Navigation Systems and Radar Services

Same tolerance as everywhere else in the ACS — ±100 feet and ±10° — applied to a wider set of navigation and radar tasks (CA.VI.B.S1–S7):

• Use an airborne electronic navigation system and determine position with it
• Intercept and track a given course, radial, or bearing
• Recognize and describe station or waypoint passage
• Recognize signal loss or interference and act on it
• Use proper communication procedures with radar services
• Maintain that altitude and heading tolerance

Box-management workload is not an excuse to lose it.

PHAK 16-23 publishes the normal usable altitudes and radius distances:

Two cautions from the same page: the useful range of certain facilities may be less than 50 miles — check the Communication/NAVAID Remarks in the Chart Supplement — and VOR signals are line-of-sight, so the flag comes up if you are too far out or too low.

No. PHAK 16-23 states plainly that "VOR accuracy checks are not a regulatory requirement for VFR flight" and that there are no specific tolerances for VFR — but as a guide for acceptable accuracy, use the IFR tolerances: ±4° for ground checks and ±6° for airborne checks.

The IFR rule behind those numbers (91.171) requires a check within the preceding 30 days, using one of:

• VOT or repair-station test signal: ±4°
• Designated ground checkpoint: ±4°
• Designated airborne checkpoint: ±6°
• Airway radial over a prominent ground point preferably more than 20 NM from the station: 6°
• Dual VOR cross-check: 4° between the two

Log date, place, bearing error, and sign it.

By its Morse code identification or by a recorded voice identification stating the station name followed by "VOR." Do not rely on voice transmissions alone to identify a station — many FSSs transmit remotely over several omniranges with names different from the transmitting FSS.

If the VOR is out of service for maintenance, the coded identification is removed — that absence is the alert that the station "should not be used for navigation." Receivers also carry an alarm flag for inadequate signal strength.

Receiver autonomous integrity monitoring — the receiver uses redundant satellites to determine whether one is providing corrupted information. It needs a minimum of five satellites in view to detect an anomaly, and six (or five plus baro-aiding) to isolate and exclude the bad one.

Why it matters VFR: PHAK 16-32 warns that many VFR GPS receivers and all hand-held units are not equipped with RAIM alerting capability. Without it, "no alert would be provided to the pilot that the navigation solution had deteriorated and an undetected navigation error could occur." The stated defense is "a systematic cross-check with other navigation techniques."

No regulatory requirement — PHAK 16-32 says databases "must be maintained to the current update for IFR operation, but no such requirement exists for VFR use." That is not the end of the answer.

The database drives the moving map that depicts Special Use Airspace and airspace classes. Without a current one "the moving map display may be outdated and offer erroneous information," and PHAK notes that numerous pilots have entered airspace they were trying to avoid using an outdated database. FAA guidance: if the database is not current, disregard the moving map display when making critical navigation decisions, and verify any named waypoint against a current official source such as the Chart Supplement U.S. or the sectional.

Radar-equipped ATC facilities provide radar assistance to VFR aircraft, provided you can communicate with the facility and are within radar coverage. Basic radar service includes:

• Safety alerts
• Traffic advisories
• Limited vectoring, when requested
• Sequencing, at locations where the procedure is established

Beyond basic radar service (PHAK 14-26):

• TRSA service: separation between all participating VFR aircraft and all IFR aircraft in the TRSA
• Class C service: approved separation between IFR and VFR, and sequencing of VFR to the primary airport
• Class B service: approved separation of aircraft based on IFR, VFR, and/or weight, and sequencing of VFR arrivals to the primary airport(s)

Traffic is referenced by azimuth from your aircraft in terms of the 12-hour clock, plus distance in nautical miles, direction of movement, and type and altitude if known — for example, "Traffic 10 o'clock 5 miles eastbound, Cessna 152, 3,000 feet."

Two professional catches. First, the clock position is based on your track, not your heading — with a wind correction angle the traffic will not be where the clock position says it is relative to the nose. Second, the service "is not intended to relieve the pilot of the responsibility to see and avoid other aircraft."

