Can YOU Stop A Jetliner on a Wintery Runway?


LaGuardia Airport

LaGuardia Airport

Can YOU stop a jet on a winter runway?

Whenever an airliner slides off a taxiway or runway in winter conditions, the public and the media asks dozens of questions related to one overriding concern: how could this happen?

But for every other flight that lands on a winter-affected runway without incident, there were dozens of questions correctly answered by pilots related to THIS overriding concern: how can we assure that DOESN’T happen?

I’ve been flying in and out of LaGuardia and Washington Reagan all winter, accommodating ice, low visibility and contaminated surfaces in what has been an exceptionally vigorous winter storm season. The questions and correct answers required to assure a safe flight under such conditions are neither straightforward nor simple. Here’s the decision process–YOU decide what to do.

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First, before we even depart for an airport affected by winter weather, we think about the factors that affect our landing: weight, wind, landing distance required, and runway surface conditions. And there are no easy answers any of these questions.

Weight comes first: considering stopping, you’d want weight to be the lowest possible, right? If only it were that simple: the primary, most variable weight in flight is fuel–if you reduce fuel weight to the bare minimum, you also reduce flying time to the bare minimum. The facts of life when flying into a major metropolitan airport include delays–demanding MORE flying time, thus more fuel and thus more weight. If you have only the minimum fuel aboard required to fly the distance, you are screwed: at the first delay (and airborne holding assignments of up to 30 minutes are typical) you must divert.

What you need to do is carry enough fuel to fly the miles AND accommodate typical, historically predictable enroute holding. We’ll have to be sure that we can still accommodate that weight on landing (checking landing distance charts) but that’s a separate question to be dealt with: for now, tank as much fuel as required to fly the distance and hold for a reasonable duration enroute.

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We don’t leave the rest of the questions for arrival, but we do answer them late in the flight when the variables have been sorted out: once we’re in the terminal area, we finally can predict an accurate landing weight.

So we request the data-linked landing distance chart for our specific weight which is calculated by computers back at our tech center and sent to our on-board printer. Problem for you is this: the chart also has variables you must resolve: what is the runway condition, and what is the braking effectiveness?

Those two variables can not be definitely determined because the informational reports are both very subjective: the “runway condition” must be determined in reference to varying standards. Our airline calls a runway “contaminated” when 25% of the landing surfaces is contaminated by ice, standing water or snow.

Another airline may allow 30%, another 60%, so there’s never any “contaminated” determination available other than reports from previous company aircraft. But even those are subjective–how do you eyeball 75%–and in winter storms, conditions can worsen by the minute.

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Braking effectiveness is another subjective report: what I consider “fair” braking for my jet (and I report this to the tower after landing based on what I just experienced) might be “good” for a lighter regional jet or “poor” for a heavier aircraft or and aircraft with less effective brakes. And, in heavy precip, that can change drastically in just minutes.

The landing distance charts reference “good” or “fair” in the conditional determination of braking effectiveness–but you now know that “report” is vague at best. Still, you must decide which calculation to use.

There’s also more than one chart for landing distance. The first one assumes that you touch down at the Visual Approach Slope Indicator (VASI) aimpoint which is about 1,500 feet from the runway threshold. There’s another chart that computes stopping distance from the visual touchdown markings on the runway some 500 feet prior to the VASI aimpoint. That chart, with the additional distance from the earlier touchdown point, may allow you to land based on stopping distance.

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But can you accomplish that? The “you” is key–no one on the ground can answer that. Ultimately, the captain decides, and here’s what he’s thinking: what are the winds? A tailwind will make that very difficult, a headwind will help. But can you count on either wind report? Those reports, like “braking effectiveness,” have a very short shelf life–winds change minute by minute. Do you think your landing wind is reliably a headwind, or at least not a tailwind? Again, YOU have to answer that based on subjective reports.

As far as the visual touchdown aimpoint, are you going to be transitioning to this new, shorter target from an instrument approach, which has a more distant touchdown point more like the VASIs? If so, do you have adequate distance, time and visibility to do so? And the skill?

