VOR Navigation Basics for Aviators

VOR navigation isn't the most user friendly way of getting around, but once you understand a few basics and some recipes on how to use the darned system, it's really not that bad.

I am writing this blog post with the student pilot in mind, but hopefully the private pilot who never really understood VOR navigation will learn something too.

As with many aspects of aviation there are two ways to work with any system: the concept and the actual use. The concept is something you do during simulating or at home with pencil and paper. A very good and free simulator can be found here and I affectionately call it Tim's Airnav. Actual use of the system as I describe below means understand what you want to do, then follow the recipe for that item. If you are in the cockpit and working on the conceptual part, you are in the wrong place. You should be home at the kitchen table. The cockpit is a great place to make sure you can use the VORs, but not a place to understand how they work. The degree to which this is true is proportional to turbulence and how fast the weather is closing in.

There are three procedures you frequently encounter with VOR navigation:

1. Intercept a radial and fly inbound (inbound means fly towards the VOR)
2. Intercept a radial and fly outbound (outbound means to fly away from the VOR)
3. Fly direct from your current position to a VOR

Before we proceed there are some concepts we must agree on or I will be writing into the cone of confusion or perhaps addressing the zone of ambiguity. :-)

A single VOR station is composed of a group of antennas on the ground that fire at different times, in a prescribed order, emit a group of radio signals during each cycle. Your cockpit VOR receiver receives these signals and enables you to determine on which of 360 radials your aircraft is located. A radial is an electronic "line of position" (navigator's acronym: LOP). A line of position is a line on the ground on which you are located. If it is a radial then you can state you are on a line that starts at a position on the earth (the VOR station) and tracks the surface of the earth on a magnetic direction which is the value of the radial. Radials are numbered 000 to 359. The 000 can also be referred to as the 360 degree radial. A technician turns a knob at the ground station and rotates all 360 radials so that the 000 (360) radial points at magnetic north for that particular spot on the earth. Remember that the angle of magnetic north from geographic north varies from place to place on the surface of the earth - that's why it's called "variation". Having radials reference magnetic points on the compass simplifies the life of the pilot because cockpit references to direction are made via magnetic references (usually a magnetic compass, magnetic flux detection, etc.).

Next concept, is the radial. Think of a VOR transmitter as a dot on the ground from which 360 lines emanate. These lines are called radials. Each line is numbered 000-359. Each line is a radial. Whoops, I repeat myself, but intentionally. A radial starts at a VOR transmission station and radiates FROM (note the emphasis on "from") the station. For example, the 090 radial (magnetic direction is expressed in 3 digits with a leading zero or leading zeroes) radiates from the VOR and creates an electronic ground track towards magnetic east. It doesn't matter if I jump on the 090-degree radial and I fly towards the VOR or I fly away from the VOR, I am still on the 090 radial - direction of flight is irrelevant. Let's fly towards the VOR on the 090. This means the aircraft is tracking magnetic west (track=270 deg. magnetic). One mile away from the VOR the aircraft is still on the 090 and still tracking 270 deg. magnetic. A moment later the airplane crosses the VOR. At the crossing all radials come together - it's big mess and it's called the "Cone of Confusion". However, if I ignore the drunken CDI on my omnibearing selector (OBS) display, it will eventually settle down as I keep heading west and if all goes well, I cross the VOR, leaving the 090-degree radial behind and now I am flying outbound on the 270-degree radial heading away from the VOR and into the sunset. Remember radials start at the VOR and radiate out from there. A specified radial does not cross the VOR station. In this case, we track inbound on the 090 radial, cross the station, and are then tracking the 270-degree radial.

Summary, all radials have a number and an origin at the VOR - they emanate "FROM" the ground-based VOR transmitter.

