ADS-B–I Hadn’t Considered That

Almost immediately after the Germanwings Airbus A320 had crashed in the Alps a very detailed plot of its flight path was available worldwide.

The flight of the Airbus was tracked from takeoff to a final position report that ended very near where the airplane hit the mountains. The plot showed altitude, groundspeed, vertical speed and track in detail. It was immediately apparent that the airplane made a fairly rapid but steady descent from cruise altitude to impact with the speed essentially constant.

It’s the first major accident I can think of where such flight path detail was immediately available to everybody and it’s all thanks to ADS-B.

Radar has, of course, tracked a number of doomed flights in the past. But radars are under the control of government agencies and it usually takes weeks, months or even years before radar plots are released. And radar is surprisingly imprecise and coverage gaps are common.

But the details of the A320 flight path were posted on websites around the world and hashed over on TV and internet sites very shortly after the accident. The onboard flight data recorder will have more information such as indicated airspeed, flight control positions, power settings and so on, but the recorder won’t have any better, or even as good, a track of the actual flight than what was available to all instantly.

What is at work here is the automatic operation of ADS-B. That’s what the “A” stands for–automatic. Once ADS-B equipment is installed it goes about its job of automatically sending out the identity, position, altitude and velocity of the airplane, including while the airplane is still on the ground. ADS-B updates that information with a new broadcast at least once per second and the accuracy is within a few meters.

Compare that to how radar and transponders work. A radar requires a directional antenna to determine the azimuth from the radar site to the target. Radar also needs to time the round trip of a transmission and reply to determine distance from the site. That yields a bearing and distance from the radar site to the target.

For its part the transponder in our airplanes does nothing until it is interrogated by a radar or traffic detection system in another airplane. When it is interrogated the transponder can only reply with our identification–the four-digit discrete code and the unique ICAO code if the transponder is Mode S–plus the pressure altitude data of Mode C.

So the radar equipment must plot the bearing and distance information to establish the actual location of the airplane. Then the electronics mix in the Mode C reply to determine altitude. After several radar “hits” an approximate flight path can be determined including ground speed, vertical speed, altitude and track.

But even short range radars get new “hits” only every couple or three seconds, while long range radars may get a new return only every seven or more seconds. That’s a long time when an airplane is moving at more than 400 knots as the Airbus was for the entire descent.

ADS-B is, however, reporting its actual position and velocity. There is no need to plot anything. ADS-B automatically says “I’m here, at this altitude, flying this fast, with this vertical speed, and along this track” all based on the global lat-long grid. All you need is a very simple and inexpensive receiver to know everything about an airplane with ADS-B. Radar needs a vast network of huge hardware and computers that only governments can afford.

The FAA has installed more than 600 ground stations to receive and process ADS-B data. But private networks are installing thousands more receivers around the world and linking them via the internet. Individuals participate by assembling a receiver and hooking it up to their computer. That means soon there will be complete ADS-B reception coverage nearly everywhere except over the open oceans.

The wide open nature of ADS-B data worries many who are concerned about privacy and security. And that’s a valid concern.

But there is an ADS-B benefit I hadn’t considered before this accident. For the first time accident investigators will have precise and detailed information about the flight path of an accident airplane that is nearly as useful as a flight data recorder. In most general aviation accident investigations there is very little to go on. Sometimes there is a radar plot but it’s usually incomplete and certainly not precise. But with ADS-B installed in most airplanes in a few years we can know much more about what happened in an accident, even though, as in the case of the A320, we can’t immediately know why it happened.

Every new technology is designed to solve a problem or create a new product or service, but there are always unexpected issues. It is the same with ADS-B. The system is designed for traffic surveillance and separation, but the immediately available flight path data will also bring unexpected and unintended other results. What will they be? Only the years ahead will tell.

Posted in Mac Clellan's Left Seat Blog | 32 Comments

You Gotta Love The T-Bone Approach

For decades when I got to pick my landing airport I always went for one with ATC radar coverage. Being vectored for the approach is safer because you have a second set of eyes watching where you are and tracking safe altitudes.

The safety edge of radar vectors became automated years ago with low altitude alert software installed in the controller’s radar. Even if the controller doesn’t notice you deviating from a safe altitude for your position the software sees it and sounds a loud alert that the controller passes on to you.

But I have to say that safety was really secondary in my thinking. The real reason I wanted to land at airports with radar coverage is speed and convenience. Radar vectors for an approach were almost always less complicated–and thus less time consuming–than flying to an initial approach fix followed by some sort of course reversal or holding pattern before you actually got started down final approach to the runway.

And if you were unlucky enough to arrive in the airport area when there was another IFR flight around you could be delayed many minutes waiting for that airplane to cancel IFR so you could start the approach.

I’m using the past tense here because the situation has changed thanks to thousands of new GPS based RNAV approaches. Particularly WAAS-aided LPV approaches that nearly all have the T-bone configuration.

