Contents:
Use a tape recorder; ...Aircraft
Radios; ...The Radio; ...Emergency
Locator Transmitter; ...ELT Update;
...Automatic Direction Finder; ...RADAR;
...The Transponder; ...How
the Numbers Work; ...Radar Separation;
...Radar Identification; ...Data
Block; ...Transmitter Failure on Radar;
…Radio Reception Quality; …
Finally, after over thirty years, I have come upon a recorder that will really do the job of recording all of a ground/flight lesson without requring any attention. At $100 it is not inexpensive but it will give you a continuous three hours of recording on a 90-minute tape. It is the Sony Cassette-Corder Model TCM-50DV. It is self reversing and will play at half speed while recording. The negative to all this is that, unless you have another player capable of half-speed playback you must playback on the Cassette-Corder. This can partially be overcome by getting a Radio Shack power adapter of 1.5~3volts so you don't need to use batteries to playback. Get Radio Shack AC Adapter CAT. NO. 273-1654B
If you use a tape recorder on your flights, you must be sure that your patch cord has the proper impedance. A Radio Shack cord with gray or black connectors will work with a 9-volt portable system. An aircraft hard-wired system operates on 12 or 24 volts and must have a 1-meg resistor installed to prevent overdriving the input to the recorder. The use of a tape recorder is the best way I know to improve learning retention.
As many of you know I have always taught and flown with a tape recorder operating. My preference is that the student provides both the recorder and tapes while I will provide the patch-cord. I make the cords in groups of four for economy. I have never charged for them and have lost count of how many are in use. They can be made for about $10. An instructor might want two of them so as to be equipped for both the hard-wired 12-volt (with resistor) and the battery powered 9-volt (without resistor) intercom.
The benefits of recording instruction are several. The student is relieved from note taking and can easily review and take notes later when time is not so precious. The student will be able to review radio procedures and radio situations of which he was oblivious at the time of recording. The instructor is less apt to give instruction for which he might be exposed to liability. Common example is failing to require clearing prior to a turn.
I am now including the Radio Shack part numbers and the actual manufacturing instructions. Failure to use stereo components may mean that your headset will function in only one ear.
Cat No 42-2387 6-ft shielded audio cable. (stereo) Makes two
patch cords.
Cat No 274-1546A Three conductor heavy-duty, shielded 1/4"
phone plug (stereo) Buy two to make two.
Cat No 274-302c Dual headphone adapter (stereo) Buy two to make
two.
Cat No 271-1356 1 megohm resistors (5) Makes five patch cords.
These resistors are not required for battery (9-volt) intercoms.
Assumption:
If you do not know how to use flux and solder and work in a tight
space, it might be better to have someone else follow the directions.
Procedure:
Cut audio cable in half. Three feet is plenty long for cockpit.
Carefully use sharp knife or razor to remove 3/4 inch of rubber
shielding from cut end of cable. Foil is not important but wires
and covering must not be exposed yet.
Take metal phone plug apart and slide knurled outside spring first
over the cable. Failure to make this important step means you
will need to take everything apart afterwards.
Select one of the small resistors and cut one wire to within 3/8-inch
of resistor and make a hook with needle nose pliers . Clip hook
on to the grounding hole of the phone plug. The one nearest the
end. Now might be a good time to solder this connection. Bend
the wire at the other end of the transistor back over the resistor.
Wire this end of the resistor to the bare woven ground wire using
a minimum of wire required to keep the resistor in the groove
and the wires clear. Good time to solder and cut off excess wire.
Now remove about 3/8-inch of red and black insulation from the
ends of the remaining wires. Fold the wires over the holes and
solder them. I don't believe which hole is critical. You want
to make sure that no wires are touching where they shouldn't.
Slide the knurled part of the phone plug up the wire and screw
the plug together. Plug one side into the splitter and you're
ready for taping. Just plug the splitter into the aircraft phone
jack and your headset into the other side of the splitter.
I have used this taping system ever since headsets and intercoms
became available in the early seventies. Prior to that I used
the tape recorder and tried to talk over the cockpit noise and
even later kept the recorder under one of my headset earmuffs.
Not everything is important but a pilot with instructional ambitions
might do worse than saving some tapes for future reference.