Now the part that messes up the beginner and a lot of experienced folks, the notion of the "TO" and the "FROM" flag on the OBS display. If you turn the OBS dial and you center the CDI with a "FROM" indication then the value you read at the top of the protractor is the radial on which your aircraft is positioned. If you center the CDI and a "TO" indication is shown in the TO/FROM window, then you are on the radial indicated on the bottom of the protractor. Confused? If so, don't feel alone. It's not so bad once you understand the reason for this and it revolves around the fact that humans aren't very good at flying with reverse sensing. Keep reading for more on this topic.

To illustrate the reverse sensing concept, suppose you desire to fly the 090-degree radial towards the VOR, cross the ground station and keep going into the sunset on the 270-degree radial. Suppose you have passed the VOR, you have 270 dialed on top of the OBS protractor scale, the CDI is perfectly centered and the OBS displays a "from" indication. This means you are on the 270 radial. Suppose the aircraft drifts southward. This would cause the CDI to drift to the right side of the display. It's telling you that the radial you have tuned in (270 deg.) is on your right and you aren't on it anymore. You need to turn the aircraft a few degrees right to re-intercept the 270 deg. radial. If the needle drifts to the left of the display while the aircraft parallels the 270 radial, you have drifted north and you must turn the aircraft to the left to re-intercept the 270 radial. If you are flying parallel to the desired radial and the needle is on the left, you need to turn left to intercept the radial. For a CDI on the right the radial is on your right and you must turn right to intercept. In both cases you turn into, or "towards" the needle to intercept the radial.

When flying outbound from a VOR station: dial in the radial you desire to track on the top of the OBS display, keep the needle in the center (you will have a "from" indication). If the needle moves left, turn left a little; if the needle goes right, turn right a little.

The conceptually troubling part for many pilots is that what happens when flying inbound towards the ground station, for example flying in on the 090 radial and you incorrectly dialed in 090 on the top of the protractor? If the needle is centered, you are on the 090 radial and the TO/FROM flag will indicate "FROM". Now let's suppose that your aircraft drifts north. Which way does the needle go? Where do you want it to go? You want it to go to the left of center to tell you to turn the AC left to re-intercept the 090 radial. Does it? Answer: NO! Why? Because when you have a radial value dialed in and you are on that radial, the system assumes that you are heading away from the ground-based station. In this case, you have dialed 090 and have a "from" indication. This introduces a very important concept: the VOR receiver in your aircraft knows nothing about the heading of your aircraft. It's is only telling you where you are in relation to a radial. If you are north of the 090 hanging by a skyhook with 090 dialed into the OBS and you spin the aircraft on its cable, the CDI will not change (right of center in this case) regardless of where the aircraft is pointing at any moment as you spin on the skyhook. If you are on the 090 radial it will be centered as your aircraft makes its 360 rotation on the skyhook. If you are to the south it's the same as north except the needle is to the left of center as you do your swivel trick.

So, there is an implicit assumption that you are always going outbound on a given radial and that the CDI shows your deviation from the radial based on the assumed outbound direction of the aircraft. But we are going inbound to the ground station on the 090! If you put 090 on the top of the OBS display and intend to fly the 090 inbound you will have to be straight-jacketed when you land because the needle will always be going the wrong direction relative to your deviation away from the 090 radial: If the aircraft drifts north, on your westward heading the needle moves to the right side! If you turn right to intercept - ouch, you are flying away from the line! If you keep your current position, but magically move the aircraft 180 degrees so you are going away from the VOR, then the needle is telling you the correct direction to turn to re-intercept the 090 radial. The fact that it goes the wrong way when you go inbound on the 090 with 090 dialed in and a "FROM" indication is called reverse sensing. The manufacturers of the receiver system said we can help pilots with this problem (I made this up, but it works even if it's not true). If flying inbound on a radial, we can have them dial in the reciprocal (radial + 180) which is 270 degrees (090 + 180) and correct sensing will occur. So imagine what would happen without a TO/FROM flag: if the aircraft is on the 090 radial, the needle would center when either 090 or 270 is dialed into the selector, but one would give you reverse sensing! Solution: put a TO/FROM flag on the display to tell the pilot if the aircraft is on "real" radial (emanating FROM the VOR) or he has dialed in the the "virtual" radial, or the reciprocal (270 is the reciprocal of the 090 radial). Problem solved. So, if I am on the 090 radial and I am inbound to the VOR and I dial in 270, I see a "TO" indication, and the sensing of the CDI needle is now correct so that if I am north of the 090, the CDI is to the left and so on. You are still on the 090 radial as you go inbound, but now you have correct, not reverse sensing.