Stancie and I were headed home to Michigan from the Bahamas last week. Because of the requirement to stop in Florida to clear U.S. Customs we need a fuel stop en route. In the past I had used Lexington, Kentucky because it has good approaches and radar. But the London airport also has a long runway, good approaches, and fuel that is at least a buck fifty cheaper and is only about 60 miles away. But London has only limited radar coverage from Indy Center while Lexington has full approach control at the field.

The weather was low over most of the southeast that day. It was forecast to be above minimums for London but it was almost certain that flying an approach would be necessary either there or at Lexington.

But London, like thousands of other airports, now has GPS based LPV approaches to both runway ends. And the approaches are the T-bone type which simplifies the approach to match or maybe exceed radar vectors for convenience and ease.

The T-bone configuration has two initial approach fixes astride the initial fix that is on the extended centerline forming a T-bone shape. The fixes at the end of the bone are five miles or so from the final approach centerline.

Because of the precision of WAAS GPS, and the turn anticipation logic that is built into approved navigators, you fly directly to the initial fix closest to your position. The distance countdown to the fix plus the turn anticipation command makes it easy to turn onto the new course without overshoot, something almost impossible with old VOR, NDB or localizer guidance. With those analog signals you didn’t know for sure you were nearing the course until the needle started to move, and that was usually too late to turn more than a few degrees without overshooting.

About 40 miles south of London I asked the Indy controller for clearance to UNMODE, the T-bone fix on the south end of the LPV approach to Runway 24. He issued the clearance, I selected it from the initial approach fix options offered by the Garmin GNS 530W and that was it.

The 530W guided me to UNMODE, directed me through the about 40 degree heading change to ODUBE on the final course. Nearing ODUBE the box again anticipated the turn of 90 degrees so I watched the moving map show my track turn nicely inside the fix and center up on final. Once established the 530W switched automatically to LPV approach mode and had perfect ILS-style guidance to the runway.

There is no way radar vectors from my northerly en route course around to intercept the Runway 24 final could have been shorter or easier or quicker. And I had perfect situational awareness at all times during the approach. And the 300 foot decision height and one mile visibility minimums are the same for the LPV as for the actual ILS that serves Runway 6 at London.

I am dubious that the satellite based navigation advancements and ADS-B surveillance of NextGen will add capacity at the nation’s truly busy airports because runway capacity, not so much airspace, is the limit there. But at the thousands of little used airports across the country the LPV with its T-bone shape is cutting flying time and increasing situational awareness greatly compared to old analog guidance approaches.

So if you fly IFR we are now getting payback for the investment in advanced WAAS GPS navigators. The T-bone and LPV have made the thousands of little used airports as convenient as those with radar. And the TAWS terrain warning that is available in most WAAS navigators provides the backup the software in controller’s radar does to alert us of a mistake. At least these parts of NextGen are living up to our hopes.

Posted in Mac Clellan's Left Seat Blog | 4 Comments

We Are Pilots Forever

I received the notice that I had to renew my driver’s license. The good news–if there was any–is that I could do it online and the state would simply reuse the photo from last time.

As I was entering the credit card number to pay for a few more years of driving privileges it crossed my mind that I had never renewed my pilot’s license. There is no expiration date on the certificate. I guess it expires when I do, but I can’t find that in the FARs anywhere.

Over the 45 years or so of flying I have had a whole bunch of different actual certificates. Every time I added a new certificate level or a new rating, along came a new piece of paper. Each carried a date of when it was issued, but none listed expiration.

Most recently I was issued the plastic card with nearly illegible printing. My friend and aviation writing legend Richard Collins and I joked at the time that the new tiny type was actually an eye test. If you couldn’t read that faint small print, you couldn’t fly. I’m close.

There are at least two pilot certificates that I can think of that do expire–the CFI and the student pilot. The student pilot certificate limit makes sense. After all, we want people to progress toward the private and not be students forever. I guess the term limit on CFIs also makes sense because the FAA wants to be able to update and change the emphasis of pilot training. Renewing the CFI puts the instructor in contact with the FAA or its approved courses which provides the opportunity to remind instructors of what the FAA now thinks are the most important topics to reinforce during instruction.

But the same case could be made for limiting the duration of any pilot certificate. But the FAA doesn’t. I wonder why?

The rules have a wide open backdoor requiring renewal in the form of an FAR 61.56 flight review every two years. All of us, at a minimum, must complete the review to legally fly. But the results of the review, when it happened, what topics were covered and so on are not reported to the FAA. The review is not a pass or fail check but a minimum of an hour of ground and then hour of flight review with a CFI in any airplane you are rated to fly.

The FARs pile on other requirements to keep your license valid to carry passengers or to fly IFR, or to fly in airplanes requiring type ratings. But to fly solo under VFR in a basic airplane a flight review every two years will meet the minimum requirements.

The FAA isn’t nearly so lax in wanting to know where we live. You must have on file your current permanent mailing address. If you move you have to report the new address within 30 days. And a P.O. Box or general delivery address won’t do. You must report a location. And if your residence doesn’t have an assigned address you must provide the FAA with specific directions on how to find the place.

I’m not sure why the FAA is so focused on where we live but doesn’t ask or record how much or even if we fly. Is it some morbid leftover from a need to find next of kin? Maybe.

