If your mechanic seems over-cautious and self-protective in his approach to maintaining your airplane, he has good reason.
Click here for the full story.
Recently, I attended a two-day, FAA-sponsored, aviation maintenance symposium in Southern California, along with a few thousand other A&P mechanics
who were there to renew their Inspection Authorizations. The symposium featured many informative presentations by experts in many different facets of aircraft maintenance. One that I found
particularly fascinating -- and also frightening -- was a session about mechanic's liability given by two exceptional aviation trial lawyers, Stuart R. Fraenkel and Douglas C. Griffith.
Fraenkel is a founding partner of the Los Angeles office of Kreindler & Kreindler LLP, the largest U.S. aviation law firm representing plaintiffs.
He is a maintenance expert, a Marine Corps veteran who served as a crew chief on CH-46 Sea Knight helicopters and A-4 Skyhawk jets, who now makes his living representing plaintiffs in air crash and
other aviation litigation, including lawsuits against maintenance shops and mechanics.
Griffith holds a degree in aerospace engineering as well as a law degree. He served as a Marine combat pilot who flew AH-1W SuperCobra attack
helicopters in Operation Desert Storm and received the Distinguished Flying Cross, several Air Medals and the Navy Commendation Medal. After leaving active duty, he worked for eight years at large law
firms defending airlines, aircraft and component manufacturers, maintenance facilities, pilots and mechanics (against plaintiff lawyers like Fraenkel). Griffith is now in private practice specializing
in aviation defense work.
Here were two formidable hired guns -- one dressed in black, the other in white. I just knew this was going to be interesting! Here are some highlights (or lowlights, depending on your frame of
reference) of what they talked about.
Mechanics and repair stations that perform improper maintenance have always been subject to FAA certificate actions (suspension or revocation), civil penalties (fines) and lesser administrative
sanctions (warning notices, letters of correction, remedial training, etc.). But during the 1960s and 1970s -- the heyday of piston general aviation (GA) -- such enforcement actions against GA
mechanics were exceedingly rare. That's no longer the case.
In 1978 the FAA amended its maintenance regulations (14 CFR Part 43) by adding a new rule (§43.12) making it a violation for any person or firm to "... make, or cause to be made, any fraudulent or intentionally false entry in any
record or report this is required to be made, kept, or used to show compliance with any requirement under this part [of the FARs]."
Back in the 1980s, the agency had taken steps to soften its traditional bad-boy image, billing itself as "a kinder, gentler FAA that's here to help you." An important element of that facelift was a
de-emphasis on enforcement actions. However, all that changed in the wake of the May 1996 crash of ValuJet Flight 592 and the congressional investigations that followed. By the end of 1996, both FAA
Administrator David Hinson and DOT Secretary Federico Peña found themselves unemployed, and under new management the FAA added hundreds of additional maintenance inspectors and issued orders to
its field offices to start counting noses and kicking asses.
The word went out to the FSDOs loud and clear: No more Mr. Nice Guy. No more singing Kumbaya with certificate holders around the campfire. The unofficial FAA slogan became "we're not happy until
you're not happy," and §43.12 became a key weapon in the FAA's new war against rogue mechanics and maintenance facilities.
In plain English, §43.12 makes it a violation for a mechanic or repair station to "pencil whip" a logbook entry, maintenance release, yellow tag, etc. (Believe it or not, there was no explicit
regulation prohibiting this prior to 1978!) So if a mechanic or shop makes a logbook entry stating that some airworthiness directive or service bulletin was complied with or that some other work or
inspection was performed in accordance with manufacturer's instructions, and if the FAA discovers that the work wasn't actually done as documented, the mechanic or shop is toast.
The penalties for violating §43.12 are extraordinarily severe. An individual mechanic accused of violating it almost certainly faces revocation of all his FAA certificates and will likely be
looking for a new career. A repair station can face daunting fines up to $250,000 per violation and/or revocation of its repair station certificate.
How To Avoid Them
That said, it's not all that difficult for an honest and reasonably conscientious mechanic to keep his nose clean and avoid getting in trouble with the FAA. The regulations that govern GA mechanics
(Part 43) are vastly more concise and understandable than the ones that govern GA pilots and aircraft owners (Parts 91 and 135). In fact, Part 43 contains a grand total of 13 rules ... that's it! And
those rules are remarkably straightforward.
