all other approaches

Non-precision Approaches
VOR--NDB--GPS--LOC--ASR--LDA--SDF approaches do not have vertical reference other than the altimeter and the direction of the approach may not be aligned with the runway. You will be expected to manoeuvre for the landing. The minimum descent altitude (MDA) may be very near the low IFR altitude of weather. The MDA may be relatively high depending on distance, terrain, and type of approach. You cannot leave the MDA without seeing the runway. Just seeing the ground is NOT enough.

The design limits of the system set the minimums. The approach is named by the navaid and runway at the airport. The navaid may be before, beside, on, or beyond the airports. A margin of error is built into the plate by TERPS (rules for making approaches) but the expectation is that the pilot will fly the procedure perfectly so as to maintain these safety margins. The non-precision approach usually does not parallel the runway centreline; instead the electronic line takes us to the end of the runway at an angle. There is no electronic vertical guidance. A turning manoeuvre is going to be required for landing. The MDA will vary with the terrain, lighting available and system used

A pilot has a choice of doing the approach with vectors or as 'own-nav'. Vectors are easier since ATC usually sets you up with a 30-degree intercept to your inbound course. Your 'own-nav' may require that you reverse your direction of arrival. This means using a procedure turn or a holding pattern to make the turn-around, and begin your descent when established. There are required reports at the fix inbound and when established from the procedure turn.

The chart will have course, altitudes, frequencies and times for you to utilize during the approach. The approach is segmented into three parts:
1. Initial segment gets you lined up for the approach.
2. Intermediate segment usually begins the descent.
3. Final segment gives you a timing point, minimum descent(s), and missed approach point.
4. Missed segment which begins at the missed approach point with a direction, and climb required.

A non-precision approach has four segments; each segment begins at a defined point. The initial approach segments begins at the IAF. At the intermediate approach segment you are established on course and descending. The final approach segment usually has a FAF but not always from which time or DME is used to guide the descent to the MDA. You do not leave the MDA until seeing the runway. The fourth segment is from the missed approach to the missed approach fix. The route and altitudes for each segment are shown in plan and profile views. By flying the published headings and altitudes you are protected from obstacles.

Being "Cleared for the Approach" by ATC means that you can follow the published procedure. By following the publish routes at the published altitudes you are 'guaranteed' not to hit any ground object. That is, providing you have correctly set your altimeter. Historically the 'chop and drop' has been the accepted procedure and could be used in familiar situations. Otherwise, the stabilized approach using the airspeed, time, and descent rate is to be preferred. Descent from the FAF to the MDA have traditionally been of the 'chop and drop' type but today the use of DME makes stabilized descents more common. The VDP (visual descent point) either created or charted makes it possible for the pilot to prepare for a landing for straight in approaches.

The purpose of the non precision approach is not to put you on the runway. Its purpose is to get you down out of the clouds and in sight of the runway. The pilot is expected to navigate to the missed approach point. Only if clear of the clouds will he will be allowed to manoeuvre visually to the runway. MDA are usually below standard pattern altitudes and will require a higher level of manoeuvring skill. Practice your short approaches in better conditions.

If you descend to the MDA and see the runway but not in time to make a normal landing, you must climb to circling minimums before turning. In the turns you are required to keep the airport in sight at all times. You do not descend below circling minimums again until lined up with the visible runway. Non-precision approaches at night should only be flown if there is a VASI. If at first you do not succeed…quit and go to a better place. Most approach accidents occur during the second attempt.

You can use or make a visual descent point (VDP) as a landing aid. TERPs require a VDP for all straight-in non-precision approaches except for procedures with remote altimeter setting, where the descent path is below a required step-down altitude and where it would be between the MAP and runway. No VDP will exist where an obstacle exists. The absence of a VDP serves as an obstacle alert.

The VOR and NDB approaches do not have the options of precision approaches. Only Minimum Decent Altitudes exist. The circle to land minimums have Height Above Airport numbers parenthetically rather than runway numbers. The circle to land altitude and distance is determined by aircraft category speed. For straight-in minimums there are three requirements:
1. Approach aligned within 30-degrees
2. Approach must cross the runway threshold
3. Descent gradient cannot exceed 400 feet per nautical mile.

Non-precision approaches, while less accurate, are easier to fly because the altitudes are mostly level flight with only one needle to follow. On reaching the minimum descent altitude you should have established a personal visual descent point from which a normal straight-in landing can be accomplished. Other wise do not descend below the circling minimums.

Localizer types of non-precision approaches are the localizer, LDA and SDA. Other non precision approaches are the VOR, and the Airport surveillance radar approach (ASR). ASR approaches require a published plate. A given approach may be entered as (1)a straight in approach or (2) as a full approach.

--Once on the approach use power for descent, level and climb
--Work load must not interfere with control.
--Focus only on the turn when turning.
--Consider downwind landing instead of circling.
--Make small power changes even to climb.
--Never bust minimum altitudes.

Descent from the FAF to the MDA have traditionally been of the 'chop and drop' type but today the use of DME makes stabilized descents more common. The VDP (visual descent point) either created or charted makes it possible for the pilot to prepare for a landing for straight in approaches.

Approach Minimums for Non-precision

Circling minimums require a ceiling.
Get down to the MDA well before the airport.
You win by being allowed to make a scud run to the airport.
Nonprecison approaches should be flown precisely.
Level off at the MDA and let person not flying look for airport.

Complex Approach Minimums

Lowest minimums only if:
1. Local altimeter setting
2. Identify 2.5 DME fix
3. Straight in landing

Stepping Up to the Step-Down Approach
The step-down is used to give the non-precision approach lower minimum descent altitudes. The basic non-precision without the step down takes you to the MDA right after the FAF. The step-down requires that you make one or more altitude stops before reaching the MDA. The steps are based upon aircraft category and the altitudes are critical with minimal obstacle clearances.

There are two methods of doing the approach. One is to follow the published procedure and chop-and- drop between each step while maintaining a constant ground speed in the drop and level flight. The other option is to calculate the rate of descent for the entire procedure and initiate that rate of descent at a constant ground speed throughout. The latter procedure will allow you to cross each fix at the proper altitude in a stabilized airspeed approach. 

IFR Go-arounds
Take all the training you need to get rid of any inefficiency or poor techniques. Unless you have begun your landing descent at a valid visual descent point (VDP) with the required visual references you must make a go-around. Primary to any go-around is the immediate application of all available power. You do not have full power unless you take off carburettor heat. Do NOT look into the cockpit. Keep your eyes outside. Hold heading with rudder. Lock your elbow against the door and fly level holding heading. Lose altitude if you must, the aircraft will fly and accelerate better in ground effect. On reaching climb speed as determined by sound or a quick glance. Remove flaps only if necessary for climb. Initiate a climb.

