Thursday, June 29, 2006

Pilot-Defined Instrument Departures

If you fly small aircraft under Instrument Flight Rules (IFR), you may not be used to flying departure procedures or you may be used to flying the same ones each time you file IFR. You learned during your instrument training that these procedures all have the same goals: Keep pilots from running into obstructions right after takeoff and simplify the delivery of IFR clearances. Unfortunately, there is some confusion surrounding departure procedures because the terminology has changed back and forth. Add the way different GPS receivers handle departure procedures and matters are made more complicated. To my mind, there are four varieties of departure procedures: those devised by the pilot, Obstacle Departure Procedures, DPs, and SIDs. I'll discuss pilot-devised departure procedures in this installment.

Departing an airport in uncontrolled airspace (Class G in the U.S.) and for which there is no defined procedure, the pilot needs to do thorough planning. Let's say you're departing Shelter Cove, California for an IFR flight to San Jose. The IFR clearance you receive might sound something like this:
Bonanza 12345 is cleared to San Jose Mineta Airport via, when entering controlled airspace, direct Mendocino, Victor 27, Point Reyes One arrival ...
There are no instrument procedures defined for Shelter Cove, so use the appropriate VFR sectional and IFR low altitude en route charts, your knowledge of the local terrain, your aircraft's climb performance data, and some common sense to devise a strategy to climb to a safe altitude for vectors to Mendocino.

The Maximum Elevation Figure on the VFR sectional for the area where Shelter Cover is located is 4,400 feet. The Minimum Off-Route Obstruction Clearance Altitudes on the IFR low altitude en route chart sector for Shelter Cove is 6,400' with a MORCA of 5,000' for the sector to the south, and 9,800' to the East. The Minimum En route Altitude for V27 is 6,700'. The airspace surrounding Shelter Cove is Class G (uncontrolled) from the surface to 1200' AGL, with Class E (controlled airspace) beginning at 1200'. Should the ceiling at Shelter Cove be below 1200', keep in mind that after takeoff you will be operating in instrument conditions in Class G (uncontrolled) airspace until you climb to 1200' .

Departing runway 30 at Shelter Cove with a climbing left turn to heading 180 looks to be the way to go since there is quickly rising terrain to the north and to the east. The bad news is that the left turn takes you out over the Pacific Ocean, so it helps to have plenty of confidence in your aircraft. Here's what a G1000 would display on the ground at Shelter Cove.

If you're flying a G1000-equipped aircraft, now is the time to have the terrain feature enabled on the moving map. Whenever you see red on the terrain display, there is terrain less than 100' from your current altitude. Yellow means terra firma is between 100' and 1000' of your altitude. The absence of any colors (or black, if you have the topographic data turned off) means you're more than 1000' above terrain. If you have a hand-held GPS that displays terrain data, don't use it for primary navigation but by all means use it to enhance your situational awareness. Here is the PFD with the inset map in the lower left side of the screen set to show terrain data.

Here's what the PFD might look like climbing out from runway 30 at Shelter Cove.

As you begin the left turn toward the Mendocino VOR and begin to gain altitude, you'll begin to see more yellow than red on the terrain display.

Intercepting the direct course to the VOR, almost all of the yellow and red have disappeared.

If you plan to depart VFR and pick up your clearance airborne, the weather conditions should allow you to climb to a sufficient altitude to establish radio communications with the ATC facility that provides departure control for the area. The last thing you want is to get airborne in deteriorating weather only to find you can't raise ATC on the radio or that ATC can't identify you on radar to issue your clearance. Due to terrain and the remote nature of the location, Oakland Center has limited radio and radar coverage in this area, so your best bet would be to call Flight Service on the phone to get your IFR clearance while still on the ground at Shelter Cove. Last time I was at Shelter Cove (about a year ago), my cell phone couldn't get a signal, but there is a pay phone nearby. You can see why they call this area The Lost Coast.

