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Pilot Radio Communication
Pilot communication manual for student flight training
This is a copy of our Pilot Communication manual- Please excuse any typo's or broken links
Radio Operation
AA 12 Audio Panel
• ICS/Volume knob — Sets headset volume, usually about one third up from left
• Vox/Squelch — Set too low = cutout, set too high=static, usually one third up from left
• Transceiver selector knob — Selects Xmit and Receive radio, up to 3 comms.
• Receiver selector knobs — Top row selects comm receive only through headset, bottom row selects
• nav radios through headset. Can have one radio xmit/rec and other radios rec simultaneously.
• Pilot ISO/Norm switch — Isolates pilot from passengers
• TX light — Illuminates when a radio is transmitting.
King KY 97A— Comm only radio, 720 channel
• Off/on/volume knob — Turn right to turn on, increase volume. Pull out to set volume level. Frequency display — active on left, standby on right.
• Arrow button -~ exchanges standby for active frequency
• Inner/outer frequency selector knobs — outer large knob tunes big numbers (XXX.000), outer small knob tunes
000.XX numbers, i.e. .85, .90, .95
• Pull small knob out to tune .OXX frequency, i.e. .925, .975
• “CHAN” button — Push to activate nine frequencies in memory storage. When “CHAN” pressed, frequency dials cycle through frequencies in memory.
Buttons on cyclic will also flip-flop frequencies and change memory freqs.
Transponder Operation
King KT76C Transponder — 4096 codes with altitude encoding altimeter (how do you know?) OFF/5TBY/TST/ON/ALT knob
• OFF — turns transponder off.
• STBY — Basically a warm-up position, on but not transmitting, not as important now that xponder is solid state.
• TST — Illuminates all display features to verify they all work and runs self diagnostic.
• ON Transponder is transmitting location without transmitting altitude info. Essentially no Mode C.
• ALT — Transponder transmitting location and altitude readout. This is normal operating position.
IDT button — This is the “ident” button. This “blossoms” your aircraft on controllers screen to make stand out. Only necessary to push and release.
VFR button -~ This will immediately change the code to 1200.
Code Entry Buttons - These are the 0,1 ,2,3 Used to input your assigned “squawk”. Normally set to VFR code of 1200. There are certain codes that you want to avoid (unless they are applicable):
• 7700 — emergency
• 7500—hijack
• 7600— loss of comm.
CLR button — erases code entered one number at a time, starting from the right (allows corrections)
Left display window — displays altitude in hundreds of feet that is being sent by encoding altimeter to ATC, designated by “FL”
Right window display — displays 4 digit code that you are “squawking” and what mode Xponder is in, i.e. “ALT” when altitude reporting
Other display — “R” lights when Xponder is replying to an interrogation.
ATC Pilot Glossary
More on AIM page 819
Abeam — An object or point app. 90 degrees to the right/left of aircraft track
Affirmative – Yes
Altitude readout indicates — Used when ATC has an unconfirmed Mode C radar return.
Cleared for takeoff Cleared to land
Cleared for the option — Tower clears pilot to make t n g’s, full stop landing, low app, etc at pilot’s discretion.
Cleared into Class B airspace — You need to hear this BEFORE entering any Class B airspace.
Confirm — ATC wants you to confirm the question, such as “4SH, confirm 1,500”
Expedite — ATC wants you to do something as soon as possible, such as takeoff, clear the active runway, etc.
Go ahead — Normally used in communications, proceed with request.
Go around — Immediately discontinue landing approach and re-enter pattern.
Have traffic — Use when you see the aircraft traffic that ATC has alerted you to.
Heavy — Aircraft potentially over 255,000# GW. Significant because of wake turbulence.
Immediately — Do it right now!
Looking — Use when you don’t see aircraft ATC has alerted you to. Maintain — As in maintain runway heading, maintain a certain altitude, etc. Negative — No
Negative contact — Same as “looking”, probably more correct if you really want to be conformist.
