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FAR 91.215 Transponder Requirements; ...Web Radar; ...Radar Facilities; ...Norcal Approach; ...Oakland Center; ...Military Radar; ...ATC Radar Accountability; ...VFR Radar Advisories; ...Class B Airspace; ...Class C Airspace; ...Basic En route Procedure; ...The Handoff; ...Operational Procedures; Rules of Thumb; Radar Facilities and Weather; …Radar Weather Interpretation; …Looking at Doppler Radar; …The Best from Radar Communications; …Radar Communication; …ATC Radar Acknowledgment; …Transponder Failure; …The Danger of Expectations; ...Flying Without ATC Radar; …Flight Following (Advisories); ...

The CCR BRITE in the first week of September will be certified so that aircraft may be asked to ‘ident’ to distinguish one 1200 squawk from another. For the past year two aircraft in conflict could not be easily identified other than by pilot position inquiry.

FAR 91.215 Transponder Requirements
--Any airborne aircraft with a transponder is required to have it on. Mode C, if available, must be used.

--VFR use requires that Mode C be on when within 30 nautical miles of the primary airport of Class B airspace. See Sectional.

--Mode C is required in Class B airspace, and positive control areas (above 18,000'),

--Mode C is required in Class C airspace and above the lateral limits of the Class C airspace to 10,000'.

--Mode C is required above 12,500', below a positive control area (Classes B and C) if over 2,500' above ground level.

--Mode C is also required within 10 nm or airports at Billings, Montana, and Fargo, North Dakota. (Trivia question)

MODE 1 - military usage
MODE 2 - military usage
MODE 3 - civilian usage
MODE 3/A basic 4,096 code equipment
MODE 3/B not used
MODE 3/C altitude encoder equipment
MODE 4 - military usage

Then there is the occasional older aircraft that will waddle through the system with the old 64 code MARK "X" or
MODE "X" box.

CODE 1200 through code 1267 are VFR with the vast majority of aircraft simply using 1200.

Codes 1270 through 1277 are allocated to Govt. agencies for use as a ground/surface based alignment of radar systems. These reply on the assigned discrete code 3/A and a special 3/C return not associated with the elevation of the target.

CODE 0000 block has some general usage in the system
CODE 0100 through 0700 are allocated for terminal radar approach control use.
CODE 1000 through 7400 are allocated by ARTCCs.
CODE 7500 = hijack
CODE 7600 = radio failure (NORDO)
CODE 7700= emergency.

MODE 3/C - Altitude encoded signals transmit down to the ground based on as altimeter reading of 29.92. Upon receipt of the signal the ATC computer converts the 29.92 value to actual altimeter setting for the computer area concerned. The computer transmits in 100-foot increments only.

If ATC shows you at 1,500 feet MSL, your aircraft would continue to transmit that value so long as you operated not lower then 1,450 feet and not higher then 1,549 feet.

Web Radar
Weather radar is available at the following sites.


Radar Facilities
Oakland Center, Bay Approach, Travis Approach. In the years immediately preceding 2004 the Northern California Radar facilities have been progressively moved into the Sacramento Mather Field area.  The current term has been changed several times so it is now Norcal  Approach/Departure as the case may be . Travis Approach remains the same in name and service

. Some of the radar areas are depicted on charts and some are not. Those depicted require that communications be established or a clearance given be prior to arrival. The San Francisco Class B boundaries and information is shown in blue. An additional 30nm circle around San Francisco requires Mode C operation. The Class C airspace around airports having radar is shown in magenta has a ten mile inner circle in which a call up is required to approach just as though were Class D airspace. The outer 20 mile circle has a permissive call up.

In most situations the frequency and controller for approach or departure will be the same. The call up to approach or departure depends on whether you are coming or going. Your first call is brief, who you are and who you are talking to. If you received your transponder code while on the ground, your call-up gives only your identification and altitude.

