me the shape of the track marks may suggest that the left mainwheel braked harder than the right one. The left track is more pronounced. Also the marks on the left track are more distinct at the point where the track starts to curve more to the left. There are three distinct darker patches, similar to what would result if "pumping" on the brakes.

The hypothesis would then be that there was reduced braking power on the right main gear. But I admit it sounds far-fetched. The difference between left and right track might just as well be due to drifting snow filling the right track. FDR will tell, I presume.

When it comes to the nose gear, I think those faint tracks are real enough. If there was some frost on the grass, it would not get much displaced when the nosewheel rolled over it, unless the wheel was skidding. The main gears with brakes applied are another matter and they would tear up the frost easily.

Just my 2 cents

[ChristiaanJ]

3g shutdowns ...
As an electronics engineer who hasn't been active for years, I do find 3g shutdowns by design a bit strange.
It's pretty easy these days to design a device which can stand much more; in fact I'd be willing to bet that your average flash-RAM ipod packed in a few inches of polystyrene would stand a LOT more.Well, IIRC we went from scratches on foil to wire recorders to magnetic core memory to tape recorders to hard disks to flash memory.
So far we don't know what type of FDR was on this particular aircraft.
I would agree, that for a recent FDR with solid-state memory, a 3g limit seems faintly ridiculous.
It seems odd even for an HD type recorder.... portable PCs get that sort of "input" regularly. I admit it would probably leave a "scratch" on the record, because it takes milliseconds, not microseconds, to lift the head and park it.

As an aside, re back-up power, after a, say, 10g event, or full loss of all power, we may not want the recorders to run TOO long... they may well be damaged enough to overwrite the data we want to look at ....

CJ

[West Coast]

NTSB - CVR & FDR (http://www.ntsb.gov/aviation/CVR_FDR.htm)

A little bit of info on both the CVR and FDR.

[PJ2]

While we're waiting for further from the NTSB, the recorder sub-thread is indeed interesting. Of greatest interest will be, did a "3g switch" turn off the recorders on this airplane as it was hitting the berm after the small ravine "leap"? Of secondary interest, did the same kind of puzzling arrangement shut off the Madrid MD83's recorders, an accident of which this one was very nearly a copy. The Madrid aircraft's subsquent hard landing from the initial stall would certainly have been greater than 3g's. To repeat, I know of a greater-than-3g landing and the recorders kept going. This has to be really old technology.

Rere back-up power

That was the problem with SR111 of course - there is a crucial six minutes or so of flight and CVR information that was lost because all electrical power was lost as the fire progressed through the overhead panel. A separate source of power for both recorders has been in discussion since that accident. This accident may highlight such a change. We'll see.

[ChristiaanJ]

PJ2,
In this particular case, a "3g cutoff" would only have impeded recording the final bumps, not the initiating events.

But from what's been said here, one does start wondering about FDRs and CVRs... is enough being done to make sure they go on recording when they should?

Let's tread very carefully here, but ... for instance.... when the power to the FDR (CVR, QAR) disappears does that mean automatically everything else is already off-line?

CJ

[thcrozier]

It just seems to me that many events could initiate with a > 3G load, and that the design of any recording device should be such that it would continue recording subsequent events until the aircraft reaches a stationary state, assuming that the event is not an in-flight explosion or other total destruction of the aircraft.

Shouldn't these devices be capable of recording events right up to the point of total catastrophe? They are clearly designed to survive catastrophe, but if they stop recording when things are just becoming uncomfortable, what use is that?

[PJ2]

CJ;
In this particular case, a "3g cutoff" would only have impeded recording the final bumps, not the initiating events.
Yes, understand, thanks.
when the power to the FDR (CVR, QAR) disappears does that mean automatically everything else is already off-line?
Likely so in the scenario I image - the recording devices would simply keep falling back on the "next" source of power until the last source, likely battery-backup, was exhausted, say, after 10 or 15 minutes. Likely longer wouldn't be needed because an airplane at that stage of electrical capability isn't going to be in the air long. (That said, there have been some interesting A320 DC Essential Bus failures, (DFDR is powered by the AC1 bus), which have blacked-out all or partial instruments, as we know). I note for example, that the Bombardier Global Express accident report cited above, indicates that the DFDR is powered by the DC Essential Bus - that type of bus, as indicated by it's name, is "normally" a backup power source for the main DC busses for essential services only so it appears as though Bombardier has considered this scenario - I'm guessing here of course.

[sean737L1011]

From my experience I remember the B737 with winglets being very squirrely in strong gusty crosswinds. Applying significant or full aileron correction into the the wind seem to be the only way to keep it tracking the runway center line.
Guys that applied minimal or no aileron correction because they didn't want spoiler deployment seem to be all over the runway.
Maybe they caught the runway edge/lights?

[PJ2]

Sean737L1011;
From my experience I remember the B737 with winglets being very squirrely in strong gusty crosswinds. Applying significant or full aileron correction into the the wind seem to be the only way to keep it tracking the runway center line. Guys that applied minimal or no aileron correction because they didn't want spoiler deployment seem to be all over the runway.
Then there is either a certification or a training issue, (perhaps over-controlling the rudder). Also if one doesn't have one's feet on the floor but instead rides the toes at the top of the pedals, there is a risk in inadvertently applying brakes, although the risk is to the downwind brake being applied because it is downwind rudder being applied. Regardless, no transport should require "full aileron" into wind to keep the wing down - the roll-spoiler drag pulling the aircraft into wind can be a real issue - some worse than others. The 320 requires no aileron below 20kts if I recall the AOM advice.

[flynerd]

Looks like something may have broke on the nose wheel bogey during TO runup.
Thumping sound heard in cockpit and TO abort called by crew.

Could these pics show the nosewheel bogey?

http://i42.tinypic.com/293jzn9.png
=============
http://i42.tinypic.com/2mhdlzs.png

John

[etesting2000]

At the speed reported by NTSB they were near or at Vr as I have heard reported. I have dealt with imbalance, worn scisorse on nose wheel gear
that shook like hell after rotation. An AC that size should not be affected to that extent. Should not. But possible. But to take the AC off the runway? Perhaps an extream shimmy called for an abort but what then? Still too many questions.

[Green-dot]

flynerd,

Comparing the size of the wheels with other features of the aircraft to determine scale and assuming the picture from the right side of the aircraft was taken with a tele lenz, I guesstimate that to be a main wheel bogie.


Green-dot

[FullWings]

This is an intriguing accident.

What do we know so far?

* There was an RTO initiated at >100Kts.
* They reached 119kts (IAS?) before decelerating.
* After about 2,700' of roll (2,000' go, 700' stop), they left the paved surface.
* Brakes/tyres are reported as being in working condition.
* The historical METARs show a crosswind but well within limits for a dry RWY.
* "Noises off" during the takeoff roll.
* Recordings stop at 89kts after impacting a taxiway/road/earth bank.

What don't we know:

* What the RTO was commanded for - engine failure, loss of directional control, etc.
* What happened with RTO braking, reverse, spoilers, etc.
* The flying control inputs during this time.

Speculation:

I would assume that as the aircraft started to drift to the left, corrective action would have been taken (right rudder) and that would have soon gone to full deflection if the drifting continued. This is pretty much a reflex reaction for an experienced pilot and may have happened prior to the RTO decision. From the reported weather and aircraft speed at the time, there should have been no issues with Vmcg (if an engine problem) or crosswind limits. But the 737 still veered off the runway to the left...

What could have caused this?