The medical certificate does give the FAA a more or less steady flow of information on pilots, at least enough to know the pilot was still alive at the time of the medical examination. That’s how the FAA determines you are still an “active” pilot. And you remain “active” for the duration of your medical certificate’s valid period which is two years for we older types and five years for the under 40 crowd.

But even that every two or five year sample of pilot’s continued existence is about to change. Already pilots flying to the sport pilot rule don’t need a medical. Neither do those flying gliders or balloons. And soon, one way or another, the ability to fly privately using a driver’s license instead of medical will be expanded and more “active” pilots will disappear from the rolls.

So here we are in what appears to be the most highly regulated activity in the nation–flying–but the government knows very little about us. On the other hand, the states keep pretty close tabs on us as drivers demanding a new license be issued every couple or three years. Even our dog’s license expires every three years. But as pilots we fly on forever. Pretty good deal.

However, real life doesn’t work exactly that way. A friend in Florida was recently taking care of the estate of his recently deceased very elderly mother when he came across a new Florida driver’s license that was issued and put into the mail to her several days after her death.

On paper–now plastic–we can be pilots forever. In Florida, at least, I guess you can be a legal driver for longer than anyone would guess.


Posted in Mac Clellan's Left Seat Blog | 20 Comments

Airplanes Hate Cold Weather

I find it very strange that airplanes can do so well with very, very cold conditions after they are in the air, but have all kinds of trouble with unusually cold weather on the ground.

We all know about congealing oil and other problems with starting a very cold piston engine. Most piston airplane owners in the cold country have installed heaters that warm at least the oil, and some heat up the cylinders, too.

But cold soaking brings on lots of other potential problems that engine preheat just won’t address.

In my experience very cold conditions almost always attack anything that’s inflated. Tires, for example, always lose at least some pressure. That makes sense because cold air–or nitrogen or any other gas–takes up less space than when warm. The air doesn’t need to leak out of a tire for it to lose pressure.

And airplane tires are pretty small compared to a car tire so they hold a smaller volume of gas, and usually at a higher pressure. My little six-inch nose tire is supposed to be pumped up to 60 psi. Check the pressure after a really cold spell and it’s often down in the 20s without a leak, or at least a leak a patch can fix.

Another airplane system that loses pressure with cold temperature is an oleo strut. The gas pressure is retained by O ring seals. Cold shrinks the O rings by at least a little and there goes some of the gas. Since oleos function at very high pressure compared to tires, it doesn’t take much of a gas loss to drop the gear strut down to a risky level.

It’s usually the first few cold days of winter that calls for servicing the landing gear struts, and with luck that added gas volume may get you the rest of the way through. But if you have a really below average cold snap like we have had in the northern tier of states the strut can easily go flat again. The O rings aren’t necessary bad, and new O rings probably won’t change anything. It’s the darn cold.

Fuel tanks, fuel pumps, fuel hoses and especially fuel bladder tanks really object to being cold soaked. If all the connections are tight and O rings and gaskets are in good shape you may make it through those sub-zero nights. If not, you’ll find the weak point.

That’s what happened to me when I went to launch for the Bahamas after days of zero or even below, which is very unusual for us being right on the shore of Lake Michigan. It was many degrees colder inland, but that didn’t help me.

The main gear struts were clearly down, the tires needed a shot of air but that looked like my only problem. Until the fuel truck topped the tanks. Then avgas started to run out of the fairings under the wing root and drip of the trailing edge of the flap. More like a stream of fuel than a drip.

Well, I thought that was the end of our trip south and that one of the three fuel bladder tanks in the wing would have to be replaced. But the experts at Executive Air on Muskegon Airport where I base quickly found a cold related, but less serious problem than a bladder leak.

What had happened is the cold shrank the gasket that sealed an access port into one of the bladders where the fuel quantity sensor is located. The screws holding the access plate were safetied but between the screws working a little loose and the cold shrinking the gasket fuel was running out. Tightened screws and a gasket and the leak was fixed.

Something similar happened last year when the airplane went in for annual. There were some fuel stains around one of the bladder tanks. But as soon as the airplane warmed up in the shop there was no sign of a leak that could be found. Some fuel seeped from somewhere in the cold, but stopped seeping when warm.

But we fly airplanes up into cold air, very cold air at higher altitudes. Standard temp at jet cruise level is -56 degrees C. And airplanes seem to do fine with that cold. Why?

The difference is that we climb into the cold with the airplane and its systems operating instead of subjecting them to extreme cold at rest. An operating airplane warms itself in many ways, and most airplanes can’t remain aloft long enough to match the hours or days of a ground cold soak. Some very long range airplanes that stay at high and cold cruise altitude for 12 or 14 or more hours have had trouble with fuel freezing or water being trapped where it can freeze and do damage, but that’s not an issue for most of us.

That’s why for certification jets and other transport airplanes must undergo cold soak testing. The airplane has to be flown to some extremely cold location, left outside for hours, usually over night, and then wake up and function without any added heat. It’s a tough test.

My airplane like other piston airplanes didn’t have to survive a cold soak test for certification. And it may not have passed. But at least it’s warming up now here in the Bahamas hoping for warmer conditions when it gets back to the shore of Lake Michigan.

