Videos Of Challenger 600 Crash In Aspen Colorado

[Don Hudson]

JL, I asked my friend your question this afternoon. His response was straightforward: balanced against weight and complexity, (cost and reliabilty), aircraft (rather, wings) designed today do not need "triple-slotted flaps".

The McDonnell-Douglas products from the DC4 on had double-slotted flaps, (including the MD11); I believe the latest Airbus (A320 on) are single slotted. The last triple-slotted aircraft designed was the B727.

blues, that's a fabulous (and instructive!) photograph, thanks.

[Don Hudson]

JL, further on triple-slotted flaps: "When we were chatting you asked why the B727 might have triple-slotted flaps where none of the others have had such complicated designs. I have located that B727 case study and I think the design was driven by airline requirements. They say that 'a prime 727 requirement from Eastern Airlines was to operate a Boston-La Guardia - Washington-Atlanta-Miami flight without refuelling; in order to achieve this mission it was necessary that the first landing at La Guardia be made within a field length of 4900 ft with a full payload plus a heavy load of fuel (maximum landing weight)'. This will obviously put a premium on low approach speeds, hence pressure on the flap system to deliver the utmost lift. They were looking for approach speeds around 110 kts and landing fields below 5000 ft. They targeted a CLmax of 2.9 apparently, which is way beyond the capability of double-slotted systems."

[boestar]

Don:

I seem to recall requirements for Short Field landings and Take-offs in the design as well. By todays standards the 727 isn't really a short field aircraft but in its youth that was a driver. Mexicana went one step further with the Jato to achieve high and hot performance.

727 Had Triple slotted plus Krugers plus slats. Very similar to the 747.

[JL]

Thanks Don et al...one tends to forget that aircraft design goes well beyond the requirements to operate safely; gotta make money with the darned things too!

[DEFCON]

Don

Regarding the 747 - 800; do freighters come new with pax windows, or might this aircraft be something like an executive version?

If we're to give the flight crew the benefit of doubt, it's likely that they found the snow to be of the non-adhering type and 'assumed' it would 'all' blow off on takeoff. Perhaps it did, but only the crew would know for certain now. On the other hand; there's always a hero out there that doesn't realize he's in waiting to become part of the news at 6.

Do you recall winter operations at Pearson in the pre-1989 days? My favorites were the Friday night departure traffic jams during periods of inclement weather. Everyone had the pre-departure Type 1 spray job at the gate and then proceeded to sit in line in the falling snow while they waited for a ridiculous amount of time to go on 24R, or was it 23R at that time? Anyway, the aircraft involved in that day were as likely to be hard-winged birds such as the DC-8s, F-28-s, BAC 111's, DC9's and so on as it was those that were slat equipped. This situation was accepted by pilots and ops departments as common at most all major North American airports during bad weather winter rush hour periods.

With contamination being what it is, why weren't aircraft going in on takeoff on a regular basis? My guess; even though their hearts were in their throats, the pilots only became overwhelmed when something unexpected went wrong such as was the case in the low power application in the Air Florida Washington crash, or the roll and crash of the DC 9 at Denver due to the pilot's snap rotation. Nonetheless, I believe, all aircraft have lot of built in redundancy that keeps the show moving forward at times when operations should not be undertaken and that factor continues to go a long way in protecting everyone involved from poor policies, decisions and pilot technique. Regardlesss, every so often, the grim-reaper decides to intervene and add an unexpected cog to the mix, which then becomes the master link in the crash chain.

[DEFCON]

With respect to the Challenger crash; can any one provide the flap setting that would be used at this high altitude airport and guess what it might be in a 30kt tailwind at the approximate landing weight of this aircraft? To follow-on; would the high altitude landing configuration issues fail to provide automatic inhibition of the stick-pusher in this case?

[boestar]

Don

Regarding the 747 - 800; do freighters come new with pax windows, or might this aircraft be something like an executive version?

If we're to give the flight crew the benefit of doubt, it's likely that they found the snow to be of the non-adhering type and 'assumed' it would 'all' blow off on takeoff. Perhaps it did, but only the crew would know for certain now. On the other hand; there's always a hero out there that doesn't realize he's in waiting to become part of the news at 6.

