Pageg3.5 IFR Systems
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Contents
Contents
…Genesis of the Approach; …ATC at work; …Who's
in Charge?; …Using the System;
…Flight Check of IFR Navaids by FAA;
…Letters of Agreement; …Major ATC Pilot Problems; …ATC
Separation; …Final approach;
…Block Altitudes; …ATC
RADAR Sectors; …Separation Standards;
…Center Facilities; …Radar Help; …IFR
Separation from IFR; …IFR separation
from VFR; …VFR separation from
VFR; …Visual separation;
…Diverging Course; …Radar surface movement; …When
ATC Screws-up; …Radar failure;
…IFR Without Radar; …ARTCC Weather Radar; …Radar
Service Terminated; …LORAN;
…Global Positioning System (GPS);
…Uncontrolled Airspace; …ATC Weather; …Runways;
…Runway Departure Safety Zones;
…Instrument Departure's Three Zones
of Obstacle Clearance; …VASI;
…Tri-color VASI; …PAPI;
…AWOS Weather; …Reading
Charts; …Using ATC in Emergencies;
…Letters for Words; …Transition Level; …
Genesis
of the Approach
The flight time alone to make an ILS costs $1,800,000. The
pilots of the airplanes are rated as airspace system inspection
pilots. They were specialists in making new procedures as needed
that are then sent to the Flight Procedures Section. The computerized
airport information is obtained from Oklahoma City and is reviewed
by the specialists to select the type of procedure that will best
fit into the terrain and obstructions. The selected procedure
is then fitted into the arrival structure and existing enroute
structure. Last, the specialist comes up with a missed approach
procedure.
In 1970 I had an occasion to fly with the FAA specialists in a DC-3 while they put in the ILS at Salinas, CA. We flew from Oakland and flew for four hours around and out from the Salinas airport never above 1200 feet. We landed for lunch and flew another four hours doing the approach over and over in its entirety. A month later I discovered that there was something wrong with the procedure and they were going to do the entire flight all over again.
Apparently there was something that the flight inspection aircrew that followed on to flight check the procedure found did not fit in the TERPS requirements. When finished the procedure is sent to the FAA Flight Procedures Branch in Oklahoma City. Finally, the National Flight Data Center reviews the procedure, checks all the numbers and sends it to a cartographer. The procedure is produced as a NOS chart as accurate as possible in every TERPS requirement and specification.
ATC
at work
The VFR conditions responsibility to see and avoid rests with
you, the pilot. ATC’s responsibility, authority and accountability
for separation exists only under IFR conditions for IFR vs. IFR
flights. A controller who ‘violates’ minimum separation
standards is under zero- tolerance standards of performance. All
other ATC services are subordinate to IFR vs. IFR separation.
Because of this responsibility and accountability the controller
has the authority to assign IFR aircraft altitudes, headings,
routes, and clearances. Under the same VFR circumstances the controller
can ignore VFR flights but he cannot order or command. For VFR
aircraft the controller is limited to advisories and suggestions.
As a VFR PIC you can reject any ATC advisories or suggestions.
A computer detected non-collision bust of 500' or less will be
addressed by administrative action. (Warning letter) A loss of
separation reported by the computer can require recertification
of the controller. Reading back ATC clearances as you have heard
them is a good practice in the event of ATC's failure to correct
the readback. If you are directed to call a particular number
by ATC reply "Roger" but you do not "have"
to make the call. Instead fill out the NASA form to protect your
behind.
If an approach has "radar required" as a note, the approach
cannot be flown except under a radar watch. On any approach it
is good procedure for you to request a "call" for any
fix even though you may be able to determine the fix with your
equipment. Some radar fixes do not appear on the charts. You can
request that ATC call the FAF for you if you wish.
On an approach the radar vector approach gate is normally a mile
outside the marker or the FAF. Radar normally tries to vector
you well outside the gate but can on request give you a close
in or far out vector. Don't let ATC vector you in so close to
the marker that you don't have time to stabilize the approach.
Don't accept vectors to the marker.
You are asked to maintain a speed to match that of the following
jet. ATC has three techniques to place you into this situation:
the tight vector to the FAF, the high speed final, and the slam
dunk. All of these are contrary to what you would use in training.
I have, on occasion, requested a vector 360 so as not to be pressed
by following traffic. ATC may request that you maintain speed
up to a certain point, even the threshold. If ATC asks for a higher
approach speed than you can handle...just say "unable".
You are PIC. Ask for another option. If ATC gives you a too steep/fast
arrival from above the glide slope, miss the approach and ask
for another vector. It is important that both ATC and you have
an understanding as to when you will slow down.
The next problem is being held well above approach altitude. Years
ago at Las Vegas I heard an airliner being so held and then told
to descend for the approach. The pilot complained throughout the
descent and finally had to execute a missed. I later found out
over coffee and doughnuts with a neighbor that he had been the
Captain involved. Getting down for the small aircraft involves
getting the aircraft as dirty as possible and keeping the engine
warm. You could try to do this after a high speed descent but
you risk engine damage. It is wise to pre-plan your procedure
selection before it happens and advise ATC of your intentions.
Don't promise ATC anything you can't deliver. Call upon controllers
for help during emergency situations, but as PIC you must make
and stand behind your decisions.
Who's In
Charge?