If you do not have the runway at MDA/DH, you may not be where you should be. In this case you cannot afford to lose altitude. Leave the plane in a landing configuration if it is able to climb reasonably well. Practice making full ‘dirty’ go-arounds at altitude. Also practice getting a better climb after you are well into the go-around.

Don’t press a touchdown that is going to be long on a short runway. When there are strong cross winds expect to make your go-around early in the approach when your needles have trouble finding centre.

Go-around Essentials
Flight visibility is the governing factor in Part 91 instrument approaches. The reported ground visibility is a factor only in that the FAA may call your 'flight visibility into question. One way to improve your preparation for the missed is to incorporate your missed approach configuration of gear, flaps, and airspeed into your approach configuration.

The use of an autopilot-coupled approach presents a problem if the missed approach is not also coupled to the autopilot. I have had pilots have real difficulty with the missed because of the transition from autopilot into a hand flown missed.

When things go wrong on an approach the best option, as in other landings, is to go-around as required by the missed approach procedure. This is recognized as a very correct --command decision. The decision is followed by the number one priority of flying the airplane. You do this by applying full power, cleaning up the configuration at a climb attitude.

The decision altitude or minimum descent altitude is the height above touchdown elevation and not the runway threshold. The importance of flying a clean approach is that you will be executing the missed approach in protected airspace. The accident record of missed approaches is that only about five related fatal accidents occur per year. Considering all the missed approaches made this is a very good record.

You are in protected airspace that extends for 15 miles with a 40' to 1' terrain clearance plane, which requires a climb rate of 253 fpm. Do not make any turns until reaching the specified plate altitude. Turning too soon can be just as fatal as turning too late. Breaking off an approach requires that you climb straight to the missed approach and follow the published turn procedure.

If you are flying the circle to land approach, the missed approach procedure requires that you circle back to the runway with the missed approach procedure. You are not obligated to then fly to your alternate. The purpose of the alternate is to advise ATC what to expect if radio failure should occur.

Don't try to hard to succeed on an approach. Pushing your luck and skill is the road to failure. Making the missed approach means that weather was below minimums, not that you were a failure as an instrument pilot.

Failure to initiate the approach in a timely manner statistically kills far more pilots than does the missed. The worst killer is the second approach made because the pilot saw the runway in passing.

Don’t second guess the go-around. Do it!
Use full power
Hold heading and altitude until reaching climb speed and afterwards.
Climb with flaps if you can.
Clean up plane.

Straight-in Approach
The tower is not responsible for any traffic separation until that traffic is on the ground but arriving traffic must be far enough out to allow surface traffic to clear the runway before touchdown. There is no ATC separation by the tower while you are in the air even though you may be talking to the tower. There is a hazard associated with the straight-in approach. Aircraft viewed directly from the rear are difficult to see since there is no relative motion. Motion is the first thing the eye sees. An airplane both in front of you and lower is even more difficult to detect. Use the radio.

The straight in approach is so called because it does not use a course reversal to become established on final course. Radar vectors can be used to bring you so as to intercept the final approach course. A no procedure turn (NoPT) transition is possible when the feeder route has both direction and altitude for an easy intercept and descent. An approved transition must have a minimum altitude, distance and heading. Approaching from a hold is allowed when the inbound leg is aligned with the final approach course. May be prohibited by note. The DME arc is a curve route to intercept the final approach course. NoPT is required but DME is.   Per the FAA legal interpretation, unless cleared otherwise by ATC, intercept the arc at an IAF.

Straight-in minimums are not published or available when the final approach course is not within 30 degrees of the runway centreline OR a normal rate of descent cannot be used from the MDA to the runway. When the approach plate has a number as part of its title then the runway is within 30 degrees and the straight-in is authorized and the minimums are published. Any time you fly such an approach with a crosswind component corrected by your heading, the airport will not be over the nose of the airplane.

At many airports the approach to the runway on the chart may require either a downwind landing or a circling approach. Lower minimums will apply to the downwind landing. You will need to adjust your airspeed to get the desired ground speed caused by the tailwind. If the tailwind is only 10 kts it will double your landing distance.

Localizer Approaches

No different than when first used in 1930
Two focused directional antennas at 90 and 150 Hz
Signals overlap from departure end of runway down centreline for about 18 miles.
Aircraft receiver compares amplitude (power) of signals to get 1 to 1 ratio existing only on centreline.
Blue or shaded side of approach is always to the right.
Back courses reverse sensing of ILS requiring pilot to fly away from needle unless reversal built-in.
6 degree course accuracy to threshold.
OBS should be set to approach course as a reference heading only. (disconnected).
Back course ILS is non precision localizer approach.
Localizer directional approach (LDA) flies like a localizer approach but can bring you in to runway from 30 degree angle.
Some LDAs have glide slope.
Simplified directional facility (SDF) approaches uses poor quality antenna with course width of 6 to 12 degrees.
Use approach chart to obtain reference descent rate in fpm.
Bracket this rate to get and keep correct slope
Your primary pitch instrument for straight and level at the MDA is the altimeter (the one with the numbers).
A clearance to the ILS approach is likewise a clearance for the localizer but with higher minimums.
An ILS/localizer approach has two FAF's only one of which is timed. The interception point of altitude with glide slope is the FAF for the ILS.
You cannot fly the Localizer if you have flown the ILS to below the MDA for the localizer.
The LOC (localizer) only and VOR approaches look pretty much the same as an ILS except that they don't have the "go up/go down" glideslope needle, just a "go right/go left" needle.
The VOR and localizer are on independent circuits. They require independent checkout.

Checking Localizer
A localizer can be checked for accuracy by departing a runway served by that localizer. Tune to LOC frequency while taxiing and note CDI movement as you move on to runway. CDI should center as you line up on runway centreline. This will not work at CCR 19R except at the very end of the runway due to offset. VOR frequencies end with an even decimal: .2, .4, .6, etc. Localizer frequencies end with an odd digit: .1, .3, .5 etc.

VOR Approaches
VORs with HIWAS do not have two-way communications.

91.25 Requires 30 day check of VOR accuracy before IFR use.
Use of VOT give zero From or 180 degrees To with allowable error + 4 degrees.
Ground checkpoints in AF/D +4 degrees
Airborne checkpoints in AF/D +6 degrees
Dual VOR check within 4 degrees
VOR idents in a series of four followed by DME ident.
VOR deflection is 10-degrees from centre to side
Any time dual VORs have a common problem it is probably the shared antenna

On a VOR approach, the VOR can be located at:

Missed approach point
Initial approach fix
Final approach fix or
Miles from the airport.