Reduced to their bare essentials, those rules simply require that a mechanic:
- Do all work "by the book" in accordance with manufacturer's instructions or FAA guidance;
- Use the proper tools in accordance with manufacturer's recommendations or industry practice;
- Do all work in such a fashion that the aircraft is safe to fly, conforms to its type design and complies with all applicable ADs and airworthiness requirements;
- Accurately record and sign off all his work in the aircraft maintenance records; and
- Get supervision whenever he does work that he's never done before.
Pretty commonsense stuff, isn't it? A mechanic who makes a good-faith effort to comply with these few basic rules is very unlikely to find himself in trouble with the FAA.
Unfortunately, a mechanic who follows the FAA's regulations to the letter and is right at the top of his Principal Maintenance Inspector's Christmas card list isn't out of the liability woods ... not
by a long shot. If an aircraft he works on winds up in an accident, the mechanic may easily find himself hauled into court as a defendant in a civil lawsuit, accused of negligence for allegedly
performing improper maintenance and facing ruinous money damages and legal expenses.
A mechanic may be found to be negligent and liable for money damages even if he can prove that his work was in scrupulous compliance with all applicable FAA regulations. That's because most
maintenance-related FARs are considered to be minimum standards. The "prevailing standard of care" in the industry is presumed to higher.
Under tort law, there's no need to show that a mechanic violated a regulation in order to find him negligent. It is only necessary to prove that he "failed to exercise such care as would be reasonably
expected of a prudent person under similar circumstances," either by doing something a prudent mechanic would not do or by failing to do something a prudent mechanic would do. Furthermore, it is not
necessary to prove this "beyond a reasonable doubt," but only by "the preponderance of the evidence" -- in other words, the jury need only be convinced that it's more likely than not that the mechanic
In the context of aircraft maintenance, this "prudent person" standard can be mighty fuzzy. Suppose, for example, the plaintiff attorney representing the widow of an air-crash victim alleges that a
mechanic who worked on the aircraft was negligent because he failed to comply with a mandatory service bulletin. We all know that, under FAA regulations, there is no requirement to comply with
manufacturer's service bulletins (even so-called mandatory ones) for aircraft operated under Part 91, unless the service bulletin is explicitly mandated by an FAA airworthiness directive. In point of
fact, the vast majority of Part 91 operators do not comply with the vast majority of manufacturer's service bulletins.
But can a mechanic be judged to be negligent if he fails to comply with a service bulletin? Would a prudent mechanic have complied with such a service bulletin? What if the mechanic recommended that
the service bulletin be complied with but the aircraft owner declined to authorize the work? How do you suppose a jury of citizens who have no background in aviation, aircraft maintenance or FAA
regulations would decide these questions?
"Mr. Mechanic, when you performed the annual inspection on the airplane operated by Widow Smith's husband, were you aware of Cessna Service Bulletin SEB76-43 calling for the number two frammis at the
distal end of the primary portoflan armature to be replaced with an improved part? Please explain to the jury why you elected to approve the aircraft for return to service without replacing the
frammis, contrary to the manufacturer's published instructions?"
If you're a mechanic, this is the stuff that keeps you awake at night.
The GARA Effect
Back in the salad days of piston GA, civil suits against GA mechanics and shops were relatively rare, simply because few GA mechanics and shops had enough assets to make them worth suing. Aircraft
manufacturers like Cessna had deep pockets and product liability insurance, so they were the primary targets of air-crash litigation. Even if the cause of the crash seemed unrelated to the hardware
(as is usually the case), the aircraft manufacturer would be sued anyway and would often wind up paying substantial settlements rather than incur the huge legal defense costs of going to trial.
Things changed dramatically on August 17, 1994, when President Clinton signed into law the General Aviation Revitalization Act of 1994 (GARA), which immunized GA aircraft manufacturers against product
liability for aircraft older than 18 years. The GARA immunity is extremely broad and protects the manufacturer from being sued even if an aircraft is proven to have design defects that caused a crash
and resulted in injuries or death.