Friday, June 23, 2006

Rejected Takeoff

Prior to the flight the pilot-rated passenger and first pilot discussed who would operate the aircraft. The passenger would occupy the left seat and taxi the airplane to the active runway, while the first pilot would occupy the right seat and do the flying. The passenger did not remember if the parking brake was set or released prior to beginning his taxi, but did remember that the aircraft did not pull to the left or right while taxiing. Upon reaching the active runway and getting the airplane lined up, the first pilot took control of the airplane and advanced the throttle. The passenger said he didn't feel like the airplane was accelerating properly, and when he asked the first pilot if the airplane was accelerating properly, the first pilot replied, "Yes." As the airplane continued down the runway on its takeoff roll, and sensing the airplane was still not accelerating, the passenger asked the first pilot if he wanted him to put some flaps on. The first pilot replied, "No," and there were no further communications between the passenger and first pilot. The airplane continued off the end of the runway and through a 66 foot grass overrun before going over an embankment and impacting trees. The aircraft subsequently came to rest inverted at the bottom of a ravine. The fuselage and tail section of the aircraft were oriented up and parallel to the slope of the ravine, while the nose and left wing of the aircraft were partially submerged in the adjacent canal which borders the edge of the ravine. Witnesses to the accident thought the pilot was doing a high speed taxi, that the airplane reached a maximum speed of approximately 50 miles per hour, and that there was no attempt to abort the takeoff roll. Several witnesses reported that the engine didn't sound right, was making noises, and was not running smoothly. A post accident examination of the airframe, engine, and propeller did not reveal any anomalies which would have precluded normal operation of the aircraft.

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:

The failure of the pilot to abort the takeoff roll. Factors contributing to the accident included the failure of the aircraft to accelerate for undetermined reasons and the trees.
Handling an engine failure in a single-engine aircraft during the takeoff roll might seem like a no-brainer, but it requires immediate and sensible action by the pilot if there is to be a favorable outcome. I'm always surprised by the number of certificated pilots with whom I fly in single-engine aircraft who do not brief the handling of emergencies before takeoff and climb-out. Not only is it important to self-brief if you are the only pilot on board, it's just as crucial to discuss the possibility when there's another pilot or an instructor on board.

In fairness to GA pilots, the Practical Test Standards do not require a rejected takeoff demonstration for single-engine private pilot and commercial candidates. Student pilots learn to do countless takeoffs and landings, so it's no wonder that we're spring-loaded to commit to a takeoff. However in the accident cited above, both occupants were retired airline pilots, each with several thousands of hours of flight experience. Each pilot knew how to brief a takeoff and how to abort a takeoff in an airliner. The accident illustrates that in a GA aircraft, the pilot in command needs decision making skills based on something other than Kentucky windage.

Rejecting the takeoff in a single engine aircraft while you're still on the runway is easy - close the throttle, maintain directional control, brake as needed, and exit the runway or evacuate the aircraft. What you need is some objective and subjective criteria to aid your decision as well a plan of action should you decide to abort.

Computing takeoff and landing performance is actually a 14 CFR 91.103 requirement, so if you are not at sea level on a standard day, or if the plane is close to gross weight, it's time to get out the handbook and run the numbers. Departing a big city airport with 6000 to 10,000 foot runways, it's easy to become complacent. Takeoff calculations in these cases helps you identify an abort landmark - a point down the runway where you should be airborne. Read the fine print in the performance charts carefully, since many GA aircraft manuals are famous for the large print giveth and the small print taketh away. Remember, too, that this performance data tends to be biased toward a new aircraft and a highly-skilled and current pilot. When in doubt, add a fudge factor of at least 50% to the suggested takeoff distance.

Identify an abort landmark where you predict the aircraft should become airborne. If you reach that landmark and you're not off the ground, reject the takeoff and keep the plane on the ground, where you'll have plenty of time to troubleshoot the issue.

In addition to objective criteria for accepting a takeoff - RPM in the green, manifold pressure above 25 inches, oil pressure and temperature normal, airspeed indicator alive - it helps to have subjective criteria for aborting. The engine running roughly or back firing, the plane pulling to one side, excessive nose wheel shimmy, or the feeling that something just isn't right are all good reasons to keep the plane on the ground.