VOR Minimums
Fewer options for the VOR and NDB than for the ILS. Some non-precision approaches lower the minimums when light systems exist. The MDA boxes do not include DA(H). Circle to land minimums are based on HAA elevation as shown on the right side of the chart. Numbers in parentheses are Heights Above airport (HAA). Radius of the circle for category A aircraft is 1.3 nm. The speed you fly determines the aircraft category. If there is no speed/time chart then timing is not authorized.

Straight-in-minimums require three things:
1. Runway alignment within 30-degrees
2. Approach must cross threshold
3. Descent to be less than 3.77 degrees or 400' pnm.

Intercepting a Radial

Along an airway a 45 degree intercept
On approach use 30 degrees
10 degrees maximum on the ILS and use rudder for 5 degree corrections

In some instances a greater than 30-degree arrival may not require a hold. The FAA may design an approach where the hold is so removed from the final approach fix (5 nm) that sufficient time for course alignment exists.

VOR Checks
There are 6 ways a VOR can be pilot checked for errors:

Ground check point
Dual VOR check
Radio shop check
--Designated airborne check
Homemade" check

Every VOR has a dedicated monitoring system where other navaids may or may not be monitored. Monitors check the signal and any required accuracy on a status panel with alarms and lights. Unmonitored navaids cannot be used to meet alternate requirements of IFR flight and are noted in the A/FD either with and N/A on an approach plate or with a ‘tower closed’ note. The pilot who is using an unmonitored navaid for an actual approach had better maintain a constant listening watch on the frequency and flags.

ADF Features
The NDB approach is designed to have protected minimum obstacle clearance is 300 feet vertical and 1.25 miles wide at the facility. A formula is used to determine the protected space as the missed approach point which amounts to 6000' wide per mile. You have 30 degrees angular space, 15 degrees to each side, to miss the runway and still have protected airspace. The PTS standards allow only 10 degrees bearing error to the approach course.

Low frequency radio 200-1600 KHz with both loop and sense antennas. Not limited to line-of-sight but by power. HH power good for 200 miles down to compass locator or locator outer marker (LOM) at 15 miles.

The ADF course is the intended magnetic flight direction. When ATC directs you to fly with reference to an NDB they will always give a bearing from or to the station. The to or from may be either way by ATC while meaning the same thing. If you are in doubt as to ATC intentions reverse the term and direction used by ATC and ask for confirmation.

Rotating the azimuth card makes the ADF into a pseudo Radio Magnetic Indicator (RMI) without the remote compass. In the RMI the azimuth card rotates automatically. With the ADF you must set the card to the desired magnetic heading. The heading selected in the course line + the predicted wind angle. You are trying to get the tail of the needle to indicate the approach course line. When the tail of the needle indicates to the right of the course line you will turn to the right for about 30 seconds before returning to the WCA heading. Works the same if the tail moves to the left. Once you have turned the card it is best to leave it alone unless you have grossly misjudged the WCA.


When NDB is used to form airway the magnetic bearing from the NDB is used to form the radial.
--An unused ADF is likely to get needle problems
Not all ADFs use two antennae.
Check an ADF malfunction by going to ANT mode (Some needles will 'stow' at 90 degrees.)

NDB Flying

Set HI with compass
Turn to fly direct to NDB
Fly until needle is off the heading. Its deflection is the wind direction.
Turn to the needle twice the displacement.
When needle deflects by the original deflection amount, take out half the correction and see if needle stabilizes as a indication of correct drift correction.
Repeat the process as distance permits.
On station passage turn to inbound course with wind correction applied.
Use NDB course line as wing leveller.

Standard Outbound Tracking

Initially the needle is at 180
Hold the course but any needle movement indicates direction of the wind.
When needle is displaces 5 degrees, make 20 degree turn toward needle.
When needle tracks 20 degrees take out 10 degrees.
You will know you are tracking correctly when needle deflection is constant.
Repeat as necessary.

Intercepting a Bearing:

Turn to desired magnetic heading. Needle deflects to station.
Turn toward needle double the deflection.
Fly heading until needle deflects half of intercept angle.
Turn to original desires heading. Needle should be centred.
Repeat as required.

If you are constantly correcting you heading to fly to the NDB, this is an indication that you have not made a wind correction and are flying an arc to the NDB. Without the wind correction information that should be determined inbound to the NDB, you have only one option. Fly the charted bearing from the station. This is not the way it should be done but this method has a good chance of keeping you within the allowable error range.

ADF Orientation

Set magnetic heading of aircraft to the top of the ADF card.
Tail of needle gives bearing from station.
The ADF can detect thunderstorms
ADF needle is unreliable in a turn. Use timed turns for changes.
Monitor frequency when sole source of navigation.
Consider putting magnetic bearing to the station on top.
Once established make only small heading changes.

Simple NDB Approach
The difference between the NDB and the others is that there isn't a single dial in your cockpit that you can refer to, to see your tracking error. You must combine the information presented by the HI and the ADF, if you wish to accurately track to or from an NDB

You can practice learning to track using the NDB. When flying cross-country, work on finding the proper crab angle. Good visualization practice. But during the approach, people under stress may misinterpret the dials and ‘correct the wrong way. Flying the NDB approach, which has an NDB located 4 miles west of the threshold of runway 09.

270 <----- /------- * -- 090 --> 9__________________|/045 / 225

When cleared for the NDB 09 approach, so you could simply "home" to the NDB, which is your IAF (Initial Approach Fix). ‘Homing’ with an ADF simply consists of keeping the needle on the ‘nose’ of the aircraft, or on the zero at the top of the ADF indicator. With a crosswind, our just flying the needle will get us there. Spend any excess time studying the plate.

Get the important items:
A pproach - the right plate?
M inimums - MSA, PT, FAF, MDA
O vershoot - quickly review which way, how high, how far
R adios - ADF tuned and identified. Radar, ATC, CTAF
T imes - get a time to the Missed Approach Point (MAP), VDP?
S peeds - groundspeed based on wind

Passing the NDB outbound, some type of procedure turn. Course reversal is easiest but always to the published turn side. Otherwise, visualize what the wind is doing to you on each straight leg of the procedure turn, and make a correction for it. A crosswind, crab into it. A headwind, increase your time significantly. A tailwind, decrease your time slightly. Headwinds hurt more than tailwinds.

Cockpit checks now. Check your Heading Indicator against the compass. You cannot fly an accurate NDB approach without an accurate heading reference.

Major NDB problem is lack of ident process. NDB navigation relies on the accuracy of the compass. Compass deviation must be applied to NDB bearings. Avoid flying an NDB using an outbound track from a distant station. Configure before beginning the approach. Don’t home, track to an NDB. This means apply a course correction that negates the wind effects. NDB station passage is noted when the needle is off the wingtip.

High powered AM stations can be good for 500 miles. The accuracy of the ADF is directly related to the accuracy of your compass and your HI setting. Compass corrections of the compass apply to the NDB. The recency of a compass card is important.