There are a few exclusions from GARA's immunity. Aircraft with 20 or more seats and aircraft engaged in scheduled passenger-carrying operations are exempt. The immunity does not apply to injury or
death of medevac patients or persons not on board the aircraft. Nor does it apply if it can be proven that the manufacturer intentionally concealed or withheld information about a known design defect.
But for the overwhelming majority of piston GA aircraft flying today, GARA provides the manufacturer with bulletproof immunity against air-crash lawsuits.
At first glance, GARA sounds like a Good Thing (unless you happen to be an air-crash victim or aviation plaintiff attorney). In the pre-GARA era, the GA manufacturers spent hundreds of millions of
dollars defending themselves against bogus air-crash lawsuits and that burden was passed on to aircraft owners in the form of higher aircraft and parts prices. Common sense suggests that if an
aircraft has managed to fly accident-free for more than 18 years, it seems fair and reasonable to take the manufacturer off the hook. Congress obviously thought so when it passed GARA more than a
The rub is that taking the aircraft manufacturers off the hook in most piston GA air-crash lawsuits didn't make those lawsuits go away. It simply increased the liability burden for everyone else
involved with the accident aircraft, including engine and component manufacturers, aircraft owners and operators, and especially mechanics and maintenance facilities. In the wake of GARA, there
has been an explosion of civil suits against maintenance folks.
Just as with manufacturers, maintainers are now frequently getting sued over air crashes that were almost certainly caused by pilot error rather than improper maintenance (as most crashes are). But
the maintainer or his insurance company must still bear the financial burden of defending the suit and must still face the real possibility that a skillful plaintiff's attorney will convince the jury
to find the maintainer at least partially liable for the crash.
This litigation explosion has created a nasty second-order problem: Liability insurance for mechanics and shops has become extraordinarily difficult to obtain in recent years. Many underwriters have
abandoned the maintenance market, leaving maintainers with few market choices and little competitive pressure to keep premiums affordable. As a result, many shops and most individual mechanics are
forced to "go bare" and those lucky enough to be able to find insurance often pay exorbitant premiums for unrealistically low coverage limits.
To illustrate this risk, Fraenkel and Griffith offer the following nightmare scenario which, while obviously hypothetical, is undoubtedly derived from a composite of actual air-crash cases:
Peter Pilot of Charlie's Charter Service is flying passengers in a 1980 Cessna T210 on leaseback from Oscar Owner and maintained by Mike Mechanic of Aircraft Repair Corp. During
approach in IMC conditions and while being given extensive vectoring from ATC, Peter Pilot is twice observed deviating from assigned altitude and heading and has to be given corrections. Shortly after
the second correction, the Cessna enters into a spin and crashes, killing all on board. Witnesses report to the NTSB investigator that they heard the engine sputter.
NTSB investigators determine that Peter Pilot's medical expired a month before the crash. The toxicology report showed the presence of antihistamine medication in Peter Pilot's blood. The Cessna's
tail section is located approximately 100 yards from the main wreckage. Mike Mechanic of Aircraft Repair Corp. had overhauled the airplane's TCM TSIO-520 engine 10 hours prior to the accident but --
at the direction of Oscar Owner -- did not comply with a TCM mandatory service bulletin.
18 months after the accident, the NTSB releases its probable cause determination: Peter Pilot became disoriented under IMC and lost control of the aircraft. A contributing factor was Mr. Pilot's use
of an over-the-counter cold medication.
The families of the dead passengers file a civil suit. Defendants include the estate of Peter Pilot, Charlie's Charter Service, Mike Mechanic, Aircraft Repair Corp., Oscar Owner, Cessna Aircraft
Company and the United States government (who provided ATC services). In pre-trial motions, the judge dismisses the suit as to defendants Cessna (because of GARA) and the United States government
(because the air traffic controller's actions were deemed to be immunized under the "Discretionary Function" exception to the Federal Tort Claims Act).
The plaintiffs demand a jury trial. By law, the NTSB investigation findings and probable cause determination are inadmissible at trial, so the jury never hears about them.
The end result of the trial is a judgment for the plaintiffs in the amount of $10 million. The jury allocates fault as follows: 10% to Peter Pilot and his employer Charlie's Charter Service; 10% to
Mike Mechanic and his employer Aircraft Repair Corp.; and 80% to Oscar Owner.