The FCC has permanently abolished radio station licensing requirements and fees for U.S. Aircraft.
Navaids Available in the US as of 1997
VORs 1027
ILSs 1197
VASIs 1308
Aircraft frequencies are the same worldwide. Non-military aircraft use Very High Frequencies (VHF); the military uses Ultra High frequencies (UHF).
Frequencies:
ADF 190-535 (1605) kHz (Kilohertz) thousands of cycles per sec.
VOR/LOC 108.0-117.95
VHF COM 117.95-136.0
Glideslope 328.6-335.4
XPONDER 1030-1090
DME 960-1215 (1605)
RADAR 5350-15700
The antenna for a given frequency is 1/4 the frequency length. This length can be electronically as well as physically determined. This allows best radio performance. Antennas have a size determined by the frequency. The higher the frequency the shorter the antenna. A com radio has a wavelength close to two meters and the antenna is close to 1/4 that length. Loran C has an antenna similar to a com antenna. The ELT antenna is slightly more than a foot long. The VOR antenna is V-shaped. A combination VOR antenna and glideslope. The glideslope antenna is often inside the cockpit close to the top of the windshield.
Marker beacon antenna is on the bottom of the aircraft. The antenna is about three feet long and attached at two points. Later models are canoe shaped fiber glass fittings about eight inches long. GPS are teacup saucer sized rectangles or ovals on top of the plane.
As often as not the antenna is at fault when radios work poorly. Vibration and dirt affect both transmission and reception efficiency. Any cracks in the metal or plastic of an antenna housing will open the door to corrosion. During preflight look for cracks and corrosion.
The frequency of a radio is the number you use to determine the number of cycles per second your radio can both transmit and receive. A combination of crystals inside the radio make a large combination of selected frequencies possible. Most modern radios have 720 different frequencies. If you should need to use a 25-kHz frequency on your 720 channel radio, it is nice to know that any final digit readout that ends in 2 or 7 is followed by a 5 even though it does not show. Some radios have switches for this feature but if no switch exists just remember than 123.72 is really 123.725
Varying the compression of the basic frequency transmits the aircraft radio's vocal changes (modulation). Frequency modulation (FM) is not as subject to electrical disturbances as is the more common commercial amplitude modulation (AM).
The aircraft hand microphone is noise canceling. This means that positioned properly the propeller/engine/wind noise will be mostly eliminated. Proper positioning means that the mike is held close to the mouth. A normal speaking voice should be used. If the mike is held sideways by the casual communicator, a hiss or whistle can occur to the listener. Holding the microphone too far away allows aircraft noise to enter along with the voice.
The Emergency Locator Transmitter (ELT) is a 1970 congressional imposed device, which because of technical deficiencies has been unable to perform adequately. ELTs are activated by impact but include hand activation. In 1991 only 61 out of 2037 transmissions were legitimate. All others were false alarms. 97% of past ELT signals have been false alarms. In 75% of the accidents where an ELT transmission was required the ELT failed to operate. In 1992 the time between "last known position" and location of accident by ELT averages 17 hours. If a VFR flight plan is filed the search time is decreased by 48 hours and 63 hours for an IFR plan.
You should know that the General Aviation ELT technology is such that it will be hours before the ELT will actually activate a search. Average time is two hours before search begins. Up to 50 hours before search begins is not unusual. Having a cellular phone is a better option. /Call /afrcc 800/851-3051 for starting an immediate search. ELT's are destroyed or fail to operate 75% of the time. Accident activation rate is only 12% with a 97% false alarm rate. There are 30,000 ELT activations a year.
The satellites in space, both Russian and American, require two passes over two hours apart to confirm and locate a signal source. Search and rescue satellites (Sarsats) interprets any 121.5 broadcast of over 30 seconds as an emergency. ELT location can take from 45 seconds to three hours. ATC facilities are "supposed" to monitor 121.5 but often have the volume too low to hear. Present doppler system accuracy + 20 miles. A GPS type used for ten years is under development fore civil use.
U. S. has SAR (Search and Rescue) centers at Langly, Virginia and Elmendorf, Alaska. Search begins with 'phone search' contacting local authorities to eliminate a false alarm. Civil Air Patrol, COAST GUARD, local authorities conduct actual search. 24 other countries have terminals used for reception of signals.