The latest version of traffic control (TRACON) radar is the ASR-9. Weather circuits are included into TRACON radars but tends to eliminate airplanes when on. Weather depiction can be turned on but the controllers are not competent to make interpretations. Everything changes with ASR-9. ASR-9 is similar in color and display to aircraft radars. There are six levels of precipitation display. Level three and higher should be avoided by all aircraft. The controller who selects the level 3 key has all precipitation level three and higher shown brightly, levels 1 and 2 are shown at low intensity on the screen. As a pilot who is exposed to weather you should be prepared to ask the controller if he has ASR-9 radar display. Ask how many lights he has available (1 to 6) for light aircraft anything over 1 suggests that landing is a good option. Controller liability makes them generally reluctant to give weather advisories without hedging what they say

Norcal Approach
Norcal Approach , formerly Bay Approach, was  for many years was is located near hanger 10 at Oakland airport. It has multiple backup computers and two radar antennae. The #1 radar is at Oakland Airport adjacent to runway 29. The backup is at Moffett Field. The primary region of Bay Approach is the San Francisco Class B airspace which overlies the Oakland Class C airspace and part of the San Jose Class C airspace. Some of the sectored frequencies overlap. The call is always, "Norcal Approach". The frequencies and sectors are on the sectional's frequencies list and shown in appropriate (blue/magenta) boxes on the San Francisco Area chart.

Oakland Center
Oakland Center is based at Fremont on the sectional it is coded as ZOA. Parts of it have been incorporated into the new Norcal site. It has triplicate back up computers and remote communications lines from the Oregon border to Bakersfield, East to Utah and half way across the Pacific. In many instances you must be at certain minimum altitudes to establish radar contact. You may be able to communicate and still not be high enough to be in radar contact. Each sub-region of Center's airspace has a discrete frequency. ZOA frequencies are not on VFR sectionals.

Military Radar
Most military bases offer civilian radar service. The area may be sectored by frequency. The frequencies are available in the sectional frequency list. Call up would be as, "Travis Approach". Most of these services are limited as to altitudes. If you are climbing, you may well be handed off to ZOA (Oakland Center) after passing through a given altitude.

ATC Radar Accountability
ATC radar is used by the controllers to expedite the movement of traffic. The system is designed and operates for the convenience of ATC. The individual pilot becomes insignificant and can only be assured of the benefits of radar by being both proficient in communication and aware of the limits of radar. Radar contact occurs when ATC has identified you on the PPI display scope. Radar contact in no way relieves you of your responsibility to see and be seen and to avoid flight into terrain. While you are expected to comply with any assigned headings and altitudes, you are also obligated to question any such assignments that you deem hazardous.

ATC does not provide VFR flights with terrain separation. Terrain avoidance is a pilot responsibility per FAR 91.119. VFR pilots should never expect ATC to provide any warnings about terrain. Night VFR, off-airways, or marginal VFR conditions under FAR 91.103 require special planning.

ATC radar does not show terrain. Blocks of airspace have Minimum Vectoring Altitudes (MVA) that can be displayed. These are IFR altitudes that allow 2000' in mountains and otherwise 1000' terrain clearance. VFR flight below these altitudes is relatively common but radar has no specific knowledge of terrain below the MVA. If you have Mode-C on your transponder radar may have Minimum Safe-altitude Warning (MSAW) or Low-altitude Alert System (LAAS) but this is often MVA and no lower.

Radar advisories can be terminated to VFR flights just on the say-so of the ATC specialist. There are some automatic terminations that apply to IFR flights but can be applied to VFR situations. It is very possible that a VFR flight may just be dropped from the system without the pilot ever being told. You should have some general idea of the region and altitudes for a given radar facility. If you have not been in communications for a while, just ask for a radio check. You may have flown off the scope without being noticed. Never leave a radar communication frequency without advising ATC.