Do you recall winter operations at Pearson in the pre-1989 days? My favorites were the Friday night departure traffic jams during periods of inclement weather. Everyone had the pre-departure Type 1 spray job at the gate and then proceeded to sit in line in the falling snow while they waited for a ridiculous amount of time to go on 24R, or was it 23R at that time? Anyway, the aircraft involved in that day were as likely to be hard-winged birds such as the DC-8s, F-28-s, BAC 111's, DC9's and so on as it was those that were slat equipped. This situation was accepted by pilots and ops departments as common at most all major North American airports during bad weather winter rush hour periods.

With contamination being what it is, why weren't aircraft going in on takeoff on a regular basis? My guess; even though their hearts were in their throats, the pilots only became overwhelmed when something unexpected went wrong such as was the case in the low power application in the Air Florida Washington crash, or the roll and crash of the DC 9 at Denver due to the pilot's snap rotation. Nonetheless, I believe, all aircraft have lot of built in redundancy that keeps the show moving forward at times when operations should not be undertaken and that factor continues to go a long way in protecting everyone involved from poor policies, decisions and pilot technique. Regardlesss, every so often, the grim-reaper decides to intervene and add an unexpected cog to the mix, which then becomes the master link in the crash chain.

Defcon:

there is usually a margin put in place but there are several factors that reduce that margin. Perhaps a little contamination woud be fine on the wings except that there is a football team seated in the rear of the aircraft causing a slight aft Cof G movement. When you start combining factors (some of which you may not even be aware) thats when the metal meets the ground.

[boestar]

With respect to the Challenger crash; can any one provide the flap setting that would be used at this high altitude airport and guess what it might be in a 30kt tailwind at the approximate landing weight of this aircraft? To follow-on; would the high altitude landing configuration issues fail to provide automatic inhibition of the stick-pusher in this case?

You pose a good question here. The aircraft "landed" which met all the conditions (from what we know) to deploy the spoilers (wheel speed >40kt and throttles idle, WOW) advancing the throttle will put the spoilers back down but will the inhibit of the stick pusher still be active. I believe it will not because Radar Altitude is used. however who knows what that nasty bounce did.

[Don Hudson]

DEFCON, my memory was incorrect - it was a passenger version of the -800; the takeoff was from Payne Field and I assume the airplane was on a test flight with crew-only on board. Probably light as a feather. So to speak...!

Yes, do I ever remember YYZ in pre-1989 days! BTW, the DC8 wasn't quite "hard-wing" as it had slots inboard of each engine pylon, more (I guess) to control airflow around the pylon than do the traditional job of slats.

[Mizar]

Lightweight, good acceleration, probably rotated at a reasonable rate and had loads of lift. But being the test pilots they are, they likely would not have done that in a Challenger or RJ.

You might find that quite a few pilots at one of our airlines in Canada have taken off with some certain amounts of frost on top of the wings of their 737NG, and it was done quite safely too.

As a final note, you may remember that I mentioned the Dryden crash and why would somebody takeoff in that aircraft type(someone who was very new to jet ops) when it had contamination. He must have gotten away with it before and thought he could do it again but failed to consider or be aware of the sensitivity of his hardwing jet to contamination.

I post a quote from a previous accident which appears to match my theory about the Dryden accident.

"AAR 70-20 Ozark DC9-15 27Dec68 at Sioux City Iowa; quick-turn during early morning, then T/O in freezing rain. Crew acknowledge that some ice had accumulated on the aircraft during the approach and ground stop. // Though Ground Agents advised him of ice accretion, the Captain elected to NOT remove the structural ice from the wing. // Crashed during takeoff -stall. Low time captain, low time F/O. Very short prior layover. Very little swept wing experience. Crew reported to investigators that they had done takeoffs with slightly iced wings IN OTHER AIRCRAFT (staight-wing), and thought they could safely do so under similar conditions in the DC9."

On this thread, I have basically been questioned as to why I would post information about the sensitivities of hardwing jets as compared to the slatted versions to contamination. It is quite simple. Compared to the nice white collar pilot jobs most posters here now experience, there is a whole other world out there where rules are bent if not broken from time to time(Just ask your next flightcrewmember about some of their flying experiences in the early days of their career). This is just reality. When you tell these guys should always de-ice because it is dangerous not to, you are of course very right. But that doesn't change the mindset of some who have gotten away with things multiple times and think they always can.