ATC exists to ensure enough safe separation between IFR traffic
in controlled airspace. Additionally ATC will provide control
tower airport services, route control for IFR aircraft, and weather/traffic
information. The advent of radar dramatically changes many of
the ATC functions giving ATC the ability, but not the responsibility,
to control and navigate aircraft. ATC is not primarily responsible
for obstacle clearance as written and diagramed in approach plates
and charts. The pilot who expects ATC to take over these latter
responsibility is not using a full deck of FARs. However, anytime
ATC issues an off-airway clearance or vector, ATC is responsible
for terrain clearance. It is up to the pilot to know if an ATC
vector or other instruction is correct or incorrect. If doubt
exists, the pilot should get a clarification. If safety is not
a problem do as ATC directs, but if something seems wrong and
cannot be adjusted to your satisfaction, declare an emergency
and take the safest option.
Student and I had requested IFR to Oakland and received routing
to San Francisco. We waited for new clearance flew it and made
full stop. Requested Napa and received routing to Livermore; waited
for new clearance flew it only to be put into a 25 minute holding
pattern. Flew the hold three times and then canceled clearance.
Requested IFR to Concord. (Home) It was an excellent lesson in
how the system works.
Using
the System
Knowing what to expect is when the pilot holds the winning
hand. Then the pilot is prepared to question any change of direction
or altitude. He is also prepared to follow any ATC directive because
it is within expectations.
ATC is regulated by rules not readily available to the pilot. The antenna system available and in use may limit ATC to requiring aircraft to fly the full procedure instead of getting vectors. With vectors there will be no procedure turns. A ceiling 500' above minimum vectoring altitude or minimum instrument altitude allows the controller to vector for a visual approach so long as visibility is three miles. Once the airport is in sight and reported so to ATC you can get a visual approach clearance. At larger airports you must report a specific runway before being able to get your clearance. An alternative to this procedure is for you to identify and acknowledge that you see a specific aircraft to follow as specified by ATC. By doing so you relieve ATC of any avoidance accountability. A visual approach is not an IFR procedure even when on an IFR flight plan.
There must be an instrument approach procedure before you can get a visual approach. A contact approach does not require that there be an instrument approach procedure.
When weather is variable about vectoring minimums the controller
may bring you in for a look. This means he will bring you into
the final approach course in the hopes that conditions will break
for a visual approach. This vector will take you into the vector
'gate'. The 'gate' is a point that radar uses one mile before
the FAF. The vector clearance includes your distance from the
marker, altitude to maintain until established and the "cleared
for the (type & runway)
approach". Any vector inside the 'gate' must be approved
and accepted by the pilot since there will be little time to make
adjustments.
Just today had the specialist called the outer marker by the
name of the marker for another airport, nearby. Completely confused
the pilot flying. It took several communications to get things
straight. First we had to confirm that the clearance was for our
aircraft. Then we had to clarify the name of the fix, especially
after the controller used it incorrectly a second time.
When on an approach, momentary 'radio problems' may make you miss
the tower giving you RVR minimums that preclude you from making
the approach. Should the radio problems persist until you have
passed the FAF, you can shoot the approach.
There are several ways to get an IFR clearance. The easiest is at a controlled airport and entering the Tower Enroute program. The second easiest is where the Tower Enroute clearance may not be available. You just ask for a Tower Enroute to an approved destination and as soon as you get into the system ask for an amendment.
Prefiling is always an adventure since it is very unlikely
you will get what you filed for unless you use the AFD and get
a 'preferred route'. Even with the preferred route filed and given
as a clearance, you will probably be vectored across the corners.
Telling ATC that you have LORAN or GPS capability makes cutting
corners all the more likely. It does little good to ask
for short-cuts from an approach or departure control. Wait until
you get handed off to the next facility and begin negotiating
there.
I often get the feeling that the way you perform on the radio and in following instructions makes a great difference in how ATC accepts your negotiating requests. Sometimes a delay in getting a short-cut seems to depend on letting conflicting traffic to clear first.
The most interesting of system entries is from an uncontrolled
airport when you use a phone to
get a void time clearance. Most of the AIM references to this
system entry has not been changed since the advent of the cellular
phone. My recommendation would be to get all loaded and ready
to go and then phone the FSS for your clearance. If you tell them
that you are ready, they can get a very short 'time off' for you.
ATC likes this since it does not tie up so much airspace. A ten-minute
time/altitude block on an airway or radar sector can cause quite
a traffic back-up.
The 'pop-up' entry is the easiest if you can set yourself up
properly. This means that you can position yourself over a 'known'
location or intersection, have the correct contact frequency,
and say what you need to say to get into the system. You should
have the proper charts and plates available and perhaps even studied.
The 'pop-up' can be a bit dicey if you make radio contact but
are below an altitude where ATC cannot issue a clearance until
they have radar contact. I faced this situation on a May, 2000
light between Salina KS, and Kansas City, MO. I had no charts
or plates, but with the help of
ATC was able to complete the flight safely.
Flight
Check of IFR Navaids by FAA
--Specific intervals
--Fix accuracy
--Centerline
--Missed obstacles
--Approach obstacles
--Fly edges of approach area
--Fly approach all the way at minimums
Letters-of-Agreement
An LOA puts in writing the extent to which ATC can pass information
from sector to sector and airspace to airspace by Standard Operating
Practice (SOP). These LOA/SOPs cover parachute jumping, military
operations, airspace delegation, SVFR procedures, emergency responsibility,
and IFR procedures.