Most of us think airplanes have personalities, and mine does. It now hates the cold in its old age a lot like the pilot who flies it.

Posted in Mac Clellan's Left Seat Blog | 3 Comments

Airplane Windows Add Safety–And Comfort

Plenty of window area in this Sonex

The largest possible window area is obviously a safety advantage when it comes to seeing and avoiding other traffic, or even when looking at the runway while landing. That’s why most fighters and aerobatic airplanes have transparent canopies.

But windows also add–or detract–from comfort for all occupants of an airplane. The right window design makes any cabin feel more spacious and welcoming, and can also ease the discomfort of turbulence.

The Klapmeier brothers understood this when they were laying out the original design for the Cirrus. That’s why the SR20 and SR22 have big windshields, large windows in each door, and even more importantly large rear windows. In many airplanes passengers in the second row are left sitting down in a cave with a very limited view of the outside world. But not in a Cirrus. The brothers had flown enough with family members and friends in the backseats of other airplanes to understand how important this is.

Another design that did a nice job with the windows is the Bonanza, and the many Beech models it spawned. In the Beechcrafts the windows sweep up into the overhead helping to make the cabin feel larger than it really is, even for the second row of seats.

The epitome of window perfection is the Gulfstream line of business jets. In the late 1950s when engineers at Grumman were creating the stately Gulfstream I turboprop–the first purpose built turbine business airplane–they included huge oval windows in the cabin. Passengers loved them, and every Gulfstream since has had the trademark ovals. In fact, for the super speedy and super ultra long range G650 Gulfstream increased the size of the oval windows by nearly a third.

But big windows come at a price. It’s not that the transparent material costs so much, but the structural accommodations required to design in large windows is costly and heavy. And then there is the cost of annoyance and suffering when you just don’t want all of that sunlight beating in on you.

The structural penalty for big windows is mostly in weight. No matter what material the actual transparency is made from it can’t carry structural loads. That means the load carrying elements of the airframe have to be designed around the window opening instead of following their most efficient path.

In unpressurized airplanes the weight and materials costs of larger windows isn’t nearly as great as in pressurized airplanes. Perfect examples of the window size penalty in pressurized airplanes are the P Baron or the Cessna P210. Both pressurized airplanes evolved from unpressurized versions and in each the window size was cut down markedly to reduce the amount structural and transparency strength required, and thus help control weight.

In transport airplanes windows need to be redundant so failure of one layer or pane of the transparency won’t create a decompression so you can see how the weight of a big window adds up. And in the cockpit windshields and their frames have to withstand the impact of a large bird at 250 knots. Add in the heating elements and it’s easy to see how a big windshield, no matter how much pilots love them, adds weight plus construction and maintenance costs.

Early Citations are an oddity in windshields, birds and the FARs. The Cessna business jets had two Vmo (maximum indicated airspeed) limits, one for below 8,000 feet and a higher red line for above that altitude. The reason is that the airplane met the bird impact rules at the lower Vmo but, under the rules, the birds that endanger the windshield did not fly above 8,000 feet. I always wondered if the birds had read the FARs, or had altimeters for that matter.

The primary price pilots pay for big windows comes when the sun is shining. The greenhouse effect is no myth. Sit under a transparent canopy on a sunny day for very long and you are soon wishing for shade, even if it’s cold outside. Most pilots and builders of canopy airplanes devise a shade of some sort to pull over the center of the overhead for relief. But even with a shade it can quickly become unbearable under the canopy on a hot sunny day, especially on the ground.

Big windshields also extract a toll in suffering when flying toward the sun. The pilots who suffer most are those on the transatlantic routes. Flights typically leave the U.S. in the evening but the crew quickly catches up with the rising sun in the east and are broiled for the second half of the flight and arrival. The return trips usually depart in the late morning and chase the sun across the ocean assuring the pilots will be blinded and toasted for the entire trip.

Nearly all passenger cabin windows have screens and blinds to pull so being blinded and cooked is mostly a pilot problem. Pilots have propped up just about anything in the cockpit windows to block the blinding glare. And one company, Rosen, has made a very successful business of building articulating arms that allow you to position the sun visor almost anywhere over the cockpit windows. Designers of new airplanes are including effective sun glare protection devices in the original layout of the cockpit. It’s that important.

But no matter how annoying the sun may be, I still prefer being in an airplane with well designed windows. I can usually come up with some way to shade myself when needed, but there is nothing you can do to change that little slit of a windshield that is left in too many airplanes as the instrument panel glareshield has risen to accommodate ever more avionics displays.

And if you want to know what passengers think of the importance of windows just ask a Cirrus or Gulfstream salesman. They know.

Posted in Mac Clellan's Left Seat Blog | 8 Comments

What the Heck is WAAS?

WAAS has been in the news a lot lately as airplane owners study the coming ADS-B mandate and how to deal with it. We are constantly reminded that the crucial element of ADS-B “out” is a position sensor that uses WAAS-aided GPS.

