According to National Transportation Safety Board investigators, the American Airlines Boeing 757-200 that ran off Runway 19 while landing at Jackson Hole, Wyoming, on November 19,  2010, was missing a bushing, indicating that “the linear actuator in the automatic speed brake mechanism had been improperly installed.” Without the bushing, a cam and switch could have become misaligned and caused a malfunction. Investigators found no discrepancies in the aircraft’s air/ground, autobrake, and thrust reverser systems.

If you haven’t read my earlier post “Fastest Tricycle in the West,” I recommend you do before continuing here as I take a look at what this finding means, which is that investigative attention is now focused on the speed brake/spoiler system on the 757.

First, the terms “speed brakes” and “spoilers” both refer to hydraulically actuated panels on the upper (sometimes lower) wing surface that remain flush (“stowed”) with the surface unless the pilot automatically or manually extends (“deploys”) them. The diagram below shows the location of the 757’s various speed brake/spoiler panels.

In flight, the “air/ground” switch prevents some of these panels from extending and limits the amount of extension on others. This is an important safety feature. If every one of the panels deployed while airborne, the increase in drag and loss of lift would seriously degrade (or possibly destroy) the ability of the airplane to maintain flight. Many normal flight conditions, however, benefit from selective use of speed brakes to control airspeed and increase rate of descent.

Full extension of all panels is highly desirable in two situations on the ground: during an aborted takeoff, or on either a normal or emergency landing. In all cases, reducing airspeed (inertia) quickly is the objective to prevent overrunning the departure end of the runway.

Cockpit voice recorders (CVRs) and digital flight data recorders (DFDRs) capture information essential to the investigation of any inflight or ground incident or accident. A CVR does exactly what you would expect by recording the voices of the cockpit crew. A DFDR monitors multiple aircraft systems and flight/ground parameters, and this inforamation can be “mined” during the investigation.

This 757’s DFDR showed that the speed brakes were manually extended by the flight crew during the approach. While this is probably not a routine procedural action for the 757 (I’ve never flown one), it is perfectly reasonable for the pilot to use speed brakes to help shed excess speed if necessary when on the approach.

The speed brakes were in the armed position for landing. Again, this is a normal action, especially when considering that although braking action was reported as good, the crew would have assumed that the runway was to some degree contaminated with snow. To manually deploy the speed brakes on a 757, the pilot might pull aft on the control handle. To arm them, the pilot might lift the handle up, where it locks into place.

Automatic speed brake deployment occurs when the air/ground switch (typically fastened to the main landing gear, shown at right on a well-worn Cessna Citation) detects compression of the landing gear strut(s). The handle in the cockpit physically moves when this occurs, and normal procedures call for the crew to confirm that the automatic system does in fact deploy the speed brakes and be prepared to deploy them manually should they malfunction.

Although the DFDR does not monitor the position of individual spoiler panels, it provides a time-sequenced record of events. In this case, the air/ground system registered that the aircraft touched down, but then for about one-half second switched back to the air mode before registering ground for the remainder of the rollout. This is not normal (unless the aircraft bounced, but there’s no indication that this was a hard landing). Nor is the fact that during that half second, the speed brake handle momentarily moved toward the down position and then returned to armed.

The thrust reversers, strictly under manual control by the pilot, began to deploy during that half second and remained in the “in-transit” position for about 10 seconds. They then moved to stowed and back again to in-transit, this time for six seconds, before becoming deployed. It took 18 seconds from the time the reversers began moving until they were fully deployed.

This makes no sense. I can’t believe the pilot intentionally did anything with the thrust reverser controls to cause this sequence, and it indicates to me that they malfunctioned. What follows is speculation, but it’s not unfounded.

As noted in my previous post on this incident, the 757 has a reputation for thrust reversers “refusing to engage” and problems with the air/ground logic system. I think these two are not only inter-related, but demonstrate cause and effect.

To say that a thrust reverser deployment inflight is a serious emergency would be an understatement in the extreme. To help prevent that from occurring, when the air/ground logic system “tells” the airplane that it’s airborne, the thrust reverser controls are physically locked in the stowed position. They become unlocked only when the aircraft is on the ground and the air/ground logic system accurately communicates that to all the other related systems.