That does not mean that Mike Mechanic and Aircraft Repair Corp. are responsible for only $1 million, however. State law provides for "joint and several liability" for economic damages, which means
that all five of the defendants are equally liable to the plaintiffs to satisfy the entire amount of the $10 million judgment. Conceivably, the plaintiffs could come after Mike Mechanic for the entire
$10 million and leave it up to him to go after the other defendants for their share.
Is it any wonder that so many A&Ps seem over-cautious and self-protective in their approach to maintenance these days? (Is it paranoia if space aliens really are after you?)
The A&P's Dilemma
In the good ol' days before GARA, an A&P's maintenance decisions were guided by two principal concerns: (1) Is it safe? (2) Does it comply with FAA regulations? Those are precisely the two
considerations a mechanic should be concerned about.
But in today's post-GARA world, the prudent A&P is now forced to worry about a third concern: (3) How will it appear to a civil jury that knows nothing about aviation after being spun in the worst
possible light by a skilled plaintiff's attorney? That is a very different standard indeed and has had a tremendous chilling effect on A&P maintenance decision-making.
Consider the following situation: An owner brings his Cessna 310 to an A&P mechanic complaining of nosewheel shimmy. The mechanic investigates and discovers that the cause of the shimmy is that the
bolt holes in the upper torque-link attach-lugs in the nose gear trunnion are worn, elliptical and sloppy. The mechanic must now decide how to correct this problem.
The mechanic finds that a new NLG trunnion (p/n 5842000-211) costs $3,151 from Cessna. He locates a used, serviceable trunnion from a salvage yard costing less than half that amount. In either case,
the mechanic estimates that replacing the trunnion will require about $1,000 in labor.
The mechanic also considers the possibility of repairing the existing trunnion by reaming the worn attach-lug holes oversize and installing a couple of NAS bushings to restore the bolt holes to their
original dimension. Although Cessna has not explicitly approved such a repair, the mechanic believes that it would functionally restore the trunnion to good-as-new condition, and would be a minor
alteration that conforms to acceptable industry practices. The cost of such a repair would be $15 for the bushings plus $150 in labor.
The mechanic considers all of these repair options safe and legal. But he worries what might happen should the customer's airplane ever be involved in a nose-gear collapse accident and the mechanic
finds himself as a defendant in a civil lawsuit -- perhaps a subrogation action by the aircraft owner's insurance company against the mechanic and his shop.
If the A&P repairs the existing nose strut with bushings, a plaintiff's attorney might well ask him to explain to the jury why he made a repair that was not authorized by the manufacturer. If he
replaces the damaged trunnion with a serviceable one from a salvage yard, a plaintiff's attorney might well ask him to explain to the jury why he decided to install "an undocumented part from a
junkyard" instead of a proper Cessna part with an FAA Form 8130-3 attesting to its airworthiness.
After due consideration, the A&P decides that his safest course of action is to install a new, documented trunnion from Cessna. The aircraft owner winds up paying $4,151 rather than $165, and is a
mighty unhappy camper. The owner quietly vows never to patronize the A&P's shop again. This is not a good outcome for either the A&P or the owner.
A&Ps are faced with such decisions all the time: What to do about an engine that is past TBO that the owner wants to continue in service because it's running fine and not making metal? How to deal
with a costly service bulletin that the owner doesn't want to comply with? The A&P believes that keeping the engine in service or ignoring the SB is both safe and legal, but is understandably worried
that such actions might not appear reasonable and prudent at trial before a jury of aviation-challenged citizens.
A Possible Solution
During their presentation, Fraenkel and Griffith suggested an approach that mechanics and shops might use to deal with this difficult dilemma: The maintainer should shift the decision-making burden to
the aircraft owner (where it belongs) and document the owner's decision to make it clear who it was that made the decision.
For example, the mechanic could record something like this: "On April 17, 2007, I advised the aircraft owner of Cessna Service Bulletin SEB76-43, which calls for the number two frammis at the distal
end of the primary portoflan armature to be replaced with an improved part. The aircraft is operated under Part 91 and therefore service bulletin compliance is not required by regulation. After a
thorough discussion of the technical and regulatory aspects of this service bulletin, the aircraft owner decided that he did not want this work to be performed, and instructed me not to do it."