Finally, landing rollout must be done exactly right: spoilers deployed, reverse thrust promptly initiated at the proper level, and brakes applied promptly and correctly. That sounds easier than it is.

First, spoilers normally are automatically deployed–but that deployment needs certain prompts: main wheel spin-up is a primary trigger, and patchy ice may keep wheels from spinning, delaying auto deployment, even as you eat up critical landing distance. Or, like last month, I landed my 737-800 on a wintery DCA runway without the auto-spoiler system working. I agreed before dispatch on the flight that I could and would do so manually. My judgmental call, a fact of life in airline flight operations.

Regardless, the point is, the crew must assure spoiler deployment and effective reverse thrust AND full braking–all in a millisecond when landing distance is critical.

As crucial, you must put the jet down on the exact spot–neither before nor absolutely, not beyond–and put it down firmly to ensure wheel spin-up, essential for traction and auto-spoilers. If you’re the ignorant smartass getting off the plane after that trying to be witty by saying “You must be a Navy pilot, that was a carrier landing” or “I guess the brakes work,” I’ll ignore you–but the crew will write you off as an ignorant smartass just the same.

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There’s no feeling worse in the cockpit than the anti-skid system releasing the brakes on rollout, even if you’ve done everything correctly, but that’s essential too: the system applies braking force to the very brink of a skid, beyond which there’s no braking, just sliding. If you’ve calculated your stopping distance based on “fair” reports, you can expect some releasing as the brakes do their job. All the more reason for a firm and accurate touchdown.

I expect and require every landing to be on the correct speed (faster makes stopping more difficult) and on the right spot, even at DFW Airport with miles of runway to spare, simply because it must be (for me) the rule rather than the exception when I fly to LaGauardia, Washington Reagan or Santa Ana-Orange County with shorter runways. “Pretty” landings are a Hollywood contrivance and have no place in the actual profession.

When we stop safely and exit the runway, that’s because we correctly solved the puzzle: weights, speed, touchdown point, winds, and braking distance. For passengers, that means a safe trip completed. For the cockpit crew, the work is only beginning: all of these variables must be dealt with successfully again in order to execute a safe take-off or abort on that same winter-affected runway.

The airline industry in the United States has an enviable safety record, which is why the very rare incident gets so many media headlines. The real news is, overall, airline pilots are doing their job very well.

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26 Responses to “Can YOU Stop A Jetliner on a Wintery Runway?”

  1. Hi Chris, what recourse do you have if for whatever reason you get to your destination and the plane’s overweight and you know you won’t be able to stop the plane within the numbers on the landing distance chart?

  2. It says it all !! Excellent explanation Chris…

  3. peggywillenberg Says:

    Thanks for an accurate, non-speculative report (as usual). CNN is currently dragging out the so-called experts and having a field day with this story.

  4. peggywillenberg Says:

    Here’s some of that accurate reporting…look at the silhouette of the jet. MD-88? I don’t think so…
    http://www.cnn.com/2015/03/05/us/new-york-plane-runway/index.html

  5. comanchepilot Says:

    Would it be legal for you to land your 737 there?

    Contaminated runway.
    7000′ length
    Braking Action good to fair.
    Runway 13, winds 020 12.

    I was looking at a 737-700 manual and the landing distance is 8,300 on a contaminated surface.

    It was snowing pretty hard – they could not see the incident from the control tower. . . .

    • I don’t know what chart you’re referring to, but in actual practice, there are several landing distance charts, none of which say “contaminated runway.” There are the FAA charts, the Boeing charts, and the airline’s charts and all three are different. They are simply showing stopping distance based on different factors, separated into “good” or “fair” braking action–never heard of “good to fair.” Some charts also include temp and wind corrections. I don’t know where you came up with “8,300” feet but I’ve been in and out of LaGuardia all year and never landed until it was legal to do so. Not sure what Delta 1086 experienced, but I doubt they landed with the tailwind you used in your calculation.

      • comanchepilot Says:

        good to fair means good – and fair. . . . separately . . .