The 20 centers of the U.S. subdivide authority and responsibility
to other facilities through LOAs. The LOA set airspace dimensions,
procedures, responsibility, authority, time periods, sectors.
LOAs can exist between two airport Class D airspaces. Pre-set
LOA reduces the communications and procedure stress by working
according to a plan.
Different divisions of ATC have developed methods of moving
traffic via a system that is relatively unknown and unknow-
able to pilots. Towers can launch traffic into TRACON air space
as part of a departure clearance including a transponder
code that tells TRACON about the aircraft.
Tracons work on a system of 1000' vertical separation and three
mile lateral separation. LOL aircraft will depart along a
route with an altitude restriction so that the departure allows
multiple aircraft to get in the air and on their way. This is
a pre-
coordinated procedure developed in-house by ATC to make a system
work where otherwise it wouldn't.
APREQ is a variation of the LOL in which individual controllers
make an 'Approval Request'. A controller from one
position are moved to other conditions to help maintain a wider
awareness of the entire system. A pilot request may
require that a controller make an APREQ to allow a selected aircraft
to intrude into another controllers airspace to
facilitate its movement. As a pilot, knowing that APREQ exists
makes it possible for me to take airway shortcuts that
avoid extensive enroute excursions.
Every controller is give a three dimensional airspace designed
to keep similar procedures together and make the work-
load reasonable. I once sat for 15 minutes at a sector screen
where the controller had to talk like a tobacco auctioneer because
the supervisor had combined his sector with another. It was disconcerting
to see how this controller was so loaded up. One incompetent pilot
could have sent the entire mess into a collapsing house of cards.
Major
ATC Pilot Problems
--Entering ARSA/TCA without authorization
--Runway incursions
--Altitude deviations.
ATC Separation
ATC separation is done in three dimensions, vertical, lateral,
and longitudinal.
Vertical separation is based on altitude. The amount of altitude
separation is different for IFR from IFR and IFR from
VFR and VFR from VFR. The hemispheric rule usually applies but
is often evaded when aircraft are being sequenced for
approach, separation will be maintained. Obstacle clearance is
1000'. Every altitude assigned must be above the minimum
vectoring altitude. (MVA) VFR aircraft can be cleared to fly below
the MVA.
Once cleared for IFR you are separated in all airspace except
Class G. An IFR pilot can fly in Class G without dealing
with ATC but without ATC being at all responsible. ATC will separate
only IFR from IFR in Class E airspace. The tower
of Class D will do its best with or without radar to provide separation
but VFR separation is not guaranteed. Class C
ATC separates all IFR from IFR as well as VFR inside the 10 mile
ring. In the 20-mile outer ring of Class C IFR from
IFR is provided but not from VFR. This is because VFRs are not
required to accept ATC control between the 10 and
20-mile arcs.
TRSAs which surround some Class D airspace separate IFR from
IFR but not from VFR since VFR is not required to
participate. Class B provides total separations of everybody from
everybody else. Class A gives total separation. 18,000
to 29,000' IFR from IFR is 1000'; above 29000' its 2000' vertical.
Lateral separation from displayed obstacles is 3 miles. Visual
separation is not allowed by IFR aircraft from obstacles,
even if in sight. Radar separation remains in effect. ATC radar
is used to maintain airspace separations such as special
use airspace (SUA) and jump zones.
Longitudinal separation is normally 3-miles in trail. The aircraft
in front cannot be heavier than the plane behind and the
tower must be able to see the runway's turnoffs. Where wake turbulence
is a factor four-mile separation is required by
small aircraft behind large aircraft and five miles behind the
757. Small aircraft must be six miles behind very large aircraft.
Small aircraft are all that weigh less than 41,000 lbs. Once a
pilot accepts responsibility for separation by saying that he
has a 'point-out' in sight then what happens is totally his responsibility
until he says he has lost sight again. Best option is
to request vectors for greater spacing.
When you ask ATC for a change in altitude, you must realize that
what happens TOTALLY depends on the amount of
separation such a change would allow. Those of you who fly slick
airplanes realize that failure to descend means that you
will have difficulty slowing down when you get closer in. The
turbo does not enjoy being shock-cooled. Just last week
we were denied a descent and vectored on to the ILS just in time
to have a false glide-slope center. The same thing
had happened several months before and the required rate of descent
could not be maintained because of the turbo.
We executed the published missed far above DH. This time we expedited
the descent to catch the FAF altitude check
but it was neither pretty nor smooth.
On the missed we headed toward another airport and were shortly
informed that we could expect a long hold. I had the
pilot slow to approach speed some 15-miles out from the holding
fix. Just as we got to the fix we were cleared for the
approach. Piece of cake. Our slowing gave the controller the separation
that he needed so we did not need to hold.
Final
approach
On final you should realized that at the outer marker you are
five miles out and 1500’ above the runway. Within the lateral
limits of the CDI the slope or steps of the approach will keep
us above any obstacles. As we descend to 200’ above decision
height the lateral limits become so constrained that full CDI
deflection occurs at the end of the runway in only 500’.