According to Fraenkel and Griffith, a contemporaneous written record like this, signed by the mechanic, would go a long way toward convincing a jury that the mechanic was not negligent in failing to
comply with the service bulletin.
Many A&Ps might be inclined to record such information in the aircraft's maintenance records. However, a knowlegeable aircraft owner would find such a logbook entry objectionable, and rightfully so.
FAR §43.9 requires that
a mechanic's maintenance record entry contain "a description of the work performed." A logbook entry describing work not performed is neither required by regulation nor appropriate.
A much better way for an A&P to handle this is to document such things in a letter to the aircraft owner. The letter should be signed and dated by the A&P and countersigned by the owner acknowledging
receipt and agreement. The A&P should give a copy of the signed letter to the aircraft owner and retain the original for his records. This procedure will protect the A&P without creating problems for
the aircraft owner.
This approach is hardly a universal solution to the problem of mechanic's liability and the chilling effect it has on maintenance decision-making. Unless he is blessed with 20-20 foresight, it's not
easy for a mechanic to document every possible decision that might subsequently be used as a basis for an allegation of negligence.
Also, many aircraft owners just don't want to get involved in the messy details of maintenance decision-making. They expect the aviation maintenance professionals they hire to make maintenance
decisions on their behalf. Such an owner may feel alienated if their mechanic hands them a "CYA letter" placing the burden back on him.
Such an attitude is fine, so long as the owner understands that today's savvy maintenance professionals, if left to their own devices, will usually make decisions that minimize their exposure to civil
liability. Such decisions often are very costly to the aircraft owner. An owner who is concerned about controlling his maintenance costs will need to get involved in the decision-making process, and
to be willing to accept responsibility for those decisions.
See you next month.
Microsoft Flight Simulator X is one of the most powerful PC simulators available, and practicing GPS approaches with FSX is a great way to prepare for (and decrease expense in)
flight in a real plane.
Click here to read this chapter.
[Editor's Note: Recently two flight instructors wrote a book on how to use Microsoft Flight Simulator X (FSX) to enhance
pilot training and to provide sim-only pilots a guide to making their flying more realistic. AVweb is reprinting several chapters from this book, the first of which was Chapter 13 -- Weather. To download the FSX files they refer to here, visit the publisher's Web site and click on Downloads.]
No Ground Station Needed
All the approaches you saw in [Chapter 17 in the book] used a signal from a ground-based transmitter. You've already seen how GPS provides for greater accuracy than most VORs, so why not use it for
approaches? You can use a GPS for approaches, but the process is a little more complicated because you must load the approaches into the active flight plan of the GPS. Lucky for you, the
approaches are kept in the GPS database, so it's pretty easy to get and use them after you know how the system works.
You can worry about how to load and activate GPS approaches while flying the airplane a little bit later in this chapter [Ed.: To be published next month], but you need to review a couple quirks of
the GPS approach plate first.
A Basic GPS Approach
The GPS Rwy 23 at Shelton, Wash., (KSHN) is about as simple a GPS approach as you can get (see Figure 18-1). The initial approach fix (IAF) is OYRED. There is no frequency to tune because the location
of OYRED is determined entirely by GPS. OYRED is referred to as a waypoint and is the IAF for this approach. The final approach fix (FAF) is also a waypoint. In this case, it's PORSY. If you
were receiving vectors to this approach, you would be vectored to intercept the line between OYRED and PORSY at 2,000 feet and be cleared for the approach. After crossing PORSY, you would descend to
860 feet and look for the runway.
The missed approach point (MAP) on a GPS approach is also a waypoint. Usually, this waypoint is at the threshold of the runway and is named for the runway. In this case, that's RW23. So, there is no
timing of the GPS approach. Either you see the runway and land before reaching the MAP, or you fly the missed approach.
The GPS provides guidance through the missed approach as well. In this case, it takes you to a waypoint called CARRO. That waypoint happens to be over an NDB with the same name, but you can use your
GPS to get you there rather than relying on the less-accurate ADF. (See "GPS for DME and ADF" at right.)