An operable coded radar beacon transponder with Mode A 4096-code or Mode S capability plus automatic pressure altitude reporting in 100-foot increments (91.215(a)). That altitude-reporting half is what turns a radar target into a usable traffic advisory — without Mode C the controller sees where you are but not how high, and the advisories you receive about other traffic degrade the same way when the other airplane is a primary-only target.

The airspace where that equipment is required is covered in full under Task I.E — know the list from there and be ready to apply it here.

The operating rule is what bites in flight: under 91.215(c), in that airspace or in all controlled airspace, if you have an operable transponder you must operate it, Mode C included.

Required in Class A; and below 18,000 feet in Class B and Class C; within 30 NM of a Class B primary airport surface to 10,000 feet MSL; above the ceiling and within the lateral boundaries of Class B or C up to 10,000 feet MSL; in Class E at and above 10,000 feet MSL in the 48 states excluding at and below 2,500 feet AGL; and in Class E at and above 3,000 feet MSL over the Gulf of Mexico out to 12 NM from the coastline (91.225).

Two link frequencies (PHAK 14-26): 1090 MHz extended squitter (1090ES), shared with Mode A/C/S transponder operations, and 978 MHz, the Universal Access Transceiver (UAT). Equipment must be operated in transmit mode at all times except in the narrow cases of 91.225(f).

Cross-check, then downgrade gracefully.

• Recognize it: NAV flag or loss of ident on the VOR, a RAIM or integrity annunciation, an unexplained jump in position, or a course indication that disagrees with your dead reckoning.
• Verify with an independent source — the other receiver, a second VOR, pilotage against the sectional, or the DR heading and clock you have been keeping.
• Fall back to pilotage and dead reckoning. PHAK 16-32: "VFR pilots should never rely solely on one system of navigation. GPS navigation must be integrated with other forms of electronic navigation, as well as pilotage and dead reckoning."
• Use ATC for radar position and vectors if the picture is not resolving (PHAK 14-26). Anything worse belongs in Task VI.D.

1. Tune the frequency and check the ident before you trust the needle.
2. Twist the OBS until the needle centers with the TO/FROM you intend; if it centers FROM and you want to go to the station, rotate 180°.
3. Turn to the course on the dial and let the needle tell you what the wind is doing.
4. Bracket: when you drift, turn back toward the course, and as the needle recenters roll out on a heading that includes a drift correction — not back on the original heading. PHAK's worked example starts with a 10° correction, finds it excessive when the needle moves the other way, and settles on 5°.
5. Do not chase fluctuations. PHAK 16-26: if minor needle fluctuations occur, wait a moment to see whether the needle recenters before changing heading. And "just turning toward the needle will cause overshooting the radial and flying an S turn."

VOR: the course deviation needle fluctuates, then settles, and the TO indication changes to FROM (PHAK 16-26). If you pass to one side of the station, the needle deflects toward the station as the flag flips. Time of passage is the first positive fix you get on the leg — record it.

GPS waypoint: the distance stops decreasing and begins increasing, the TO/FROM or waypoint sequences to the next leg, and the bearing pointer swings through. A fly-by waypoint sequences before the fix; a fly-over sequences over it.

The examiner is listening for you to announce passage and immediately convert it into a groundspeed and a revised ETA — the Task VI.A habit applied to radio navigation.

In many VFR installations, PHAK says, antenna location is "more a matter of convenience than performance," and part of the aircraft may block the antenna's view, increasing the chance of losing signal — unlike IFR installations, where care is taken to give the antenna a clear view of the sky.

It is worse for hand-helds on window suction cups: "signal loss may occur in certain situations where aircraft-satellite geometry causes a loss of navigation signal. These losses, coupled with a lack of RAIM capability, could present erroneous position and navigation information with no warning to the pilot." Note also that mounting a receiver in the aircraft — a panel or yoke holder — is governed by 14 CFR part 43; consult a mechanic.

