Seething About the Buffalo Crash

By Robert Mark on March 1st, 2009

I don’t know what makes me more angry, the story in the Wall Street Journal that claims investigators are pointing the finger of blame at the pilots of the Dash 8 Q400 in the Buffalo crash a few weeks ago, or that from a pilot-training perspective we seem to be reliving a reality that should be all too familiar after the ice-related 1994 ATR crash in Roselawn Indiana, as well as the Brasilia crash near Detroit in 1997. Q400The issue of pilot qualifications and training are sure to make headlines again soon, as well, after Buffalo – not to mention pilot hiring standards, crew duty times and an overall focus on the bottom line. The historic conflicts between NTSB recommendations and actions taken by the still leader-less FAA are certain to get in the way as well.

While the NTSB’s job is gathering all the facts to determine a probable cause, I – as a flight instructor – see issues related to wing contamination that should be well-known to other aviators, like letting the autopilot fly the aircraft in icing conditions. I’m not waiting for every single detail to emerge before I remind students and fellow pilots that ice of any part of the airplane is nothing to screw around with. It seems senseless that any pilot is forced to reread the basics of aerodynamics on lift generation, but as long as people keep breaking airplanes in ice, we seem to have little choice. The myriad of NTSB accident reports related to ice are a great place to begin reinforcing the deadliness of complacency around contamination of wings and tail plane.

Absolutely Right, or Wrong?

The real question now seems to be whether the Dash 8 crew in Buffalo experienced a wing stall due to ice build up, or a tail-plane stall because of the frozen water attached to the rear airfoils. That’s why the NTSB will be replaying the data recorder again and again over the coming months.

What makes this accident so frightening to anyone who flies were the NTSB comments about how the Dash 8 captain added power and pulled back on the control column – enough to overpower the stick shaker – when the aircraft stalled. If that was a traditional wing stall incident, that was absolutely the wrong action to take.

If, however, the tail-plane stalled, adding power and pulling back on the column was the right reaction. DH6 jetwhineIn either case though, an incident like this at low altitude left few recovery options and hence the urgent need to shake other aviators up until they realize the seriousness of ice on the wings or tail surfaces.

We’ll need to wait for NTSB to determine the cause for certain, but watching this old NASA icing-research video is an eye-opener because of the eery similarities between the script and the details emerging from Buffalo. The video comes to us courtesy of the Aviation Chatter blog.

If you fly an airplane IFR, this 22-min. video is a must see. Pay particular attention to the recovery of the airplane from a full stall about two thirds of the way through the show.

Although the video was designed around aircraft with un-powered flight controls, it reminds us all of the issues the Continental Connection pilots may well have been dealing with, especially the abrupt changes to a wing’s ability to generate lift with a load of ice when the first notch of flaps was added and the aircraft slowed.

Warning: This video does includes classic aerodynamic discussions that could scare the heck out of some pilots and with good reason. Carrying a load of ice on an airplane forces you to become a test pilot, so realizing that an airplane could take your life if you become complacent about an issue like ice is not all a bad thing. Here’s an interview I did with WRHU radio about the crash.

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19 Responses to “Seething About the Buffalo Crash”

  1. Patrick Flannigan Says:

    You wrote “the Dash 8 captain added power and pulled back on the control column – enough to overpower the stick shaker – when the aircraft stalled. If that was a traditional wing stall incident, that was absolutely the wrong action to take.”

    From a small plane perspective, this is true, but it sounds like the captain was responding accordingly (but perhaps prematurely) to a wing-stall in his airplane.

    Although I do not fly the Q400, my company’s stall profiles require that I respond to a stall or impending stall very similarly in the CRJ-200.

    Our stall recovery technique requires that we call “set max thrust, spoilers in” and pull back to maintain pitch. Essentially, we are trained to power out of the stall rather than pushing the nose forward as pilots of smaller airplanes are trained.

    Speaking from simulator experience, I can tell you that it is very easy to be too aggressive in recovery, which can lead to a stick pusher. Pilot/Stick pusher induced oscillations are also quite common in new-hire simulator sessions.

  2. Terry Says:

    Not trying to flame you or nitpick, but I have a couple of issues with your post.

    Most importantly, you state “If, however, the tail-plane stalled, adding power and pulling back on the column was the right reaction.” Pulling aft is correct. Adding power, however, will aggravate the condition, according to the NASA video.