When I consider the evidence available, I’m dubious about the NTSB’s finding that nothing was wrong with the air/ground logic system.

If the air/ground switch malfunctioned on touchdown and didn’t transfer to ground mode, that could explain why the thrust reversers didn’t operate as designed. And although the passenger video mentioned in my previous post doesn’t provide a view of the 757’s spoilers, they might have malfunctioned for the same reason.

In that event, not all the spoiler panels would have deployed, nor would those that did have extended to their maximum designed angle relative to the upper wing surface. Under this scenario, the inertia-depleting effects of thrust reversers and speed brakes/spoilers would have been severely hampered.

That said, and to reiterate an important point from my previous post on this topic, by regulation the landing data used to determine if the 757 could land safely on the available runway length with the existing aircraft gross weight, weather, and runway surface conditions cannot include the beneficial effects of using those two systems.

I’ll be watching for further information and follow up as necessary to put a period at the end of this story.

I received this from Bill Schwoeble, friend and fellow veteran aviator, who received it from a classmate in United States Air Force Undergraduate Pilot Training. Along with the humor, a wonderful dose of logic underlies these words. My thanks to Bill for sharing.

AN OLD FARMER’S REFLECTIONS ON LIFE

“Your fences need to be horse-high, pig-tight and bull-strong.”
“Keep skunks and bankers at a distance.”
“Life is simpler when you plow around the stump.”
“A bumble bee is considerably faster than a John Deere tractor.”
“Words that soak into your ears are whispered . . .  not yelled.”
“Meanness don’t just happen overnight.”
“Forgive your enemies; it messes up their heads.”

“Do not corner something that you know is meaner than you.”
“It don’t take a very big person to carry a grudge.”
“You cannot unsay a cruel word.”
“Every path has a few puddles.”
“When you wallow with pigs, expect to get dirty.”
“The best sermons are lived, not preached.”
“Most of the stuff people worry about ain’t never gonna happen anyway.”

“Don’t judge folks by their relatives.”
“Remember that silence is sometimes the best answer.”
“Live a good and honorable life. Then when you get older and think back, you’ll enjoy it a second time.”
“Don’t interfere with somethin’ that ain’t bothering you none.”
“Timing has a lot to do with the outcome of a rain dance.”
“If you find yourself in a hole, the first thing to do is stop diggin’.”
“Sometimes you get, and sometimes you get got.

“The biggest troublemaker you’ll ever have to deal with watches you from the mirror every mornin’.”
“Always drink upstream from the herd.”
“Good judgment comes from experience, and a lotta that comes from bad judgment.”
“Lettin’ the cat outta the bag is a whole lot easier than puttin’ it back in.”
“If you get to thinkin’ you’re a person of some influence, try orderin’ somebody else’s dog around.”
“Live simply, love generously, care deeply, speak kindly, and leave the rest to God.”
“Don’t pick a fight with an old man. If he is too old to fight, he’ll just kill you.”

And . . .

Low altitude aerobatics are an especially dangerous way to spend time. A friend sent me a link to a series of pictures capturing an amazing event in which the pilot in my opinion uses up whatever bit of good luck he had on that day.

It reminds me of the saying: I’d rather be lucky than good.

Click on this link and you aren’t going to believe it.

Last August I joined facebook to utilize the triad of website, blog, and the most powerful social networking platform on the planet. It may be popular off the planet as well. I mean, how would we know?

Anyway, according to a friend who knows about these things, it’s the “New Internet,” and we’ll ultimately do everything there. Wonderful. I can’t wait to be more confused by it all than I am right now.

In that spirit, I received this from my sister-in-law. I don’t know who wrote it, but I’d like to meet him. Here’s the testimonial:

When I bought my Blackberry, I thought about the  30-year business I ran with 1800 employees, all without a cell phone that plays music, takes videos, pictures, and communicates with Facebook  and Twitter. I signed up under duress for Twitter and Facebook so my seven kids, their spouses, 13 grandkids and 2 great grandkids could communicate with me in the modern way. I figured I could handle something as simple as Twitter with only 140 characters of  space.

That was before one of my grandkids hooked me up for Tweeter, Tweetree, Twhirl, Twitterfon, Tweetie, Twittererific, Tweetdeck, Twitpix, and something that sends every message to my cell phone and every other program within the texting world.