Asymmetric forward thrust? Unlikely, as both thrust levers would have been closed during the RTO; difficult to only close one and at the speed they were at this would lead to a SE TO. Asymmetric reverse? Possible but this shouldn't cause a problem as it's factored into the limits (normal proc. for engine fail == only 1 reverser left). Uneven braking? Again, possible but I wouldn't have thought enough to take you off the side.

It *seems* to point towards some loss of control authority... Hydraulics - but that would take multiple failures to lose the rudder. A "nosewheel hardover"? Might explain nosewheel marks on the runway. A Flight control jam, either external or in the cockpit? Has happened before with loose items going behind the pedals and limiting travel. Where do the "rumbling noises" fit in to all of this? Normally something to do with tyres/brakes but they're apparently OK... Incapacitation - yes but I'm sure we'd have heard something by now after the debriefs.

Bit of a teaser but at least all involved survived.

[Zeffy]

Could these pics show the nosewheel bogey?


During the Monday evening press conference, NTSB stated that the nose gear was underneath the aircraft.

Links to pics as well as videos of the press briefing:
9NEWS.com | Colorado's Online News Leader | Experts to analyze recorders from charred plane (http://www.9news.com/news/article.aspx?storyid=106452&catid=339)

[theron]

have there been any reports of alarm sounds in the cockpit before the call for RTO?

in the scenarios being suggested would/should a warning alarm have been sounding? for example, asymetric thrust/engine fire etc?

[snowfalcon2]

What could have caused this?

Speculative:

Local icy patch on the runway combined with a gust? Have we seen any runway friction coefficient data prior to and after the event, other than "dry"?

There are some anecdotes that hot jet exhausts could cause loose snow on the runway to melt and freeze to ice. Would affect the rotation zone where the exhausts are directed downwards. Don't know if it's pure BS or something which might only occur with afterburner heat.

[BOAC]

Things were certainly stacked up against - definitely not somewhere I would like to have been:-

apparent damage to right stab, either engine or tyre?

strong wind from the left

hi-speed RTO

you are left now with either less than full reverse on No2 (if it was engine) or autobrake RTO (if defective right gear - NTSB statement acknowledged), either adding significantly to the left yaw.

inhospitable off-piste terrain

Speedy recovery to all.

[etesting2000]

NTSB reported that Both engines responded to reverse thrust.

[Belgique]

TheShadow said (posts 111 and 118)
.
1. "Unusual Sound"
= rolling with one main-mount tire on the port bogey deflated/underinflated/deflating - yet undetected and causing detectable vibration only latterly (once at high-speed), as it flailed, broke up and provoked a subsequent directional control issue - causing the abort (GETS MY VOTE FOR LIKELIHOOD).

This would also explain the ensuing divergence and departure from the runway.
2.
Bumping and rattling
Perhaps add to the previous conjecture that a section of loose (but not yet detached) tread on any tire can cause the sort of bumping and rattling (i.e. rotational asymmetry) that was noted during the take-off [and caused them to abort from 119kts].

.
Not likely to have been related to nosewheel shimmy.
Shadow's conjecture seems to be a logical sequitur to what's said in this (http://www.usatoday.com/travel/flights/2008-12-22-denver-air-accident_N.htm) USAToday Article:
.
The jet's tires began making marks indicating a possible skid after it had traveled 1,900 feet, Sumwalt said. It left the 12,000-foot runway after 2,650 feet, he said.
.

[RatherBeFlying]

The first officer has also told investigators that the plane was pulling away from the center line as it reached about 103 mph before taking a sudden left turn off the runway.Hopefully the FDR will show parameter changes at this point.

[RiverCity]

snowfalcon2

There are some anecdotes that hot jet exhausts could cause loose snow on the runway to melt and freeze to ice. Would affect the rotation zone where the exhausts are directed downwards. Don't know if it's pure BS or something which might only occur with afterburner heat.

You don't need anecdotes for this. It's very common at stop signs and traffic lights, where automobile exhaust pipes melt snow and/or ice while waiting, it freezes and the next car slides right through and into cross traffic.

If this is what you mean, the pilots could well have hit black ice while something else was going wrong and it was just one more thing they didn't need to deal with. Obviously, not *the* cause, but part of the chain of events.

[Willie Everlearn]

Not likely a crew would reject for a blown tyre. It must have been more significant? Certainly not at high speed.
(see Boeing Take Off Safety Training Aid)

[Graybeard]

3G cutoff of recorder power does seem lower than needed. But this is FAA, where 50G SLF bodies are strapped in place with 9G belts and who knows what strength seat rails.

-----
PJ2: "Likely so in the scenario I image - the recording devices would simply keep falling back on the "next" source of power until the last source, likely battery-backup, was exhausted, say, after 10 or 15 minutes. Likely longer wouldn't be needed because an airplane at that stage of electrical capability isn't going to be in the air long. (That said, there have been some interesting A320 DC Essential Bus failures, (DFDR is powered by the AC1 bus), which have blacked-out all or partial instruments, as we know). I note for example, that the Bombardier Global Express accident report cited above, indicates that the DFDR is powered by the DC Essential Bus - that type of bus, as indicated by it's name, is "normally" a backup power source for the main DC busses for essential services only so it appears as though Bombardier has considered this scenario - I'm guessing here of course."
-----

Transport aircraft, as you know, have AC generators on the engines and APU, and use rectifiers to power the DC buses. Essential buses typically have multiple power sources, as does the Emergency DC or Battery Bus. Adding non-emergency items to the battery bus requires installing a larger capacity battery, to maintain the 30 minutes or so required operation after the generators quit. Rolling the dice, you can see the wisdom of not putting the DFDR and CVR on the battery bus, especially the older motorized recorders.

Bizjets like the Global Express, and regional airliners have 28 VDC generators on the engines and APU, and use inverters for AC requirements. You then see why the recorders are on the DC bus in those planes.

GB

[Continuous Ignition]

The question I have is this, do COA 737 pilots fly all types of 737 at that airline? Do the 737NG guys fly the 737 Classics too or are they a different bid location?

Just curious what kind of recent experience that crew had with the handling aspects of a Classic with winglets fitted... Seems COA just started adding them to the older 737 fleet.

[theron]

The jet's tires began making marks indicating a possible skid after it had traveled 1,900 feet, Sumwalt said.

did he really say that? it seems like a mis-interpretation to me (there are a lot of misquotes/mis-interpretation/writers license used in that article which you may notice if you watch the videos linked below). Here is a quote taken directly from the videos of the news conference on monday:

(part1; 00:55 - 01:22)

"The beginning of the tyre marks began ninteen hundred feet from the threshold (from the beginning) of runway three-four right. So the main landing gear started showing rubber on the runway nineteen hundred feet from the beginning of the runway. Now, 100 feet past that is when the nose gear started showing tyre marks on the runway."


part1: 9NEWS.com | Colorado's Online News Leader | Video (http://www.9news.com/video/default.aspx?aid=67989)
part2: 9NEWS.com | Colorado's Online News Leader | Video (http://www.9news.com/video/default.aspx?aid=67991)
part3: 9NEWS.com | Colorado's Online News Leader | Video (http://www.9news.com/video/default.aspx?aid=67993)

they are each approximately 15 mins long.

[wileydog3]

The plane went off the end of the runway, as wikipedia says it did, because they aborted too late. The rudder trim did not cause them to leave the side of the runway. That's a huge difference.

The rudder trim WAS mis-set and full deflection. Power was added slowly and there was a problem of crew communication. The Capt then tried to correct the drift with the nosewheel steering which also was ineffective. At that point, an abort decision was made and the aircraft went off the end of the runway.