What about the landing data for the airport from which you are departing? Computing the landing data for your departure airport might come in very handy if you have to return for an immediate landing or if you have to perform an off-airport, forced landing. Landing data is also important because light, single-engine aircraft can get into some pretty short runways. With high density altitude, it's not uncommon to be able to land on a small strip in the mountains, only to find you do not have enough runway to takeoff.

Airborne in a single-engine aircraft and still at a low altitude or in the clouds, your options are limited if something goes wrong shortly after takeoff. You are probably going perform an off-airport landing, the question is where? If you fly out of the same airport(s) on a regular basis, why not learn the location of the flattest, least populated, most obstruction-free areas near the airport? This is as much for the protection of people on the ground (who have not accepted the risks of flight that you have) as it is for your own protection. The survivability of a forced landing in smaller aircraft is quite good if you land on a flat, firm surface with few obstructions. The smaller the aircraft, the greater the odds you'll walk away provided you fly the plane all the way to a landing. The longer you maintain control, the better your odds.

If you are departing IFR, have an approach selected that you'll use to return if something goes awry. Departing Oakland on runway 27 left or right, I often see the few pilots who even have bothered to think about an unplanned return choose the ILS RWY 27R as their emergency approach. If you are departing to the west in a twin-engine aircraft, it's quite possible you could limp around 8 miles or so back to the east to begin the ILS. But with a single-engine, you need something better. You're departing to the West, so why not select an approach that arrives from the West - such as the VOR RWY 9R or GPS RWY 9L? Or if all else fails, know a VOR radial or heading that will take you back toward the airport or your emergency landing site.

A great exercise is to fly to a quiet airport that has a reasonably long runway and practice aborting takeoffs. One of my favorite places to do this sort of thing is Castle Airport in Merced. A former B52 base, now a public use airport, it has an incredibly long runway.

It's tough to make the decision to not even start the engine if the numbers just don't add up. It's even tougher to reject a takeoff when you're rolling down the runway, you haven't estimated the takeoff performance, and you haven't come up with a plan of action as the trees at the end of the runway loom larger and larger.

Wednesday, June 21, 2006

Sharp Glass

The Control/Performance approach to instrument flying divides the instruments into two groups. The attitude indicator and tachometer/manifold pressure instruments are control instruments and should allow you to precisely set your pitch attitude and power. All the other instruments are performance instruments that tell you if you have the desired airspeed, altitude, rate of turn, and vertical speed.

I encourage pilots transitioning to a glass cockpit to concentrate on flying a specific attitude - just the opposite of what you might have learned to do in an older plane with a crappy, unreliable, vacuum-driven attitude indicator. Glass panel aircraft have very precise attitude indicators and with a little experimentation, you can derive a set of pitch attitudes and power settings that will give you the cruise, climb, or descent performance you want.

For example, when flying straight and level at a cruise power setting in a Cessna with a G1000, keep the yellow triangle and pitch bars right on the horizon.

At a slow cruise setting use for holding or approaches, set the power for the lower airspeed, then adjust the pitch so the yellow triangle is about 2˚ to 3˚ above the horizon.

To climb, pitch up about 8˚ and set climb power. You can fine tune the pitch attitude to get the speed tape to stabilize on your desired cruise speed.

During descent, set your descent power, then adjust the pitch attitude so the yellow triangle is no more than a 2˚ or 3˚ pitch down. If your airspeed is too high, remove some power. If the airspeed is too low, add some power. If you're descending on an instrument approach and there is descent angle listed, pitch for that angle on the attitude indicator.

A strategy for deriving the baseline power settings is to let the autopilot fly the plane straight and level, or in a foot-per-minute climb or descent, then notice what power settings and pitch attitudes give you the desired performance. Remember that these baseline pitch and power settings are a starting point, not absolute values set in stone. Adjust the settings to account for changes in density altitude and how heavily or lightly you have loaded the plane.

Baseline pitch attitudes and power settings will help you be less of a slave to the twitchy numbers on the tape displays. Changing your habit to focus on the attitude indicator in a glass panel aircraft may take some time, but results should be rewarding. Try it. I think you'll like it.