So much for the conceptual topics, let's jump to cockpit pragmatics. There are 3 recipes you need to know. To select which one of the 3 recipes you need to accomplish your task, you first need to define the task to be accomplished. For example, do you want to intercept a radial and go to the VOR station or do you want to intercept and fly away from the VOR station?

The following assumes you have tuned in and ID'ed the VOR by its Morse code. The following precludes the use of calculating reciprocal courses - cockpit math should be avoided at all costs:

Recipe 1. Intercept a specified radial and fly in towards the ground station, let's assume the 210 deg. radial:

1. Dial in 210 on the bottom of the OBS protractor (a "TO" indication appears)
2. Note direction of needle relative to center: Left or right of center?
3. Decide on angle to intercept the radial (45 deg. intercepts are common)
4. View the top center of the OBS and scan 45 degrees in the direction of the needle and note value
5. Turn airplane to a heading of that value to fly a 45 degree intercept towards the desired radial
6. As the need sweeps towards center turn to a heading equal to the value on top of OBS
7. As you maintain this heading and a centered needle, you are flying towards the ground station on the 210 deg. radial

Recipe 2. Intercept a radial and fly away from the ground station, assume the 210 deg. radial:

1. Dial in 210 on the top of the OBS protractor (a "FROM" indication appears)
2. Note direction of needle: Left or right of center?
3. Decide on angle to use to intercept (assume 45 deg. intercept again)
4. Moving view from top center of OBS protractor 45 degrees in the direction of the needle  and note value
5. Turn airplane to a heading of that value to fly a 45 degree intercept towards the desired radial
6. Wait for needle to sweep towards center, as it does, turn towards value on top of OBS
7. As you maintain this heading and a centered needle, you are flying away from the ground station on the 210 deg. radial

Recipe 3. Fly direct to the ground station from your present position:

1. Turn dial, look for a "TO" indication
2. While maintaining a "TO" indication, center needle
3. Read value from top of OBS protractor
4. Turn aircraft to a heading equal to the value on top of the OBS protractor
5. Make appropriate corrections to keep the CDI needle in the center
6. You are on your way to the VOR
7. When the TO/FROM flag and the CDI move erratically you are on the VOR

Memorize these 3 recipes, especially if you are a student pilot - works every time. Again, nothing conceptual here just recipes.

Beginner warning: if you have a strong wind blowing the aircraft away from the line as you do your intercept, it may take a long time to make the intercept. Too shallow of an intercept can lead to the same problem. Trying increasing the intercept angle, but avoid using more than a 60-degree intercept.

An example: You desire to intercept the 090 radial and go inbound. You are somewhere east of the ground station. You dial 090 on the bottom of the OBS (that puts 270 on top). If you are north of the 090 radial the CDI will be towards the left of the display. Look at the top, it says 270. Count 4 big lines (10 deg.) and a small line (5 deg.) towards the needle across the protractor arc which yields 225. Turn your airplane to 225 degrees magnetic to obtain a 45-degree intercept. The needle will swing towards the center as you approach the line. As it does, turn your aircraft towards 270 degrees magnetic and keep the needle in the center. You are on your way to the VOR, tracking the 090 radial.

Ask yourself what it is I want to do and then select one of the recipes.