• Check for RAIM capability. If none, "be suspicious of a GPS displayed position when any disagreement exists with the position derived from other radio navigation systems, pilotage, or dead reckoning."
• Check database currency; if expired, disregard the moving map for critical navigation decisions and verify waypoints against a current Chart Supplement or sectional.
• Expect intermittent signal loss on hand-helds, possibly with no RAIM warning.
• Plan on the ground. Enter user-defined waypoints before flight, "not on the fly," and verify the planned flight against a current sectional — PHAK cites cases of pilots using another pilot's waypoints that were not where the flying pilot expected.
• Minimize head-down time and keep a sharp lookout for traffic, terrain, and obstacles.
• Learn the box. "Most receivers are not intuitive" — learn the keystrokes and knob functions on the ground, using the manufacturer's tutorial or simulator.

Supplementary position-awareness aids for RNAV-equipped VFR aircraft — useful for pilots unfamiliar with an area, for defining existing reporting points, and for navigating in and around Class B and Class C and Special Use Airspace.

• Names are five letters beginning with "VP", retrievable from the database, not pronounceable and not for use in ATC communications. A VFR waypoint collocated with a charted visual checkpoint is pronounceable by the checkpoint's name and may be used with ATC.
• Charting: a stand-alone VFR waypoint uses the four-point star; one collocated with a visual checkpoint carries a small magenta flag.
• Traffic: be especially vigilant near them. GPS accuracy means fewer off-course deviations among aircraft, so everyone flies the same point — PHAK recommends monitoring the available ATC frequency regardless of airspace class and turning on landing lights near a VFR waypoint.
• Using one relieves you of nothing under part 91, and they are for VFR conditions only.

An EFB is "a system for pilots or crewmembers that provide a variety of electronic display, content manipulation, and calculation capabilities" — charts, documents, checklists, weight and balance, fuel calculations, moving maps, logbooks (IPH 5-10). A tablet is a portable electronic device, not an EFB, unless it hosts and actively displays Type A or Type B software.

Depending on the type of operation, EFB use may require FAA authorization via OpSpec, MSpec, or LOA — relevant the moment your commercial certificate puts you into a part 135 or 91 subpart K cockpit. Governing guidance: AC 120-76, AC 91-78, AC 20-173, and FAA Order 8900.1 (IPH 5-10).

Risk items to name on the checkride:

• Battery state and a charging source
• Overheat in a sunlit cockpit
• A backup (paper or a second device)
• Data currency
• Mounting that does not block controls or the view
• The discipline not to bury your head in it

Say what level you are using and why. PHAK 2-27 reports on glass-cockpit study data: when pilots who had flown EFIS for several years were required to fly maneuvers manually, the results "clearly showed some erosion of flying skills" — on normal maneuvers such as turns to headings without a flight director, "the EFIS group exhibited somewhat greater deviations than the analog group." The recommendation follows directly: pilots of automated aircraft should occasionally disengage the automation and manually fly the aircraft to maintain stick-and-rudder proficiency.

Practical rules for the ride:

• Know what mode you are in and what it will do next — announce mode changes.
• Program on the ground; verify in the air. Any reprogramming en route gets a second set of eyes or a deliberate pause.
• If the box argues with you, turn it off and fly the heading. Heading and clock always work.
• Cross-check the automation's answer against pilotage, the DR log, and a second nav source before you act on it.

Call the appropriate approach control or center frequency for your position — off the sectional, the Chart Supplement, or the EFB — and give the standard four: who you are, where you are, what you want, and your altitude. For example: "Approach, Skylane One Two Three Alpha Bravo, two zero miles southwest of the field at four thousand five hundred, request VFR flight following to Kilo Alpha Bravo Charlie."

Then expect a squawk, expect to be asked for your type and destination, and operate the transponder on the assigned code (91.215(c)). Remember the service is workload-permitting basic radar service — safety alerts, traffic advisories, limited vectoring on request, and sequencing (PHAK 14-26) — and that you remain responsible for navigation, terrain, airspace, and see-and-avoid.