Monday, June 19, 2006

Broken Glass

I've had the opportunity to watch numerous pilots with significant experience flying aircraft equipped with steam gauges (individual, round dials) transition to flying a glass cockpit. For some pilots, the transition goes pretty smoothly. For others, the transition can be tiring and a bit mind-numbing. The more experience a pilot has with steam gauge instruments, the longer the transition seems to take.

Pilots who have experience working with a variety of computer applications or prior experience with GPS units seem to have less trouble with the glass cockpit's button pushing and knob twisting. If you have eschewed computers and most things technical, you're going to have a steeper learning curve in a glass cockpit. But even if you are adept at pushing buttons and turning knobs, scanning and interpreting a glass panel can still be tough to learn.

Regardless of whether your aircraft has steam-gauges or glass, flying by reference to instruments involves the same steps.

Scan the instruments and cross-reference the indications.

Interpret the instrument indications.

Control the aircraft based on the instrument indications.

Here's a steam gauge panel with the standard six pack layout and one of several suggested scan patterns.

When flying a glass panel, the airspeed, attitude, altitude, and vertical speed are basically in the same locations as a steam gauge six pack: Airspeed in the left, attitude in the top center, heading in the bottom center, altitude on the right, vertical speed also on the right.

The power instruments (tachometer & manifold pressure) are usually not shown on the primary flight display (PFD), but on the multi-function display (MFD) to the right of the PFD. And the familiar turn coordinator is missing. Slip/skid information is shown as a two-piece triangle in the pointer at the top of the attitude indicator. Rate of turn is shown on the heading indicator as a magenta trend bar. This is unfortunate because while rate of turn and coordination are next to each other in a conventional turn coordinator, they are separated by quite a bit of space in a G1000 PFD. I think it's the lack of a separate turn coordinator is what throws many experienced pilots, and for good reason.

To my mind, the glass cockpit can be initially harder to fly and will remain hard to fly unless you fly it regularly for a while. First of all, many older GA planes have attitude indicators that are just plain crude. The old style steam gauge attitude indicators (AI) may show a slight turn when the turn coordinator is showing wings level. They also have a tendency to give slightly inaccurate readings when rolling out of a turn or when leveling out from a climb or descent. So it's understandable that pilots (perhaps unconsciously) do not completely trust the AI and learn to cross-reference the AI indications with the altimeter and turn coordinator.

The second reason that glass panels are harder to fly stems from the unreliability of vacuum-driven gyro instruments and vacuum pumps and the way pilots are trained to fly in steam gauge aircraft. Since the gyro instruments and vacuum pumps aren't terribly reliable, the FAA requires instrument rating candidates to show proficiency flying partial panel - with the heading indicator and AI covered up. Many instrument instructors, myself included, begin to cover up the AI early in a pilot's instrument training so they are forced to rely on the turn coordinator and altimeter to keep the aircraft straight and level. So here's what many pilots unconsciously see when they fly a steam gauge panel in instrument flight. Okay, maybe most pilots still look at the heading indicator, but you get my drift.

The FAA describes two basic methods of instrument flying: Primary/Supporting and Control/Performance. The primary/supporting approach is the one most often taught in small aircraft, for reasons I'll discuss below. The primary/supporting approach teaches you that in any given flight regime there is just one primary instrument each for pitch, bank, and power. And guess what? Most of time, the attitude indicator is not a primary instrument for pitch or bank. The only time the attitude indicator is a primary instrument is when establishing a climb, a descent, or a turn.

The Control/Performance approach was historically seldom taught in small aircraft because, quoting the FAA's Instrument Flying Handbook, it requires instruments that "... display immediate attitude and power indications and are calibrated to permit attitude and power adjustments in precise amounts" The crappy vacuum instruments in most older GA aircraft just don't meet these requirements, but the sensitive AHARS (attitude, heading, and reference system) in glass panel aircraft most certainly do fit the bill.

Pilots with significant steam gauge experience often try to fly a glass cockpit by responding to changes in the various tape displays, but these number displays (airspeed, altitude, vertical speed) tend to fluctuate regardless of how smoothly you fly. Trying to pay attention to the endless stream of numbers is like trying to follow the plot of a movie with a chatty friend babbling endlessly in your ear.