Flying an outbound NDB track from a distant beacon should be avoided. Before you start on approach you must be configured and on speed. Homing does not work inbound. Track to an NDB if you want to remain in protected airspace. You must track outbound from an NDB by getting on the outbound bearing and then correcting for any crosswind to remain on that track. This must be done before starting on the approach.

Final Approach Tracking.
Turn initially to a heading of 090 and begin descent started to get your altitude for the FAF (Final Approach Fix). This is usually lower than your procedure turn altitude. Be sure to keep a 500 fpm descent rate going, use 600 or 700 fpm if you have a tailwind.

If there's no wind, a heading of 090 will take us right to the NDB. Rather than using any tracking and correction technique just simply home to the NDB. Needle on the nose, back to the NDB. By homing to the NDB, we are assured of a station passage. On Passing the NDB (the FAF) inbound, turn back to 090 and start a descent, down to your MDA (Minimum Descent Altitude). Essentially, after station passage just fly a heading of 090 until you see the runway, or your timer runs out at the MAP. At a ground speed of 90 knots, it will take 2 minutes to travel 3 nautical miles to a 1 mile final for runway 09, at which time you should be visual with the runway, and start your descent from the MDA.

But let's say we've got a 30 knot direct crosswind, which is a lot at 500 feet AGL. If we get a good station passage, and just ignore the wind by flying a heading of 090, after 2 minutes the crosswind will have pushed us 1 nm off course. Instead of being 1 mile from the runway threshold, we will be 1.4 miles, which is a pretty good return for such a simple procedure.

If you think about it carefully, it's actually going to be better than that. With a strong wind from the north, while homing to the NDB after the procedure turn for the FAF, let's say we eventually weathervaned to a heading of 070 at station passage. After we pass the station inbound, during our turn from 070 back to 090 we will travel somewhat north, or upwind of the desired track, so we probably won't drift a whole 1 nm downwind.

Also, if you have a higher groundspeed than 90K, you will be affected less by the crosswind. There's less time for the crosswind blow you off course after passing the FAF. The neat thing about the above NDB approach is that at no time did you ever have to track using the ADF. You always flew and maintained headings.

NDB Cold approach
The NDB is the easiest 'cold approach' to make.THE COLD APPROACH (no opportunity to use the 6 p's)

Frequencies at top of chart Locate VOR's relative to approach
Check/recheck OBS settings
Write time and MDA/DH on hand
The side of the published procedure turn is mandatory
A published teardrop procedure is mandatory
The completion distance from the fix is mandatory
It is TOO LATE to study the plate inside the FAF
Base all wind corrections on the point of the ADF needle.
The arrowhead will point the direction the wind is going.

You should know that the NDB power and range are in the Airport/Facility Directory. The ADF needle always points to the station and the tail of the needle give the aircraft position. To get your magnetic bearing to an NDB you must use your imagination to put the ADF needle over the HI. Changing the ADF card makes the process more difficult, leave it on zero.

The curved path that occurs when flying to the NDB without any wind correction is called a oxodromic curve. Tune in the frequency and the needle will always point to the station. The needle that is not pointing to the station will either point to the left or right of the station. Make your correction for wind or course by correcting to the direction of the needle, left or right. In each case you must make a heading change that is greater than the needle deflection.

You should not try to track a course until you have intercepted the course. Once intercepted you must track with the understanding you will need to intercept again and again. This is especially true in NDB holding patterns.

If you’re Fussy:
Slightly modify the above procedure. With a groundspeed of 90K, we know that two minutes after passing the FAF we should be visual with the runway, and in position to start descending on final. So, passing the NDB inbound, turn to a heading of 090 and hold it as accurately as you can for one minute. After one minute, observe the ADF indication. Let's say that it's now 190 relative. This means we have drifted south (to the right) 10 degrees during the one minute after we passed the FAF.

To correct for it, we turn left 20 degrees to a new heading of 070 for the remaining one minute. This 20 degree correction for a 10 degree drift is exactly the same track correction method you used as a student pilot on your private pilot flight test.

Newer is not always better. Within a mile at low altitudes the VOR is more accurate than unaugmented GPS. The GPS is always better than the NDB for accuracy. The two levels of GPS use are the Standard Position Service which is within 100 meters 95% of the time and within 300 meters 99.99% of the time. The second service is for the military only as precise positioning Service.


Can predict loss of signal.
The antenna is not shielded by structure
Broader data base.

GPS Approaches
GPS will provide for non-precision operations into small airports. The presence of obstacles may not be depicted. GPS is not conducive to windshield scan. Best to have a third person aboard who is supposed to watch for other aircraft.

IFR has a higher level of skill requirement but the use of ATC services, especially radar, is a given so the process is simpler. If you plan to use a GPS approach at a given airport, your alternate must have an instrument approach procedure other than the GPS. IFR GPS must have FAA approved flight manual supplement and current database. Must query FSS for GPS NOTAMs. File as /G aircraft

By using the FAF as a waypoint instead of the Airport you can get the distance to the runway threshold.
Ask for spelling of waypoints and intersections used in your clearances if you plan to use GPS.
The unusual spellings of waypoints are called 'neologisms.
GPS approach descents often have VDPs. (Visual Descent Point)
VDP is based upon MDA (minimum descent altitude) and required visibility to see airport.
GPS use is not authorized as substitute for DME or ADF if information is not in database.
VDP are located so that a normal approach to landing can be made if the airport is in sight.
Use GPS course line as wing leveller.

Garmin 530 (430)

Failure to hit the GPS/CDI (Course Deviation Indicator) switch before and after the approach can kill you.
Before the FAF you must be on GPS; on the approach you must be on CDI; on the missed you must be on GPS
An autopilot with heading and altitude hold is essential if you expect to use the GPS without a copilot.
Never try a GPS procedure the first time in a non-radar environment until you have flown it in VFR first.
530 Programming:
Revert to vectors when ATC gives you your first initial heading to intercept the final approach course.
Activate the approach when ATC clears you for the approach.

1. While en route select the approach you are going to use.
2. Select the transition IAF you expect to use. When cleared for the approach and assigned a crossing altitude, you can…
3. Activate the approach--If ATC does not use your anticipated IAF you must reload the GPS from setup #1.
4. Change is from the airport as the GPS destination to the CDI with the IAF as the active waypoint.

The GPS cannot fly the missed approach.
Any approach not approved for the GPS will take you through the approach but will not remind you to
go to GPS for the missed.
The missed will be a straight out on the course line as a dashed lines rather than the published missed. You must use paper.
Do not fly a dashed line do not use the GPS which will fly you direct to the missed fix. This may fly you into a mountain.