    Secondly, Colgan operates as Continental Connection, not Continental Express. The only two carriers that operate as Continental Express are ExpressJet (the original wholly-owned carrier; spun off by Continental a few years ago) and Chatauqua, using both ERJ and CRJ equipment (although the CRJs are going away). Continental Connection carriers use turboprop equipment (Colgan with the Q; Commutair with the older Dash (-200) and I believe they still have some Beech 1900s, but I could be wrong there).

  3. Robert Mark Says:

    Terry:

    You are correct about the Express vs. Connection point. Proves what they always say about posting late at night … mistakes are more common.

    On the tail stall I’ll need to go back and watch it again. As I recall the stall recovery in the Twin Otter, the pilot pulled aft on the control wheel and added power.

    But honestly as they said, that video was filmed under conditions as controlled as possible.

    Wing and tail ice turns every aviator into a test pilot.

  4. Robert Mark Says:

    Patrick:

    We’ll all be wondering for some time whether the Colgan crew reacted properly for the situation or merely reacted that way most of us might have in a similar situation.

    The point is that pilots flying airplanes with ice are really test pilots whether they want to be or not. How many of them were taught that in their training?

  5. Patrick Flannigan Says:

    You’re absolutely right: every time you pick up ice, you are flying an original design wing, and there is no telling how it’s going to react to varying loads and speeds.

    As far as tailplane icing goes, there is remarkably little training on the issue. It was never mentioned in basic flight instruction, and as far as I can remember, we did not discuss it in ground school with the airline.

  6. Graeme Nichol Says:

    I remember viewing the NASA video some time back, before the Buffalo crash. Then reading about the Buffalo crash, I wondered if this could have been reacted.

    The response was to reduce power and raise the nose, I think. Quite counter intuitive! I’m not sure many of us get to that level of knowledge or experience in 3000 hours.

    I believe most Dash 8 pilots are taught about tailplane stalls. The US Navy variants were apparently not good for any icing conditions!

    All pretty academic for a mere SEL pilot! But interesting none the less.

    Thanks for sharing!

  7. Dylan Says:

    As the facts come out, I believe we are going to discover that the real problem was the failure of the pilots to add power after leveling off on the approach…

  8. Jim Says:

    Regarding icing- if you look at Appedix C to Part 25, you’ll find the icing certification tables. It says a plane must be able to continue to fly after descending 6,500 feet for a length of 20 miles (17.4 nautical).

    This chart, and standard, came from the Air Force in 1952. It represented the Air Forces’ C-54 (DC-4), and what it was expected to be able to survive 99% of the time.

    In those days, aircraft flew ABOVE the icing layer, and then descended through it upon arrival at destination. That’s why it shows 6,500 feet- (the descent through potential icing) and 20 miles (17.4 nautical, or the distance required for a C-54 to drop those 6,500 feet). That’s far enough for the plane to get under the stratus cloud deck, and onto final approach.

    The table was NEVER intended to represent icing flight for the entire duration of the flight. Certifying to Appendix C only means that a plane has demonstrated it can pass through that kind of flight profile.

    As a result, all FIKI airplanes today are NOT certified as capable of flying indefinitely level, inside stratus, building up ice.

    That table only provides for a duration in the icing conditions of about 8 minutes, at a descending speed of 150 miles per hour.

    Roselawn, Monroe, and Buffalo were all doomed the minute the FAA approved flight into icing using table C, and then NOT putting an 8 minute limit on an icing encounter.

    The mistake, from when the CAA adopted the Air Force’s table in 1955, continues today.

    Don’t fly in ice.

    Period.

    If you want to survive.

  9. Jim Says:

    By the way-

    the Air Force initiated that icing study, and compiled that table, which is now Appendix C to Part 25, in 1951 and 1952.

    The did it at the request of the Civil Aviation Administration, (CAA), predecessor to the FAA.

    The CAA wanted all kinds of data on Commercial sized aircraft – as at the time, only the military was gathering and analyzing data on different kinds of crashes.

    The data on icing, as well as other data on causes of aircraft crashes, was asked for as a result of this crash, in 1950, where a DC-4 crashed into Lake Michigan.

    http://www.michiganshipwrecks.org/dc4.htm

    True story.

    The first large passenger aircraft to apparently lose control, and crash, with the loss of more than 50 lives, was Flight 2501, A DC-4 , in 1950.