If this information about the Ozark crash could somehow have made it via a forum thread to the Dryden pilots who had likey gotten away with it many times, an accident may have been averted. That is why I post this information.

[Vsplat]

I've resisted the temptation to post on this forum for some time. This thread however warrants an exception.

Don, of all the people I know, I think you rank among the most humble, yet knowledgeable. It makes me smile to see you still engaged here, as in the other orbits we share. May your input, and influence, long continue.

To those who would use this tragic accident as a springboard for waging a personal argument based on speculation about what was going on, perhaps a reminder about one of aviation's oldest rules is in order.

Every lesson we have ever learned in aviation has been paid for with the blood of a colleague. This entire thread started because two of our own have just made that investment, once again. Perhaps we can pause the rhetoric here and allow the NTSB to get to the bottom of things.

I have read this entire thread, top to bottom - the assumptions regarding what is accomplished by the low-energy regime, the lessons of Dryden, the regulations and their application. I must actually be getting as old and crusty as the mirror says, because, quite frankly, I have to say that I've never seen such a trainwreck of cherry-picked quotes, misunderstood references and reverse-engineered history as the cat-flight here has drawn out. While it all muddies the water and makes it hard to see what's right, it does suggest some of what is wrong.

I would recommend a sound reading of Don's posts - not only for the information to be found there, but the clear definition of what is known and what may yet be learned. An invitation for others to add what they have learned, and to build from there. That is how safety is advanced - not by laying out quotes as though they were trump cards.

There's been talk here of experience. At the end of the day, maybe the experience that matters most comes at the graveside of a colleague, or in the days of waiting and wondering that haunt family and friends after an accident. I seriously doubt that many of us who have walked that walk would sink much stock into a war of quotes and verse.

I am reminded why regulations exist - because the reasons behind them are so quickly forgotten.

Vs

[Moon The Loon]

Welcome back...

[Mizar]

As a follow-up, I thought I would post some information about ice contaminated swept wing jet accidents. Strictly the accidents themselves that I am aware of. There can be further factors, the Air Florida accident had unintentionally significant reduced power. Others had rapid rotations in combination with their contamination. But unless the hard wing aircraft pilots are making secondary errors at a rate of about 10:1 compared to the other pilots, there must be another reason for the high accident rate which the NTSB has already stated is the increased vulnerability of the hard wing aircraft to contamination. Please feel free to add to the list as there may be more accidents.

Slatted aircraft:

Air Florida 737-200 Washington

Non-Slatted aircraft:

27 Dec 1968 Ozark DC-9-10 http://aviation-safety.net/database/record.php?id=19681227-1

26 Jan 1974 THY F-28 http://aviation-safety.net/database/record.php?id=19740126-0

27 Nov 1978 TWA DC-9-15 http://aviation-safety.net/database/record.php?id=19781127-0

15 Nov 1987 Continental DC-9-10 http://en.wikipedia.org/wiki/Continental_Airlines_Flight_1713

10 Mar 1989 Air Ontario F-28 http://en.wikipedia.org/wiki/Air_Ontario_Flight_1363

17 Feb 1991 Ryan Air DC-9-15 http://www.airdisaster.com/reports/ntsb/AAR91-09.pdf

22 Mar 1992 USAir F-28 http://en.wikipedia.org/wiki/USAir_Flight_405

5 Mar 1993 Palair F100 Skopje http://aviation-safety.net/database/record.php?id=19930305-1

4 Jan 2002 CL600 Challenger Birmingham U.K. http://www.caa.co.uk/docs/33/factor200439.pdf

21 Nov 2004 China Eastern CRJ200 http://en.wikipedia.org/wiki/China_Eastern_Airlines_Flight_5210

28 Nov 2004 CL600 Challenger Montrose, Co. https://www.ntsb.gov/investigations/fulltext/AAB0603.html

25 Jan 2007 Air France Regional Fokker 100 http://aviation-safety.net/database/record.php?id=20070125-0

14 Feb 2008 Belavia CRJ200 http://en.wikipedia.org/wiki/Belavia_Flight_1834

[Mizar]

To those who would use this tragic accident as a springboard for waging a personal argument based on speculation about what was going on, perhaps a reminder about one of aviation's oldest rules is in order.