ATC radar facilities primarily provide IFR to IFR separation. Secondarily, they will give VFR traffic advisories, navigational assistance, weather information, vectoring, ground speed and safety precautions as work load permits. The VFR pilot is responsible for traffic avoidance but ATC will "take over" if a collision risk exists. VFR flight following is not a substitute for a clearance into Class B or C airspace. When radar coverage does not reach, flight following ceases. There are no VFR separation standards and altitude bust may result only in ATC giving you the current altimeter setting as a gentle reminder. With sufficient altitude you can get flight following anywhere in the U.S. Even at relatively low altitudes you can get it in the non-Sierra part of California.

VFR Radar Advisories
Initial Call-up in Class C and B Airspace
Basic callup

In most situations the frequency and controller for approach or departure will be the same. The call up to approach or departure depends on whether you are coming or going. Your first call is brief; who you are talking to and who you are. If you received your transponder code while on the ground, your call-up gives only who you are talking to, your identification and altitude as level, climbing or descending.

Getting a local ATC radar frequency is not always easy for the VFR pilot. It may be listed in a blue box for Class B airspace and a magenta box for a Class C. You may need to request it from a nearby tower or FSS. The FSS frequency may not be the correct one for your sector of radar coverage but it will get you into the system. You could get old IFR charts and plates as a source for radar frequencies. The way you make contact with a radar facility makes an impression that is likely to affect the service you receive. It shouldn't but it does. The initial contact, unlike that to a tower or an FSS, should give only the name of the facility, your full call sign, and possibly "over". You will understand the 'why' of this better if you visit a radar facility. Until then just do it.

When the controller returns your call-up, you give again your full identification, type of aircraft, /(slash code) position (departure point), altitude (final altitude), your destination. To do this well you should practice before initial call-up. Giving the destination lets the controller select a code that lets other controllers up the route know where you are going. The better your flight following radio procedures, the better you will be preparing for your IFR rating and the better overall radar service you will receive.

Under VFR flight following you must be assertive and in charge of your flight. Do not rely on the controller to tell you to climb, descend or make a heading change. You just state that you and doing so, and do it. If it makes a problem for him he will so advise by making a "suggestion". If you get confused or into trouble, admit your difficulty and state your willingness to accept help. 20% of ATC controllers are pilots many at commercial level or better.

The altitude limits of radar means that just when you need it most, it will not be available. Much the same limits exist for radio communications. If you are in conditions that put you both below ATC radar and communications, it is time to get on the ground. Many FSS or Flight Watch frequencies can be used through remote outlets where other ATC frequencies are not available. It never hurts to have another radio frequency option along your route.

ATC can cancel VFR advisories/following at any time. Should this occur because of lost radar contact, you should ask for the next available frequency that can resume these services along your route. Most often altitude will be the limiting factor as when flying the Sierras or other remote areas. You can monitor the frequency you just left or expect and get some idea as to the altitudes and conditions experienced by other aircraft. Center frequencies are not usually available to the VFR pilot but can be obtained from IFR charts for VFR use.

Since VFR difficulties can develop into emergencies, a VFR pilot must know how to get ATC radar assistance and its limitations. ATC cannot tell the pilot what to do; the pilot must make all decisions. ATC can advise or suggest only. A pilot can request MSAW (minimum safe altitude warning) or LAAS (low altitude alert system) assistance but beyond that radar is limited by the system display to providing MVA (minimum vectoring altitude) as the 'safe' altitude. An individual controller may not have sufficient knowledge to vector you to successively lower MVA sectors and it doesn't hurt to ask.

Finding an ATC Point Out
Look at least 30-degrees to each side of the call

Radar call-ups only after initial contact of:
F -facility
I -identity
O -over…

IPAI/DS (pronounced eye-payds)
I - identification (call sign)
P - position (15mi sw BWI)
A - altitude (level 3000, or 4500 for 7500, etc.)
I - intentions (landing BWI) *OR* D - destination
S - squawk code


Use the acronym PACER for just a flight following call-up
P - Position
A - Altitude
C - Conditions (VFR/IFR)
E - en-route
R - Request

Class B Airspace
Not available to student pilots without instructor endorsement.
Be sure that you initiate Class B airspace communications early enough to avoid entering before getting a clearance to enter. Know your positions and altitudes in relation with the Class B airspace so that no entry will occur prior to entry. If the controller fails to give a clearance to enter, be sure to ask for it and get it, before intruding into the Class B airspace. With the latest Class B and Class C airspace requirements, it is not unusual to have a considerable delay before establishing contact. Controllers are often on the phone or processing data that prevents immediate response. In the LAX area it may take five or more minutes before a busy controller can get to a new arrival. General Aviation IFR/VFR flights can expect few, if any, direct or shortest route flights in Class B airspace.