Properly flown you have guaranteed obstacle clearance. The new
TERPS criteria obstacle clearance above obstructions at five miles
is 755’ and at DH the new criteria provide 122’. Non-precision
approaches provide 250’ obstruction clearance throughout
the approach. The lights that have reference value for an approach
and landing are the runway lights, the end identifiers, approach
and VASI.
Block
Altitudes
There will be times when IFR flight conditions make it difficult
to impossible to maintain an altitude. Actually almost any time
you can request a block altitude. The block gives you a practice
playground between two altitudes that are above the minimum instrument
altitude of FAR 91.177 or minimum vectoring altitude. This way
you can legally fly so as to be actual by picking up clouds a
few hundred feet higher or lower inside your block. Cloud scooping
it is called.
ATC
RADAR Sectors
Controllers live by rules in 7110.65. A radar controller separates
aircraft as they move through "his" airspace. ARTCC
or Air Route Traffic Control Center cover all the wide open spaces
between Terminal facilities. Terminals funnel aircraft to and
from their airports. Airspace is transferred from ARTCC to Terminals
and thence to airports by Letter of Agreement (LOA)s. "Letters
of Agreement", often unpublished and unknown to pilots, exist
between ATC facilities. These letters allow special flight routes,
altitudes and procedures.
"Radar contact" does not guarantee terrain clearance
any time you are below MOCA or MEA altitudes. ATC radar airspace
is different than a pilot's airspace. A tower may by LOA (letter
of agreement) lose control of a part of its space under certain
weather conditions or because of the needs of an adjacent airport
approach. It helps the pilot to know the ATC preferred direction
of traffic and airspace alignment. Hayward has a LOA with Tracon
to release the top 1000' of its Class D airspace at all times.
Alameda has a similar agreement. CCR and APC release to Travis
control of airspace above a fixed altitude during IFR conditions.
This appears to the pilot as part of the SVFR clearance.
Some sectors and frequencies are more "quiet" than others. On weekends sectors may be combined so the frequency you normally select will be only monitored so as to assign the active frequency. One sector will feed into another sector by means of a "handoff" Several such sectors may feed to a final controller. If too many aircraft are loading up the final sector some of the outlying sectors may be required to "spin" (hold) aircraft to lessen the final controller's load. The "spin" may consist of a completely different routing.
The handing off of an aircraft from one sector to another requires coordination. This means asking approval via phone/computer of the adjoining sector's controller if the will accept another aircraft. Controllers are not allowed to violate adjoining sectors. Your vector may be simply to avoid an adjacent sector. Every favor one pilot receives, delays another. The controllers can't make all the phone calls in time to meet requests in complex environments. Computerized handoffs are rapidly replacing the phone.
Aircraft on the controllers screen have a data tag that gives call sign, type, groundspeed, altitude readout and may include destination, type of flight and a controller letter of identification. The new automated handoff has some problems since the airspace sectors is often subdivided several times. When a controller notes that an aircraft is leaving his airspace he tells the computer. The computer then decided who gets the aircraft. The originating controller may not know who gets it. If the aircraft fails to make the proper radio contact we have a loose cannon in the system. When the Mode S transponders get used every aircraft will have a permanent code.
A "pointout" is similar to a handoff but allows an aircraft to nip through a corner of a controllers airspace without changing frequency or making radio contact. ATC can do this without the pilots knowledge.
Separation
Standards
Some ATC calls are courtesy calls, some are ‘point outs’,
some are advisories, and some are mandatory advisories. The pilot
must learn to listen to the tonal variations of the controller
to separate one from the other since there is no other obvious
distinction.
ATC contract..."provide separation". If standards are violated a "deal" occurs which causes economic and training problems for controller. To protect themselves from the minimums controllers maintain greater than minimum required separation. Separation can be both horizontal or vertical and need not be both. a ‘snitch patch’ in the computer tells if separation is less than standard. Makes a ‘deal’ for the controller
Standard separation is determined by aircraft type, altitude, type of ATC facility, stage of flight (departure, cruise, approach) weather, and antenna distance. If visual separation exists by pilots or by ATC the separation may be much closer than 5 miles. If aircraft are separated by altitude the separation may be as little as 2.5 miles.
A limiting separation factor is the distance of the aircraft from the antenna, class of airspace and size of aircraft (heavy). Minimum is miles within 40 nm of antenna; 5 miles beyond 40 nm. Center (ARTCC) uses 5 nm standard separation and 1000’ below FL290 regardless. Terminal areas most likely 3 nm and 1000’ with visual separation allowed. Vertical rules are same everywhere. There are no standards of separation for VFR aircraft. Only in Classed B and C is IFR separation mandatory. Class B separation of IFR/VFR is 500’ and 1500’. Class C separation is 500’ and ‘green between. In Class C there are no mandatory advisories. VFR advisories are given as load allows.
IFR aircraft fly in a cylinder 10 nm (ARTCC) to 6 nm (terminal) diameter. The cylinder extends 1000' above and below the aircraft, ATC normally allows much more space.
Your encoding altimeter must be within 300' because the "snitch patch" of center's radar is set to alarm if altitudes encroach on 700' separation. An encoder off by 300' could set off the alarm. If you should wander more than 300' off IFR assigned altitude and ATC questions, delay your response until altitude is within 300'. Better yet, advise "unreadable" while making the correction. "Snitch" is found (1993) only in ARTCC radars.