Radar contact — ATC has positively identified you on radar.
Radar service terminated — Used by ATC when leaving their airspace or if controller gets too busy. Readback correct — ATC confirming you have correctly understood their instructions, usually for clearances. Report — ATC wants you to let them know when you are at a certain point, i.e. “Report left downwind, 28”.
Resume own navigation — Usually used when you had been given radar vectors around traffic or to a location.
Roger- Last transmission was understood. Often overused.
Runway heading — Used with “maintain” usually in Class C or B to initially get you away from airport.
Say again, please — Never be afraid or embarrassed to say this!
Say altitude — In thousands and hundreds of feet, i.e. 1,500 “45H, level one thousand five hundred”.
Say heading — Use magnetic heading from compass or directional gyro.
Squawk XXXX— The 4 digit code that you input into the transponder. “Squawk VFR” 1200.
Standby — Wait until ATC gets back to you, usually used when they are very busy.
Taxi into position and hold — Cleared to taxi/hover onto the runway but NOT cleared to takeoff.
Traffic in sight — You reporting seeing an aircraft that ATC has alerted you to.
Traffic no longer a factor — You can stop looking for the traffic.
Unable — Cannot comply with ATC request, i.e. “4SH, can you give me 150 knots on final?”
Verify — Essentially interchangeable with confirm.
Wilco – Will comply. You are going to comply with the instructions just given.
Terms not to use
No Joy
ATC & Radio Procedures
Will learn to hate or love ATC, but you are going to have to deal with, so better develop skills.
Setup while warming up. Know the frequencies that you are going to use and setup accordingly. You may be tempted to use both radios, but not rec for awhile. Use GPS for listening only, like ATIS or AWOS or even 123.02. You want to have the mike very close to your lips, this reduces wind and other noises (don’t need to lick)
English is language of aviation worldwide. You are in the system, just like a 747 so conform! Not the place to display individuality.
Phonetic alphabet and nine — to avoid confusion
Can just use “Helicopter such & such”. Fixed wing will use Cherokee, Bonanza, etc. ATC may ask; “554SH is a Robinson R22” is sufficient.
Plan what you are going to say, think it through. This will help eliminate the “uhuhuhuhuh’s” and that is good. Try to be economical. For example, don’t need to use “Control” with ground or approach/departure. It also helps if you can anticipate what ATC is going to say.
Listen before you talk —in both uncontrolled and controlled environment. Most important with controller from embarrassment point. You may hear only one side of conversation, especially with center or app.
Most transmissions are a combination of; Who you are talking to (only on initial contact), who you are (ALWAYS), where you are (what altitude with center and app) and what you want. Tell where you are when taking off.
N# is for USA aircraft — no need to state unless going to Mexico, Canada, etc
Use entire N# until ATC shortens it first, could be A/C with same last three numbers/letters (554SH & 654SH) or could even sound the same.
In uncontrolled airport, state full intentions around traffic pattern. However, with center, app or tower, you may want to just call up without giving spiel and let controller get back to you. lf= real busy, not busy at all or you have a real long request that you don’t want to repeat. Discretion. Do not ask over and over if getting no response, go back to previous frequency and check to see if radios are set up OK. Frequency when changing controller is in standby, can go back to it if no answer.
Talk at reasonable speed and don’t be afraid request information over (say again). Go ahead and tell that you are a student pilot. If ATC tells you to report over some landmark and you don’t know, tell that you are unfamiliar with area. Same thing about airport, ask where transient parking is, ask which taxiways if don’t know or get lost. You don’t have copilot to read map.
Class B & C departure — Call before you are in hover so can write clearance info down
Need to repeat “to do” information like where to report, cleared for takeoff, cleared for landing, etc. Not necessary for info call like wind speed, in radar contact, clear of traffic, etc —just acknowledge with call sign.
When approaching C or B, get ATIS beforehand and let approach know. Also let tower know when you switch over or they will probably ask.