Monitor frequency to determine use. Be sure to remain clear of Class B airspace both horizontally and vertically.
"Norcal Approach Cessna 1234X over" If no response, wait 30 seconds and call up again. The controllers are often on the phone or processing data that prevents immediate response. When their work load permits they will say...
ATC: "Cessna 1234X Bay Approach go ahead"
34X: "Cessna 34X Birones Reservoir at 3000 squawking 1200 VFR Concord to Half Moon Bay request flight into the Class Bravo airspace at 3500 enroute"
ATC: "34X Standby for squawk" ( Standby means not to make any response. )
ATC: "34X Squawk 0734 and ident"(Turn X-ponder to STANDBY, reset code, set to ALT, push the IDENT button. )
34X: 34X squawking 0734
ATC: "34X Radar contact" acknowledge with 34X.
ATC: "34X traffic 12 o'clock 1 mile" Navy A7 at 2000 climbing"
34X: "34X negative traffic will accept vectors"
ATC: "34X turn right 340"
34X: "34X right to 340 have traffic"
ATC: "34X with reference to traffic proceed own navigation via G.G. Bridge and shoreline"
34X: "34X own navigation"

Do not enter Class B airspace until you receive a specific clearance to do so. Always write down squawk and frequencies. Always repeat back squawk, frequencies, headings, and directions as much as practical. All assigned altitudes and headings be maintained since traffic clearances are determined thereby.

Class C Airspace
The Class C airspace system has a ten mile inner circle in which a call up is optional to an ATC approach facility or the tower just as though it were Class D tower airspace. Whether you talk directly to the tower or to Norcal Approach depends upon your direction of arrival and altitude.  A Communications is a FAR requirement as is transponder operation in Mode C. The outer 20 mile circle has a permissive call up. Class C airspaces are charted with altitudes in magenta outlines.

Operational procedures
1. Get the ATIS
2. Use the correct frequency
3. Practice for smoothness/accuracy/completeness
4. Check for frequency congestion
5. Full aircraft identification + student pilot
6. Position and altitude
7. Request and expected reporting point
8. Initial Class C airspace call up:
"Podunk approach Cessna 1234X student pilot over."
DON'T ENTER THE Class C airspace UNTIL ACKNOWLEDGED. (No clearance required.)
"34X (position-altitude) with ATIS and full intentions and any special request.
Initial Tower Call-up "Podunk Tower Cessna 1234X student pilot Position at altitude request left base entry for the right will report 2 mile base"

Basic En route Procedure
Initial call-up to get into the system before you have a transponder code (squawk) is always:
Blank Approach Cessna 6185K over
If no answer...
Check your radio switches and frequency
Wait 30 seconds and try again

When ATC radar responds they need certain information for their computer.
1. Aircraft type and identification
2. Present position and destination
3. Present altitude and final altitude
4. The ATIS letter if you are inbound for landing

There is a 'canned' procedure for saying this:
Cessna 6185K is a Cessna 150 Walnut Creek
landing Oakland out of one-thousand six hundred
for two thousand five hundred with Alpha
ATC will assign a transponder code:
1. Write down the assigned code
2. Say back the code as...
85K understand squawk 5234
3. Place selector on standby
4. Set in assigned code
5. Place selector on altitude
6. If ATC does not advise in radar contact, say
85K squawking 5234

Occasionally, you may immediately be given a squawk or just to remain clear and standby. Be sure you understand the significance of what ATC says. Normally, you will be assigned a squawk and may or may not be told to IDENT. Do not IDENT unless told to. The IDENT button causes a flashing IDENT to appear on the controllers scope adjacent to your data block. The discrete transponder code does more than just identify the aircraft. It often is used as a destination indicator so that other sector controllers know where you are going.