So if the constantly changing numbers on the various tape displays, the dazzling array of colors, are a distraction, how are you supposed to fly a glass panel aircraft? I'll talk about some glass panel flying strategies in the next installment.

Saturday, June 17, 2006

What Color is Your Parachute?

Saturday. Beautiful, warm, VFR weather. Father's Day. This is just the combination to strike fear into the heart of a flight instructor. Why? Because everyone and their dog will be flying and with an instrument student under the hood, the only thing between you and a mid-air or near miss is your two eyes. So what's a flight instructor to do? Go flying, keep your eyes peeled, hope you get to fly a plane with TIS (Traffic Information Service), and that you'll be flying in an area where TIS is provided. The other thing I did today was to suggest to my student that we practice holding pattern entries at a fairly high altitude over an out-of-the-way VOR near the coastline.

The holding went well and we were also lucky enough to get traffic advisories from Oakland Center. In fact, the controller seemed to be in a particularly friendly and helpful mood, in spite of the number of aircraft requesting services. I told him that we were finished holding and wanted to go to Petaluma. He told us to squawk VFR and frequency change was approved, then added that there were numerous targets heading into and out of Petaluma and to use caution. And he was right.

Petaluma is a non-towered airport - there is no control tower. Some pilots refer to this as an "uncontrolled field," a misnomer that belies a basic misunderstanding of a pilot's rights and responsibilities. There is control at non-towered airport - each pilot using the airport is to adhere to the procedures described in AC90-66A Recommended Standards Traffic Patterns for Aeronautical Operations at Airports without Operating Control Towers and the recommendations in the Aeronautical Information Manual. While there's no air traffic controller telling people what to do at these airports, each pilot is supposed to use self control and follow the rules. Here are some highlights from these two sources.
Turn on landing and anti-collision lights to make your aircraft easier to see.

If your aircraft has a radio, self-announce your position and intentions over the Common Traffic Advisory Frequency (CTAF) on Unicom.

Remember that not all aircraft have radios at non-towered fields so be vigilant for traffic and adhere to basic right-of-way rules. Use caution for possible ultralight, glider, balloon, and parachute operations.

While straight-in approaches are not prohibited, it is preferable to do a 45˚ entry to the midpoint on the downwind leg.

Piston aircraft should use 1000' AGL traffic pattern altitudes, turbine aircraft should use 1500' AGL, or the altitudes specified for the airport in the Airport/Facilities Directory.

Report 10 miles from the airport, giving your aircraft type, the last three digits/characters of your tail number, positions relative to the airport, altitude, and intentions. Give similar reports at 5 miles out, entering downwind, turning base, turning final, and exiting the runway.

Fly a standard traffic pattern or the traffic pattern established for the airport (found in the Airport/Facility Directory).

Combine these conventions with basic right-of-way rules, plus a dash of common sense and operations at a non-towered field should remain under control. Alas, this is not always the case. Just as in the world of automobile driving, the flying world has its share of pilots who don't know or don't remember the rules, or they simply don't want to bother to follow them.

In addition to the usual confusion caused by a lot of air traffic, today several pilots at Petaluma were using an unapproved radio technique I find ineffective, confusing, and just stupid. Instead of just identifying themselves with their aircraft's manufacturer or type and the last 3 characters/digits of their tail number, like "Piper 33 Xray," virtually all of the aircraft were saying things like "Blue on White Warrior."

Hello? Virtually all GA aircraft are some color or another on white. In fact there were so many "blue on white" aircraft self-announcing their positions today, that everyone was getting confused. Several pilots were referring to their position using local landmarks that out-of-towners were unlikely to know - another unapproved radio technique. And the reason there was so much traffic? There was some sort of fly-in, though I never found out what it was.

As we approached, I thought about a instigating a subtle parody of these other pilots by identifying us as "crimson on white Tobago," but decided to stick with the textbook procedure. We maneuvered for a 45˚ entry about 3 miles out, managed to get on downwind with little conflict, and someone holding short of the runway asked if we could extend our downwind to allow a couple of departures. "Sure can" was our response because it pays to be polite. But not everyone was polite. One pilot, who sounded old enough to know better, began shouting at other aircraft, then blurted out "Goddamn it!" Nice, very nice. We got some fuel and got out of there fast.