        Chris – if you go listen to this atc recording of the accident [and its technically not recorded since it was snowing so hard they could not see the accident airplane] LGA tower was reporting 020 @ 12 both before and after DL 1086 touched down –

        – about 2:30- and thereafter you have a airport vehicle reporting the incident . …

      • Really? You think you are going to Google your way to a hypothetical conclusion about the cause factors in this incident? Glad you’ve given up the supposed “contaminated runway” landing chart hypothesis, but you’ll need to take your tailwind speculation elsewhere, too. Even if a METAR reports 020/12, it’s obsolete as soon as it’s given.

      • comanchepilot Says:

        wait one minute Captain – I NEVER mentioned a tailwind – because there wasn’t one. A cross wind perhaps but there is not enough of a tailwind component to worry about.

        Unless they touched down way too fast [which is an option] the airplane touched down in a driving snowstorm. I simply first ASKED A QUESTION – which is could you have landed your 737
        LEGALLY this morning with a snow contaiminated runway and then, using either the Good or Fair landing distance chart, could you have legally landed your aircraft on a wet runway.

        i’m not accusing anyone of anything and you are being hyper defensive about something I did not even say.

        If you go back through YOUR responses you will see that i’m giving you the Runway 13 runway length, the wind, and then asking you to look up wet or snow or dry, braking action good and fair.

        now, I’m not TELLING you anything – I’m asking Captain. Would it have been legal for you to land a 737-800 at LGA this am under those conditions? Question mark means it is a question – not a statement. . . . .

      • If 020/12 is not a tailwind on 13, we really don’t fly the same physical aviation properties and if you think any tailwind at LGA is “negligible” (no such thing among the actual pilots flying in and out of LGA), I’d say we really have nothing more to discuss. So we’re done.

      • comanchepilot Says:

        yep – its a 4 knot tw component . . . insiginifigant …

      • Actually, a 4 knot tailwind correction would put the landing distance over the runway available, which seems significant to me. You really are dabbling in technical issues way beyond your level of competence, so there rest is moot. Stick to what you know, and don’t expect to have your unwarranted and inaccurate speculation shared here.

      • More to the point, the accident didn’t involve a 737.

      • Or, as I said when I heard about the incident, I’m not surprised it was an MD-80. I flew that jet for over twenty years and it’s always a challenge on degraded surfaces.

  6. Cedarglen Says:

    I agree with every word and thank you, Chris for clearing the air. Again. The effective team, armed with good data can safely land under those conditions. You’ll never hear a comment from me beyond, “Thanks for doing it right,” and hell no, I don’t care about the ‘plop and stop,’ (That’s why I have a good seat belt, and a great pilot with a strong airplane.
    Today’s LGA event is unfortunate and we will wait a year or so to know what small puzzle part failed.
    Like many, even as a novice, I recognize that the media reports are absolute trash. (I don’t watch TV – with good reason.) Event reporting from the *New York Times* was do blatantly horrible that I quit reading! The factual errors and dramatization are disgusting, IMO. I do not know what went wrong. At this point, no one else does either, but we’ll learn in time. Injuries were none, or minor and that sure works for me. A great post, captain and please, keep us flying straight and level when the media folks too often get it wrong. Staying home it the best course, but if one must travel, ridding behind men an women like you in seats 0A and 0B is a good choice. This paid bit of SLC remembers that your soul is also on the line. Regards, -C.

  7. Something that baffles me is why individual airlines have their own standards for various things. Here you mention runway states, others I have heard include taxi speeds, go around criteria, fueling etc.

    Why don’t the airline community, regulators, manufacturers come up with “best practises” and have everyone stick to that, updating them over time as necessary?

    Surely it is safer for everyone to use common standards, make training more uniform, not waste time/effort/money in each airline coming up with their own.

    • In a way, they do: the primary regulatory agency, the FAA, approves everything the individual airlines do. But, there no “one size fits all” solution because there are dissimilar mixes of aircraft and types of flying.

      I do believe that every airline Flight Department, in their own way, tries to ensure the safest operation possible. I know every pilot, regardless of airline, certainly does.