My phone was beeping every three minutes with the details of everything except the bowel movements of the entire next generation. I am not ready to live like this, so I now keep my cell phone in the garage in my golf bag.

The kids bought me a GPS for my last  birthday because they say I get lost every now and then going over to the grocery store or library. I keep that in a box under my tool bench with the Bluetooth  phone I’m supposed to use when I drive. It’s red. What’s up with that?

I wore it once and was standing in line at Barnes and Noble talking to my wife and everyone within 50 yards was glaring at  me. I had to take my hearing aid out to use it, and I got a little loud.

The GPS looked  pretty smart on my dashboard, but the lady inside that gadget was the most annoying, rudest person I  had run into in a long time. Every 10 minutes, she would sarcastically say, “Re-calc-u-lating.” You would think she could be nicer. It was like she could barely tolerate me. She would let go with a deep sigh and then tell me to make a  U-turn at the next light. Then if I made a right  turn instead   . . . well  . . . let’s just say it was not a good relationship.

When I get really lost now, I call my wife and tell her the name of the cross streets, and while she is starting to develop the same tone as Gypsy, the GPS lady, at least she loves me.

To be perfectly frank, I’m still  trying to learn how to use the cordless phones in our house. We’ve had them for 4 years, but I haven’t figured out how I can lose three phones all at once and have to run around digging under chair cushions and checking bathrooms and the dirty laundry baskets when the phone rings. Who the heck moves them, anyway?

The world is just getting too complex for me, and it even messes me up every time I go to the grocery store. You would think they could settle on something themselves, but this sudden “Paper or Plastic?” every time I check out just knocks me for a loop. I bought some of those cloth reusable bags to avoid looking confused, but I never remember to take them in with me.

Now I toss it back to them when they ask me by replying, “Doesn’t  matter to me. I’m bi-sacksual.” Then it’s their turn to stare at me with a blank look.

I was recently asked if I tweet. I answered, “No, but I do toot a lot.”

I  know some of you receive this are not over 50. I sent it anyway to allow you to forward it to those who are and to make the point that we senior citizens don’t need anymore gadgets. The TV and garage door remotes are about all we can handle.

Speaking of remotes, have you heard about the snippet of conversation (supposedly true) between three old guys sitting in a coffee shop in West Texas shortly after the April 2008 story broke about the raid on the Yearning for Zion ranch?

They were talking about polygamy, and one of the guys says, “Why would anyone want more than one wife? It’s hard enough getting control of the remote as it is.”

And it’s hard to argue with the wisdom of that.

For non-pilots who usually fly in airliners and rate a flight based on the landing more than any other criteria, and who judge the quality of the landing by the touchdown, let me expand your knowledge of this most important pilot task by pointing out that when the wheels meet the concrete it ain’t over yet.

The reason is that the airliner has just become the fastest tricycle in the West, and the potential for mayhem still exists in the form of inertia: a property of matter by which it continues in its existing state of rest or uniform motion in a straight line. Some of you may remember the formula: inertia equals mass times velocity squared. What this means is that something really heavy (like an airliner) going fast (well over 100 mph) has bunches of inertia waiting to cause the pilot a real headache if something goes wrong.

To avoid inertia-related problems, the pilot needs to reduce it. Since lowering gross weight at that moment is not possible, slowing up is the only option, and modern airliners offer the pilot three ways to do that: brakes, spoilers, and thrust reversers. Spoilers are panels built into the top of the wing (shown in color on the diagram of the Boeing 757 upper wing surface) that can be raised into the slipstream to create drag. Thrust reversers deflect a portion of engine exhaust forward. (The dark ring at the rear of the Boeing 777’s engine pictured on the right is a deployed reverser) Both are very effective at shedding airspeed, especially early in the landing roll when speed is highest.

At touchdown speeds, brakes are the least effective of the three, which leads to an interesting safety measure when figuring landing data: all landings are planned without considering the beneficlal effects of spoilers and thrust reversers. It’s as if they are “extra.” Although you normally use them, you never count on them.