The original 737 trim switch had a rectangle on top of it and it was near where the jumpseater would rest his/her feet. It was VERY easy to run the trim full deflection and the indicator was not the most easily visible indicator on the airplane.

Lots of problems including crew duty, rushing, inexperience, missed items on checklilst... not pretty.

[wileydog3]

Not likely a crew would reject for a blown tyre. It must have been more significant? Certainly not at high speed.

Ever had a tire come apart? Friend of mine had one on the 737 and said it was like being inside one of those paint can shakers at Home Depot. The whole airplane was shaking.

Not an easy decision when near V1, the whole airplane is shaking and you are accelerating at 7-10kts/sec. Offers a very confusing picture to the pilot.

[Willie Everlearn]

Overhead photo doesn't show the shadows of the Spoilers that would have been required/deployed during an RTO (B737 AFM). If the right engine is still in reverse, wouldn't the flight spoilers still be up? (possibly retracted during Evac items)

[armchairpilot94116]

Continental 737 crash: Pilot called for rejected take-off (http://www.flightglobal.com/articles/2008/12/23/320466/continental-737-crash-pilot-called-for-rejected-take-off.html)

[golfyankeesierra]

Just speculating, but maybe something hit the steering cables (again).

An offset nosewheel caused the 737 in this incident (http://www.pprune.org/rumours-news/153831-klm-off-runway-bcn.html) to depart the runway after landing. Was because of a birdstrike on the steering cable during take-off. Check out the photo's on page 3; feathers still visible.

[FLCH]

--------------------------------------------------------------------------------

The question I have is this, do COA 737 pilots fly all types of 737 at that airline? Do the 737NG guys fly the 737 Classics too or are they a different bid location?



Answer is they fly all types... Carmen (PBS) sees to that

[Murexway]

Well, if the nose gear (at last report) is still buried under the nose, perhaps examination of it will shed some light once they lift the fuselage.

I once wrote up a nose wheel shimmy on takeoff and the mechanic at the next station called me over once they got the nose jacked up. He said, "Watch this", and took one of the nose tires in both hands and shook it side to side. The scissor link had somewhere on the order of .25 - .50 inch of play, instead of the "normally" acceptable few thousandths of an inch. The mechanic said that that much play could have resulted in a failure on my next takeoff. As he put it, "You'd be in the grass so fast you wouldn't know what happened."

[misd-agin]

Swedish Steve (http://www.pprune.org/members/111121-swedish-steve)




A 100,000+lb aircraft bouncing on a squirl? Perhaps.

I pushed back a B777 in the summer and we forgot to remove a rubber chock behind the mainwheel.
We didn't notice it until we passed it in the tug!


Friend had a thump on rotation in a 727. Banging noises aren't that uncommon(unloaded strut hitting bump, etc).

Doing next preflight F/E finds the remains of a deer in the nose gear.

[Belgique]

"The beginning of the tire marks began nineteen hundred feet from the threshold (from the beginning) of runway three-four right. So the main landing gear started showing rubber on the runway nineteen hundred feet from the beginning of the runway. Now, 100 feet past that is when the nose gear started showing tire marks on the runway."
.
Distinctive main-gear tire marks on a runway would seem to indicate either a skid or the marks left by a mostly deflated (then suddenly failing/failed/and thereafter flailing) tire remnant. To what extent such an event (one good and one failed tire) would produce a marked swerve in a significant crosswind? More to the point, whether a failed tire readily (or rapidly) then induces its companion tire to fail? That would depend on the speed, roll distance and the effect of anti-skid braking. You can debate the physics forever and that's about all you can do - because few of us have ever been in such a suddenly deteriorating situation on takeoff. Two failed tires on one side, soon after abort initiation, would definitely do it however. The swerve would be uncontrollable.
.
An unusual bumping and rattling noise on takeoff - that changed its cadence and severity/amplitude with increasing speed - would be instinctively associated (by the handling pilot) with an undercarriage (i.e. failing tire) source. At any point below V1 such an abnormal noisy situation would be most likely to promote an abort decision (in most cockpits I've flown in)..... no matter what the boeing scribblies might say or recommend.

[737bomar]

sorry wiley
I don't buy the misset rudder trim
I have more than 17k hours in 737, I ve never seen this happen

[misd-agin]

wileydog3 (http://www.pprune.org/members/120442-wileydog3)

Join Date: Sep 2005
Location: No one's home...
Posts: 310


Quote:
The plane went off the end of the runway, as wikipedia says it did, because they aborted too late. The rudder trim did not cause them to leave the side of the runway. That's a huge difference.
The rudder trim WAS mis-set and full deflection. Power was added slowly and there was a problem of crew communication. The Capt then tried to correct the drift with the nosewheel steering which also was ineffective. At that point, an abort decision was made and the aircraft went off the end of the runway.


Wileydog3 - The rudder problem didn't cause them to go off the side of the runway. Failure to abort in a timely manner caused them to go off the end of the runway.

V1 = 125 kts, Vr = 128 kts. Throttles retarded at 130 kts. Departed end of runway at 34kts.

ASN Aircraft accident Boeing 737-401 N416US New York-La Guardia Airport, NY (LGA) (http://aviation-safety.net/database/record.php?id=19890920-0)

Interesting, one NTSB board member dissented. Disapproved of an a/c commander only having 5500 hrs TT(2600+ in type). FO's time not mentioned.

[wileydog3]

sorry wiley
I don't buy the misset rudder trim
I have more than 17k hours in 737, I ve never seen this happen

I don't doubt you... if you say so. But I have a few thousand in the 737 also and remember the old rudder trim and the indicator on the -300/-400. I also know the guy who was in the left seat and some of the guys on the investigation. The rudder trim WAS full scale deflected on the LGA crash. And the round knob on the rudder trim replaced the old one with the rectangle.

read the probable cause of the LGA crash here...
ASN Aircraft accident Boeing 737-401 N416US New York-La Guardia Airport, NY (LGA) (http://aviation-safety.net/database/record.php?id=19890920-0)

Mis-set rudder trim may not have played a part in this DIA crash but I am familiar with the LGA accident..

[wileydog3]

misd-agin.. don't know how to say this any other way but the mis-set trim contributed to the accident and yes, they aborted late and yes they went off the END of the runway, not the side. But during the roll there were excursions.

As for an NTSB dissenter and arguing 'only 5500 hrs' one would have to wonder what his position would be today with some 121 carriers.

[Airbubba]

The rudder trim WAS full scale deflected on the LGA crash. And the round knob on the rudder trim replaced the old one with the rectangle.

And in the LGA accident there was a Pan Am pilot on the jumpseat. He was in uniform and assisted in the evacuation. The next day's New York Times had him in a white hat labeled as the captain of the USAir plane.

It was conjectured that the rudder trim may have been displaced by the jumpseat rider's foot or perhaps a meal tray set on the pedestal to serve coffee. ALPA hid the crew in a local hotel for two days before they would allow the feds to interview and do drug tests. I'm not sure they would get away with that these days.

As for an NTSB dissenter and arguing 'only 5500 hrs' one would have to wonder what his position would be today with some 121 carriers.

That would probably be enough to get an interview with a recently bankrupt major carrier.:)

Actually, as I recall, the LGA accident was the catalyst for requiring consolidation hours after IOE before being paired with another crewmember new in type.

[TonyWilliams]

Bizjets like the Global Express, and regional airliners have 28 VDC generators on the engines and APU, and use inverters for AC requirements. You then see why the recorders are on the DC bus in those planes.

I'm pretty sure thattThe CRJ series uses four AC generators (one each engine, one APU, one ADG/RAT). The EMB-120 uses three DC starter/generators.