New GPS precision approach plates include stabilized approach angle and decision altitude instead of MDA.
GPS non-precision approaches will include glide angle, visual descent point, and threshold crossing height (TCH) where descent angle crosses threshold.
VGSI is new FAA term (visual guidance slope indicator). This is used on non-precision GPS approaches where
the approach slope is actually above the VASI slope.
Non-precision GPS approach uses a MDA so it is important not to go too fasts and avoid a long landing.
A published VDP should be used as a missed approach point because circling is excessively dangerous.
The missed approach can only initiate a climb, no turn is allowed until past the MAP.

GPS in an Emergency
You can use GPS to position yourself on short final to a runway under the worst conditions if you have practiced a
relatively simple procedure. There are several requirements.

You must be able to fly timed distances on precise headings.
You must have an aircraft that is willing to remain airborne.
You must have a GPS receiver with a suitable data base.

You will need to fly a modified airport pattern much as you would in VFR conditions. Try this lesson in VFR conditions around a seldom used airport until you perfect the procedure. GPS locates an airport by a reference point called the ARP. This point is usually near the center of the airport itself. You want to remain relatively close to the airport. You intercept a direction to the ARP that is 90 degrees to the longest runway. Since you want to be about 1/2 mile from the runway on your abeam the numbers downwind you will anticipate your turn to downwind by turning when .3 from the ARP (Airport Reference Point). A standard rate turn should position you about 1/2 from the runway on a parallel track. Turn base at 1 mile from the ARP and make an early turn to final to a heading that will allow a 30 degree intercept to the bearing to the ARP. The descent throughout the procedure should be from pattern altitude and at approach speed before turning base. A normal descent should place you over the runway with some excess altitude as a safety margin. Never accept an ATC final approach speed higher than your flap or gear speed.

GPS as a Substitute

Locate DME fix
Fly a DME arc
Fly to/from NDB
Locate NDB cross-bearing
Hold at NDB

Emergency ADF Use:
If you lose your AI, HI, etc. and need to fly a particular heading, you can use the ADF as a very useful and reliable aid. Tune to the most powerful station available. With that as a guide you will be able to fly straight and make turns by the required number of degrees.

Visual Procedures
A visual approach allows an aircraft on an IFR flight plan to fly in VFR conditions under ATC control to an airport. Clearance requires VFR conditions at airport and en route, airport in sight and any traffic in sight.

Visual approaches are not an instrument approach, rather they are an IFR procedure giving means for avoiding a full IP during good conditions that avoids cancellation of your IFR plan. Local weather of VFR minimums is required. The pilot is responsible for all obstacle clearance and has given up the right for a missed approach and going IFR again. Recommended altitudes are mandatory as is the recommended flight track. Part 91 visibility have never been defined. You are protected from IFR planes you do not admit seeing. Visual approaches greatly increase the PIC responsibility of the pilot.

You are not on an instrument approach procedure even though you are adhering to instrument flight rules. If there is any doubt as to the success of a visual procedure, you should remain IFR. Both visual and contact approaches must be flown in VMC. A visual approach can be flown to any airport if ceiling and visibility are above minimums of 500' above minimum vectoring which is always at least 1500 AGL. Though similar, the visual and contact approach are not interchangeable.

Either ATC or pilot can initiate visual approach when you can tell ATC you have the airport in sight or if you have preceding traffic in sight and will maintain separation and wake avoidance. If you see the airport but not the traffic ATC must provide separation. Radar service is terminated when you change to tower frequency. The visual approach clearance does not include missed approach instructions. Missed approaches are handled as a go-around.

A visual approach requires a 1000’ ceiling and 3-mile visibility. What you do visually depends on the ATC clearance. If you are cleared for a named and charted visual approach, you must fly the charted procedure. If your clearance is not named and charted you can fly VFR to get where you are going.

To conduct a visual approach you must be on an IFR flight plan and have airport or traffic in sight with weather at least 1000 and 3. ATC can give clearance at an airport without reported weather if 1000 and 3 is expected. Visual approaches are allowed even if vectoring weather minima do not exist as long as 1000 and 3 do exist. If there is no weather observer the radar controller must be told that you are VFR before he can give you a visual approach. Once you have accepted a visual approach, you are responsible for all traffic separation.

Imagine that the airport/approach is a beautiful woman. You can have visual any time you want, but you've got to request contact.

Visual Approach

ATC or pilot initiation
Ceiling 1500' or better or pilot must be able to maintain VFR.
Pilot maintains separation and wake avoidance

Can be offered by ATC or asked for by pilot if ceiling is 1000’ and visibility 3 miles. You must remain clear of clouds. You must have any preceding traffic or the airport in sight. Traffic and wake avoidance is up to the pilot.

On top conditions may be difficult in convective conditions. Clouds often rise at 3000 fpm. Let ATC know so you can file IFR. Ask for an alternate IFR clearance in case of communications failure. You must see and avoid all other traffic but also report all altitude changes as though IFR.

If you are dealing with IFR as a process within a complex maze of strict, unwavering rules requiring passive compliance, they you don’t know how to use and fly the system. there are a number of time and fuel saving ways of using the system to your advantage.

Once you accept a visual approach from ATC you are responsible for wake turbulence avoidance. If doubts
exist be prepared to query ATC as to ground speeds and separation.

The visual approach does not require that the airport have an instrument approach or SIAP
You will fly to a specific navaid point and be cleared for the visual approach.
You must see either the airport or traffic to be followed.
You should expect to get an escape clearance if things go wrong.
You are in IFR conditions and below minimum vectoring altitudes.

Contact Approach
An IFR pilot can shift responsibility, control and liability out of the hands of ATC by requesting a contact approach. This allows deviation from published procedures and allows flight to the airport where visibility is reported to be at least one mile. The pilot must maintain ground contact, remain clear of clouds and provide obstacle clearance. Only you, the pilot, can do this; ATC cannot. The contact approach has the pilot responsible for terrain clearance, clear of clouds and flight visibility. ATC must have a procedure (including the published misssed) available should IMC flight be required by the pilot unable to maintain the contact approach.

Don’t descend until in position to land. Obey minimum safe altitudes and obstruction clearance features. This is a form of scud-running that is safe only if you are familiar with the area. Don’t ask for a contact approach unless you really know where you are and will be all the time. You must have one mile visibility and fly clear of clouds as though SVFR. One mile visibility can suddenly go lower. Don’t hesitate to contact ATC and get an approach clearance. ATC will provide separation only from other IFR traffic and SVFR traffic. The contact approach is a substitute for an IFR approach.

Must be pilot requested and ATC approved. Only airports with IAPs and weather reporting. Cannot be used to reach other airports. Pilot is responsible for obstacles and radar service ends with frequency change.