WAAS stands for wide-area augmentation system. Or if you want to be one of the avionics cognoscenti you would call it SBAS for space-based augmentation system. Neither one of those terms says much about what WAAS is and how it works.

The bottom line information is that WAAS corrects errors in the GPS navigation solution over a wide area. The “wide area” for WAAS is pretty much all of North America, plus offshore water on both coasts and most of the Caribbean. WAAS compatible systems are in place or being constructed by other nations around most of the world.

As I’m sure you know GPS uses a constellation of satellites orbiting the earth at an altitude of about 11,000 miles. The GPS navigator detects the travel time of signals from several satellites to calculate the distance to each of those satellites. The position of the satellites is known so the GPS navigator triangulates using the measured distance from the satellites to establish a 3-D position.

Unlike a radar, or DME, that use a timed round trip of an electronic signal to calculated distance GPS relies on an extremely precise clock. When a GPS receiver locks on it synchronizes its clock to the satellites. The satellites in turn are synchronized to supremely accurate clocks on the ground. With all the clocks in synch the GPS navigator knows exactly when the signal left the satellite so it can calculate how long it took the signal to reach the receiver and thus calculate the distance from the satellite.

Basic GPS has a useful accuracy of around 10 meters though rarely errors can be larger, possibly as much as 100 meters. Errors in the GPS solution come from slight variability in the clocks, small position errors for the satellites, but most importantly, from distortion as the weak signal travels through the earth’s ionosphere and atmosphere. Ten meter accuracy–about 33 feet–is plenty good for en route navigation, and even for non-precision instrument approaches. But that isn’t nearly good enough for precision approaches. And the errors in vertical calculation are particularly troublesome when you want guidance to within a couple hundred feet of the ground without being able to see it.

WAAS corrects these fundamental GPS errors so that nominal accuracy both laterally and vertically is better than 2 meters.

To work its magic WAAS employs a network of ground stations at precisely surveyed locations. These stations know exactly where they are so they compare that known position to the real time calculated position from “raw” GPS signals. The WAAS ground stations create an error correction signal that is sent up to non-GPS communication satellites that are in geostationary orbit. The WAAS correction signal then comes down to a GPS receiver along with the basic GPS signals and the errors are corrected in the airborne navigator.

Equally important to the position error correction is what navigation types call “system integrity.” Basic GPS provides a position fix at one hertz, or once per second. That sounds fast, but consider that if you are flying an instrument approach at 120 knots you will cover 200 feet each second. If a position fix is missed because of some kind of signal problem you will travel another 200 feet before the next possible fix. By the time the navigator is sure there is a problem you will have gone many hundreds of feet, way too many when flying in the clouds close to the ground.

WAAS enables a navigator to fix its position six or more times a second so there are multiple opportunities to find an error. WAAS also contains information on the integrity of the system and sends a quick warning of a problem. So with WAAS a pilot will see a warning flag very quickly if there is a navigation problem, which is exactly what you need when flying a precision instrument approach.

The creators of the ADS-B NextGen system found these WAAS capabilities to be essential if the system is going to allow reduced separation of IFR traffic. If we’re going to fly closer together while in the clouds we obviously need–both controllers and pilots–to know exactly where we all are in 3-D. We also need to get the earliest possible warning if the system is failing or unacceptable errors are creeping in. That’s why WAAS, or a navigation system that equals WAAS-aided GPS, is required as the position sensor for the ADS-B out signal.

I’m unwilling to wager that even with the surveillance and navigation precision of WAAS and ADS-B that we will reduce IFR traffic separation in a meaningful way. The technology makes it possible, but I’m not sure that emotionally pilots or the public want to fly closer than 3 miles from another airplane at the same altitude in the clouds. And even if you do fly closer, will there be enough room on the runway for the airplane ahead to land, brake and turnoff?

The precision of WAAS and ADS-B makes virtually no sense for the VFR pilot where even the worst 100 meter navigation accuracy is more than enough, and missing other traffic by at least a mile, not a few meters, is the goal. But so far the FAA is sticking with its single standard of WAAS for ADS-B position sensing for big jets and little pistons.

Posted in Mac Clellan's Left Seat Blog | 17 Comments

Back To Which Basics?

T-37 was the “basic” for more than 50 years

Getting back to basics is an eternal theme in aviation. If only every pilot could have learned to fly in a Cub and still land one in a 20 knot crosswind aviation would be better off, many say.

And I agree with them if your plans are to spend your entire career flying basic piston airplanes. But for other types of flying the basics of a Cub may not apply. In fact, the techniques that are so essential to Cub flying may be the wrong ones to use flying other classes of airplanes.

The emphasis on basics and getting back to them crossed my mind when reports emerged that the flight data recorder shows the crew of the TransAsia ATR 72 that crashed shortly after takeoff apparently shut down the good engine. It seems clear one engine failed shortly after liftoff, but the ATR is fully capable of climbing away with a safe gradient on the remaining engine. And pilots practice that in initial type rating training and every recurrent session.

What could have caused the crew to move a cockpit control at a critical time that would shut down the good engine? Could it have been getting back to the basics of twin training?