[Centaurus]

It was conjectured that the rudder trim may have been displaced by the jumpseat rider's foot or perhaps a meal tray set on the pedestal to serve coffee

Maybe so but I experienced a rudder trim runaway in the B737-300 simulator. If you tweaked the knob and let it go (as you would), the damned trim slowly ran to full deflection. During that session the instructor was constantly criticising my handling of engine failure after take off as I was having considerable difficulty in keeping wheel central and applying correct amount of rudder. Later we discovered that each time I touched the rudder trim after it had been centralised at my request by the PNF the aircraft started to rock and roll. This was due to the rudder trim going uncommanded full scale.

Had the same experience in a real 737-300 while doing trim checks prior to start. Never trusted it after that and always double checked setting after making rudder trim changes.

[snowfalcon2]

The NTSB briefing in my opinion all but ruled out tires as a root cause. Only one main wheel tire was blown (right side inner wheel) and Mr Sumwalt explained that the track marks indicated it was OK until late in the event when the plane got its other damage. No mention of treads ripping off either; NTSB said there was no debris on the runway and the damage to the wheel was described more like "a gash".
Nosewheel is under the fuselage so not examined yet. But I'd think that if it had been wobbling due to shimmy, it would have left oscillating marks on the runway. No mention about that either; Mr Sumwalt said NTSB has found nosewheel track marks on the runway but that was somewhat beyond the point where main wheels started to "leave rubber on the runway".

The FDR information together with detailed wind data becomes more and more interesting.

[golfyankeesierra]

Don't think rudder trim has anything to do with this incident, but they do happen!

Maybe so but I experienced a rudder trim runaway in the B737-300 simulator. If you tweaked the knob and let it go (as you would), the damned trim slowly ran to full deflection. During that session the instructor was constantly criticising my handling of engine failure after take off as I was having considerable difficulty in keeping wheel central and applying correct amount of rudder. Later we discovered that each time I touched the rudder trim after it had been centralised at my request by the PNF the aircraft started to rock and roll. This was due to the rudder trim going uncommanded full scale.

Had the same experience in a real 737-300 while doing trim checks prior to start. Never trusted it after that and always double checked setting after making rudder trim changes.

Collegue of mine had it during flight. Since the 73's are all bent and it's common to use the rudder trim with A/P on to center the controlwheel (to avoid spoilerdeflection), he was using the trim a little bit. Before he knew he was flying crosscontrolled with a fully deflected trim. Turned out to be a sticky residue of coffee or something in the switches.

[Huck]

ALPA hid the crew in a local hotel for two days before they would allow the feds to interview and do drug tests.

It was a hospital, as I recall.

It was also surrounded by the city's SWAT team at one point. The district attorney was up for election I believe....

[theron]

Belgique, please watch the videos, you are speculating about things that have already been ruled out in public by the NTSB during their news conference on monday i.e. two failed tires on one side.

The NTSB also said that the tire marks left on the runway indicate that all the tires were fully inflated until after the initial event, although one tire has a gash in it, this is thought to have happened during the distance travelled off the runway. However, they still didnt rule it out 100% as a cause.


Snowfalcon2, i would be more concerned if the nose gear rubber marks on the runway started in the same place as the main gear, to me (not an expert) a 100 feet gap between nose and main gear marks seems about right on an aircraft of this length.

another quote from the video:

"One of the things we would typically look for was how was the airplane configured for take off, and we were able to determine that the flaps, the slats, the speed brake and the trim were all in a position consistent with a normal takeoff. The flaps were set at 5 degrees, the slats were set at normal take off associated with 5 degrees of flaps, the speed brake was down and the trim (the stabaliser trim) was set at a takeoff that we would normally expect to see for takeoff.

The tires, certainly there is a lot of questions out there about the tires and brakes, and we found absolutely no flat spots on any of the four main landing gear. Bear in mind we still dont have access to the nose gear because its tucked under the fuselage right now. No flat spots on the main landing gear tires and with the exception of one of the tires (which I'll talk about in just a moment) all of the 3 main landing gear tires were inflated to the normal inflation pressure. The one that was an exception to that was what I'll call the number 3 tire, thats on the right hand landing gear, the inboard tire. That tire did have a slash in it, but i want to point out the physical evidence of the tire marks that we've seen indicate that at the time that the air plane departed the runway and as it started through the (I'm calling it grass, its really ice i guess these days) but as the air plane was going through this grassy area and going over taxiway whisky charlie the physical evidence form the tire marks indicates that all 4 main landing gear were inflated at the time that the airplane was going off the runway and going through this grassy area. Our prelimiinary thoughts would be that this deflation occured during the impact sequence. We will do further study of that.

Now the brakes, the brake manifolds showed no leaks, they showed no locked brakes (no evidence of locked brakes). The brake stack (which would be the brake pads) the brake stacks looked good and the brake wear pins (which would give you an indicaton of how much the brakes have worn) the brake wear pins looked good and in the eyes of the NTSBs systems groups chairman he said there appears to be alot of life left in these brakes. so there is no indications from the physical examinations on scene of any brake problems, at this time.

the power plants (the engines) the on scene examination of the engines and the information of the flight data recorder contains no information, no evidence, to leads us to believe that there was any pre-impact problems associated with either of the two engines."

videos again:

part1: 9NEWS.com | Colorado's Online News Leader | Video (http://www.9news.com/video/default.aspx?aid=67989)
part2: 9NEWS.com | Colorado's Online News Leader | Video (http://www.9news.com/video/default.aspx?aid=67991)
part3: 9NEWS.com | Colorado's Online News Leader | Video (http://www.9news.com/video/default.aspx?aid=67993)

[Airbubba]

It was a hospital, as I recall.

I was told it was one of the airport hotels but you may be right.

From the NTSB report:

The Safety Board is extremely concerned that no federal investigators were allow to speak to the pilots of flight 5050 until almost 40 hours after the accident. Specific requests to USAir and ALPA to interview the pilots and to have them provide toxicological samples were made about ten hours and again about 20 hours after the accident. USAir representatives stated they did not know where the pilots were sequestered.

The Air Line Pilots Association representatives initially stated that they also did not know where the pilots were, then later stated that their location was being withheld so they could not be found by the media. This complicated the investigative process to a great degree. The sequestering of the pilots for such an extended period of time in many respects borders on interference with a federal investigation and is inexcusable.

It was also surrounded by the city's SWAT team at one point. The district attorney was up for election I believe....

Yep, and seems like he filed charges of vehicular homicide against the pilots, the charges were dropped when the feds claimed jurisdiction.

Had the same experience in a real 737-300 while doing trim checks prior to start.

In the old days we used to run the trim through to the limits to make sure it worked. Inevitably, someone would get interrupted and the trim would be left way out of position.

Now, the preflights I do only check to see that the trim is set.

[wileydog3]

ALPA hid the crew in a local hotel for two days before they would allow the feds to interview and do drug tests. I'm not sure they would get away with that these days.

Again, due to knowing some of the individuals in this accident (in the cockpit and on the investigation) there were no drugs involved. You may remember the DA in New York was running around making lots of legal noise about the crash and culpability.

And yes, I think you are correct about new rules for crew pairings coming out of this accident.

[wileydog3]

Centarus This was due to the rudder trim going uncommanded full scale.

Had the same experience in a real 737-300 while doing trim checks prior to start. Never trusted it after that and always double checked setting after making rudder trim changes.

Checking after making changes or making an input is always a good idea and yes, for a while it seemed there were incidents of trim being used and going full deflection. Exciting...