--The contact approach can only be asked for by the pilot.
Minimum conditions are 1 mile visibility and clear of clouds.
ATC does not like the contact approach since its safety is directly related to how familiar the pilot is with the area.
ATC will never clear a contact approach aircraft below the local minimum safe altitude.
Requested by pilot
Clear of clouds and
1 mile visibility
Pilot responsible for obstacle clearance

Saving Time and Money 

The contact approach is a way to use the system more efficiently
The contact approach reduces the time to destination.
Preferred routing in and around Class B airspace is circuitous
On IFR plan and you see the ground surface you can request a contact approach
The airport must have a standard or special IFR approach.
The SIAP or special instrument approach procedure is your escape if the contact approach doesn’t work.
A contact approach is an IFR approach.
There is no altitude restriction
Approval is required by the tower and may be required from the radar facility.
Once cleared for the contact approach you are out of the IFR approach system.
Once cleared you must fly visually using SVFR minimums to the runway.
You are responsible for obstacle avoidance.
Standard separation is applied from other aircraft.
Do not continue a contact approach if you must enter an IFR condition.

ATC and Visual Approaches

Determines airport visibility
Gives alternate (missed) instructions
Provides separation until handed off to tower

Contact Approach ......................................................Visual Approach
Only pilot initiated ......................................................Pilot or ATC initiated
Airport required to have instrument procedure charts ..Vectors possible
Clearance must include missed
Basic VFR minimums exist and can be maintained
approach instructions
ATC has 1 mile at airport
ATC radar separation

Weather minimums
SVFR minimums for pilot and ATC ................................1500' and 3 miles

Pilot responsibility
Pilot obstacle clearance .................................................Maintain basic VFR when cleared to follow

Enables file IFR to airport without weather reporting.
Area weather must forecast VFR. (New night VFR)

Only at airport with instrument procedure ........................Clearance limit to nearby intersection
Airport reporting statute mile ground visibility.
Not to be used to transition to another airport.

The release of an aircraft to tower frequency ends radar service. There have been many instances where the has been verbal confusion between the pilot and ATC. ATC asks you to have runway in sight, you respond with,
"airport in sight". there is a difference and the difference has resulted in many wrong-runway landings as well as wrong airport landings. Additionally ATC records show that pilots are often mistaken when reporting, "Have traffic".

Types of Vectors

Long-range provided by centre
Short-range into a instrument approach procedure.
Delay or spacing vectors for traffic separation
Re-route as a short-cut
Shortcut to IAP segment not final approach. Limited radar coverage you are required to make any procedure turn. 91.175(j) Usually safer to fly the full approach.
Weather avoidance requests by pilot and his responsibility.
Departure during climb but below MVA. Only on IFR departure or on missed. May be above MVA or MIA
To final so no published course reversal required. 20-30-degree intercept angle. Don’t turn on to final without ATC approval.

Pilots Responsibility Using Vectors: AIM 5-5-6

Prompt compliance with headings and altitudes
Challenge any perception of incorrect headings or altitudes.
Advises ATC if a vector would cause FAR violation
Terrain and traffic are pilot’s responsibility.

ATC Responsibility Giving Vectors

For separation
For noise abatement
For convenience
When pilot requests
IFR planes at or above MVAs
VFR planes at any altitude or as assigned. "Maintain VFR, separation not provided."

Approach by Vectors
Do not repeat everything. ...cleared for approach is enough.

Important item: Cleared for approach is NOT, repeat NOT, a clearance to descend below any altitude shown on the plate.

ATC position given is only informational and need not be repeated.
ATC turn heading is advisory and need not be repeated or even followed if pilot judgment suggest a better alternative.
ATC altitude is usually present altitude which need not be repeated. An altitude restriction should be repeated.
ATC reporting requirement should be acknowledged.
Duty of pilot is to fly approach and acknowledge the clearance with any restrictions or requirements given by ATC.
Clearance usually gives a fix, crossing altitude, and approach clearance.
Acknowledge only that you have the clearance, only if you are familiar with the fix, altitude, and approach.
Approaches can only be entered via radar vectors or by use of a procedure.
Course reversals can be made by a procedure turn or by a holding pattern. Sometimes both occur on the same plate.
Only by reading the plate carefully can you determine if the hold is also a course reversal procedure. A plan view in bold line tells you yes.
Advise ATC that you will descend in the hold to allow reasonable descent on leaving the hold. Extension of the hold is limited to one minute but this can be done at 200 knots.
When ATC tells you to hold at a five-letter fix, to hold in a cardinal direction, or to hold on a radial, draw the hold and then decide how you are going to turn around. Fly through the fix in every case and then take your pick. You can always turn outbound and make a course reversal. Asking ATC for a helping vector will not work on a checkride.
Do not expect to be able to fly a holding arrival if you have not configured before your arrival and reduced the potential for distractions. Don’t fly instruments unless you are proficient and current. Get all the ATC help you can but remember that only you can make the decisions.

Vectors and Not Talking

Think before you talk to reduce excess verbiage
You will know when to talk when you understand the system.
Good controllers know the limits of good pilot performance.
By telling the controller the specifics of your aircraft he can plan your vectors and approach.
The less you say the more you will get.
Comply with an ATC instruction in a timely manner
Listen to your vector instructions, requiring a 'repeat' messes up the ATC planning.
Know what to expect for you're outside the marker vector heading.
You don't have time to write down vectors to final.
ATC expects you to turn when so instructed. Turn first, Time, Twist, Throttle, Talk last
When told to change frequency, comply but don't omit things like the ATIS or requests.
The approach is a nonstop region of activity.
The en route is a more casual region of activity.
Learn to anticipate what comes next so you will be ready.
Quick accurate vectoring is more an art than a science.
After a time the controller knows the wind correction and gives appropriate headings.
The 'approach gate' is one-mile outside the outer marker or 5-miles from the runway.
Ideally you will be vectored to intercept two-miles outside the FAF.
You will never be vectored inside the FAF.
If you see that a vector is not working, fudge to make it work.
Don't talk about any fudging you do. Check your HI against the compass.
Never fudge on a vector that is for obstacle clearance or separation.
The turn-on heading and clearance works if you get through the gate.
Recognize ATC mistakes and correct them without talking about it.
Instrument flying is a constant pattern of compliance and adjustment.
Small errors are not talked about, big mistakes are.
Give readbacks when in motion after the fact this way your readback confirms the fact..