A radar target may not be in ATC contact so the altitude is only ‘indicated’ not confirmed. Traffic advisories are a part of flight following which includes weather advisories, terrain, obstruction, and low altitude alerts. asking for flight following and being given flight following leaves out the rest of radar flight services. You can even request that traffic advisories be omitted from flight following.
An IFR flight with visual contact on VFR aircraft is allowed to maneuver to avoid without regard to an ATC clearance. The radar controller is required to advise you if your target merges with another on the screen. The advisory may just to indicate how far above or below you the altimeter reading indicates. Giving ATC your indication of visual contact relieves them of responsibility. ‘Mode-C intruders’ are aircraft that have encoders but are not in communication contact with ATC. Many radars can give you two-three minute warnings if such an aircraft is in conflict with your route.
Center
Facilities
Radar is a multifaceted term. The antenna of a center is known
as a sensor. Several sensors have their radar returns made into
a mosaic the presents a single picture via digital computers for
each controller’s sector.
Each antenna either an ARSR-3 or -4 has two parts, the search
antenna and the transponder interrogator. Some -3s cannot get
primary targets at all.
Center antenna turn slowly and search in slightly over 10-degree arcs at a time. At a distance the 10-degree arc covers so much distance that a target blip can be a mile long at the 100-mile range setting. At five turns a minute the antenna a target can move several hundred feet between return updates.
Updates are processed to allow the best antenna data to the controller. This data can be used to forecast future positions and to give direct route vectors with a couple of clicks. Projections allow conflict alerts and Minimum Safe altitude Warnings (MSAW) warnings. None of these work within 25 miles of your destination. Carry a sectional.
Center can help with weather because of the multiple antenna
used. One antenna can show the front of a weather condition while
another antenna will show the back side. Light precipitation is
shown as slashes. Where two antenna (sensors) have overlapping
slashes there will be areas of Hs. Pilots should be told by ATC
to avoid areas of such Hs.
Radar
help
Center radar is not good enough to safely call step down fixes.
TRACON can call fixes that are on their screens. There is no way
to know extent of radar coverage to secondary airports unless
you get some idea of the minimum vectoring altitude from the SVFR
clearances given. SVFR clearances usually give an altitude that
in poor conditions indicates the letter-of-agreement separation
altitude of a Class D and TRACON. You might just ask ATC what
it is.
All radar facilities have differing capabilities. Center antenna rotate slower than TRACONs and has a more limited vectoring precision. Center is a mosaic of a number of long range radars and a given controller has a limited sector scan for working aircraft in a specific area. Within 40 miles of the antenna separation is 3-miles; beyond that it is 5-miles.
I have, on occasion, had ATC indicate that I am drifting off an airway centerline. This is even though my CDI is centered. The solution is to indicate that you would like a vector to intercept his center line. It is the pilots responsibility to know where both high and low terrain lies. This information is best obtained from a sectional.
The NEXRAD is a set known as WSR-88D which has both a clear
air mode and a precipitation mode. In the precipitation mode the
size of droplets can be determined.
IFR separation
from IFR
--VFR-on-Top and visual climb/descents responsibility: A VFR
on top clearance is all right below a cloud deck or between layers
as long as you can remain VFR and meet cloud clearance-criteria.
ARTCC 5 miles/1000' Relieves ATC only during altitude change.
Class B 3 miles/1000' Other aircraft need not be visible.
Class C 3 miles/1000' Use when possible.
IFR
separation from VFR
ARTCC nothing When IFR pilot agrees to keep visual separation,
ATC is relieved of responsibility.
Class B 1.5 miles/500'
Class C conflict/500' Pilot may climb, descend or get closer than
ATC minimums.
TRSA 1.5 miles/500'
VFR
separation from VFR
ARTCC nothing
Class B 1,5 miles No requirement but you may get traffic advisories
and safety alerts.
Class C nothing Be careful in Class C.
TRSA 1.5 miles
Visual
separation
ARTCC limited Must report aircraft in sight to ARTCC
Class B allowed then must report passing clear. Seldom used.
Class C allowed ATC controller uses his visual contact of allowed
aircraft involved to expedite
TRSA When a pilot acknowledges visual contact he relieves ATC
of responsibility for
separation.
Note: There is no time duration limit on this exchange
of separation responsibility. A pilot can hand back this responsibility
to ATC by advising that visual contact cannot be maintained or
is lost.
Diverging
Course
ARTCC no
Class B allowed This means IFR aircraft at same altitude may be
allowed to break minimums if their
Class C allowed courses are divergent.
TRSA allowed
Radar
surface movement
Guidance and control system (SMGCS); Special low visibility,
RVR less than 1200', taxi routes with lighting and surface markings.
Green taxiway centerline lights, 2 red lights on each side of
the taxiway serve as stop bars, these are ATC controlled. At no
time shall a pilot cross an illuminated red stop bar. Flashing
yellow lights are across taxiway in runup area as taxi-holding
position lights. Position markings are pink circular numbered
marking along taxiway. 3 amber lights across center of taxiway
are holding bar indicators.
See the AIM for latest on airport markings...a MUST
When
ATC Screws-up
The ATC system requires that the pilot maintain the situational
awareness required to know when something is missing from a clearance,
a route, frequency change, or a procedure. Be prepared to question
ATC instead of waiting for them to recognize a problem. Be prepared
to protect yourself by knowing what is supposed to happen.