You see a big holding pattern at OYRED. This holding pattern is for course reversal if you are not getting radar vectors for the approach. Note that it is not a procedure turn and, therefore, must be
flown as a holding pattern. The procedure would be to cross OYRED and fly either a direct entry or a parallel entry as needed. When you returned to OYRED, you would be lined up with the final approach
course and could continue on to PORSY and fly the approach. These "holding patterns in lieu of procedure turns" (HILPT) are standard fare for GPS approaches.
As you saw in Chapter 11 [about the Garmin G1000 panel], you can enter VOR stations into your GPS, and the GPS treats them like waypoints. You can't use a GPS for VOR approaches willy-nilly, however.
The approach must say "GPS" somewhere in the title for you to have the privilege of using it. You must also be able to retrieve the approach from the GPS database. The VOR approaches at KPAE and KPUW
must be flown with a VOR as your primary navigation source. That doesn't mean you can't use your GPS to help verify that you're in the right place and give you a bird's-eye view on a moving map. But
you can't fly the approach using the GPS.
Other approaches give you the option, such as the VOR or GPS Rwy 6 at Hoquiam, Wash., (KHQM) shown in Figure 18-2. Note that because this approach is really a VOR approach that has simply been
approved to fly with GPS, it does not show the traditional waypoints you expect for a GPS approach. It shows the VOR and DME information instead.
There is still an advantage of flying this approach with GPS. The approach has two sets of minima. The lower one of 620 feet requires that you can identify four DME from HQM. Without DME on board the
aircraft, the lowest you could go is 740 feet. GPS can substitute for DME, however, and D 4.0 should appear as a waypoint when you fly the approach using GPS. The VOR approach requires timing or DME
to identify the MAP. The GPS version shows RW06 just like any other GPS approach.
Note: Watch the Notes
The notes for the VOR or GPS Rwy 6 state that the approach is not authorized without a local altimeter setting. It's possible you could get all the way to KHQM and have ATC tell you the ASOS
transmitter on the field is busted. Neither you nor they can get the local altimeter, so you can't shoot the approach. Reading notes should be an important step in your pre-approach
Although GPS is one way of determining your position without using any ground-based transmitters, several others exist (although they are mostly used by the military or airlines). The FAA has begun
renaming GPS approaches as area-navigation (RNAV) approaches. Anyone who has equipment that meets the required RNAV accuracy can fly the approach, regardless of how that equipment gets its
position. If it says RNAV in the title, then you can fly it with your GPS -- assuming the approach is in the database, that is.
Take a look at the RNAV Rwy 7 approach to Oak Harbor, Wash., (76S) shown in Figure 18-3. Three possible IAFs are charted for this approach: one at ICILA, one at ORCUS, and one at LUCRI. Notice, too,
that LUCRI is marked (IAF/IF). IF stands for intermediate fix. This is because an approach starting at ICILA or ORCUS will still cross LUCRI.
Note as well that WATTR is not labeled as an IAF and doesn't say NoPT. If you are arriving via WATTR, you must cross LUCRI and then fly once around the holding pattern before crossing LUCRI a second
time and proceeding inbound. That makes the transition from WATTR a true transition route, which you can see by the thinner arrow used to depict it on the approach plate.
Note: Easy Airspace
The approach plate for Oak Harbor shows three kinds of airspace you like to stay out of: MOAs, alert areas, and restricted airspace. A side benefit of IFR is that ATC takes care of keeping you out of
this airspace if it's hot when you're on vectors. During an approach, however, it's up to you to stay on course and away from places you're not supposed to be.
This is also the place to note the difference between the waypoint stars without circles around them and the waypoint stars with circles around them. Ones without circles are fly-by waypoints.
This means you may begin your turn before you actually cross the waypoint. The only one with a circle is VUCUS, the MAP. VUCUS is a fly-over waypoint. You must completely cross the waypoint
before beginning any turn. MAP waypoints are always fly-over.