The rudder on the 737 is a very powerful flight control and it was quite easy to demonstrate that with a 60deg bank turn, one could wait until 5deg of a desired heading and with quick rudder input, you could immediately roll out. My first introduction to very powerful rudders was on the KC-135 which said something like a rudder hard-over could exceed 90deg in less than 3-5 seconds.

[wileydog3]

Huck is correct. The New York DA was looking for headlines and there was a rush to judgment. ALPA did exactly what it was supposed to do and that was defend its members from zealous government nitwits.

Unfortunately, we only have to ponder Rep Oberstar to see that big league nitwits are still in demand in politics.

[Graybeard]

They achieved 119 knots in less than 1900 feet. Is that within normal bounds, even given the cold temperature effect on density altitude?

[misd-agin]

Graybeard - Headwind component would be around 12-16 kts so they had to accelerate about 105 kts in 1900'.

Seems feasible.

[CAPTDOUG]

After listening to the detailed NTSB report given in Denver it seems to me (35 years in the USA airline business as a pilot and very intimate with Continental procedures)

Being that:

I do not believe the 737 has nose gear brakes therefore this would explain the NG markings 100 feet beyond the main gear markings.

AND:

The NTSB said that all systems including engines, flight controls (including rudder placement and trim) brakes and wheels were operating normally

AND:

The inbound flight crew (who was on board as a DH crew) said they had no problems or write ups on the AC

Therefore:

Then nose gear probably shimmied to a high degree ( a very common occurrence) just prior to V1 therefore braking a stabilizer or other NG steering part locking the NG 10-30 degrees to the left. If so the Aerodynamic rudder forces would not over come the nose gear forces forcing the AC off the runway.

But we will see!!!

[beechf33a]

Why was runway 25 or 26 not used since the winds were more favorable from the west? Were these runways available at the time? Why wasn't ground clearancde to one of these runways since they are both were 12000 feet? This would have elilminated the cross wind problen at runway 34L.

[snowfalcon2]

They achieved 119 knots in less than 1900 feet. Is that within normal bounds, even given the cold temperature effect on density altitude?

The way I understood it from the NTSB briefing video was:
1) the first officer noticed drifting off track when passing 90...93 knots.
2) runway track marks indicate a skid began at 1900 feet from threshold.

So far there is no official data linking elapsed time, distance and airspeed together, as far as I've seen, but from the above one can deduce that at 1900 feet the speed was in the order of 90 knots. The maximum recorded speed was 119 kts and Mr Sumwalt from NTSB made it reasonably clear that this was further down the takeoff run, i.e. the airplane continued to accelerate after it departed the runway centerline track.

[DC-ATE]

"Why was runway 25 or 26 not used since the winds were more favorable from the west?"

Now when did ATC ever let you take off into the wind?!?! That's not really a dig at ATC, but it always seems like there's a "preferred" runway and it's never into the wind. And, unfortunately, most pilots will just "go along" with things rather than "disrupt" the flow. However, I might add, that I was one of those who always seemed to be a "trouble maker" and request the runway 'I' wanted rather than the one "normally" used. Even if it meant I delay, I was willing to wait. I only wish more pilots would do the same. Glad I'm retired!

[FullWings]

I do not believe the 737 has nose gear brakes therefore this would explain the NG markings 100 feet beyond the main gear markings.
I've been thinking along the same lines. For the NG to leave tracks on the runway, there must have been quite a 'slip' angle between where the airframe was tracking and where the tyres were pointing. It is also one of the few parts left which haven't been inspected. From distant memory, "rudder fine steering" on the 737 is limited to something like 8degs, so normal operation shouldn't leave a trail of rubber behind...?

Then nose gear probably shimmied to a high degree (a very common occurrence) just prior to V1 therefore braking a stabilizer or other NG steering part locking the NG 10-30 degrees to the left. If so the Aerodynamic rudder forces would not over come the nose gear forces forcing the AC off the runway.
Sounds plausible, especially as an RTO would dramatically increase the loading on the NG, pulling the aircraft more off the runway. I still remember the tendency of the 737 nosewheel to wobble, even though it's been a long time since I've flown one.

[hbiwe]

Whatever happened might have had something to do with the fire which developed very fast (source of origin??), the loss of control with the sudden noises heard and the aircraft subsequently veering to the left. The whole right side, starting from somewhere around wheel well is completely burned, the left side intact. Just makes me wonder, what was going on. Since the jet "by coincidence" departed to the left....

[repariit]

I would like to know the condition of the nose gear scissor links. Anyone know when they will lift the wreckage? I’ll bet they are separated.

[misd-agin]

CaptDoug - unfortunately there's information that the issue started well prior to V1.

35 yrs as a pilot and you're posting your version of what happened this early in the game? :ugh:

[pattern_is_full]

"The way I understood it from the NTSB briefing video was:
1) the first officer noticed drifting off track when passing 90...93 knots.
2) runway track marks indicate a skid began at 1900 feet from threshold.

....and 3) Plane travelled another 700 feet before actually departing the runway.

"Why was runway 25 or 26 not used since the winds were more favorable from the west?"

As I mentioned prviously, I heard at least one other plane request 26 for LANDING as I was pax on inbound United flight to KDEN. (and it was approved by ATC)

To depart on 26, however, requires about a 3-mile taxi north and east into the prairie, whereas 34 L/R begin adjacent to the terminal with only about a 300-yd taxi.

Departing runway 25 is a shorter taxi, but requires taking off UNDER traffic inbound for 34 L/R.

Since most here, and presumably the 1404 pilots, thought the winds were within the capabilities of a 737, I guess it didn't seem worth the time.

[West Coast]

Rwy 25 was in use at the time of the accident. I was in the back of F9heading to it to commute home after my 3 day. DEN has a habit of sending you to the rwy that least conflicts with other aircraft. If your going west, runway 25, if your heading east to south its one of the 34's. Usually 34R. As far as the comment about possible conflictions with 34L/R and departing 25, there is none. The runways are far enough apart that they can do simo ops. I've overflown traffic departing 25 when landing north.

[beechf33a]

The NTSB will ultimately determine if wind was a factor in this accident. If wind was a factor then ATC must share the blame.

[FIRESYSOK]

How can ATC be to blame? The only way I can see that is if they misreported the winds. You must be joking.

[captplaystation]

Having to accept out of wind (or even down-wind) runways is a worldwide problem, usually due to the "noise-brigade".
As long as their voices are heard louder than ours it will be the norm at places like AMS, BRU & ZRH in Europe.

[West Coast]

If wind was a factor then ATC must share the blame.

More like the airports runway use program.

[DC-ATE]

Read my post #199.

Ultimately the Captain decides what runway to use, or NOT to use, even if it means going back to the gate! Wake up guys/gals.....who's in control? Or better yet, who is ultimately responsible?

[averow]

Edmund,

I wonder if the designs are relatively "frozen", despite advances in electronics, IT, etc. It may not be feasible to upgrade the FDR faster than every 5-10 years, due to a desire for uniformity.

[beechf33a]

I said shared responsibility. Read some of the NTSB reports. When the final NTSB report comes out and if the cross wind was a major factor you watch some blame assigned to the controller.

[DC-ATE]

The only way ATC could be blamed is if they gave false information.

Although in this litigious, I suppose anything's possible.

[beechf33a]

The primary responsibility for ATC and controllers is safety. Expedited and uniform traffic flow is secondary. Active runways are generally assigned based on prevaililng winds. In this case the active runway should have been 25 or 26 which the wind favored. Yes, pilots are ultimately responsible for safety of flight but they also have to depend on controllers for safety.