Please, please, don't use the "white Cherokee, turning final" style phraseology at non-towered airports. It's not sanctioned, it's confusing, it dumb, and it's potentially dangerous. Use the last three digits/characters of your tail number preceded by your aircraft model or manufacturer and include your altitude with your location, just like you would when talking to ATC. And if you have a chance to do something courteous or help someone out at a non-towered airport, why not do so? Set a good example. We have enough bad examples out there.

Heading out of Oakland today and then heading back in, I saw something that I've seen several times in the last two weeks in TIS-equipped aircraft: An aircraft target with no altitude reported, just north of the Mormon Temple (about 6nm from the Oakland VORTAC on the 355 radial). A few days ago, the TIS in a plane I was flying barked out "Traffic! Traffic!" as we passed. I was looking high and low, but saw nothing.

Today, I got the urge to ask the Oakland Tower controller if he was painting a target in that location with no altitude tag. He kindly explained that this was some sort of phony datum target used by Norcal to calibrate their radar. I thanked him and mentioned that it makes TIS give traffic alerts, but he assured me it was not for real. I wonder, does Norcal have any idea what a pain in the fundament this phony target is for pilots of TIS-equipped aircraft? At the very least, they should inform us that it's there.

Friday, June 16, 2006

Your Call is Important to Us

Being a professional flight instructor can sometimes make one feel like Rodney Dangerfield ("I get no respect!"). One area where this is most obvious can be interactions with ATC. While many, many controllers are helpful with the oddball requests that instrument instruction can generate, others are not so understanding. In their defense, flight instruction results in unexpected requests and non-professional pilots may have non-professional radio technique. Scheduled operations are more predictable, pre-filed, and staffed by skilled and experienced pilots. Still there are times when ATC seems, well, grumpy.

me: Oakland Center, Skyhawk 12345, 2000, climbing 3500, missed approach at Petaluma, direct Point Reyes

OC: 345, radar contact 4 miles northwest of Petaluma, say intentions

me: 345 requests vectors for the Santa Rosa ILS 32, missed approach, then VFR flight following to Oakland

OC: 345, I'm too busy for multiple approaches, say request

me: 345 requests the Santa Rosa ILS 32

OC: 345, I'm unable multiple approaches, say request

me: Ah, I'm confused, we're only asking for one approach, the Santa Rosa ILS 32, 345

OC: 345, I'm unable multiple approaches, so it will have to be a full stop landing

me: Request the Santa Rosa ILS 32, full stop

OC: Fly the Point Reyes transition and report established ...

The really strange thing about this was that we continued to monitor the frequency and heard very little going on. Perhaps controllers are feeling resentful that the FAA has (as is allowed by current laws) foisted a new contract on them after months of unsuccessful bargaining. Since the government can simply dictate the new contract, it's odd that they even bother to bargain. But hey, that's just me ...

We all know where this is heading: Being charged for ATC services. The so-called pay-per-view is already in place in some countries and now it seems that it's making its way, slowly and inexorably, to the U.S. Here's my view of what ATC services will look like, once you apply some old-fashioned American ingenuity to it:

Norcal: Skyhawk 123, radar contact 15 miles east of Oakland, say request.

me: Skyhawk 123 requests an IFR clearance, Oakland ILS 27 Right, information mike

Norcal: Skyhawk 123, how will you be paying today?

me: We'll use our Norcal/Macy's credit card, Skyhawk 123

Norcal: Skyhawk 123 is cleared to the Oakland Airport via radar vectors to the ILS 27, maintain 3000, squawk 4543

me: Cleared to Oakland via radar vector for the ILS 27, maintain 3000, squawk 4543

Norcal: Skyhawk 123, I see you are a gold member, would you like to upgrade to a platinum account, which offers complimentary altimeter setting and express vectors?

me: Negative, Skyhawk 123.