The ability to turn early is important on this approach. Imagine you are arriving from ICILA. You have a 90-degree turn to make when you cross LUCRI, and you'll considerably overshoot the segment from
LUCRI to JEKPO. A better choice is to begin your turn a bit before LUCRI and roll out on course to JEKPO. Part of the beauty of flying with GPS is that it looks at your ground speed, anticipates how
much room you need to make this turn, and then tells you to start your turn at just the right moment.
These approaches where IAFs are arranged in a T-shape are common for GPS/RNAV approaches. (See "More GPS Fun: TAAS and APVS" at right.)
Ground-based navigational aids radiate a signal from an antenna. This means the closer you are to the antenna, the more accurate the signal becomes. For example, if you intercept a VOR signal 40 miles
from the station, you see the CDI needle center slowly. Intercept that same VOR signal 5 miles from the station and the needle centers quickly. Intercept a localizer 5 miles from the source, and by
the time you start your turn to intercept, you're already crossing over to the other side of the course.
GPS is different. The sensitivity of the CDI needle is completely arbitrary. A single needle sensitivity won't work for all situations, though. You want sensitivity that isn't too great as you travel
the long distances between airports. A super-sensitive CDI needle would just be annoying. For a GPS approach, you want much greater sensitivity because it's more critical that you're exactly on
Approach-certified GPS units handle this problem by offering three levels of sensitivity and switching between them automatically (see Figure 18-4). During long stretches between airports, the GPS
unit is using en route sensitivity. This means that a full-scale deflection of the CDI needle is 5 miles. If you see a half-scale deflection and the GPS is using en route sensitivity, then
you're 2.5 miles off course.
When the GPS unit senses that the aircraft is within 30 miles of its destination, it smoothly transitions to terminal sensitivity with a full-scale deflection of 1 mile. The transition must
happen smoothly because if it suddenly switched to 1 mile, one moment it would look like you are on course and the next moment the needle could be half deflected or further.
As the GPS comes within 2 miles of the final approach fix on a GPS approach, it ramps down even further to approach sensitivity. At this maximum sensitivity, full-scale CDI deflection is only
0.3 miles, or about 1,800 feet left or right of course.
The FSX GPS does simulate en route and terminal sensitively realistically, but it switches to approach sensitivity the moment you load an approach rather than as you fly the approach. It also cranks
up the sensitivity only on the CDI shown on the GPS map (see "Not Sensitive on the CDI" at right) and not on your HSI needle. We think this is a bug, and we hope it's fixed in a patch.
Using the GPS
We simply can't describe all the features of the GNS 500 here. The GPS article in the FSX Learning Center is a must-read. Note that some of the techniques of the FSX GPS are not quite the same as a
real GNS 500. You'll look at the key features in context as you use them on approaches. Here's a quick orientation, though, to get you started.
The Primary Nav Page
You'll have the primary Nav page up most of the time you fly the GPS. You've been looking at it already if you used the GPS for a moving map in the previous chapter. Figure 18-5 notes the key items on
the GPS screen. In addition, you should note that the primary Nav page is also a track-up page, with the track of the airplane -- your path over the ground -- always oriented to the top of the page.
Key items on the primary Nav page are the name of and bearing to your next waypoint. Note that the bearing also appears in the map view as a green chevron along the compass rose. That compass rose is
also a distance marker. The distance from your airplane to the edge of the rose appears in the left of the map. You control this distance with the range buttons on the upper right of the GPS.
Five fields are shown on the map itself, all of which have a use. Starting in the upper left is Desired Track (DTK). This is the direct route between waypoints when you pressed the Direct-To button or
the desired routes between waypoints on an instrument approach. The latter is more important because the purpose of the approach is to have you follow certain routes over the ground at certain
altitudes. The DTK is also shown on the map as white or magenta lines. The magenta line is the segment you are currently navigating. Hence, the mantra of GPS flying: "Just put the airplane on the
Track (TRK) is the actual magnetic direction your airplane is flying over the ground, including any drift in the wind. Wind might mean that your TRK is different from your heading on the HSI. As an
instrument pilot, the actual heading is irrelevant. What you care about is TRK. If your TRK is the same as the course you're supposed to fly for that segment of the approach, you stay on course
(presuming the CDI needle is centered, that is). Since your DTK is, by definition, the course you want to fly for that segment of the approach, your DTK should equal your TRK anytime you're not
This makes wind correction quite easy: Find a heading that makes your TRK what you want, and then keep flying that heading. What could be simpler?