Radar
failure
If approach facilities do not have radar...no traffic can
be seen. When radar fails at a radar facility two backups exist:
DARC is used by Center. Cenrap is used by approach
When ARTS computer fails all aircraft are given the same discrete
code, slashes appear instead of numbers. When a complete radar
and computer failure occurs we have a reversion to CENRAP which
will use a radar signal from one of centers antennae. Separation
becomes 5 miles instead of 3. Mode C is unusable so all altitudes
must be reported. No altitude or conflict alerts can be given.
Aircraft are put into lines at different altitudes and processed
to the approach and landing in order. Pilots should expect requests
for position and altitude.
IFR
Without Radar
An approach is called "single threaded" if only one
IFR operation at time is allowed due to lack of radar coverage.
--Plan to execute the full approach procedure in non-radar conditions.
--Know and obey the altitude restrictions.
--You must make the required position reports.
--Leaving an altitude
--Procedure turn inbound
--Final approach fix
ARTCC
Weather Radar
ARTCC radar has three keys WX 1-2 and 3. which will give rain
return information on a digitized circuit. It takes 4000 feet
of clouds to make rain. If its wet where you are, figure to climb
at least 4000' to top the clouds. This information must be requested
by the pilot. Digitized Hs on his screen indicates weather to
be avoided. The controller is obligated to give you the worst
possible interpretation of any weather return.
1995 NEXRAD radar coverage is 100% east of North Dakota line to
the Gulf. WSR-88 display precipitation and wind if particulates
are present in the air. Data will go to Center Weather Service
Units and Flight Service Stations. 175 antennas will give circular
coverage out to 285 miles up to 10,000'. Most will be away from
major airports about 10 miles. It can sector scan over airport
and down main weather runway. In the future these displays will
be in the cockpit.
Radar
Service Terminated
Becoming overly dependent on radar can cause problems. You should
be prepared to operate in a non-radar environment. This means
defining your own fixes, required reporting points, and altitudes.
Without radar to help, your are responsible that your position
and altitude will provide terrain clearance. Your preflight preparation
made you aware of terrain and obstacles that intruded into your
approach route. Review the chart to make sure that the correct
frequencies are set. abandon the approach if you feel that something
isn't right.
Radar service terminated means that the pilot will become totally
responsible for the altitudes, headings, terrain, and aircraft
on his flight route. Some radar services are automatically terminated
in IFR conditions as:
1. Cancellation of IFR flight plan except where basic radar service
is always provided as in Airspace Classes, B, C, and TRSAs.
2. When on an instrument approach ATC advises to change to the
CTAF or tower frequency.
3. On completion of a radar approach.
4. VFR aircraft told to change frequency, or squawk VFR.
LORAN
If you have non IFR LORAN or GPS they can be used as advisory.
LORAN like GPS can fly you into terrain unless it has the correct
data base. The mutual use of Loran or GPS by two aircraft in the
vicinity of a given intersection or navaid greatly increases the
likelihood of a mid-air. The accuracy of these makes such an accident
probable where with the use of VORs it was unlikely but possible.
Global
Positioning System (GPS)
Paper charts will still be required in addition to a local
GPS transmitter that may or may not be capable of avoiding any
military induced GPS errors. A faulty navigation signal is flagged
within 30 seconds.
For Receiver Autonomous Integrity Monitoring (RAIM) six signals
are only required so many areas and approaches will have RAIM
"holes'. GPS overlays will be added to current approaches
primarily to improve course guidance. FAR 91.205(d)(2) says that
for IFR navigation equipment appropriate to the ground facilities
to be used must be operational and on the aircraft. The greatest
problem to be resolved is the IFR approved GPS which allows DME
and ADF substitutions on a published overlay.
GPS can confirm the information on the HI, altimeter, airspeed
indicator, VOR, ADF and correct the DME. GPS can be used to point
toward the airport. (See GPS material under VFR cross-country)
The military accuracy will be available to all as of April 1996.
If flying with a hand-held or panel mounted GPS not certified
as IFR, just file ‘GPS equipped’ under remarks
There are 4600 GPS overlay approaches. Fixes have been converted
to GPS waypoints. There is no vertical information at the waypoints.
All GPS navigation is TO a waypoint. Some synthetic fixes have
been created to allow outbound headings and for increased GPS
sensitivity on final approach. Timing is losing its importance
for determining the missed approach point.
There are GPS Phase II and III overlay procedure charts. On
NOS charts there is no way to tell the phase. Jeppesen
provides a list. Phase II requires that navaids be available but
you are not required to use them.
Phase III charts have GPS or ... this form of GPS is a stand alone
procedure. On airways you can use GPS if you also have standard
navaid devices.
GPS provides an opportunity to seamlessly bring arriving and departing
aircraft in and out of airports including taxiing.
The WAAS system will allow due near the end of the year 2000 will
allow 3000 non-precision runways to be used for
precision GPS approaches with an system error of 21 feet. WAAS
will allow accurate altimeter settings and reduce the
90% of CFIT accidents that occur within 15 miles of an airport.
WAAS has precisely surveyed station locations that
correct standard GPS system errors.
Uncontrolled
Airspace
Uncontrolled airspace is just that. Any current instrument
pilot can fly IFR in uncontrolled airspace wherever it's IFR.
Airspace below 700/1200 AGL is uncontrolled. You don't need an
IFR flight plan or clearance to operate there, regardless of weather.