1. Intercept a radial and go inbound? Recipe 1: Dial in the radial at the bottom of the display, obtain an intercept value on the needle side of the display and turn to that direction to intercept then turn onto the radial using the direction at the top of the OBS. Keep the CDI in the center.
2. Intercept a radial and go outbound? Recipe 2: Dial in the radial at the top of the display, obtain an intercept value on the needle side of the display and turn to that direction to intercept then turn onto the radial using the direction at the top of the OBS. Keep the needle in the center.
3. Fly direct to the VOR from your current position: turn the dial to obtain a "to" indication then center needle. Turn aircraft to the heading shown at the top of the OBS and keep the CDI in the center.

You do have to have an idea roughly where you are located relative to the VOR for this to work. However, for practical purposes on a private check ride, you will not be asked to, say, intercept the 090 radial and go inbound if you are west of the ground station. There are other aspects of VOR use that can cause problems for the novice, notably the cone of confusion and the zone of ambiguity. Be aware of these, but on the typical private check you will most likely get the simple intercept, fly to/from or fly direct to a VOR. As you pass over a VOR, you must fall back on the magnetic compass to maintain a constant course as the CDI and TO/FROM flag flip around erratically. Once you get a strong "from" indication you can turn to the assigned radial or stay on the reciprocal, whatever is appropriate.

If you cross a VOR and are assigned a radial that is not the reciprocal of the inbound radial, you will usually overshoot the new radial as you pass through the cone of confusion. Once you get a strong "from" indication, execute the following: turn, time, twist in that order. Turn means turn the aircraft to the same magnetic direction of the radial, time means set/reset a timer if appropriate for your navigation, and twist means turning the OBS dial to the new radial. The CDI will not likely be centered because you overshot the VOR in order to get a strong "from" indication. If this happens use recipe 2 to intercept the desire radial.

Beginner warning: The CDI indicates an angular error. Adjacent radials are very close to each other when you are close to the VOR ground station. Use small intercepts when crossing a VOR and intercepting the new radial.

Aircraft Meteorological Data Reports

For the eyes of aviators only, others enter here at your own risk :-) ....AMDAR (Aircraft Meteorological Data Reports) is really neat. Some airlines participate in putting a small data gathering device on their aircraft. As the aircraft ascends/descends, a broadcast wind direction, gusts, temperature and more (http://amdar.noaa.gov/FAQ.html gives detail) is sent to a data gathering agency. One of the more important factors transmitted is moisture content. Currently, around 140,000 samples are collected/day. This means wx folks and aviators have access to almost real time radiosonde-like sounding data. One example using this data can be found at http://rucsoundings.noaa.gov/. "RUC" stands for rapid update cycle. If you are not familiar with the display format, take the Texas A & M tutorial (link on bottom of rucsoundings page). The format is a log-p skew-t graph, something that weather experts have been using for years. However, the Java version of this graph allows you to get dew points, temperatures, wind velocity and direction, etc. in the atmosphere over the airport you selected and up to about FL400. You can also lift a hypothetical air parcel to see if it is stable or results in bad things. It's easy to find freezing levels, saturation altitudes (where clouds are liable to form, etc.). Nice stuff for aviators. Even if you only use it in a basic way.

Audio in the Cockpit

I have aways had trouble with recognizing expired timers in the cockpit. Timed approaches, arghhhhh.

I have often wondered why we don't see more integration with timers and audio in the cockpit. Just think about that ILS and the audio (male or female) saying your timer has just expired.

Or how about "time to switch tanks honey" (voice is opposite sex, of course!). Just think about how many tank switches you have screwed up as a pilot (I cannot count). It's not easy to remember to look at the clock which is often located out of the main viewing area of the pilot. Even a yoke mounted kitchen timer doesn't work in a noisy cockpit unless it has a light and it is night time. There has to be a better way!

Modern FMSs have a timer feature, but even then, an expiration message shows up as a visual somewhere you are guaranteed to not be looking when it occurs.