Every lesson we have ever learned in aviation has been paid for with the blood of a colleague. This entire thread started because two of our own have just made that investment, once again. Perhaps we can pause the rhetoric here and allow the NTSB to get to the bottom of things.

I have read this entire thread, top to bottom - the assumptions regarding what is accomplished by the low-energy regime, the lessons of Dryden, the regulations and their application. I must actually be getting as old and crusty as the mirror says, because, quite frankly, I have to say that I've never seen such a trainwreck of cherry-picked quotes, misunderstood references and reverse-engineered history as the cat-flight here has drawn out. While it all muddies the water and makes it hard to see what's right, it does suggest some of what is wrong.

There's been talk here of experience. At the end of the day, maybe the experience that matters most comes at the graveside of a colleague, or in the days of waiting and wondering that haunt family and friends after an accident. I seriously doubt that many of us who have walked that walk would sink much stock into a war of quotes and verse.

Concerning cherry picked quotes, I obviously cannot post entire reports as they would be too long and tedious.

While you may feel that I am speculating about the cause of the Air Ontario accident(you stated train-wreck of cherry picked quotes, misunderstood references and reverse-engineered history) when I say that the pilots may have flown different aircraft previously with contamination, I would like to quote a significant statement from the Mohansky commission report which says:

One can easily imagine how the message communicated during training, and in the Fokker manual for the F-28, that no snow, ice, or frost should be present on wings, may have been discounted to some extent by crews who had successfully operated (albeit in different types of aircraft) with some degree of contamination. Combined with a "bush culture" which was attributed to much of the operational management of Air Ontario, this tendency would not have been properly checked by the F-28 chief pilot or the director of flight operations. In all likelihood, the permissive management environment at Air Ontario probably exacerbated such non-standard operational practices

I am not trying to be confrontational, just to harshly examine with no emotions the root causes of accidents. I have known four commercial pilots who died in accidents. Two close enough to result in tears. But emotion should not get in the way of analysis.

[Mizar]

Hi Malcolm,

You said you were interested in an actual study comparing contamination effects on non-slatted versus slatted wings. I believe that I have found some information for you. First, to quote some online information about the researcher below:

Frank T. Lynch of Yorba Linda, Calif., is recognized nationally and internationally as an industry expert and leader in practical applied aerodynamics for transport aircraft, especially for the use of advanced technologies to improve aircraft performance and flight safety characteristics. Lynch is especially noted for his many contributions in propulsion integration aerodynamics, adverse weather effects, and testing/instrumentation requirements. He has been acknowledged as possessing an unexcelled understanding of how to use scale ground test results to predict full scale flight characteristics. His opinions are solicited by senior people in both government and industry throughout the world, and his publications are widely referenced by leading aerodynamicists aroundthe world. Lynch has been a McDonnell Douglas employee for nearly 37 years.

Second, to Cherry Pick highlights of his study:

Lower percentage losses in maximum lift capability due to leading-edge ice buildups are experienced if the ice buildup occurs on an extended/deflected leading-edge device such as a slat. The maximum-lift penalty for the 0.03 inch ice buildup on a slat would be about 10 percent at typical landing flap settings. However, the penalty could well be near 20 percent on the wing for lower takeoff flap settings,

Losses of from 10- to 20-percent are lift indicated, dependent upon whether conventional trailing-edge flaps are deployed or not.

So you can see, while there are aerodynamic losses on all wing types, they are greater for the non-slatted types, which is obvious if you think about it. Which is all that I have ever really said. More camber means more lift(although I am sure the engineering types have more technical terms to use). There are some associated charts and graphs with the study which is buried among other studies on the document I have linked to. Studies by Mr. Lynch has been quoted in NTSB accident reports.

Try page 181 of 286 on this link http://www.dtic.mil/dtic/tr/fulltext/u2/a246297.pdf

Some people have tried to expand on this to claim that I am advocating not to de-ice on certain aircraft which is not the case. I only said that non-slatted is less forgiving than slatted to contamination.

It looks like interest has been lost in this thread now that things have been clarified but it is an extremely important issue that has resulted in a lot of deaths. Glad to have been able to clear things up in the last few posts.

[boestar]

Mizar:

That

So you can see, while there are aerodynamic losses on all wing types, they are greater for the non-slatted types, which is obvious if you think about it. Which is all that I have ever really said. More camber means more lift(although I am sure the engineering types have more technical terms to use).