If the controller says "Radar Contact" acknowledge with your last three call letters. If for some reason no secondary target (transponder) is seen, you may be requested to recycle. This means to reset the numbers perhaps providing better electronic contact.

All instructions, traffic point-outs must be repeated back to the controller in acknowledgment with aircraft identification.

Any changes of altitude or direction must be communicated to ATC authorized by the controller.

When you leave a radar service area the controller will so advise you and ask you to squawk VFR (1200) and approve a frequency change. You must never leave contact with ATC approach/departure without such an approval. If you need to change frequency to contact Flight Watch or an FSS just request a 30 second frequency change. You will be told to report when back on frequency.

The Handoff
The area around a radar facility or antenna is divided into both horizontal and vertical sectors. This means that as you proceed you will be changed from one controller to the next. This is called a handoff The controller will, prior to informing you of the hand off, tell the next controller via phone/computer that you are coming and the particulars about your aircraft and operation. Then he will advise you of who to contact and on what frequency.

Once the controller has completed your data block this information can be passed via computer from sector to sector or between facilities. For this reason the 'handoff' requires a minimum of communications. As you transition from Travis airspace to Sacramento Class C airspace, the controller will say...
"85K contact Norcal Approach on 118.8"
Acknowledge any handoff by repeating back the place and frequency assignment.
"85K going to 118.5 with Norcal Approach."

Operational Procedures
So long as ATC does not bill you for their services, you would be well advised to take every opportunity to add their equipment and skills to your flight safety margin.

VFR Flight advisories are not implemented consistantly from facility to facility across the country. Some facilities are more VFR friendly than others. The more professions your radio procedures the more you increase your likelihood of getting the service you want.

The time of day and week makes a difference. a controller can be handling 2 or 3 frequencies while coordinating a bunch of handoffs an the phone line. Just because the frequency doesn't sound busy, may not be a true indication of what the controller is working with.

Just ask, "XX Center/Approach Cessna 1234X VFR request". If he's busy, he'll tell you! If he says, " 34X go ahead with your request". Be pre-prepared to give your entire request that should include;

A. Aircraft identification, type and equipment

B. Where you are, your altitude, and destination

C. Any other specifics.

Rules of thumb:
--In an airplane don't change a radar frequency without getting the ATC o.k.
--Write down the new ATC name and frequency
--Repeat back the essentials for confirmation
--Set new frequency and establish contact
--Check for congestion before using radio
--You must request any changes of altitude or course while in Class B airspace. You must advise on any changes in altitude or course in Class C airspace or other radar areas when in contact. At any time ATC may assign an altitude and heading for safety purposes. If no such assignment is made you are free to make changes as long as you keep them advised of your intentions.

The radar controller as part of FAA Order 7110.65, Air Traffic Control paragraph 2-16b is required to coordinate with other ATC facilities such as a tower your passage through their areas. You are not expected to obtain your own authorization since it would detract from your ability to maintain radio contact with your primary facility. However, if you have a specific need to contact a facility such as flight watch, FSS, or tower it is appropriate to request a 30 second frequency change for such contact. You must report back on frequency when through.

A radar traffic advisory usually gives a 'clock' direction off your nose, a distance and an altitude. Expect the 'clock' to be wrong by an hour or so. You are unlikely to see any small aircraft beyond 5 miles and in haze the distance may be less than a mile. You immediately advise, "85K looking, 85K have traffic, 85K negative traffic" as appropriate. If you can't find the traffic and feel it constitutes a hazard wait 30 seconds and say, "85K negative traffic, will accept vectors." You do this because ATC may wait too long to give you warning or to turn you. Most often they come back with, "85K traffic no longer a factor". You readback everything a radar controller tells you to do. This procedure is to prevent misunderstandings.