The ELT must be replaced as placarded on it by date of 1/2 battery life followed by A&Ps signature. It must have aircraft logbook entries as to date of installation and A&Ps signature. Since 6-21-94 ELT inspection required annually as part of annual inspection. It must be replace if activated for one hour. Data, dates and location required information for PTS. (flight test). Pilot's test of ELT is limited to three audio sweeps during the first five minutes of any hour.
The aircraft shutdown checklist includes putting 121.5 on the com radio prior to turning it off. This ten seconds is used to save the time and money that would be wasted if an Emergency Locator Transmitter (ELT) false alarm is pursued by the U. S. Air Force Rescue Coordination Center (AFRCC) now located on the East coast.
Only second generation ELTs (TSO-C91a) can be installed after
6-21-95
Battery expiration dates on ELT and maintenance record
New inertia switch will not activate on hard landings.
Can interface with Loran and GPS
Next generation is:
Emergency Position Indicator Radio Beacons (EPIRB's)
Personal Locator Beacon (PLB's) 406.025 MHz ELT's
Cost is $2,800
System can receive and download information such as position and
identification in one satellite pass.
ELTs in storage must have battery removed.
If you are planning an over water flight consider buying or renting an EPIRB type ELT which can be manually or water contact activated. The 406 ELT transmits a complete identification database for the aircraft and owner. The 406 also has a night strobe for low visibility searches. All of this will be antiquated if the potential of the GPS/Datalink is allowed on the civilian market.
The ADF was the second electronic navigational aid used in aviation. Rotating light towers came first. Fifty years ago Bill Lear (Lear jet) perfected the ADF. The technology is complicated and cost is high. An ADF takes two parts of an AM radio signal through a sense and loop antenna. Comparison of the signals through an electronic Wheatstone Bridge enables a needle to be turned to a bearing to a station. Unlike turning a portable radio for the 'null' the expensive part of the ADF is making it show "to" the station automatically. The ADF has several frequency channels and selector switch positions, which determine what is received and whether the ADF needle is operative. Commercial broadcast stations, non-directional beacons and compass locators can be used by the ADF.
Radio detection and ranging was first developed in WWII. The antenna used was a Yagi; a Japanese invention still used for TV. As a primary system it was relatively inaccurate for distance and altitudes could only be guessed at. A primary target showed as a blurry spot on a screen. Shortly after WWII the French developed a way to remove unwanted targets such as freeway traffic. The British had made a magnetron transmitter tube, just like the one in your microwave.
In much of the U.S. your transponder may be targeted by more than one Center radar antenna. However, your aircraft does not appear as multiple targets. You appear as a computer derived approximation called a mosaic. You are given a circular error of 1/16 of a mile. Thus, the 5-mile airway aircraft separation required by ATC operations orders. Terminal radar is used for Airport Surveillance approaches (ASR) because it is usually located close to the terminal airport.
+ a bit of history
During WWII the British developed a top-secret 10" x 10"
x 10" radar transceiver. It would respond to a radar-
interrogating signal by responding with a coded transmission.
A code would allow the land based radar station to distinguish
British from German aircraft on their radar screen. The radio
also contained an internal thermite bomb which, when triggered
by an inertial switch (crash), would destroy the interior of the
set. This was supposed to prevent German discovery of the codes.
(A reverse ELT?) The British code-named the system Parrot. The
United States Army Air Forces version of the system was called
IFF, for Identification Friend or Foe.
As with many WWII developments, the IFF system was designed
to prevent
a clever German ruse. The Germans were following the night bombers
back to England. German aircraft would join in the stream of returning
British bombers. They would wait until the bombers were most vulnerable,
just prior to landing, and then shoot them down. Parrot allowed
detection of these German aircraft since their (primary) return
would not have a distinctive code. Only 10 codes were available
and they were changed daily.
When radar became available for civil use the size and power
of radar antennae could pick up most aircraft but only 10 codes
had to be expanded to 64 codes. Within a brief period it was expanded
to 4096 codes because the number of aircraft in flight required
a large number of discrete codes for different type operations.
Ground radar transmits on two frequencies one is for powerful
detection the other is a trigger at a high frequency of 1030 MHz.