In piston twins with their relatively low power it is essential for the pilot to immediately feather the propeller of a failed engine to have any chance of climbing or even holding altitude with only the good engine. It’s drummed into pilots during piston twin training to quickly identify the failed engine and then secure it.

There is a long history of piston twin pilots getting it wrong and shutting down the good engine. That’s why in transport flying the procedures are to do absolutely nothing with the engine controls after a failure until the airplane is at a safe altitude and everything is stable. A quick way to flunk a check in a transport airplane is to start moving levers or switches quickly after there is an engine problem in the sim.

A jet or more recently built turboprops does not require the pilot to immediately do anything after an engine failure except maintain the target airspeed and attitude. The jet engine will simply windmill after failure so moving the throttle or shutting off fuel will not help performance. And in all but the light turboprops the propeller will feather itself if the engine fails so yanking on engine control levers can only introduce the possibility of an error.

Even an engine fire warning in a jet is treated deliberately before “punching the engine out” because false alarms are much more common than actual engine fires. “Let it burn” until you are at a safe altitude is the standard training advice.

The military learned decades ago that teaching the “basics” applies specifically to what kind of airplane you will fly. That’s why in the late 1950s the Air Force made the T-37 twin engine jet its “basic” trainer. Air Force pilots were going to fly jets so the “basics” pilots needed to learn came from a jet trainer. Many Air Force pilots flew their entire career and then went on to the airlines without ever flying prop airplanes. Would the “basics” of a Cub made them better pilots? I don’t see how.

I never flew in the military but I know many pilots who did and there is no agreement among them on whether having experience in light piston airplanes before entering the service helped in pilot training. Some believe that it did, others don’t. But almost all agree there was much to unlearn in military training if your sole pilot experience had been piston singles.

Even when the joint services created the specs for a turboprop basic trainer, which turned out to be the Beech T6A Texan, the requirements were for the airplane to fly like a jet, not a prop. So the T6A uses electronic controls to “schedule” the engine and propeller response of mimic the spool up of a jet engine, not a turboprop. An automatic system even steps on the rudder to cancel the normal propeller effects of P-factor and torque because those won’t be there in a jet. Don’t learn something that later needs to be unlearned, in other words.

I think our regulations and training system are doing a pretty good job preparing people to be light airplane pilots. But I also think the military, and some major international airlines, also have it right by teaching a different set of “basics” from the beginning. Some nations have even adopted a “crew only” license and training program for new pilots destined for a professional career. Why teach the techniques so essential for solo flying when they don’t apply to crew resource management and crew techniques. Any pilot who has made the transition from solo flying to a crew operation knows there is much to unlearn, and old habits can came back at the worst possible moment.

I’m all for getting back to basics but we should keep in mind what is “basic” for what airplanes and how we fly. Slipping a taildragger into a gusty crosswind is an important skill for GA flying, but is very much the wrong thing to do with a swept wing jet.

There are, however, a couple basics that I can think of that do apply to all airplanes. One, you need to have fuel to keep the engines running. And, two, if you can’t hold the target airspeed, heading and altitude bad things will happen. Those “basics” can’t be practiced too much.

Posted in Mac Clellan's Left Seat Blog | 42 Comments

We Used to Fly On Time. Not Anymore

Not long ago the clock was one of the most vital instruments in the panel. We navigated by timing. Not so much anymore.

Thirty-five years ago I was dinged by the examiner during the simulator portion of my first type rating checkride because I didn’t start the clock passing the outer marker on an ILS approach. Timing didn’t seem to me to matter much on an ILS. I was going to track the glideslope down to decision height and either see the runway or fly the miss.

But to this oldtimer–pun intended–I had committed a cardinal sin. What, he demanded, was I going to do if the glideslope failed? Without time I couldn’t continue on at the localizer only minimums because I couldn’t find the missed approach point without knowing elapsed time from the marker.

Of course, since it was a simulator the glideslope could fail, and it did. I had to go around and fly the approach all over again, this time with the clock counting seconds since I passed the marker.

I thought of that experience the other day when I heard a pilot ask controllers if the outer marker on the ILS he was flying was out of service. The controllers said it had been notamed out for at least a year and they didn’t think it would ever be back on the air.

That made me try to remember the last time I saw the flashing light and heard the beeps when passing the final approach fix. Did my marker beacon receiver still work? I think so. But I hadn’t paid attention to it in so long I’m not sure.

For decades we flew along with a decent idea of our lateral path over the ground thanks to the compass. But the only way we could know how fast we were covering the ground, or if in the clouds where we were, was to note the time it took to fly between two known points.

When DME became affordable to many airplane owners that helped us know our ground speed and where we were along the route, but many VOR stations didn’t have DME. And DME was of no help when tracking into or away from an NDB so the clock was still king.

The invention of RNAV was a big help in knowing where we were because you could project the signal from a VOR/DME out to a specific waypoint. But RNAV was not usable on most instrument approaches.

The really big navigation breakthrough, at least for en route flying, was development of reasonably priced airborne Loran C receivers. The Loran C signal was based on grid navigation, not the bearing and distance techniques we had been using, so you could be guided directly to any point. Just punch in the numbers for the desired lat-long and you knew how far, how fast, and what heading to fly. It was magic.