The radar handoff requires that you read back the instructions given and the frequency. If you have been listening to what other aircraft have been told you should be expecting the change. The controller has already told the next controller/facility, electronically, that you are coming. They are expecting you. Don't be in too much of a hurry. When a break in the frequency occurs the handoff call requires you merely to state, who you are talking to, your identification, and altitude.
You say...
85K to Norcal Approach on 118.8

You then change frequency to 118.8 and say...
Sacramento Approach Cessna 85K level at five thousand five hundred

Say this every 30 seconds or so until acknowledged. Double check your radio settings and frequency.

There is a procedure for changing from one transponder code to another designed to prevent the inadvertent selection of a restricted code as for Air Force One.

1. Standby
2. Select new code
3. Altitude
Have a pencil ready in your hand you can keep it there while holding the yoke (lefties) or while holding the throttle (righties)

Radar Facilities and Weather
--Do not rely on ATC RADAR for weather information
--The pilot is responsible for aircraft safety and weather avoidance
--If there is a conflict in what you see and know and ATC's information, get on the ground.
--ATC radar is unreliable when it comes to presenting weather.

Radar Weather Interpretation
There's a software who can interpret this:

Try this too:

An other software (called Digital Atmosphere):

And a lesson on weather:
There's a part of it here:
The radar report (RAREP) has both an analog and a digital section. The analog section (parts a-i) is useful for communicating precipitation type, maximum intensity, trend, movement, and location of the highest echo tops. The geographic coverage of echoes and the range of intensities is better revealed by the digital section (part j). The digital section can be understood by considering Gleim Fig. 3-3 (G250). The digital section is based on a grid system. Each box in this grid is identified by two letters. The first
letter identifies the row and the second, the column. Note that the radar site is always found in grid box MM. Digital section data are encoded in one or more groups. The coding starts with the two-letter identifier of the box farthest to the west in the most northern row, followed by one or more numbers corresponding to the VIP of the listed box and the VIPs of each grid box eastward in the same row.
Additional sections of code will be added to summarize WSR-88D veloc

Looking at Doppler Radar
--Weather Surveillance Radar known as NEXRAD covers the 50 states.
--NEXRAD radar is doppler. Unlike other radar signals doppler changes frequency, as does a train whistle.
--This doppler is unique in its ability to detect moisture and its relative movement.
--Doppler can foretell by relative speeds of two sides of a storm its ability to form a tornado.
--I had occasion to see this doppler in action while visiting a weather facility in Charleston, S.C. in 1999.
--Nexrad radar has an 80-mile range in either precipitation (blue & green or clear air red and orange modes.
--It takes from ten to 15 minutes for a NEXRAD radar screen to be fully displayed.
--The 'reading of the radar display allows interpretation of intensity, freezing level, and development.
--NEXRAD does not read weather until twenty miles from the antenna.
--NEXRAD is dependable account of threatening or adverse weather.

The Best from Radar Communications
There are some radio procedures that are relatively infrequently used by new pilots. In this tome I will attempt to clarify why some of the distinctions exist and what to say, when. The proper radar frequency is often not available to the VFR pilot. If you know a facility exists, such as Center, the local frequency can be obtained by contacting a local tower or an FSS. Every sectional chart has a Facilities Frequency section behind the chart legend. The initial radio call for such a frequency should end in the word "request" as "Napa Tower Cessna 1234X request" (All radio communications will be written without punctuation, just as they should be spoken.)

Radar Communication
Approach control is a radar facility as is the Air Route Traffic Control Center. The communications procedures are identical. The major difference lies in distances and altitudes. Approach is usually within thirty miles of a particular airport. Approach can be contacted directly for flight advisories (Preferred over flight following) which warns you of potential traffic conflicts. Such advisories are required for IFR flights but on work-load basis for VFR. Radar does not relieve a pilot from situational awareness or see-and-be-seem responsibility. Frequencies are available in the A/FD, charts and IFR plates.