You do need to follow 91.177 and 91.179 regarding minimums, however.
Can't be done? ATC says the pilot is on his own until reaching
controlled airspace.
The ultimate IFR question is whether what you did was the right
thing to do. Any arrival or departure from an uncontrolled airport
will involve IFR flight in Class G airspace. This means at least
some small portion of the flight does not have the services of
ATC for IFR separation. The purposes of the 1200 and 700 foot
transitions areas is meant to maintain IFR separation services
on the approach corridor for as long and as low as possible.
There are a few Class E airports and a number of Class D airports
that have Class E extensions activated by below
VFR minimums. These Class E airspaces touch the ground and have
ATC IFR separation services. The Jepp charts show such airports
with a small E but NOS charts show nothing. The sectional is the
best place to look. Look where an FSS airport used to exist or
where an official weather observer was once available or has been
replaced with ASOS/AWOS. The type of approach has nothing to do
with the type of airspace. VFR flights will require a SVFR clearance.
The FAA can cite you for a violation when flying IFR in uncontrolled
airspace even though FAR 91.173 says you don't need a flight plan
or a clearance. FAR 91.155 allows you to fly IFR in uncontrolled
airspace. Once you get above 700’ AGL you IMMEDIATELY must
comply with the required VFR cloud clearance. Better to stay low
and find some 1200’ transition airspace before looking for
an area where you can climb with required cloud clearance. The
FAA will catch you on FAR 91.13 for careless and reckless flight
if you don’t have the cloud clearance.
ATC
Weather
Within limits wind determines the runway ATC will select. When
wind is less than 5 knots ATC may select a noise-abatement runway
or even a downwind runway. Visibility determines the right to
do an approach, land, or takeoff. ATC is a source of advice but
the action is up to the PIC.
Ceiling requires a decision on an alternate, if the destination
weather is forecasts or reported not to give a ceiling of 2000'
one hour before or after plus three miles of visibility at ETA.
Precision alternates must have 600 and 2, non-precision 800 and
2. Ceilings from any source are legal for Part 91.
Runways
--Precision
This is the safe bet with DH 200’ HAT, lights and 1/2 visibility
--Precision with obstacles inside DH
DH 250 or higher, 1 mile visibility, may have lights. Over 250
DH means obstacles inside DH.
--Non-precision
Could have 1/2 mile visibility, clear approach path on centerline.
VASI and/or VDP, usually the ILS runway
--Non-precision with obstacles below the MDA
VASI say no obstacles on final from four miles out. If you are
unfamiliar you may or may not have obstacles.
Runway
Departure Safety Zones
An ATC clearance does not assure obstacle avoidance during
departure. Obstacle clearance occurs only when ATC radar provides
navigational direction such as radar vectors. Until such assistance
is obtained it is the responsibility of the pilot use visual charts
to avoid hitting anything. SIDs allow departure planning and reduce
communications. Use an area chart or sectional to confirm terrain
and location of obstacles. Advise departure of your need for a
specific departure or SID due to limited climb performance. ATC
will accommodate your request.
Instrument
Departure's Three Zones of Obstacle Clearance
--The first zone is from the departure end, 500' to each side
and 35' high in a 15-degree fan to each side for a distance of
two miles in a 40:1 slope or 152 ft/nm.
--Zone 2 extends from a point on the centerline of the runway
and 2000' from the approach end. This zone extends in a semicircle
arc toward the departure end at a 40:1 slope until reaching minimum
enroute altitude (MEA).
--Zone 3 extends from the same point in a 40:1 slope toward the
approach end of the runway until reaching the MEA.
VASI
If you have visual contact with the runway the FAA recommends
flying the VASI if it is available. If there is a visual descent
point (VDP)You can descend below the MDA if you have visual reference
as required by FAR 91.175(c)(3). You cannot descend below the
MDA before the VDP.
According to FAR 91.129 (d)(3) a flight into a VASI at a controlled
airport with the tower open must remain at or above the glidepath
until lower is required for landing. The rule applies only to
a VASI and not to other glideslope light system. The rule applies
only if the tower is operating.
The three-bar VASIs has two glide paths. The far two bars are for large aircraft; the two near bars are for small planes. Normal glide path is 3 degrees and upper glide path is 1/4 degree higher. Some locations have 4.5 degree glide path to give obstacle clearance. VASI is not part of instrument landing system. An inoperative VASI does not affect IFR minimums. Obstacle clearance up to 4 miles or less and 10 degrees to each side.
Tri-color
VASI
Green is on glide path, white is above and amber/red when
below.
PAPI
Four lights to left of runway. 4 white for high 2 with/two
red for just right, four red for low.
AWOS
Weather
--AWOS-3 is official weather.
--Airport may qualify as alternate airport with AWOS-3.
--AWOS-3 gives altimeter, ceiling, visibility, wind, temperature,
dewpoint, and density altitude above 1000'
--At controlled airports AWOS-3 is available only when ATIS is
not.
--Some AWOS have a phone number listed in A/F Directory.
Reading
Charts
The geographic coordinates are at the airport reference point
(ARP) shown as a circle with a +. The letter K now prefaces every
three-letter airport designator. Airport elevation is the highest
useable runway surface. Frequencies are listed as used for arrival.