Charted Flight Visual Procedures (CFVP)
Charted flight visual procedures are used for noise abatement in radar/VFR situations. original intent was to speed up arrivals. It is not an instrument nor a visual approach and does not have a missed approach segment. Not to be logged as an approach. Missed approaches are VFR go-arounds. Determining factor is visibility

Pilot Responsibilities

Acceptance of visual clearance makes pilot responsible.
Acknowledgment of traffic makes pilot responsible for separation and turbulence avoidance.
If unable to land you must remain VFR until obtaining additional clearance.
Must advise ATC if unable to follow

ATC Responsibilities

ATC will clear when pilot has airport or aircraft to follow in sight.
Minimums are 1500' and three miles visibility with the ceiling 500' above minimum vectoring altitude (1500')
Radar service cancelled when you change to tower(advisory) frequency

PAR (GCA Ground Controlled Approach) Approach  Only at some military fields.
This approach is a highly-skilled, labour intensive system being shut down by the military. It provides glide slope and azimuth direction where all turns and descents are at the direction of the radar controller.
On being given the instruction:
"All turns will be standard rate until established on the final approach. Then they will be made half-standard rate. If radio contact is lost for more than seconds, contact tower on (frequency) and execute the prescribed missed-approach procedure."

Every few seconds or so the final controller will issue course and glidepath corrections leading to the runway threshold. I was talked down to within 10 feet of the runway at Travis on a PAR twenty years ago. Great feeling. Once on the ground you may need taxi assistance.

On such approaches the controller would need to know when you had acquired visual references such as lights so that you could be cleared to land visually or to execute the missed approach.

Airport Surveillance Radar Approach (ASR)
This approach has replaced the PAR in most places with radar. Controllers are requires to practice these approaches and may be more than willing to give you a practice approach. The procedure requires that the airport have the required radar capable of giving heading information. ASR altitudes are recommended only. On final you will be given range to airport and step down altitude recommendations for each mile. Altitudes will be higher than for standard instrument approaches.

No-Gyro Approach
#1 Cover up the heading indicator.
#2 Keep aircraft under control.
#3 Do what you are told to do when you are told to do it.

When it is a dark and stormy night and the gyros quit the controller can give you assistance by means of the turn coordinator. He will tell you to turn at standard or half-rate turns to the right or left and tell you when to stop turn. An ASR approach requires that the radar range be reduced which effectively blows-up the picture size for the controller. Usually an entire scope and controller is dedicated for an ASR approach. There will be no handoff to the tower. The radar controller handles the landing clearance, rollout, and advises when to contact ground. A missed approach will continue with the radar advisories.

Visual Descent Points
The non-precision approach contains a death warrant for those who cannot get the approach elements (ducks) in a row. First, is flying the final approach course; second, comes doing it in IMC or at night; third, is a visual illusion; and fourth is getting a visual descent point (VDP). The non-precision approach usually has a minimum of one-mile visibility. Localizers have 3/4 mile and with lights it gets down to 1/2 mile.

Proceeding to the threshold at MDA means that you must dive to reach the thousand-foot markers. This means you will arrive at the runway too fast for a normal landing. The solution is to figure a VDP and use it by timing. Descend from the VDP with proper flaps and power configuration for landing only when you see the runway environment. Personally I use the VDP as a marker for turning downwind during circle-to-land procedures.

The easiest way to get a quick visual descent point is to use the MDA number and use the two left digits as the number of seconds to take off the approach time. Example: Approach time 2 minutes 16 seconds. Approach MDA 420 feet. Take 45 seconds (close enough) off leaves one and on-half minutes for reaching the VDP.

IFR Mountain Approaches

Check the reliability of any navaid before initiating descent
failure to remain on the centreline could drastically affect the quality of your navaid signal.
Adverse weather is much worse in the mountains
Microclimates near the airport usually go unreported.
Canyons make their own winds, vortices and drafts. Smooth air is rare.
Day winds flow uphill usually making tailwind landings necessary.
AWOS systems are being installed in mountain passes and at mountain airports.
Mountain flying not recommended unless ceiling 2000 above terrain and visibility of 15 or more.
Don't go into an airport at night that you have not first flown during the day.
Daylight mistakes are usually correctable. Night mistakes cause accidents.
If no procedure turn depicted, it is not authorized.
Slow down before the FAF to assure ability to descend.
Once on the approach you are guaranteed separation even without radar.
Hills along the approach course are usually unmarked and always unlighted.
Missed approach points are far before the airport. Slow down so you can get down.
The MDA allows only enough for a safe missed approach. Any lower the option may be only to land.
Below the MDA you must provide your own obstacle clearance and avoidance.
There is not natural horizon into mountain airports.
Make sure there is a VASI to give you glide slope guidance but only when you can see the lights.
Roads often parallel the instrument approach course. Car lights can mislead you as to runway location.
If you lose the airport below the MDA any turn may impact terrain. You have run out of options.

Circling No-Nos, Maybes and Must Dos

It is not JUST an IFR descent to a VFR landing
Circling is an approach at half the usual pattern altitude.
Thirty circling accident per year with over half involving fatalities.
Circling killers are going below minimums, steep turns, descent before on glide path.
Intended landing must be on normal glide path without excessive manoeuvring
Do not descent below minimum altitude until visual slope indicator interception.
Do not descend to published minimums if not required to do so by weather.
Visual loss of airport or runway requires a missed.
Prelude to a circling accident is a continued approach into weather below minimums
An improperly set altimeter is another prelude to a circling accident.
Any bank angle in excess of thirty degrees is considered steep.
If you can't keep the airport in view flying a normal sized pattern you are flying toward an accident.
Pilot ego is a circling killer flying toward an accident.
A late or delayed missed is still another prelude toward an accident.
Keeping the airport in sight in IFR conditions requires realistic training for proficiency.
A series of steep turns will not salvage a poorly planned approach.
Bank angle has a direct effect on stall speed. Fly a pattern that allows shallow banks.
Refer to FAR 91.175)(c)(3) for runway visual requirements for landing.
On a circling approach do not descend on base below minimums.

Circling Cautions

Don't drop the gear until on final.
The circling approach in actual conditions is the most dangerous approach.
The circling approach has only 300' obstacle clearance.
If during the circle you must go missed when beyond the MAP, you should climb and turn toward the
airport. Then initiate the published procedure.
Circle to land is in two parts; first find the airport and then find the runway.
In non-precision approaches you never know when to go from IFR to VFR.
When non-precision approach has only circle-to-land minimums even a straight in is o.k. The minimums are related to the climb required for the missed
Circling minimums are mandatory when descent gradient for straight-n exceeds 400 feet per mile.

Requirements for Best Training

Actual conditions
IFR to VFR transition
Full stop taxi back landings.
Teach hazards of circling approaches in VFR practice
Teach short approach landings as basic circle to land requirement.

RNAV Flight Plan

1. Radar required
2. Random part must be during enroute phase
3. Conventional transitions must be filed at both ends
4. Must avoid restricted/prohibited and TFRs by three miles.
5. RNAV distance to airport uses the ARP or airport reference point near centre of field.

Transponder Landing System

System pings on transponder frequency/code. Antenna arrays on ground work with computer to give time of arrival for distance (range) and position relative to angle of arrival (glideslope). Tracking error is computed and coded to make localizer/glideslope needles work like regular ILS.