[DC-ATE]

'beechf33a' writes:

"The primary responsibility for ATC and controllers is safety. Expedited and uniform traffic flow is secondary. Active runways are generally assigned based on prevaililng winds. In this case the active runway should have been 25 or 26 which the wind favored. Yes, pilots are ultimately responsible for safety of flight but they also have to depend on controllers for safety."

1st two sentences are alright. Third sentence is not necessarily true. 4th sentence would've been nice but not required. Apparently you haven't done much flying. Or, have you done any?

Bottom line once again: the Captain has the ultimate authority AND responsibility.....period.

[West Coast]

Active runways are generally assigned based on prevaililng winds.

Generally being the operative word. If the airport has a runway use program in effect (and most major airports do) then that will determine the active runways.

Below is the KABQ runway use program. Its the most detailed one I could find in short order. It goes far beyond simply assigning a runway based on the winds. If DEN ATC was working within the constraints of it's plan then I think the individual controllers will fare well.

http://www.cabq.gov/airport/documents/noiseabatement.pdf

Below is a partial excert from DEN's program.

Boeing Company (http://www.boeing.com/commercial/noise/denver.html)

[DC-ATE]

Yes...and note the following two paragraphs contained in the Denver info.

"Pilots of departing aircraft requesting to use a runway or deviate from flight tracks other than in conformance with this Informal Runway Use Program for reasons of operational necessity are expected to advise DIA Ramp Control prior to pushback or upon initial contact. When able, DIA Ramp Control shall advise that the requested runway or flight track is a deviation from this Informal Runway Use Program."
-----------------------
"The FAA ATCT will assign runways deemed to have the least noise impact. If, in the interest of safety, a runway different from that specified is preferred, the pilot is expected to advise ATC accordingly. ATC will honor requests and advise pilots when the requested runway is noise sensitive."
-----------------------

All the Captain has to do is ask/advise.....simple.

Please note also, that I in no way am implying that they used the 'wrong' runway in this incident. That has not been brought out.

[beechf33a]

I cannot understand why you think I am questioning the pilots athority and think I have no flying experience. Anyone with any flying experience should know that the pilot is the ultimate and final athority, period! For your information I have most all the single and mullti ratings including ATP. I have about 6,000 hours mostly as flight instructor. Also, I have an A&P and AI. I had three years experience in the Navy as an air traffic controller befor being accepted for flight training. I was a Naval Aviator when I left the Navy. Only the best were accepted for training and then it was a weeding out process. Any average person can learn to drive an airplane. Most pilots would wash out of controller training.

[DC-ATE]

"I cannot understand why you think I am questioning the pilots athority and think I have no flying experience. Anyone with any flying experience should know that the pilot is the ultimate and final athority, period!"

That's what I've been trying to point out. Yet you keep bringing up ATC's possilbe role in this incident. All I'm saying is unless ATC gave false information that the crew based their decision on in this case, ATC was not at fault.

I'm glad you realize that the Captain has the ultimate and final AUTHORITY.

Good luck with your flying.

[Murexway]

"The primary responsibility for ATC and controllers is safety. Expedited and uniform traffic flow is secondary. Active runways are generally assigned based on prevaililng winds. In this case the active runway should have been 25 or 26 which the wind favored."

Sorry beechf33a, but things don't always work like that in the airline world.

[DC-ATE]

"Sorry beechf33a, but things don't always work like that in the airline world."

I've been trying to point that out.

[PJ2]

things don't always work like that in the airline world.
No they certainly don't and it's naive to think they do.

The captain will always prevail in a request for a more into-wind runway but at a place like Denver, Chicago, Kennedy, Toronto (especially), and others it will almost always cost a 30 to 60 minute delay or a very long hold on arrival and fuel is always an issue.

In fact, the neighbourhood "noise police" have more "authority", in terms of being listened to and taken seriously by airport authorities and politicians, than the captain, when it comes to runway use. It's why airline captains aren't politicians and why politicians could never be airline captains.

[beechf33a]

To: DC-ATE

We really have no disagreement. I was trying to point out what the NTSB would probably say in their final accident report if wind was a major factor. For example go to www.faa.gov (http://www.faa.gov) and read the final report number AAR-07-05 concerning the wrong runway take off at Lexington, KY on August 27, 2007. The pilot was cleared to runway 22 but actually took off on 26 which was too short. The pilot did not comply with the clearance, yet the NTSB listed seven items where the controller contributed to the accident.

Best regards

[Murexway]

Well, now you're starting to mix apples and oranges. That wrong runway accident isn't even in the same ballpark with the DEN accident under discussion here.

If the winds and runway conditions were within limits at DEN for the accident aircraft (which seems to be the case), the fact that there was a crosswind will not be a contributing factor any more than the captain getting out of bed that morning.

[West Coast]

I'm trying to figure out why you think ATC may take a hit. If ATC was complying with the use plan (which a quick review indicates they were) then any NTSB finding will point its finger at DEN airport authorities and not the individual controllers.

[Murexway]

"The captain will always prevail in a request for a more into-wind runway but at a place like Denver, Chicago, Kennedy, Toronto (especially), and others it will almost always cost a 30 to 60 minute delay or a very long hold on arrival and fuel is always an issue."

So right. One afternoon at LGA I was overweight for the runway in use by the time they put extra pax onboard and we taxiied, so I requested a different runway from the tower. As best I remember, the tower operator's reply went something like this:

"Sure, no problem. But we'll have to turn the flow around for the entire New York metro area. Expect a four-hour delay."

I burned down for about 40 minutes and departed on the runway in use. :O

[RobertS975]

Aren't both LGA runways the same length at 7,000 feet?

[WhirlyBob]

Since no one has yet mentioned this bit of good news, I thought I would:

Pilot in Denver runway crash released from hospital (http://www.denverpost.com/breakingnews/ci_11315037)

The Denver Post is also reporting that the NTSB plans to move the wreckage "early next week" so they'll finally get a look at the nose gear. Should be very interesting ...

[PJ2]

RobertS975;
Aren't both LGA runways the same length at 7,000 feet?
Well, they are but that's only the beginning of the decision-making process, notwithstanding traffic. WAT (Weight-Altitude-Temperature) limits, departure runway obstacle clearance data, (13 and 22 esp), and winds may individually or collectively dictate different weights for the two runways, 31/13 or 04/22.

Also, (and you may already appreciate this), the airplane may be able to "do it" but should anything occur which compromises an "on-limits" takeoff performance, there is no defense for the decision. It is by-the-books or no-go.

Murexway;
If the winds and runway conditions were within limits at DEN for the accident aircraft (which seems to be the case), the fact that there was a crosswind will not be a contributing factor any more than the captain getting out of bed that morning.
Absolutely correct.

WhirlyBob;
The Denver Post is also reporting that the NTSB plans to move the wreckage "early next week" so they'll finally get a look at the nose gear. Should be very interesting ...
Yes it should but the thinking behind this interest is, itself, interesting.

Would the demonstrated crosswind for the 73' assume nosewheel steering until liftoff and if so, what is the effect of the available rudder throughout the takeoff roll in the demonstrated crosswind condtions? The steer-by-wire nosewheel steering disconnects on the A320 at around 105kts, (but used to disconnect at 75kts or so as crosswinds were an issue on rudder alone). I fully realize they're not quite the same design or certification process/outcomes due types but all the same, the demonstrated crosswinds for each type are about the same. I also realize that we still don't know what the source of the reported vibration was and how uncontrollable, if at all, such made the airplane. Nor do we know what the recorders indicate even though they've been read. I suspect, perhaps like many, quietly, that the pedals and rudder were hard right and braking was close to hard on the right bogie.