But Loran C wasn’t accurate and reliable enough for precision terminal and approach navigation so we were still timing and turning and tuning, at least I think that’s what the “three Ts” stood for.

Then GPS was perfected. Suddenly–at least it seems to have happened suddenly in my memory–we always knew exactly where we were, where we were going and how fast. The extra WAAS satellite signal corrects GPS errors to the point that we know our position and track within a couple meters. The WAAS-based LPV approach equals the ILS signal in vertical and lateral guidance and always shows your distance from the runway with equal precision. What am I going to do if the glideslope fails and I didn’t start the clock? Who cares?

Another irony is that many GPS navigators start the clock for you. When your groundspeed hits a preset threshold the GPS starts the flight timer with no required action from you. Want to know how long you have been flying? Look at the GPS. I still do write down takeoff time after I have the airplane cleaned up in cruise, but I do that more out of fear that I will somehow mistakenly reset the timer than out of worry that the GPS box will fail.

The ultimate irony is that GPS is actually the most precise and exquisite time measuring system ever created. The navigator locates its position by measuring miniscule differences in travel time of extremely weak signals sent from satellites orbiting about 11,000 nm above the earth. GPS timing is so incredibly precise that a second we used to note is an eternity. So we still know where we are and where we are going thanks to time keeping.

The one standard maneuver that I can think of that is still measured by time instead of distance is the holding pattern leg. But even when holding the GPS creates a racetrack on the map and shows the little airplane flying over the track.

Do I miss all that hacking the clock and tracking the time? No. I have plenty to do just flying the airplane.

Posted in Mac Clellan's Left Seat Blog | 10 Comments

A Rational Way to Deal With ECI Cylinders

The FAA is simply determined to get rid of thousands of ECI cylinders used on big-bore Continental engines.

Last August the FAA issued a proposed AD that would have required approximately 36,000 aftermarket cylinders built by ECI to be junked, most of them after only 500 hours of operation. The proposed rule also called for repetitive inspections and grouped cylinders by serial number.

The NPRM drew many, many comments, most of them against the proposed AD. But earlier in January the FAA came right back at airplane owners with a revised proposal that essentially requires the cylinders to be removed from the engine after 1,000 hours of operation.

It’s true that 1,000 hours is better than 500, but to me it still isn’t necessary to accomplish the FAA’s objective. Even the NTSB, not exactly a devil may care outfit when it comes to safety, commented that the cylinders should be allowed to fly on until recommended TBO. But the FAA has again ignored the NTSB’s advice, and the advice of everyone else who commented.

The FAA says it has determined that the affected ECI cylinders suffer head separation at a much higher rate than other cylinders. There have been a few instances where the aluminum head did crack and break free from the steel cylinder barrel. Obviously that cylinder no longer functions, and there is at least some risk of fire because fuel and probably spark is still being fed to the failed cylinder head. By there have been no fatal accidents caused by these failures.

It’s impossible for the FAA to know with certainty anything about the failure rates of any cylinder or piston engine component because the data just doesn’t exist. The FAA does get service difficulty reports if shops take the time to file them, but there is absolutely no way to know how much of the universe the reports represent. It’s just hit and miss.

But, I fear the evidence fight is over. For whatever reasons the FAA is absolutely determined that the affected ECI cylinders are “unsafe”–the FAA word. So the FAA objective should be to remove the cylinders from engines in the least disruptive and costly way.

Here is how that can be accomplished. Issue an AD that forbids any ECI cylinder in the affected group from ever being reinstalled in any engine after it has been removed for any reason.

The fundamental problem is that piston engine parts are certified without life limits and without any requirement to document time in service. A cylinder, for example, remains airworthy as long as a licensed mechanic or repair station says it is. And that cylinder can be repaired in all kinds of ways and be returned to an airworthy condition.

But absolutely nothing is known about cylinders once they are removed from an engine because there is no requirement to record anything. For example, at the last annual two cylinders on my high-time engine were simply worn out. The shop bought two overhauled cylinders to replace them. The overhauled cylinders came with the required yellow tag saying they had been repaired and inspected and are airworthy.

But nobody has any clue how many hours are on those cylinders, or even what type of engine they came from. Those cylinders could have been on a turbocharged engine with the higher heat and stress involved but are now on my naturally aspirated engine. They could have come from a 520 and are now on my 550 engine. And the cylinders that came off my engine went to that overhaul shop as a “core” and were most likely repaired and are on yet another engine.

It is this “certified forever” concept of piston engine parts that is, or should be, the issue with ECI cylinders. Without an AD the ECI cylinders the FAA is worried about could fly on being repaired and overhauled repeatedly with no records kept about time in service.

My idea of an AD that simply doesn’t allow reinstallation of one of the covered cylinders would cost owners only the “core” credit we get when a cylinder is replaced or the engine is overhauled. The core credit is typically a few hundred dollars because the overhaul shop that sells you the repaired cylinder needs your old cylinder–the core–to repair and resell. So in this case you wouldn’t have a cylinder to exchange so you would be charged the core credit.