Norcal: Skyhawk 123 is 3 miles from NAGVY, fly heading 240, maintain 3000 until established, cleared ILS 27 right.

me: 240, 3000 until established, cleared ILS 27 right, Skyhawk 123

Norcal: Skyhawk 123, be advised that you account is overdue so I will only be able to offer you the localizer with no glideslope and the approach lights will be set to low.

me: I sent a check last week!

Norcal: We haven't received it, contact the Oakland tower 118.3, and thanks for using Norcal/Macy's

Sunday, June 11, 2006

LightSpeed Mach1, Five Months Later

Back in December of 2005, I wrote about my then new LightSpeed Mach1 headset. I have now flown several hundred hours with this headset and I have some observations to offer to those considering a new headset.

Overall, I think this headset is excellent for me. The headset is an in-ear, passive noise reduction design that can be used with a variety of ear tips. Initially, I found the blue foam tips to be the best and most comfortable fit. Yet when you wear the headset for a while, the blue foam tips absorb oil from your ears and begin to lose their shape. This reduces the noise blocking ability and, even worse, the ear piece that has the microphone boom, while very light weight, will begin to sag and the mic won't stay put. I found that after two weeks of daily use, I had to replace a pair of the blue tips.

The folks at LightSpeed were very helpful in providing more of the blue ear tips, but they also offer a custom ear mold option. For an additional $140, you can purchase a Sensaphonics custom ear mold kit. Sensaphonics is a well-known name to musicians and stage performers for their line of custom in-ear monitors and sound-dampening ear plugs, but they also provide custom ear products for NASA. The data on the LightSpeed web site claims a significant increase in noise reduction with the custom inserts, which I found appealing. But I also wanted better, longer-lasting support for the boom mic, so I decided to go for it.

After you purchase the Sensaphonics kit from LightSpeed, you'll be referred to an audiologist in your area who will make custom impressions of your ear canals. The audiologist will charge you an additional, separate fee, but I found the cost quite reasonable. I was referred to Musician's Hearing Service and the impression process took only a few minutes. The impressions are sent to Sensaphonics and within a couple of weeks, the custom tips are sent back to the audiologist.

I went back for the fitting appointment last Friday and flew with the custom ear tips for the first time yesterday. After two instructional flights lasting a total of 3.6 hours, I can say without a doubt that this is probably the quietest headset I've ever used. The custom tips extend quite far into your ear and since the ear canal bends, you have to kind of screw the plugs into your ear. It's not hard to do, but it takes a bit of practice. I was curious how comfortable the custom tips would be. I found I forgot I was wearing them. The custom tips definitely provide adequate support for the boom mic and the sound quality is even clearer than with the blue foam tips.

Another concern was that the tight fit of the custom tips would trap air in my ears and cause discomfort during changes in altitude. I didn't really notice any pressure build-up, except during rapid descents. But simply yawning like I normally would to clear my ears during changes in altitude was all I needed to do to equalize the pressure.

This headset has a host of hard-to-beat features: Very light weight, comfortable, cell-phone or MP3 interface, and excellent passive noise reduction. The MP3 & cellphone interfaces does require the use of an internal battery, but I incorrectly reported in my original review of this headset that there was no auto-shutoff feature. I was incorrect. There is an auto-shutoff feature that saves the battery when no external device is connected. The original lapel clip for the cords was a bit fragile, but LightSpeed recognized this early on and now provide a clip with a more sturdy design.

One drawback with the custom tips is that with them installed, the unit no longer fits into the foam cut-outs in the headset carrying case. LightSpeed recognized this shortcoming and has begun offering a leather carrying case. They even offered to provide one to me at no charge.

Is this headset for everyone? Perhaps not. I suspect that some people will find the idea of having something stuck in their ears to be unappealing. Just remember that even the best external, noise-canceling headset will put pressure on your head and around your ears. I find the in-ear design is much more comfortable when flying in hot weather in aircraft that aren't air-conditioned. And for those of us who like to wear a hat to protect their face (or in my case, scalp) from the sun, this headset is perfect. Combine all this with the top-notch customer support for which LightSpeed is known and you have a product that is hard to beat.