    The icing data in the tables in Appendix “C”, of part 25, showing that a DC-4 (C-54) could survive roughly 8 minutes in icing, while it descended 6,500 feet over 20 statute (17.4 nautical) miles, at 150 miles per hour, came as a result of intense study of the DC-4 (C-54).

    They were NEVER intended to show a Q400 could fly level, within icing conditions, for more than an hour after entering those conditions.

  10. Rand Peck Says:

    I’d like to bring up a subject that I’ve not seen discussed, but must preface my remarks by saying that I have no systems knowledge of a Q400. Years ago when flying Twin Otters and Beech 99’s, which sported leading edge, inflatable deicing boots, we were taught to NEVER use the auto mode. We were directed to use manual only and wait until ice accumulation reached a specific thickness before activation. The reasoning of course, was to not inflate the boots too soon and create a cave between the wing and the ice. Once this happened, ice removal was far more difficult if not impossible. This procedure, in our New England winter environment worked well, once we learned patience and waited to have real accumulation to actually “deice.” My questions. (1) Does the Q400 have both an auto and manual mode to operate these boots? (2) If it does, do we know which mode they were using? (3) Apparently, Colgan pilots are taught to hand fly in icing conditions, but how do Colgan’s or the manufacturers manuals address deicing boot inflation? (3) Are Colgan’s pilots taught the same method that safely saw me through many New England winters, or have these procedures changed since I flew a booted wing? I’d be interested to know how technology has advanced the science of leading edge ice removal, using inflatable boots.

    Thanks,

    Rand Peck

  11. Robert Mark Says:

    That’s a very interesting question Rand. While I’ll have to look into the auto mode question, it would also be interesting to ask how the FAA’s recent announcement that there is no such thing as ice bridging might have played out here.

  12. Stephen Griffith Says:

    As for the ice bridging occurring if the boots are inflated too soon, the NASA ice training referred to above specifically says that there is no evidence this actually occurs, it is an old wives tail, and that the boots shoud be cycled early and frequently.

  13. Rand Peck Says:

    Although I dislike taking an opposing view to NASA, considering their extensive research resources, eight years of flying through New England winters with pneumatic boots was my research laboratory that formed my opinion and supported the advice offered by my elders. To my knowledge, with the exception of the approach phase, the Cessna Citatation manual recommends letting ice build to a certain level before activating the boots. The NBAA recommends that you use which ever method experience has taught you to be effective. Now there’s a solid position.

  14. Nate Says:

    A lot of talk here about ice and boots and techniques. Tail stall technique was coverd in my Brasilia ground course at my airline, power idle, flaps up and nose up, thus restoring laminar flow to the tail plane. Now, all of this talk of boot’s etc….prevailing weather was FREEZING RAIN…long before the crew even departed! Fact 1: they should NEVER have left. At my airline, any FZRA in the forecast or METAR is an automatic no go. Freezing rain aka “clear Ice”, the worst you can encounter, my friends “Boots” will not save you no matter your technique. You see the ice then covers the entire surface of the airfoil AND the fuselage! Destroying laminar flow AND adding an insurmountable amount of weight to the entire aircraft! NEVER NEVER NEVER depart into conditions where you may expect FZRA for more than ust a few minutes (and even avoid that if possible) Main cause of this crash…pilot error, ADM and succombing to the airlines desire to push a crew to get a job done and make a buck! Ironic….only wated millions on a balled up plane and many payouts to passengers and crews families…..

    God Bless you all, Fly Right!

    Tailwinds…..

  15. Nate Says:

    P.S. Boots assume mostly rhime and maybe a little mixed that is forming on the leading edges/protrusions to the airflow….clear covers all!

  16. Regional Airlines: Are Pilots Qualified? - Jetwhine: Aviation Buzz and Bold Opinion Says:

    […] has been a lot of talk since February about not just how the crew of the Dash 8 handled the ice, but whether or not they were seasoned enough to be flying in that weather in the first place. Sure […]

  17. Nate W. Says:

    “What makes this accident so frightening to anyone who flies were the NTSB comments about how the Dash 8 captain added power and pulled back on the control column – enough to overpower the stick shaker – when the aircraft stalled.”

    ?? I think you mean stick pusher, not stick shaker. The stick shaker doesn’t actually re-position the yoke, it just serves to warn of an impending stall as your speed decreases, and the wing approaches its critical angle of attack. The stick pusher acts to lower the nose, or release the back pressure, to lower the angle of attack.