If the scissors was broken in the takeoff sequence, it may or may not caster and the airplane may or may not controllable at 90kts by rudder alone. Perhaps it was a hard-over nosewheel due mechanical failure in which case we're out of test and certification data and territory and somewhat along for the ride.

Very glad to hear the captain has been released from hospital.

[beechf33a]

Personally, I am not trying to apply any kind of logic or suggest blame to anyone, just stating an opinion as to what the NTSB would say if cross wind was a factor.

[DC-ATE]

'beechf33a'

In your Post #230 you write:

"Personally, I am not trying to apply any kind of logic or suggest blame to anyone, just stating an opinion as to what the NTSB would say if cross wind was a factor."

But yet in your previous posts.....

#206 - If wind was a factor then ATC must share the blame.

#212 - When the final NTSB report comes out and if the cross wind was a major factor you watch some blame assigned to the controller.

.....it sure looks like you're will to accept/lay some blame on ATC.

[beechf33a]

#206 Poor selection of words by me. Should have said NTSB would probably assign blame. Yes, I must back off #206. Thanks for pointing this out

[manrow]

pj2 your post worries me:-

Quote - In fact, the neighbourhood "noise police" have more "authority", in terms of being listened to and taken seriously by airport authorities and politicians, than the captain, when it comes to runway use. It's why airline captains aren't politicians and why politicians could never be airline captains. - Unquote

This thread has rambled away from the important aspects, especially as no-one yet knows precisely what happened. However a number of allegations have been made as to who MAY bear the ultimate or partial responsibility.

All of this dialogue is missing the priority that the captain's authority is constantly under pressure from outside sources, whether directly involved such as ATC, or extraneous persons desirous of being re-elected who inspire noise abatement take-off procedures and routings which are frankly not safety designed, and hence need rejecting as often as any responsible captain feels appropriate.

[PJ2]

manrow;
All of this dialogue is missing the priority that the captain's authority is constantly under pressure from outside sources, whether directly involved such as ATC, or extraneous persons desirous of being re-elected who inspire noise abatement take-off procedures and routings which are frankly not safety designed, and hence need rejecting as often as any responsible captain feels appropriate.
Thank you for picking this point up which is often lost in discussions of the mundane and, unfortunately, sometimes even lost to the responsible person in the left seat. That is indeed "where the buck stops" and it is that person alone who's decisions and actions will first be questioned. The captain can do anything he or she needs to do to keep passengers, aircraft and property safe. All they have to do is justify it afterwards.

The difficulty is, in my view, not enough captains know where the park brake is nor do they use the word, "no" often enough, and instead press on with someone else's agenda "because it worked the last time".

Most of the time it does indeed work because airline procedures are not haphazardly designed or taught nor is the industry so demanding that an operation is paralyzed by due process, (although we've all seen some pretty horrendous individual operations which we'd all like to forget!).

After all is safe in the judgement of the captain, airline captains also have a duty to their company to ensure that the company makes money, within the bounds and requirements of flight safety.

Nor does any of this absolve the company officers right from the CEO/President on down to middle line management. If they are not doing their part in constantly asking the question, "Are we safe?", and ensuring that all employees know, right from the top executive, that there is an active and vigilant intolerance for compromise in safety, then they may be creating a lax or dysfunctional safety culture and may become a "contributing cause" of an accident.

That said, every captain must work within a system which itself is necessarily a compromise due to volume, fleet types and route type, (domestic/international). As stated above, a captain can request, even demand a certain runway but it may cost a very long delay. One is then instantly in the larger framed discussion regarding the use of airspace and runway allocations. To remain a good neighbour, airports will have policies of rotating runways in appropriate wind conditions so that everyone "shares" in the noiseprint.

To enlarge the frame, local city/municipal governments will, in order to enhance tax bases, grant zoning requests, often for residential areas but industrial zoning as well, on airports' doorsteps. More compromise of limited land use. One could build a small city on the land an airport takes up and while the economic benefits are enormous, so are the costs.

From "captain to the mayor's chair" in a few quick paragraphs, but these are the extended realities which impinge on the decision-making process in every operational cockpit.

[Murexway]

"Aren't both LGA runways the same length at 7,000 feet?"

Hello..... The departure runway in use had a 90 degree crosswind, while the landing runway had a direct headwind.... which would have made me legal at my full takeoff weight. Thus, I had to burn down fuel and reduce my weight in order to be legal to takeoff with a zero headwind component.

[FPP]

Let's look at this from an improper crosswind takeoff technique perspective. According to this article:
DIA crash details emerge - The Denver Post (http://www.denverpost.com/news/ci_11292044)

Forty-one seconds after Continental Airlines Flight 1404 began its takeoff roll at DIA on Saturday night, a "bumping and rattling" started, according to information gleaned from the cockpit voice recorder. Four seconds later, a pilot called for a rejected takeoff, according to the National Transportation Safety Board. Now, I know that it's improper to speculate on what caused the accident, but this seems like a good opportunity to look at good crosswind technique, which I have found sorely lacking in many pilots that I've flown with.

If there was no upwind aileron being applied, only directional rudder, then as the airplane approached flying airspeed, it is quite likely that the upwind wing could have risen, lifting the upwind landing gear, and placing all of the weight of the airplane on the downwind main landing gear. This would cause skipping, and could account for the "bumping and rattling" on the CVR.

If this were the case, then more rudder would have been applied to correct the aircraft toward the runway centerline. You would have the effect of an airplane pointing to a heading a number of degrees left of the runway heading.

Okay, now follow me here. The captain gets quite uncomfortable with this situation, and executes an abort. Four seconds later, a pilot called for a rejected takeoff, according to the National Transportation Safety Board. He simultaneously returds the throttles, extends the speed brakes (spoilers) applies reverse thrust, and the wheel brakes.

What happens when the spoilers get deployed? All of a sudden, the lift is killed on the upwind wing, all four MLG tires 'bite' the runway surface, and the airplane immediately follows its heading, which, as you remember, was to the left of the runway heading.

Of course we won't know what really happened for a while, but it's a valuable lesson for the beginning pilots here "aileron cures skipping".

[Cough]

What happens when the spoilers get deployed? All of a sudden, the lift is killed on the upwind wing, all four MLG tires 'bite' the runway surface, and the airplane immediately follows its heading, which, as you remember, was to the left of the runway heading.

Well almost. Classic 737's have a pivot on the MLG which is why they crab when they taxy. That would have alleviated the effect that you describe.

[TheMessenger]

misd-agin, where are you???????

Aren't you going to slam FPP for speculating?

Actually, I like his assumptions, speculations and theories.

[BOAC]

FPP - why post a newspaper article from 23/12 on 28/12? I think you'll find all its contents in this thread if you take the trouble to look First post here and you are dropping little gems of 'hints' from your vast experience (not given) that the Captain might just have 'done it wrong'...................:ugh:

Spare me!

[Murexway]

FPP:
Now, I know that it's improper to speculate on what caused the accident, but this seems like a good opportunity to look at good crosswind technique, which I have found sorely lacking in many pilots that I've flown with.
---------------------------------------

Don't know what you fly (Cessnas?) or how much experience you have, but rest assured, this wasn't the first crosswind takoff this CAL captain has ever made. He wouldn't be in the left seat of a 737 if he couldn't manage to stay on a dry runway with a crosswind :cool:

[golfyankeesierra]

FPP, are you a pilot?
What happens when the spoilers get deployed? All of a sudden, the lift is killed on the upwind wing, all four MLG tires 'bite' the runway surface, and the airplane immediately follows its heading, which, as you remember, was to the left of the runway heading.