Yes, there are some technical issues like how to handle a coinciding call from ATC, but I am sure that there are solutions. Audio stream mixing at this point would be good. Perhaps one timer's audio can be "critical" and used in situations like timed approaches. Critical time expiration messages would be mixed with ATC voice, perhaps a few "TIMER! TIMER!" shouts or something like that. All other expiration messages can perhaps be deferred until after ATC finishes their voice transmission. A tank switch would be in this category. In other words, non-critical times are deferred in the event of a collision with incoming ATC messages and a critical time expiration message is mixed with the ATC input.

It's about time we quit missing time expiration messages and audio seems like the best way to solve this problem.

Oshkosh 2009

I had a great time. This year I did a lot more socializing with fellow flight instructors whom I know from Palo Alto, CA. In addition, I renewed a lot of OSH-only acquaintances from last year at the house that I stayed at.

Lyle was at the house again and we can never seem to cover enough aviation topics fast enough and Karl, the king of curmungeon'ness was there too (it's a lie, he is really a teddy bear).

This was my 3rd year. The weather was great. Locals told me that it was one of the coolest summers in 50 years. It was cool because I was able to walk to the OSH terminal building (about 4 long blocks) in the morning without being drenched when I got there.

My favorite thing? (What was your favorite thing is everyone's favorite question). I don't know. It's all interesting and I always manage to learn something new. I think I enjoyed getting to know some of my fellow CFIs a lot better. Martin and I had a pen truce which helped and I always enjoy his humor even when the world seems to be melting around him. Terry is a walking encyclopedia on the history of aviation. I hope that some of it rubbed off on me. He also made me come to realize that I may like tail draggers after we both drooled over the large Sherpa with its tundra tires, great weight hauling capacity and it's extremely short field take off and landing specs.

Some say the airshow is Disney Land for aviators. I think it is wish land for aviators: I wish I had that airplane, I wish I had that airplane, etc.

It is special being surrounded by so many folks who have a passion for aviation. We all knew why we were there and we all had that gleam in our eyes.

Vwhy - Vwhynot

Summary: airspeed is a critical resource on go-arounds, touch and gos and IFR missed approaches.

When leaving the runway environment, airspeed is a critical resource. This is a no brainer when doing take offs from a full stop, but for some reason, many pilots unnecessarily let airspeed decay when conducting a go-around or touch and go by not adding take off power immediately. When deciding to climb in a draggy configuration (flaps down, gear down) it is important to immediately add power, then clean the airplane in order to minimize airspeed loss. In one extreme case, I was with a pilot doing a touch and go on a short runway who spend what seemed like an eternity looking for the flap switch, then he radioed tower to let them know he was going around. I am sure it was obvious to the tower a go-around was in progress. First fly, then talk! I teach my students that if you are not flying safely you have no reason to be talking unless perhaps it is a directive to avoid a collision. Do not be afraid to use the term "stand by" if your are in a heavy workload dealing with an "aviate" problem. Controllers will know that you are busy and will get back to them as soon as workload permits.

I teach the 5 C's which I learned from my instructor. Note the adherence to the all important priorities: aviate, navigate and communicate in that order:

1. Cram it. Don't stab the throttle - be nice to the engine, but don't wait either).
2. Climb it. When the flaps are down and the pitch is trimmed for landing, this means push on the yoke to prevent a trim stall. Eventually you will want to attain a balked or a short field airspeed, followed by Vy.
3. Clean it. Reduce flaps to manufacturer's balked landing setting or the setting used for short field take offs. Memorize your balked T/O or short field airspeed and keep this speed. Do whatever your AFM says about flap vs. gear up order - memorize this!
4. Cool it. This usually means open cowl flaps if the airplane has cowl flaps.
5. Communicate it. If this was an unplanned go-around, let tower know.

If you not aviating and navigating, you should not be talking. Never tell tower you are going around after being cleared to land until you have completed items 1-4.

Regarding IFR missed approaches, the 5 Cs apply with one twist. Upon reaching Vy, maintain it until you are absolutely positive you are clear of the highest obstructions within a conservative distance of the airport. (Study approach plates, VFR charts, MSA values, etc. for the lay of the land before your flight.) After this point, pitch the nose down and attain a cruise climb speed. At all times your climb rate must meet, preferably exceed, the minimum required climb rate for the missed approach being executed until reaching a specified level off altitude.