Sunday, June 04, 2006

A Minute to Live

On October 19, 2004, about 1937 central daylight time, Corporate Airlines (doing business as American Connection) flight 5966, a BAE Systems BAE-J3201, N875JX, struck trees on final approach and crashed short of runway 36 at Kirksville Regional Airport (IRK), Kirksville, Missouri. The flight was operating under the provisions of 14 Code of Federal Regulations Part 121 as a scheduled passenger flight from Lambert-St. Louis International Airport, in St. Louis, Missouri, to IRK. The captain, first officer, and 11 of the 13 passengers were fatally injured, and 2 passengers received serious injuries. The airplane was destroyed by impact and a postimpact fire. Night instrument meteorological conditions (IMC) prevailed at the time of the accident, and the flight operated on an instrument flight rules flight plan.

Instrument approach procedures all have the same goal: Safely direct the aircraft out of the clouds and into visual conditions so the pilot can land, while not allowing the aircraft to get too close to solid objects. You definitely don't want to run into anything while you're in the clouds, but it's still possible to run into obstructions even after you've reached visual conditions if the visibility is bad or it's night time.

There are two broad categories of instrument approach procedures (or IAPs): Precision and non-precision. The main difference between these categories is that precision approaches provide the pilot(s) with vertical descent guidance to a decision height (altitude above ground level) at a point very close to the runway. Non-precision approaches require the pilot(s) to determine their current position relative to the runway and descend to specific altitudes based on that position. There may be several step-down fixes in a non-precision approach before the pilot(s) can descend to the minimum descent altitude (MDA). Once at the MDA, the pilot(s) are not allowed to descend any lower until the required visual cues defined in 14 CFR 91.175 are present. Flown properly, all instrument approaches should provide adequate obstruction clearance, but precision approaches are statistically 5 times safer than non-precision approaches.

There are two schools of thought about how to descend to the MDA when flying a non-precision instrument approach procedure. One way is, once you have reached the point where you can descend to the MDA, to do so as quickly as possible in hopes of visually acquiring the runway environment early. The other school of thought is to fly a stabilized descent that will get you to the MDA a mile or so before the missed approach point. The crew of Flight 5966 descended at a rate of 1200 feet per minute and here's what the descent profile looked like.

Note that even with a ground speed of 160 knots, the approach chart shows a recommended descent speed of just 965 feet per minute.

I'm not a big fan of teaching instrument students to dive for the MDA and the argument that an aggressive descent might get you into visual conditions seems to have a hollow ring. I'd need to be pretty motivated (have some sort of emergency or urgent situation) to pin all my hopes on a non-precision approach with very low visibility or cloud ceiling. Fly a stabilized descent, reach the MDA a mile or so prior to the missed approach point. If you don't see anything, fly the missed approach procedure and go to your alternate or try to find a precision approach nearby.

When descending on a non-precision approach, I don't want to descend so slowly that I don't get down in time to have a chance of reaching visual conditions and landing. This is where the Jeppesen approach charts have an advantage - they list the recommended descent rate while the FAA charts require you to look up the descent rate in a separate table. If the descent angle is a standard 3˚, you can approximate a stabilized descent rate by multiplying your groundspeed in knots by 5. For example, a ground speed of 110 knots would require a 550 foot per minute descent rate for a 3˚ descent.

My rule is to never let the vertical descent rate in feet per minute be greater than the aircraft's height in feet above the ground. AC 120-71A Standard Operating Procedures for Flight Deck Crewmembers also recommends a maximum descent rate of 1000 feet per minute when at or below 1000 feet AGL. If I'm descending from 2500 feet to 500 feet above ground level (AGL), I may start with a descent rate of 750 or 1000 feet per minute. Once I pass 1000 feet AGL, an unarrested descent rate of 1000 feet per minute gives me just 1 minute before I would hit the ground. At 1000' AGL I'd start slowing the vertical descent rate. I've found that uttering the phrase "A minute to live" works wonders with instrument students who tend to descend aggressively. For GA pilots operating under Part 91, I recommend choosing a stabilized descent rate and maintaining a consistent airspeed or, if you have DME or GPS, a consistent ground speed.

Someday there will be precision approaches everywhere. Until then, make sure you give yourself more than a minute to live when descending inside the final approach fix on a non-precision instrument approach.