This trigger causes the transponder to respond on a frequency
of 1090 MHz with a coded reply that can be tailored to the aircraft.
Ground radar will interrogate an aircraft for a few microseconds
by use of a radar beam and then pause for several hundred micro-seconds.
If an aircraft is transponder equipped, transponder will reply
in a Base 8 code which will serve to identify a variety of items.
1200 identifies a VFR flight. Altitude encoders give altitude.
Discrete codes show IFR/VFR flight and/or destination as well
as being in radar contact/communication.
Presently, if an aircraft is not squawking VFR of 1200 it will
have such a discrete code. A VFR flight out of CCR contacting
Travis Approach will have a code beginning with 52--. It is possible
that you will be given a single code that will go with you from
CCR to RNO or FAT. Airliners have single codes that take them
across the country. New computer technology now lets ATC have
instant access to all aircraft in the U.S. that are on flight
plans. All United Airline aircraft can be displayed on a screen
and the individual flight identified as to aircraft, flight number,
altitude, departure, destination, and speed. This information
is available on all flight-planned aircraft.
To control the operation of the airborne set to the best advantage, the ground based radar station would radio instructions regarding the operation of "Parrot". The aircraft would be directed to "squawk your parrot", meaning to turn on the set for identification; or to "strangle (not kill) your parrot" as a directive for turning the set to standby.
The only vestige of this that remains today, other than the entire ATC system itself, is the term "Squawk", as an ATC directive for operation or code for the transponder. Old time ATC controllers may still have you "strangle" your parrot (x-ponder) if it is not working properly.
Today the transponder usually has a four position switch-- off, stby (standby), on (Mode A), and alt (altitude Mode C), a test button, and ident (identification) button, a response light, and four selector switches with numbers from 0 to 7. Certain aircraft letters and numbers cannot be reproduced but frequently the discrete code can be seen to represent a specific aircraft due to their similarity. A transponder is not legal for use unless it has been tested and inspected within the past 24 calendar months and found to be in compliance with ability to squawk a code and an altitude within + 150' accuracy.
All transponders operate on 1090 MHz. For Mode A the transponder gives back only the four digit code. For Mode C includes the altitude. This is done 600 times a second but only 20-30 responses occur during the radar beam passage. If two radar interrogations occur nearly simultaneously the transponder response may become garbled at the radar site. This often leads ATC to claim that your transponder isn't working properly. Your recycling the transponder is a way of changing the response sequence. If one radar location has had no difficulty with your transponder refer the problem site to them. Often different locations are using widely age different systems. Ask that the radar tapes be saved so that the FAA may make an analysis of the problem.
All codes are discreet and assigned by ATC to give other controllers information regarding your type of flight and destination. Operations such as VFR without advisory, VFR with advisory, IFR, destination, specific airport operation, TCA, ARSA, Local IFR, Tower enroute IFR, X-country IFR, emergency, hijack, and radio failure all have differing first two digit codes which tell ATC controllers about your flight and destination. An improved Mode S system is under development which will allow selective interrogation.
An airplane may be without an altitude encoder and operate only on MODE A or ON. Under Mode A, ATC will expect you to maintain either an assigned or agreed upon altitude and to report changes. Flight with Mode A is somewhat restricted. If you know that your transponder does not have Mode C capability, be sure to advise ATC. Know the following restrictions.
Aircraft above 10,000 feet are required to have an operative transponder with Mode C. Aircraft in Class C airspace or above the outer perimeter of the Class C airspace up to 10,000' are required to have a transponder Mode C. Any flight above the Sacramento Class C comes under this last requirement. Any aircraft in a Class B or operating within 30 nautical miles of the Class B primary airport is required to have an encoding transponder. Exceptions are made for aircraft without electrical systems and high mountain flights within 2500' of the surface. The transponder and encoder system must be inspected every 24 months. It is illegal not to use your transponder, while flying, to its highest capacity.
An aircraft without an operating transponder shows, if at all, as a primary target. All transponder targets are called secondary. Under MODE C, or ALT, your aircraft will have an encoder which tells ATC your altitude. ATC will always need to know if your altitude encoder is operating correctly. This altitude encoder is crosschecked by ATC with your altimeter setting via radio. They will remind you of the current altimeter setting and perhaps ask you to switch to MODE A if your encoder is off by more than 300'. An error of 300' makes the transponder unsafe to use for traffic avoidance purposes.