    “If, however, the tail-plane stalled, adding power and pulling back on the column was the right reaction.”

    ?? Terry’s comments above are correct — as noted in the NASA video, with a tail-plane stall, the nose must be raised (may require a great deal of force), and the power reduced (counter-intuitive close to the ground). Additionally the NASA video says to raise the flaps. These actions restore the laminar airflow over the tail plane.

    The vacuum caused by airflow separation on the bottom of the tail plane is abruptly filled by the elevator, causing the aircraft to abruptly pitch down; these three corrective actions counter the sudden loss of downward lift on the tail plane.

    —–

    I have my own theory — I don’t think icing was a physical factor in this accident. More on that after a few more points:

    They were indeed flying in icing conditions, but they had all the appropriate de-icing equipment on and working, and the Dash 8 has quite sophisticated de-icing gear (for a boot aircraft). The Dash 8 has been flying in the northeast for years without a similar incident, in similar icing conditions. This was not severe icing, at least not according to PIREPS that were taken near the time of the crash.

    The fact that the accident sequence manifested as the flaps were initially selected has misled many into thinking tail-plane icing was the cause (the center of lift moving aft, airflow pushing down on tail plane). But if tail-plane icing were the cause, the nose would have initially pitched down, not up, and it would have taken a tremendous amount of force to immediately pull the nose into a nearly 30 degree nose-up position, as we now know was achieved. Also, the addition of power would have aggravated the situation to induce the nose to pitch down even further, making the likelihood of an abrupt pitch-up even more remote.

    It seems unlikely that the icing could have accumulated on the wing without an equal or greater critical icing condition on the tail plane. The tail plane is much sharper along the leading edge than the wing, and should therefore develop a critical icing problem before the wing, unless there were a malfunction of the wing de-icing system. So it seems to me the wing would not stall before the tail plane owing to ice accumulation, provided all the de-icing systems were working properly. There were no indications of any malfunctions of the de-icing system on the accident aircraft in the minutes leading up to the crash. All the de-icing system indications were in the green the entire time, as far as we know.

    My theory is, this crew simply neglected to add power as the aircraft slowed down during the initial flap configuration. They approached a stall, and the crew failed to apply a proper recovery. The airplane was on autopilot as they configured with flaps, and slowed down very quickly as the drag increased (and the autopilot held the altitude). The Dash 8 DOES NOT HAVE AUTOTHROTTLES. This is a very important point. The crew was preoccupied with the icing conditions and checklists — and the turn to final in IFR conditions is one of the busiest phases of flight. In fact, it’s probably the busiest part of the approach phase, as the pilot-not-flying must acknowledge approach clearance, altitude, and heading instructions all at once, while running checklists, and the pilot flying is preoccupied with flying the airplane and commanding timely configuration changes. It’s easy to drop the airspeed from your cross-check, and that’s what happened here. When the airplane approached the stall the PF was slow to recognize the situation for what it was and was slow to disconnect the autopilot, fought the stick pusher, and ended up misapplying the recovery procedure, leading to the back-and-forth nose-up, power-on yaw dance and wingover that ultimately cost them too much altitude.

  18. Regional Airlines: Are Pilots Qualified? | RENT-A-PLANE Says:

    […] has been a lot of talk since February about not just how the crew of the Dash 8 handled the ice, but whether or not they were seasoned enough to be flying in that weather in the first place. Sure […]

  19. Eric Says:

    Yea, I’d say nate has it about right. Much talk about the pilot training, e.t.c.. No one is going to stick around for what these people are payed. Back to some sort of subsidized “essential air service”, or whatever it takes to keep good pilots. I think when all is known…this pilot will have responded to tail plane ice, and exascerbated a low airspeed stall (just like we learned in the Cessna). I think he responded just like some people suggest for tail plane stall (except he added power). How is any pilot to survive when there are two COMPLETELY opposite protocols with a very subtle (if even detectable), difference between the two decisions. The NASA people were going in as scientists with some altitude and expectations. It would have helped to have the AP off, for the Colgan (well the other too). What the heck do you do at 2,300 feet (at night..and it is gusty too)? Should I push, or should I pull. Nice! If you feel your ass shake than push, and if your hands shake pull? Sounds like 1930 all over again (seat of the pants). I think if there hadn’t have been a pusher, this pilot might not have confused a tail-stall induced “elevator snatch” and yanked the yoke. This is an interesting one my aviating cohorts!

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