Before you start accusing CAL pilots of poor airmanship:

A wing needs Angle of Attack to fly. Rolling down the runway the AOA is zero. It won't fly and your tires will have all the friction it needs when you abort.

Also try to find some crosswind landing video's on Youtube, preferably some crabbed (is it called traversed in English?) landings.
You'll find out that inertial is the greater force and once the aircraft touches, you'll see that it will continue in the direction of its flightpath and not the way it's nose is pointing.

[captplaystation]

FPP
I think you will find that by the time someone makes it to LHS (or even RHS) in a company like Continental they can probably manage a crosswind take-off. I am sure they are probably very grateful to you though for reminding them of the techniques involved. :D ;) :rolleyes:

BTW, I like your idea to "RETURD the throttles" :ok:

[ChristiaanJ]

FPP, are you a pilot?Are you?
Judging by your remarks you're not....
A wing needs Angle of Attack to fly.Oversimplistic.... The AoA needs to be enough for the wing to generate enough lift to take off. Rolling down the runway the AOA is zero.Nonsense. The exact AoA depends on aircraft design, aircraft configuration, loading, exact state of the oleos, and probably half a dozen things I'm forgetting. It won't fly and your tires will have all the friction it needs when you abort.By the time you're close to rotation (and add a crosswind), there are already a lot of aerodynamic forces acting on the aircraft which make nonsense (again) of your comment.

Also try to find some crosswind landing video's on Youtube, preferably some crabbed (is it called traversed in English?) landings.I think most of the people posting serious remarks here have DONE crosswind landings, and don't need to watch them on YouTube....

That said, there ARE some "interesting" crabbed landings on YouTube....
Kai Tak springs to mind.

CJ

[captplaystation]

Or Lufthansa in Hamburg :eek:

[golfyankeesierra]

Quote:
Originally Posted by golfyankeesierra"
FPP, are you a pilot?
Are you?
Judging by your remarks you're not....
Christiaan, I am not looking for a contest here.
In their FCOM's both Boeing and Airbus stress the importance of correct rotation. If you rotate too early you get a tailstrike or it won't fly at all, if you rotate too late it flies to late.
It's all about AoA, airliners don't fly just by rolling down a runway.

The reason I react is that PFF connects this incident with poor crosswind technique:
this seems like a good opportunity to look at good crosswind technique, which I have found sorely lacking in many pilots that I've flown with.
He probably flies at an aeroclub; the people I fly with have very good crosswind techniques (and know a little bit about aerodynamics too!).

[misd-agin]

The Messenger -

Sorry about being slow to respond, I was actually flying planes for a living instead of speculating about issues that some folks seem to have limited understanding of. And, as you can see, others have already questioned FPP's excellent := speculations.

I'm glad you liked FPP's "assumptions, speculations, and theories". Using all the 'large' jet time you have could you tell me what effect you think too much, too little, or no crosswind controls, would have on your jet?

Hey, I agree with FPP that it's not surprising to see less than good or excellent crosswind techniques. But that even gets debated as to what's the correct technique.

But, using all you airliner type experience, what impact would that technique have on the a/c that would lead you to think it would cause the airplane to depart the runway like the CAL a/c did?

[PJ2]

misd-agin;
But, using all you airliner type experience, what impact would that technique have on the a/c that would lead you to think it would cause the airplane to depart the runway like the CAL a/c did?
I think it would take significant abuse of the flight controls and nosewheel steering to cause an airliner to depart the runway in a crosswind.

In other words, if the pilot flying is handling the controls appropriately with regard to a strong crosswind the aircraft would not "depart the runway on it's own" in a 25kt (or so) crosswind and if the pilot flying did nothing until the airplane itself signalled that it needed help in staying straight, recovery would not be an issue and would not, in and of itself, take the airplane off the runway. Neutral controls in a certified/demonstrated crosswind does not, I think, constitute "significant abuse" of the controls but rudder into wind might, as might full aileron into wind, depending upon runway friction index. Clearly, aileron turned towards the downwind side would be abuse.

The proof, for me, of this statement is not only in the data I examine every day and the previous 35 years flying the DC9, DC8, B727, B767, L1011, A319/320, A330/340 in RHS & LHS in Canadian winters including St. John's Nlfd :}, but "out there", in the accident rate around the world in which crosswinds were a causal and not merely contributing factor - ie., there just aren't any such accidents even as there are some very spectacular landings and near-accidents in very high, (beyond "demonstrated", as at Hamburg). crosswinds. Keep in mind too, the many statements made here by other professional colleagues - that CAL crews are not low-time, start-up, inexperienced, (MPL'd!) airmen but are seasoned veterans who meet such operational challenges as a matter of course just like high-time, professional crews do all over the world. Like others who teach, in training/line indoc work I've seen some interesting approaches and very "interesting" touchdowns and takeoffs, none of which resulted in anything more than a seatcover-change and discussion.

Airplanes just don't depart runways in a 25kt crosswind without significantly altered circumstances or untoward mechanical failure.

All this said, on a slippery runway, (very low JBI or CRFI (http://bathursted.ccnb.nb.ca/vatcan/fir/moncton/WeeklyTopics/Archives/20031221/CurrentTopic.html) readings), crosswind limitations MUST be respected, not because the airplane will "automatically" be blown off the runway, for, unless the JBI/CRFI is near zero, certified crosswind limits and reductions of same using the CRFI charts are generally not a problem on sanded/urea-treated runways,... but because the moment significant roll-spoiler is introduced with big aileron displacements into wind, or, in a rejected takeoff, reverse is brought to high power settings, the airplane WILL be turned into wind or will otherwise drift downwind according to and as a result of the thrust, crosswind, drag and wheel-friction vectors.

All of this is (or should be) standard knowledge in a professional airman's toolkit, especially those who fly transport category aircraft and at the very least should be part of any airline or corporate initial and recurrent training syllabus.

PJ2

[misd-agin]

PJ2 -

I was trying to get The Messenger to reply. He's a fan of FPP's speculation and apparently an 'expert' of some type.

I'd almost completely agree with your post except that human error sometimes does creep into accidents in unexpected ways. Not saying that did happen, but until we understand what did occur I'd rather leave the speculationing to the 'experts'. :yuk:

[PJ2]

Understand - fwiw and as may be expected, I don't concur with FPP's theories but we'll see what comes of the recorders and the NTSB's account of events.

[beechf33a]

With all the discussion about cross wind, I wonder what the Boeing 737-500 manual says about a cross wind take off. Let us know 737 pilots.

[PJ2]

beechf33a;
With all the discussion about cross wind, I wonder what the Boeing 737-500 manual says about a cross wind take off.
I think, first of all, the question is addressed in the thread.

That said, you must have in mind a "satisfactory" answer which would be compared to the actual weather conditions at the time. That has been done also.

Other than this, where would this line of enquiry take you such that new information is obtained? Is there something missing in the discussion point above that doesn't apply to the 737 or crosswind ops in general? I am certainly open to such points but don't see the point of this particular question.

[Murexway]

beechf33a:

"With all the discussion about cross wind, I wonder what the Boeing 737-500 manual says about a cross wind take off. Let us know 737 pilots."

--------------------------------------------------

This isn't a training forum.

If you're so curious about flying techniques and limitations in transport catagory aircraft, I have a suggestion for you:

There are ads at the top of the forum pages for training outfits offering 737 type-ratings. Why not sign up for a course and get qualified in the 737.............. then you'll know.

[misd-agin]

beechf33a -

"Naval Aviator". What did you fly, and when?