A mistake I see IFR pilots make frequently when executing a missed in the muck is a tendency to cram in full power, but not pitch up to attain Vy afer cleaning up and in a fast airplane this leads to a lot of scary horizontal, rather than climbing flight. Remember altitude is your friend. Once the decision is made to execute the missed, not only is it important to have memorized the first few items on the missed approach, but it is equally, if not more so to execute the 5 C's first with emphasis on attaining a Vy airspeed as soon as safely possible.

Propeller Bending

Wow, was I wrong (this is the first mistake I have ever made :-).

Propeller bending as shown in the picture below is an artifact that has something to do with the way digital cameras capture images and is not really due to the prop bending. At least not all the bending you see in the photo is real propeller bending.

Thanks Andrew for the education.

Some bending does occur, but not as much as my digital camera indicates, and this is what makes prop edge dings so dangerous. Think about steel wire. With a file make a small score perpendicular to the wire's axis. Start bending the wire. Where the break will occur? At the score. As a kid, I worked on farms, this is how I would cut fence or bailing wire that was too thick to cut with pliers. I used the cutter on a plier to score the surface, not cut it, and bend it back and forth until it broke. Think of a ding then as a stress point that over several bending sessions could lead to a propeller break. AOPA says that if a ding (also called a nick) is less than 1/32" wide or deep it can be deferred to next maintenance. However, I say that if an AP is nearby holding a file in his/her hands - why not ask? :-)

Lost Procedure vs. Diversion

Prop Bending Forward on Take Off (digital camera artifact)


Diversions and lost procedures often cause students grief on the private check ride because they are high work load items. High work load items are not an uncommon occurrence for the pilot. For example, the instrument approach is a high work load item. There is a lot of preparation and situational awareness activity on the pilot's part to make sure that the approach is successful.

Executing a lost procedure for real is also a high workload activity with added element of fear that comes from not knowing where you are located (how much fuel do I have? Do I fess up? Help!).

Once you are beyond an initial difference, lost procedures and diversions are one in the same activities. The initial difference is that with the diversion you know where you are located on your flight plan (we hope) and for the lost procedure you do not know your location. Once your location is known, processes for a successful outcome are identical: turn the airplane towards a desired position, estimate time and fuel required to get there. The lost procedure is covered in all basic aviation texts. You start by circling, climbing and determining your position. Circling keeps you over the same place. Find a ground reference and keep it in sight. A barn, a pond, etc. work fine. In short, if you don't know where you are at, don't go somewhere else - keep your present position. A circling strategy for most small GA aircraft is to reduce power (around 2200 RPM in most 160-180 horsepower engines)and attain an airspeed of around 90 KIAS. Add necesary power to keep 90 KIAS, but don't get carried away because you are trying to conserve fuel and you aren't going anywhere because you are lost. Bank about 15-20 degrees which tends to form a rather stable bank and do a gentle slow climb. You can do a faster climb with more power if you know that mountains will block VOR reception. You climb to see more things and get better radio reception. If you see something you know is on the chart, point the aircraft at that object until the magnetic compass is stationary and note the heading on the compass, then resume your position hold by restarting the bank you had a moment ago. If you use the reciprocal of the direction to the object you aimed at, you can draw a line of position (LOP) on your chart from that object. You are on this line. A VOR radial will do the same. Crossing two LOPs or using a radial and a range (DME value) will allow you create a position on your chart.

Ok, now we are past the initial difference. From this point on the diversion and the lost procedure are the same.

1. Determine where you wish to go from here - the desired position

2. On your chart, position a straight edge between current position and desired position

3. Obtain the magnetic direction to the desired position (see below)

4. Turn the aircraft towards the desired position and maintain the determined magnetic direction using your heading indicator (make sure your HI is correct!)