When your flight takes you from one radar sector or facility to another the radio procedure is to only give the name of the new facility, your aircraft identification, and your altitude relationship as level at, out of (altitude) for (higher/lower) altitude. If no handoff is involved you give the name of the facility, your aircraft identification followed by "over". Read back any ATC transponder settings, frequency changes, to ident, headings, turns and traffic. Advise when traffic is in sight or "negative traffic'. The way you say things is just as important as what you say. When ATC answers, be prepared to give the following information:

1. Aircraft identification
2. Aircraft type
3. Location
4. Altitude
5. Intended route or destination.

Every radar facility is required to obtain at least one confirmation of altitude with every contact. You can save time by including your altitude with every initial contact with a radar facility. Always advise ATC if you are planning to change altitude when VFR. IFR pilots are required to report descending out of any altitude as well as the altitude they are descending to.

The initial callup to every radar facility is the same. It makes no difference if you are dealing with a Class B or C, an approach /departure, traffic control (TRACON), or a center.

Initial Call
Name of facility, full aircraft identification + "Student pilot" over
"Travis Approach Cessna 6185K student pilot over"

The reasons for this brevity is because the radar controller has a multiplicity of tasks. In addition to your frequency he may have a military one. He has a phone line for contact with controllers of adjacent areas. He often records data and writes notes. In low traffic periods one controller may have two areas and two frequencies. Under certain workload/weather conditions VFR advisories may not be possible. When this condition exists you will be so advised. A visit to a radar facility will help you be more understanding as to why the controller does not answer immediately.

A more distant initial callup procedure allows the controller to select when to contact you as his workload permits. Wait at least 30 seconds before calling again. The more efficiently you communicate the more likely it is that you will be accommodated since good communications reduce the workload.

ATC Radar Acknowledgment:
Make NO response if told to standby. When the controller is able you will be told to go ahead. However, you may be occasionally 'forgotten'.
"Cessna 85K go ahead with your request"
When the controller acknowledges your existence give the particulars of your flight and aircraft. Occasionally, a transponder squawk will be immediately assigned only to be modified to indicate additional information later on.

Full call sign; type of aircraft; Present position; present altitude and en route altitude; destination; and
"Cessna 6185K is a 150, off Concord for Half Moon
Bay out of 2000 for 2800 via Golden Gate Bridge requesting
flight advisories"

The controller will ask for anything you leave out. The type information is added to the radar data block by the ATC specialist. The present altitude information is used to check the accuracy of your transponder encoder. Once you are established at an altitude do NOT leave that altitude without first advising ATC. As a VFR pilot you are allowed to select your own altitude as long as it follows the hemispheric rule for your direction. To change you must first advise ATC. Alternatively, ATC may assign you an altitude, in which case you must request approval of any change. Your transponder code assignment will indicate IFR/VFR and destination.

The importance of correct, concise, and accurate communications when dealing with a radar facility is essential. You are required to fly assigned headings and altitudes. If you wish to change heading or altitude advise ATC. If there is a traffic conflict ATC may provide an alternative. Always write down squawk and frequencies. Always repeat back squawk, frequencies, heading, and directions as much as practical. If you need something repeated, say so. If you cannot visually locate conflicting traffic, do not hesitate to indicate that you will accept (want) a vector for traffic avoidance.

When given a handoff to another sector you just have to tell the controller your altitude. Every radar controller is required to check your transponder-readout accuracy at least once so get it over with right away.
"Sacramento Approach Cessna 6185K level at 6,500"

ATC will assign a squawk and confirm your Mode C operation by saying,

"85K squawk 5234 say altitude ident"

Do not believe that being on radar relieves you from 'see and avoid' responsibility. As a VFR flight you are relatively low on the ATC totem pole. When ATC radar advises you of nearby traffic you should acknowledge the 'point out' with.
"85K have traffic"

Do this only if you are sure of the traffic direction, distance and aircraft type. If you are uncertain or have failed to see any aircraft of the type indicated you say,
"85K negative traffic"

If after thirty seconds to a minute you still have not identified the traffic and you feel that a hazard may be involved, you should request vectors for avoidance by saying,
"85K will accept vectors"

The controller may indicate that traffic is no longer a factor or may give your a vector by saying,
"85k turn to 030"

Your response will be the direction of the turn and the heading given so as to establish the certainty of your instructions.
"85k left/right to 030"

When you are clear of the traffic ATC will instruct you to resume your own navigation.