Statement is only true with the Slats extended and a comparable angles of attack. Thats what slats are there for, to increase the angle of attack of the wing by 1) increasing the camber of the wing and 2) channelling airflow from the high pressure side of the wing to the low pressure side there by smoothing out the boundary layer and delaying separation.

In the takeoff and landing regime the slatted wing will perform better at low speeds and create more lift but I still do not think you can definitively state that a slatted wing will allow you to takeoff with contamination on the wing.

Wing contamination by its very nature is unpredictable and each occurrence will be different. Also remember that contamination will not only disrupt airflow but also adds weight to the air frame both causing more drag on the aircraft. While Slats may give you better tolerance to contamination that is NOT their purpose at all and should never be looked at as such since that will give a false sense of security to the uninitiated. Hard wings are designed to fulfill their intended purpose within their design limits and the same goes for slatted wings. Those design limits re different and each has its rules surrounding it.

Having worked Flight Test I can tell you that contamination is done on aircraft when defining the flight limitations. In Fact I have glued styrofoam to an aircraft wing in these pursuits to simulate contamination. I have see (simulated) contamination affect a slatted wing severely.

[Mizar]

Thank you Boestar,

I meant slatted wings with the slats extended of course. It does not surprise me that the styrofoam that you attached to wings had a significant effect.

I also know that you cannot takeoff with contamination on a slatted wing as it is against the law. And it is increased risk. I was just clarifying some discussion issues that had arisen and studies that have been done in response to the large difference in accident rates between types of wings. Nice to be able to hear from a test pilot.

You may have seen an earlier post about 737 NG pilots taking off with some contamination on top of their wings. I believe you will find that under specific circumstances, Boeing has approval to do so along with a Canadian operator. No doubt after appropriate documentation and training. However, I cannot find a link for this information.

Airbus has done studies on this and an older document linked here shows their stated goal to get approval to allow takeoffs with upper wing frost. I am not sure of the final result but for interest sake, here is the link.

http://www.smartcockpit.com/docs/Takeoff_With_Upper_Wing_Frost.pdf

As a aside, for many years, the FAA allowed certain aircraft operators up until a few years ago to takeoff with so-called polished frost on their wings.

http://www.faa.gov/news/press_releases/news_story.cfm?newsId=11003

No doubt there was the problem of people taking things too far and so in the name of safety, all frozen contamination was banned by the FAA, except the standard 3mm underwing frost that many of us see from cold soaked fuel and the 737NG approval.

[Kip Powick]

Cold socked???

I think Mizar has too many posts on the go... ...The post he recently responded to was written by boestar, not Manwest as I do not believe Manwest has much experience attaching Styrofoam to an aircraft wing ................... and I believe he meant cold-soaked....but we all knew that didn't we ??

[Moon The Loon]

I think Mizar has too many posts on the go... ...The post he recently responded to was written by boestar, not Manwest as I do not believe Manwest has much experience attaching Styrofoam to an aircraft wing ................... and I believe he meant cold-soaked....but we all knew that didn't we ??

No Kip: I think you meant he has too many HANDLES on the go...don't you?

[Mizar]

I think Mizar has too many posts on the go... ...The post he recently responded to was written by boestar, not Manwest as I do not believe Manwest has much experience attaching Styrofoam to an aircraft wing ................... and I believe he meant cold-soaked....but we all knew that didn't we ??

Oh well, it happens. Even to the very best of the best. I have good news for the forum, I will try to close in from my 290 posts to the 8,931 posts by Kip.

Hopefully a few others will have something to contribute to our serious subject involving aviation safety. But if not....

I believe that styrofoam used for testing of inflight icing is typically attached to the leading edge. Frost is typically on top. The most critical areas for lift seem to be the first quarter of chord of the wing. So a takeoff with ice accumulated from the previous flight would have more aerodynamic effect and certainly explains the difficulties encountered by our flight test pilot. How big were those styrofoam pieces that you used Boestar.

Then again, ever notice how many big jets have no anti-Icing capability on the horizontal stab. Apparently tests were done with significantly large pieces of styrofoam on the leading edges with no adverse effect in flight. I assume they had to takeoff to do the tests in flight with the styrofoam attached.