5. As soon as you turn from your known position, start a timer

6. While enroute to your desired position, determine the amount of time and fuel it will take to get there. Can you make it? No, then start circling and come up with a better plan

7. If an airport is your desired position, then start preparing - see below

Obtaining magnetic direction:
The best device I have seen for this purpose is a multifunction tool one my students devised to simplify the determination of direction, time and fuel. It is a transparent straight edge. Note that distance, time and fuel are linearly related to each other for a given airspeed (at a given power setting). My student used indelible ink to tick off 5 NM increments on the rule (sectional scale in her case). On a row immediately below each 5 mile tick, put amount of fuel consumed and on another row below that put time in minutes.

Ok, I realize that "speed" really means ground speed. If you use the ruler in a no-wind situation, it will tell you how far, how much fuel and how long with no math - one value below the other. If you know that you will encounter head winds (or tail winds) estimate the percentage difference. For example, I expect to fly over the ground about 10% slower than my true airspeed. This means you add about 10% to time and fuel. Of course, if you have an air data computer on board, use the wind/ground speed data to estimate the effects of wind. If you only have a GPS, start heading to the desired airport and once you have cruise airspeed look at the estimated time enroute value (ETE) and reassess remaining fuel - will you make it?

Borrowing from marine charts, magnetic direction is obtained by lining up your straight edge on your current position and your desired position (creating a desired track). Taking great care, move the straight edge towards a VOR magnetic rose keeping the edge parallel to the desired track (mariners use parallel bars). Obtain your magnetic heading off the VOR rose. With some practice it is amazing how accurate this can be as long as your ground track is reasonably short (perhaps less than 25-30 NM).

Preparing for an unplanned airport after departing from a known position
So far, so good. Now the workload really starts. Here are the essentials perhaps in the correct order:

1. Obtain the CTAF and automated weather frequency if available

2. Obtain the automated weather or contact the UNICOM or traffic at the airport to get traffic/pattern advisories.

3. Determine pattern altitude at the airport

4. Determine other pattern characteristics (left, right, obstructions, etc.)

5. When do I start my descent? Do I intend to overfly the airport at TPA+1000' to inspect windsocks and runway conditions or will I want to be at TPA 2-3 miles from the airport? Use the 4 NM/1000' rule of thumb for descent planning purposes. If you are at 5000' MSL and you need to descent to 1500' MSL subtract: 5000-1500 = 3.5 thousand feet. Multiply: 3.5 * 4 = 14 NM. This rule of thumb is based on a 120 kt ground speed and a descent of 500'/minute. If you plan to be at 1500' at the airport, then start the descent 14 NM from the airport. If you plan to be at 1500' 3 NM miles from the airport, then offset the descent slope by 3 miles and start at 17 : 14+3 = 17 NM.

6. After how many minutes from my departure point will I cross 10 NM from the airport? Announce my intentions on the CTAF to airport traffic at 10 NM, or have a handy 10 NM easy to identify ground feature in mind to clue you when to report. This can also be a VOR cross radial. If you are using GPS then look at the distance to destination value

7. Estimate how and where you will enter pattern before you arrive

8. Estimate a drop dead time - I missed the airport and it is behind me. Start another lost procedure process and find the airport from this new position. Another procedure is to use a "sentinel" which can be anything that "guards" the backside of your route. A VOR radial, a highway, a railroad, etc. Once you have crossed your sentinel, you know you missed the airport - stop, do not keep going.

The Main Message
The lost procedure and diversion are both high workload activities and can lead to significant stress, especially if you are lost because of the fear factor, and in both cases you have likely opened yourself to unknowns such as new airports, new terrain, will I have enough fuel, etc. Success depends on your ability as a pilot to keep a cool head and carefully follow the recipe (a procedure) for success. Using a diversion or lost procedure check list is a good idea. Success in all aviation high work load situations have the same demand: a cool, analytical head and clean execution of the proper procedure, one step at a time.