The final three items going clockwise around the display are distance to the next waypoint (DIS), estimated time en route (ETE) to the next waypoint, and ground speed (GS). The latter two are most
important to you in IFR flying. ETE gives you a sense of how much time you have to slow down or reconfigure if need be before crossing the next waypoint, and ground speed gives you a good sense of the
winds. Ground speed is also handy when shooting an approach that requires timing. You might be flying the approach at 100 knots, but if your ground speed is 90 knots, you use the time for the 90-knot
approach. GPS approaches don't use timing, so that's not an issue there.
You access the secondary Nav page by clicking the inner FMS knob one click to the right. It's similar to the primary page but is north-up rather than track-up and without the extra information. It has
little practical use in flight training on FSX. (See more GPS info in "GPS Table of Contents" at right.)
The Waypoint Pages
Click the outer knob one click to the right and you get to the Waypoint pages (see Figure 18-6). There are quite a few, and you scroll through them with the inner knob. These offer lots of information
about specific airports, frequencies and so on. Since FSX dials frequencies for you automatically, these pages have less use than in a real airplane. The approach page, though, can be handy because it
lets you see all the instruments approaches for the airport.
To select a different approach to see, press the center of the FMS knob to activate the flashing cursor. Use the outer knob to scroll to the approach in question. Now click the inner knob to get a
pop-up menu of all the approaches, and scroll between them. Click Enter to see one in more detail. You can use a similar technique on the airport pages in the Waypoint group to view details for
different runways at a single airport.
The Nearest Pages
Turn the outer knob (without a cursor showing) one more time, and you see the Nearest pages. The most important page in this group is the Nearest Airport page (see Figure 18-7). In an emergency, this
list gives you the bearing and distance to nearby airports and tells you their runway lengths and most accurate approach. You can select any one of these airports, push the Direct-To button, and then
hit Enter to get guidance directly to the airport.
In the real world, we occasionally use the Nearest VOR page when making a pilot report on weather or the Nearest ATC pages when transitioning from VFR to IFR, but these uses really have no corollary
Note: Back To The Map
Anytime you want to get back to the map page, just hold down the CLR button. You can also just click CLR to undo your last button push in many GPS functions.
The Flight Plan Page
Pushing FPL on the GPS opens the flight plan page (see Figure 18-8). Pushing FPL again toggles it off. In the real world, there are often many waypoints here you can edit as you go. In FSX, it shows
whatever you entered in the flight planner. This might be direct between two airports, or it might be a long string of VORs and other fixes between your departure airport and your destination.
The FPL page shows your DTK and DIS to all these waypoints, as well as the cumulative distance remaining (CUM).
Unfortunately, you can't edit your flight plans on this page as you do in the real airplane. You also can't select a waypoint along an instrument approach and head there with the Direct-To button.
This makes the FPL page most useful for seeing the waypoints along an approach, but that's about it.
Note: Too Many Messages
If you're getting too many messages, such as "airspace ahead," click the MSG button three times. OFF should appear at the bottom of the GPS screen; this tells you the message feature is off. We're not
quite sure how to get the messages to come back on, though.
The Direct-To Page
Click the Direct-To button, and you can enter any waypoint and proceed directly to that point (see Figure 18-9). You can also select any airport or nav aid from the Waypoint or Nearest page and press
Direct-To to see that waypoint come up as the selected destination. Unlike the real GNS 500, going directly to a waypoint replaces the current flight plan with a new flight plan containing only the
There are other buttons, such as PROC, but you'll look at these in context as you fly some approaches.
[Editor's Note: Next month, AVweb will reprint Part 2 of Chapter 18, which includes GPS flights in the Mooney Bravo with both a six-pack instrument panel and a Garmin G1000 panel.]
To download the FSX files referred to in this chapter, visit the publisher's Web
site and click on Downloads.
AVweb will publish several chapters from Microsoft Flight Simuator X for Pilots. If you want to read the whole book, you can purchase it from the AVweb Bookstore.
To send a note to the authors about this story, please click on their names at the top of this page or click here.