      • Note that I am not questioning motivations, but rather the extra work that is done, and ultimately what seem like unnecessary differences. Maximum taxi speed or runway condition descriptions are going to be different for a Cessna versus a 747, but why wouldn’t they be identical for all 747s in the same configuration? Why don’t the safety departments collaborate with each other and the regulatory agencies, so that each airline differs the least amount, and ideally not at all?

      • I guess it’s easier said than done–even the military, which you would think could standardize flight ops, has different procedures and limits for the exact same aircraft in different services. Plus I’m not sure in the civilian world it would ever be practical to expect competitors to coordinate and collaborate in the way that would be required to standardize. In my opinion, it still does and should come down to the judgment of the pilot in command.

    • Cedarglen Says:

      Chris has already replied and I certainly will not disagree with him. I too have wondered about the variable standards. Bypassing this instant’s safety issues, MELs (Minimum safety Equipment lists), FAA and manufacturers set basic standards, airlines can make them tighter, and ***Under some, FAA-approved standards,*** can extend the required repair time limits a lot. It is a messy, complicated yet legal procedure. I do not want to overstate this or make it sound like the legacy carriers are not flying safe air planes; such is not my point and I do not believe it for a minute. However, those same carrier do fly air planes that so not instantly meet basic FAA-dictated standards for model and type. If an airline can prove the value of an alternate schedule, the FAA will likely approve it. We can read and know basic Part 121 rules, bur we do not always know about the modifications granted to individual carriers. Am I worried about maintenance or flight crew qualification issues for the airplane and crew involved in today’s event at “La Garbage?” No! Not in the hands of a major, top three carrier. Are the ‘top three’ legacies different? Yes, they are, but I have to believe that the differences stop well behind the secure cockpit door. Some domestic airplanes are filthy dirty and provide obviously substandard services. Ahead of that secure door, I’d like to believe that the qualification and training standards are approximately equal and are maintained across a pilot population of thousands.
      Yes, darn it, flying even in nasty weather is safe. You pilots will not risk their own necks to maintain a schedule, so if they are willing to go, I’m willing to go. They already know what the weather should be like as they approach our destination. and if they do not like it, they have an alternate in mind – and have had for many hours… Fasten your seat belt, keep it faastened and trust your pilot.
      -C.

  8. Captain Manno:

    How does an incident like this effect the career of the pilots involved?

    -Rich

  9. So may variables. Some runways are difficult under the best circumstances. Any time I get off a plane unharmed and alive is a great landing – no matter the bumps or jolts. No complaints from me. (Perhaps some passengers are just nervous and feel compelled to say something “clever-ish” and don’t know any thing else to say – how about “Thanks. Bye”? Non-important people you probably will never see again anyway, right? Bound to be annoying none the less.
    Enjoyed the high flyin’ post.

  10. In November of 1978, I was a passenger on a Frontier CV 580 from Farmington to Denver via Durango. Stapleton was in some rather heavy winter weather and the descent was basically uneventful to touchdown. It felt normal at first, then the big T-56 props went to reverse. It felt a bit squirrely and then we straightened out and slowed normally.
    In 1970, I was on a Western 737 from Great Falls to Idaho Falls via Helena and Butte. The landing at Bert Mooney Silver Bow County was in a very heavy cross wind. We were in a crab with the right wing down and on a bouncy final. The right main gear made a heavy contact and we bounced back into the air and then settled on all three gear with a resounding thump. When the jet bounced, I was looking out the window at the wing tip. It seemed to be less than a foot from the ground. I was fifteen at the time and more in awe than frightenend.

  11. donkensler Says:

    Thanks for the explanation. My husband and I fly into KPVD, which has shortish runways (7,166′ and 6,081′), a few times a year, and fairly often there will be a rather harsh touchdown. When he comments on it, I reply that the important thing is to get the craft on the ground and stopped, that “pretty” touchdowns that use up gobs of runway are only an option at our home airport of KDTW, and only in good weather. I appreciate that when the p-i-c plants the plane firmly on the runway as close to the threshold as possible, uses full reverse, and stands on the brakes, particularly in gusty winds or when it’s snowing, he’s doing his job of getting us on the ground in one piece. “Any landing you can walk away from (without using the emergency slides) is a good one.”

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