Requires transponder, ILS, com radio(s)
Request TLS code for transponder
Contact TLS operator by radio
TLS will cause ILS needles to go active and ident comes on
OM is operative but artificial giving sound only, no lights
Only one aircraft at a time.
Squawk code is used rather than tail number during communications.
Portable version exists.
System has built in integrity monitor
Not available to Part 91 pilots yet.

Uses of the ADF/NDB

The ADF/NDB will be with us far longer than will be the

VOR.  The radio range of WWII was essentially an ADF with up to four legs.  I practiced them on the Link Trainer during WWII twenty-five years before I became a pilot.

You can use any radio station to practice the procedures for the ADF.  Interestingly one of the PP requirements a few years ago was to make a descending spiral over a point.  I taught and practiced this procedure using the ADF.  Fly to a radio station antenna and put the needle on a wing tip and descend while keeping there.  Could be an emergency descent procedure in adverse weather if you know where the station is.  Mine is by a river and a large flat area to the west.

The beauty of the NDB procedure is the simplicity.  No frequency changes.   Only one needle to watch.  With the advent of GPS and moving maps it remains the last device I would remove from my aircraft.  You will always know where it is and where you are in relationship to it.  

You can locate your time distance from the station just as you can with the VOR.  Put the needle on the wing tip note the time and keep track of the seconds.  Fly at right angles to that direction until the needle has tracked ten degrees.  Note the number of seconds flown.  Say it took 200 seconds.  Drop the last zero and fly to the station.  Disregarding wind, it should take 20 minutes to get to the station.  Try it. You'll like it.  VOR line of sight limitations not a factor.  Hazard is you must know safe altitude to fly direct.  In my area I have a 4000' mountain to the south east of my station only eight miles away  

Using NDB approaches is the least exact approach you can fly.  The accuracy can only be improved if you can determine the required wind correction.  I have missed runways by over a mile by getting the wrong wind.  The minimums for NDB approaches are quite high. 

More about GPS

GPS Technology 
GPS approaches will gradually be renamed as RNAV approaches. 
Like driving with cell phone expect increase in head-down GPS caused accidents 
IFR access to all airports is now possible if funded.
All information about technology is perishable 
No handheld is approved for IFR 
Make and model of GPS determines what is possible 
The pilot is the weak link in full GPS utilization 
GPS does not give you cross radials for location 
GPS sequences waypoints as they occur in order. 
GPS requires manual suspension of sequence if interrupted ---Worst case scenario is break in waypoint sequence down low.
Actual IFR GPS requires proficiency of the highest order ---GPS use magnetic course adjusted from true course to give great circle track 
Distance from station affects the sensitivity of the course deviation needle in VOR or LOC 
GPS fakes this sensitivity this an en route mode -+5nm, at 30 miles terminal +1nm and at 2 miles .3nm 
Older nav systems will not be gone until after all the present satellites are replaced after 2011 
The WAAS system may be used as primary means of navigation 
Emergency use of a GPS handheld receiver is an emergency out if needed. 
How GPS Came to Be 
In 1970s U.S. Military developed this all purpose navigational system 
First satellite launch in 1978 fully operational in 1995 with 24 satellites 
It is the antenna system of the handheld GPS that affects its reliability 
GPS satellite outages are NOTAMed on DUAT Using GPS ---Minimum of four satellites are required for three-dimensional position including your altitude 
A new GPS takes nearly 15 minutes to download the required almanac and ephemeris data required. 
A GPS measures the time it takes a specific located satellite signal to get to your receiver 
Accuracy of GPS is based on probability down to 99.99 percent within 300 meters, 95-percent for 100m 
Comparative accuracy, ILS 15-30’, WAAS20-30’, VOR/DME 200/600’, LORAN 500’ 
GPS is least accurate in altitude but biggest problem is the integrity of the system itself. 
Latest GPS models are not required to follow any standard of procedure or terminology to operate. 
Differential Correction 
GPS can be easily jammed but WAAS and LAAS offers some protection over 25-mile areas of airports 
Ground stations monitor satellites and correct errors with differential information 
Third generation WAAS systems and receivers use embedded signals to create a local satellite signal 
Older GPS will work but WAAS capable will have reliability and six-second warning of lost signal 
No other equipment is required for a WAAS approach 
As of 10/04 there was only ONE WAAS approach available with more to come 
IFR En Route GPS 
Requires radar contact if IFR but not as sole means of navigation IFR Approach GPS 
En route plus GPS approaches connected to basic navs via switch confusing annunciation lights 
GPS will arm approach capability when within 30 miles of airport using terminal scale 
Two miles outside the FAF the scale changes to the approach-active mode 
New GPS have VTF feature to allow vector to final before activating autosequencing 
The approach GPS will not function if a satellite is disabled ---Approaches can be added on to a route or STAR IFR Databases 
28-day cycle where receiver will not lock out out-of-date approaches—pilot responsibility 
Database updating progressing from rear cards to front cards to burned on computer and uploaded direct 
Cost up to $700 annually, failure to have charts and plates could violate FARs 
Flying the GPS 
Waypoints must be flown exactly as sequenced in database ---Decide whether to fly vectors and traditional or only GPS since mixing may be a problem 
Land or circle to land are options to failure execute missed approach procedure 
The ‘hold’ function stops autosequencing until restarted on intercepting final approach course 
Recommended on overlay approaches to use the GPS only as a backup 
Block autosequencing when a procedure turn is required ---NoPT approaches can be flown directly with GPS autosequencing 
2nd Generation approaches use the T-shape arrivals without course reversal 
GPS approaches use holding patterns rather than procedure turns for course reversal 
IFR GPS can substitute for VOR, ADF and DME if fix is in database 
You cannot use the GPS for ADF substitute unless you also have an ADF 
Using GPS as DME may confuse countup/countdown depending on waypoint selection RAIM 
IFR GPS have RAIM with a different level for all three regions of IFR flight 
RAIM gives integrity warnings within 30-seconds, 10 seconds  
On approach and RAIM occurs fly missed approach procedure 
RAIM for an approach cannot be activated without the local altimeter setting 
-Selecting wrong IAF 
Selecting wrong approach function 
Beginning descent at approach active annunciator light ---Confusion in activating autosequencing outside FAF - Confusion when GPS changes scale outside the FAF ---Caution in selection of MAHWP button at wrong time or place ---When in doubt check a chart. 

Modes are APCH,OBS, CURSOR, and LEG ++

---OBS is for the missed, procedure turns and holding
GPS starts in LEG mode such as ‘direct to’
IFR GPS allows sequencing of waypoints as required for IFR procedures
Waypoint inserts and cancellations are an additional IFR procedure requirement s met in the cursor mode
The cursor mode allows you to scroll through the flight plan to m