Airport diagram is drawn to scale with magnetic bearing below
runway number at end of runway. Takeoff minimums, visual reference
and climb gradient is given by aircraft categories. Departure
procedures may be either for IFR or Obstacles.
…53,000 changes in Jepp charts every week;.
… Lower left corner is "Changes" Of the three options
will be 'reissue", 'see other side', 'Chart reindexed', or
a specificat-
ion as to the change.
…All chart changes are recorded and the last change is printed
on the lower left margin vertically.
…The plan view is the largest area displayed below the briefing
strip. The scale of the view is along the left side. This scale
is normally one inch to five miles but may be 7.5. The symbols
are the same as as on the enroute charts. The inbound course
is a bold line. Approach plate frequences are on the briefing
strip as well as ovals on the plan view. Dark lines can be used
as transitions while light lines cannot. A dark holding patter
indicates it is a part of the procedure.
…Profile not to scale
…Markers showed as shaded areas
…Markers have altitudes for the approach
…Compare altritude at marker to TCH on chart
…Marker altitudes are minimums unless designated by mandatory,
maximum, or recommended
…Final approach is from Maltese cross
…Precision FAF is where glide slope intercept altitude meets
glide slope.
…Touchdown elevation is highest point of first 2300 feet
of runway
…Profile distances can be confusing. FAA leaning toward all
DME rather than time.
IFR RNAV Chart
…No more charts with GPS in title. RNAV used instead.
…Extreme cold conditions cause inaccurate altimeter. See
Chart warning on briefing strip.
…TAA (Terminal arrival procedure) allow arrival from any
direction without course reversal.
…UNAYY system chart has minimum safe altitudes in several
quadrants.
…GLS is the GNSS or global navigation landing system using
WAAS with 200' and half-mile minimums.
…LNAV/VNAV (lateral and vertical) uses special altimeter
GPS charts are now named RNAV because the FAA standard will put all forms of RNAV on one chart. the minimums for different systems will be different. LNAV minimums apply to IFR certified GPS. Approach plates are designed to allow pilot nav operations. This makes the load on ATC lighter.
…Existing GPS procedures will be updated but new
GPS procedures will be called RNAV.
…Terminal arrival Areas (TAA) will now give altitude and
course information from any direction for an approach.
…lfThe purpose of the TAA program is to eliminate any need
for a course reversal of any kind.
…TAA altitudes can be used instead of the previous MSAs.
The TAAs can be flown as approach altitudes whereas MSAs were
emergency altitudes only.
…The WAAS system will give 200' minimums with 1/2 mile visibility
Using
ATC in Emergencies
Complete aircraft engine failures is relatively rare because
of simplicity, duality and strength. Of all aircraft components
the pilot is most likely to initiate a flight failure. The cheapest
engine failure insurance you can get is the best possible maintenance.
Even so, engines can be expected to give some warning. All flying
accidents could be reduced by 80% were pilots to use common sense
and a conservative approach to flying. It has been recently disclosed
that there is a 'risk-gene' that drives certain personalities
to take chances. Fuel, altitude and the 180 add reserve to the
so-called critical margin of safety.
The airport that is five nautical miles distant may be reachable in a failed-motor aircraft but it is likely that the reaching may not provide enough margin to make a landing. It is far better to use your 2-miles per 1000 feet to select a closer landing place that will allow a more normal positioning for landing. A normal landing attitude at the lowest possible airspeed at ground contact is the most survivable accident you can ever have.
In an emergency it is far better to tell ATC about your circumstances
and what you are going to
do. Only if you lack local area knowledge should you ask for directional
help.
The entrance of weather into the equation requires the pilot to start reading in-between the lines of what is happening over the radio. Night and a non-precision approach compounds the hazards of weather.
Some situations are such that very vital information is casually passed that have significance not brought to the attention of the pilot. ATC may change runways, turn up lights, remark on missed approaches and approve holding without equating these as red-flag warnings to a particular aircraft or pilot. With ATC emphasis a pilot may ask for an alternate missed, a vector for holding, or an update on existing visibility conditions. This visibility is important because if a visibility change has occurred since the pilot has passed the FAF he might wish to abort the approach. The failure to pass on information related to rapidly changing weather is hazardous to flight safety.
Letters
for Words
MNPA Minimum navigation performance airspace
RVSM Reduced vertical separation minimums airspace
AMASS Airport Movement and Safety System
MEA assures obstacle clearance and radio reception.
MOCA Obstruction clearance off airway but radio reception 22 miles.
(Jeppesen has a T)
MORA - Jepp only minimum off-route obstacle clearance within 1-
miles.
MCA - Minimum crossing altitude with associated Minimum Enroute
Altitude change to follow.
MRA - Minimum reception altitude capable of identifying an intersection
or allowing navigation.
MAA - Maximum authorized altitude because of amount of traffic
on airway.
MSA - Minimum sector altitude is pie chart depiction of safe obstacle
clearing altitudes.
Transition
Level
The transition level is the lowest flight level above the
transition altitude. The transition level is only used when descending,
and must be picked up from ATIS or Tower before landing. The transition
level is where the altimeter setting is changed
from STD to QNH. The layer between the transition altitude and
the transition level is called transition layer. It is somewhere
between 0 and 500' thick, and no level flight is allowed there.
Reason is that both QNH and STD references are used here.
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Return to IFR
Contents
Continued on IFR
Systems Equipment