If your transponder is not making a reply or is giving the wrong code ATC will request that you recycle. This means to turn it off then on and roll through the numbers again. This often is sufficient to fix the problem. If some aspect of transponder operation is unsatisfactory ATC can usually work with a primary signal. Under the escape clause "unless otherwise authorized or directed by ATC" you can be given a waiver. The willingness to ask for help when you need it from ATC is more important than whether your transponder is working. Not only can ATC give you vectors they can give you 'no gyro' aid that will get you out of IFR conditions into VFR.

At some point on a flight either you or ATC may wish to end radar service. You merely ask for a frequency change.
"85K have Concord in sight frequency change"

"85K frequency change approved squawk VFR"

Transponder Failure
If you should experience a transponder failure, be cautious about accepting flight into a radar environment where radar is the prime system. Once you land at a Class C airport without a transponder you may be unable to get out. Trick: Try to get piggy-backed on to another aircraft as a flight of two. Nice if you can get out in the direction you want to go. Radar can track a primary signal with little difficulty today. They can even attach a data block. Planed flights into Class C or even B require one hour notice
--First malfunction check is the reply light
--Some older military radars have difficulty with Mode C. Check with TRACON or Center for Mode C.
--Gear land flaps down may block reception or transmission.
--Turn off DME to see if signals are in conflict.
--Encoder must be reading within 300 feet or ATC will have you change mode.

The Danger of Expectations
When you look outside an aircraft you have expectations. If ATC has called a 'point-out' you expect to see an aircraft. You have a right to assume that you will see an aircraft. However, the quality of the 'point-out' very much depends on what you will actually see. It is not unusual for what you are looking for to be off in azimuth as well as distance. An aircraft 'point-out' that is off by 20 degrees may be well outside your focal vision. An aircraft called as being three miles away is the size of a fly at ten feet. Your visual shortcomings as well as ATC misdirection may lead to trouble.
--It takes two seconds to focus on a distant object.
--It takes 12.3 seconds to evaluate, determine the threat and take evasive action.
--Vast majority of midairs occur in VFR daylight near traffic areas.
--Head on aircraft on the horizon do not move on the windshield.

Flying Without ATC Radar
--The kiss off
Where ATC will no longer provide radar services
--Radar contact lost
--Radar service terminated…
--Frequency change approved, squawk VFR
--The losses
--No vectors
--No altitude alerts
--No procedure short-cuts, fly as published
--No traffic 'point-outs'
--No weather vectors
--No weather deviations
--Only one aircraft in airport airspace at a time
--Reports may be required
--Standard non-radar reports required (AIM 5-3-2)
--Requires readback of altitude restrictions.
--You are expected to fly closest approach
--DME arcs require use of IAF on arc.
--FAF reports are required
--Procedure turn inbound may be required
--Cancellation of IFR expected when VFR at airport.

Flight Following (Advisories)
--Immediate emergency assistance
--Company when you get lonesome
--Will warn of aircraft you may not see
--Gives you freedom of route and altitude
--Far more efficient and timely than Flight Plan
--Controllers option whether to provide service.
--Appropriate frequency handoffs and assistance.
--Warnings and vectors to prevent airspace incursions
--First hand weather via informal PRIEPs on frequency
--ATC terrain avoidance and weather avoidance vectors
--Directional vectors to destination or preferred arrival route
--Can request timed frequency change to FSS or Flight Watch
--ATC has no knowledge of intentions or validity of Mode C without radio contact

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Continued on 5.535 Weather and Wind