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 piggybacked 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.
Any MODE C traffic that has not been crosschecked will be given to you as UNCONFIRMED altitude. For this reason you should always include your altitude in the information to ATC. Advise if you are level, climbing, descending and final altitude. When you have not been assigned an altitude, be sure to advise ATC when you plan to make changes of an established altitude.
On the ground the transponder should be set to standby. This stops the squawk but allows the transponder to stay warm and ready for operation when needed. The start takeoff, emergency, and post-landing checklist should have transponder as a checklist item. Whenever changing codes on the transponder recommendation is that 'standby' be selected during the change since it prevents inadvertent discrete codes being sent to ATC. The transponder should be turned on as you taxi onto the runway for takeoff. Use of MODE C is now required in many cases as noted in a prior paragraph.
There are 4096 possible code selections on a transponder from 0000 to 7777. This is a Base 8 number system, which is used by computers as a short method of storing Base 2. Base 2 is the number system of computers. The four places of the transponder from right to left are 1's, 8's, 64's, and 512"s. We know it is a base 8 because the highest digit is 7. The eight possible digits are 0, 1, 2, 3, 4, 5, 6, and 7. Counting in Base 8 proceeds as follows:
Base 10
Place Values 512 64 8 l equivalent
0 0 0 0 = 0 This is the 'presidential' code.
0 0 0 1 = 1 (1 one)
Set as transponder to
code numbers. 0 0 0 7 = 7 (7 ones)
0 0 1 0 = 8 (1 eight, no ones)
0 0 1 1 = 9 (1 eight and one one)
to
0 0 7 7 = 63 (7 eights, 7 ones)
0 1 0 0 = 64 (1 sixty-four, no eights, no ones)
0 1 0 1 = 65 (1 sixty-four, no eights, one one)
to
0 7 7 7 = 7 sixty-fours, 7 eights, and 7 ones)
448 + 56 + 7 ones = 511
to
7 7 7 7 = 4095
4095 added to 0000 makes the possible 4096 transponder codes.
More than you ever wanted to know?
Emergency 7 7 0 0 = 4032 in base 10
Nordo 7 6 0 0 = 3968
Hijack 7 5 0 0 = 3904
VFR 1 2 0 0 = 640
Terminal Area (TRACON)
Basic separation within 40 miles of single antenna is three miles
in airport/terminal airspace. IFR/VFR separation is 1.5> miles
in Class B. Beyond 40 miles of antenna it is 5 miles.
Air Route Traffic Control Centers (ARTCC)
5 miles is the minimum for IFR. Several antenna returns are displayed
as one.
The pilot should know that under VFR conditions once you have told ATC that you have visual contact with traffic you may not receive any further radar advisories on that traffic. They may not advise you again of altitude or direction. It is up to you to evade any possible wake turbulence. ATC will let you fly right under a DC-10' wake turbulence and not issue a warning. You must be aware of this lack of protection and be assertive enough to make a 360 or whatever it takes for avoidance.
Radar Identification
1. Contact and identity established by 1-mile or runway is
'contact".
2. Radar return at specific reported position is 'contact'.
3. Radar vectors may be used to identify and establish 'contact'
4. Transponder codes are used. Mode C gives altitude that must
be validated by each successive controller.
The computerized radar is capable of showing the aircraft route, a conflict with another aircraft, range and bearing from any fix, and a minimum safe altitude warning. The code given tells the type of flight and destination. I was recently given a code at Concord that I used all the way to Santa Ana in Southern Califonria..
Infrequently a radio microphone or transmitter will fail when in radar contact. The controller can by a carefully selected series of questions determine what you plan to do. You will be asked to IDENT or not in response to the questions. The transponder can work effectively on low power long after radios and transmitters fail. Taped records are kept of radar pictures and this can be used to locate downed aircraft.
Radio
Reception Quality
5 x 5 is a radio shorthand for the grade of reception
1=worst, 5=best "5 by 5" means all ratings are 5
= best.
Signal
Intelligence
Noise
Propagation
Overall
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Airplane Radio Procedure