Runways “contaminated” with water, slush, snow, or ice complicate the landing problem because the brakes aren’t very effective for slowing the airplane if the tires aren’t in solid contact with the runway. Although the pilot still can’t plan to use them, spoilers and thrust reversers are much more valuable when landing in these conditions because they don’t rely on friction. In case you figured this explanation was leading up to something, you were right. The following borrows heavily from AVweb.

On December 29, 2010, an American Airlines Boeing 757 ran off the end of Runway 19 in snowy conditions while landing at Jackson Hole Airport. About seven inches of snow had fallen in the area since midnight, but the runway itself had good braking coefficients (a measure of braking effectiveness, which means that the pilots had no reason to suspect that runway conditions were not suitable for landing). No injuries were reported among the 181 passengers and crew on board.

The incident was partially recorded on video by a passenger and posted on YouTube. The video, taken out of a window, shows a portion of the wing upper surface and the top of an engine and has led to a fair amount of speculation by some pilots.

The aircraft appears to be on the ground prior to passing the wind sock and PAPI lights (visual glide path indicators, the four lights located near the approach end of the runway), which indicates the pilot touched down at an appropriate point and did not “land long.” In the video, the engine’s thrust reverser panel first moves just after touchdown, but it does not fully open and the outboard spoilers are not visibly deployed. Because of that, things quickly get more interesting.

A full ten seconds after touchdown, the thrust reverser panel moves from barely open to closed, and does not begin to reopen, this time fully, until approximately seven seconds later (17 seconds after touchdown). The engines do not appear to spool up (to increase the amount of reverse thrust) until roughly ten seconds later. From this we can conclude that the 757 rolls on the runway for 27 seconds before the reversers appear amply engaged. This is way too late to be of much use, and the aircraft departs the end of the runway roughly nine seconds later. That moment is very obvious on the video.

Pilots who claim to be familiar with the 757 have left comments in professional pilot forums stating that the thrust reversers on the 757 can sometimes refuse to engage. Others have speculated that a problem with the hydraulics or Boeing’s air/ground logic system (which, in plain language, “tells” the aircraft whether it’s on the ground or in the air) could have prevented the spoilers, reversers, and the brakes from working properly.

Subsequent events have focused a spotlight on the actions of American Airlines immediately following the incident.

According to the National Transportation Safety Board (NTSB), airline technicians violated standard procedures when they removed the cockpit voice recorder and the digital flight data recorder (DFDR) and flew them to Tulsa, Okla., where technicians downloaded information from the DFDR. It is common in incident investigations for the airline involved to transport the recorders on their own aircraft, to get them to NTSB labs in Washington. D.C., as quickly as possible. The airline is instructed to transport the recorders without delay and without accessing the information contained within them by any means.

NTSB: “Although a thorough examination by our investigators determined that no information from the DFDR was missing or altered in any way, the breach of protocol by American Airlines personnel violates the Safety Board’s standards of conduct for any organization granted party status in an NTSB investigation. We have revoked the party status of American Airlines and excused them from further participation in this incident investigation.”  (Note: “party status” is a term used by the NTSB to designate outside organizations that will be allowed to play a role during an investigation. American Airlines, Boeing Aircraft, and Pratt & Whitney — the engine manufacturer — would all be given party status as a normal procedure.)

There will be more to come as the NTSB conducts its investigation. In the meantime, I’ll do a bit of speculating on my own: if no mechanical malfunction is discovered, this incident will be labeled as a result of pilot error. When you touch down on a runway that might be contaminated with snow, slush, and/or ice, it’s imperative that you recognize the potential mayhem that awaits the fastest sled in the West and actively plan to avoid it.

At main gear touchdown, check throttles at idle, lower the nose gear to the runway, deploy the thrust reversers, confirm that the automatic system has deployed the spoilers, and increase reverse thrust (to the maximum if necessary) to slow the aircraft as rapidly as possible. Depending on the runway condition, test the brakes by applying them as well and be alert for anti-skid cycling, which indicates the wheels are in contact with the runway, and any tendency of the aircraft to veer off of runway heading.

Then the passengers will deplane (at the gate, not into a snow-covered field) with admiration in their eyes and nods of appreciation to you, the steely-eyed aviator, for the magnificent display of cockpit prowess they just witnessed.

(Please forgive me for that last paragraph, but I just couldn’t help myself.)