The reality is that many, even most, cylinders will develop some sort of problem during their run between major overhauls. Leaking valves are common, but rings and cylinder barrels wear, valve guides wear and so on. That means the affected ECI cylinder replacement would be spread out. When a cylinder needed to come off for any work that would be it. The cylinder would be retired. And the cost of complying with the AD would be the cost of the core credit as each cylinder is retired.

At major overhaul time all six cylinders would be trashed. The extra cost to the airplane owner would be six core credits. That’s a lot, but still so much better than junking all of your cylinders at the arbitrary 1,000 hours the FAA is proposing.

You can read and comment on the proposed ECI cylinder AD here:!documentDetail;D=FAA-2012-0002-0600

Comments are open until February 23. It may make you feel better to comment that the AD is simply not necessary, but the way the FAA blew off all of those thoughtful and supported comments in the first round I just don’t expect the AD to go away. I think the best we can hope for is to fly the affected cylinders until they need work, and then throw them away when they come off the engine. That’s bad, but not as bad as what the FAA is proposing.

Posted in Mac Clellan's Left Seat Blog | 5 Comments

What We Will Learn From Self-Driving Cars

It’s been nearly a century since gyroscope pioneer Elmer Sperry created the first true autopilot. And autopilots have come a long way since. The most sophisticated can even land the airplane, steer it down the centerline on roll out, and brake the airplane to a stop.

What hasn’t been as successful is creating and maintaining the man-machine interface between the human pilot and iron mike. In many respects the more capable the autopilot has become, the more difficult it is for the human to correctly use and manage the machine.

Now the self-driving car–autonomous operation, if you prefer–is here. Several automakers claim they could deliver a car that drives itself right now if regulators allowed it. And there seems to be wide agreement that many cars will be driving themselves down the streets and highways of the civilized world by 2020.

What this means is that instead of thousands of pilots learning to successfully use autopilots we will soon have millions, maybe many millions, of drivers doing the same thing. The expected explosion in autonomous driving machines will allow us to discover new problems, and new solutions at a very rapid pace. Nothing teaches what works and what doesn’t better and faster than having a whole bunch of people trying to learn the same thing at once.

The lessons from airplane autopilot use is that the machines are not 100 percent reliable, but the bigger problem is that more frequently the autopilot is performing as designed but the human pilot doesn’t understand how it should be functioning.

My favorite story about autopilot mismanagement came from the old King Radio company. King had a service hangar on the airport near its headquarters in Olathe, Kansas. One day an irate Bonanza owner arrived screaming that his King autopilot was trying to kill him.

The Bonanza owner said the airplane, with autopilot engaged, pitched down unexpectedly. He grabbed the controls and pulled back as hard as he could. Luckily he had a friend in the right seat who got on the controls and helped him pull. Together they pulled as hard as they could while one finally was able to pull the autopilot circuit breaker.

But the autopilot was still fighting them. It wouldn’t disengage. They both battled the nose-down control force all the way to touchdown cursing the autopilot that wouldn’t let go.

What happened, of course, is that the pilot started pulling on the controls before disengaging the autopilot. Sensors in the autopilot interpreted the pilot’s actions as the need for nose-down trim and automatically started rolling the trim in, and kept at it. By the time the pilots got the breaker pulled and the autopilot truly dead they still had full nose-down trim fighting them. They didn’t understand their original actions, and so didn’t know to simply re-trim the airplane and go land.

That’s an example of the most basic mismanagement of autopilots. More common errors are failing to understand what a mode selection will do. Or why it may or may not capture a glideslope from above. Or why it didn’t switch from roll steering to approach mode. Or what the heck is FLCH mode? And on and on.

There is a little standardization in autopilot design and function, but there are often differences in how the same autopilot operates from one airplane type to another. And, except for newer airplanes with totally standardized cockpits, there is very little complete training on how to use autopilots at the GA level.

My question is will the car guys do better? No matter how incomplete pilot training is, driving training is essentially zero. That means the car autopilot will have to be so intuitive that drivers get it right the first and every time with about the same level of instruction on how to operate the entertainment system. Well, actually it needs to be easier to use the car autopilot than the radio or there will be cars driving off to who knows where.

Driving a car in the close confines streets and roads, along with the stop and go that is part of traffic, is daunting compared to the relatively wide open spaces we fly through. But the car guys aren’t bound by evolutionary designs as we are in aviation. The car autopilot can start from scratch, using very advanced technology, and can be integrated fully during original design of the car.

But I believe there will be one issue both airplane and car autopilots share–many people just won’t trust them. I have seen that for decades in aviation where human pilots, especially when the workload is high and when they need the autopilot most, just can’t trust it and turn it off. I bet we will see the same in cars. Most of us have been driving since we were teenagers and when that darn thing does something we don’t like, or don’t expect, we’ll be looking for the off button.

However soon it happens the self-driving car can only be good news for teaching us how to make an autopilot we humans understand, and trust, at least most of the time. Let the great experiment begin.

Posted in Mac Clellan's Left Seat Blog | 9 Comments