Reporting altitudes — when changing controllers (app) just say: “Helicopter 554SH level 1,500”. Always use thousand then hundred, so no fifteen hundred. If not level, always report altitude climbing/descending through and target altitude.
Not only listen before talking, but listen for your aircraft call sign. Use Iso switch if necessary, and be prepared to silence (politely but firmly) if you need to talk. Also, don’t be afraid to report your position just because an instructor is talking to you; DPE will be looking for that.
Tower will sometimes tell you to “Contact ground .9” Always 121 .x
Helicopters can arrive/depart direct to many destinations on airport. For example, if you are at the helipad at Modesto airport and are departing, you could call up the tower and request a present position departure.
Coolness factor - do not respond to ATC without using N number. Do not respond by just clicking mike. No “roger that”, “OK’s”, etc.
Whatever you do, DO NOT SACRIFICE CONTROL OF AIRCRAFT TO TALK ON RADIO!!!!!!!!!!!!!!!!!!!!!!!
So now, let’s compare two radio calls;
“Modesto Control Tower, this is helicopter November 554SH. I am a Robinson Model R22 Beta II. I am ten nautical miles west-northwest of Modesto City-County airport and my altitude is 1500’ MSL. I would like to land at Modesto airport and I have the current ATIS information Delta.
Please respond with landing instructions. Over.” 56 Or the same thing could have been said;
“Modesto tower, helicopter 554SH, ten west, landing with Delta”. 9
ATC Situations
CENTER
When to contact — On a long trip when you are flying above 6000’ and you would like VFR flight following.
What to say — Assume you are on a trip from Los Banos to Palm Springs. You have taken off and have climbed to 7,500’ and are over Firebaugh.
“Oakland Center, helicopter 7532D over Firebaugh level 7,500 for Palm Springs, request VFR flight following.”
APPROACH/DEPARTURE
When to contact — 20-40 miles out from destination or anywhere if you would like to request VFR traffic advisories.
What to say:
1. You are approaching Class B or C airspace and landing at the primary airport; “Fresno Approach, helicopter 7532D, 20 west @ 1,500 for landing with Delta”
2. You would like VFR traffic advisories;
“Norcal approach, helicopter 7532D over Madera for Modesto @1,500. Request flight following”.
3. You are receiving VFR traffic advisories and are being handed off to a new sector; “Norcal approach, helicopter 7532D level 1,500”.
TOWER
When to contact - When you are approaching a Class D airport, are being handed off by approach control at a Class B or C airport and when you are ready for takeoff. What to say:
1. You are ten miles to the west of Salinas;
“Salinas tower, helicopter 2312J, ten north landing with Delta”
2. Salinas approach is handing you off to Salinas tower; “Salinas tower, helicopter 2312J inbound with Delta”
3. You are at SNS, ready to takeoff from 26 and you want to make a right turn departure for WVI; “Salinas tower, helicopter 2312J ready for takeoff 26, request right hand departure to Watsonville”
GROUND
When to contact —When arriving and clearing the active runway, when at parking and desiring to taxi/hover to a runway for takeoff or you are getting your “mini” clearance at a Class C airport.
What to say —
1. You have just landed at Modesto on 28L, hovered clear at taxiway Bravo and the tower has told you to contact ground. You wish to go to transient parking;
“Modesto ground, helicopter 7532D, clear 28L at Bravo for transient parking”
2. You are at Modesto transient parking and want to go to the active runway; “Modesto ground, helicopter 7532D transient parking for taxi with Bravo”.
3. You are at the helipad at Sacramento International airport and are returning to Los Banos ~
2,500’
“Sacramento ground, helicopter 7532D, helipad with Charlie, VFR to Los Banos ~ 2,500’, request present position departure”.
CLEARANCE DELIVERY
When to contact — When departing VFR from a Class B airport or at a Class C airport when so advised by ATIS.
What to say - You are at Signature Flight Support at SF0 and wish to depart from your present position VFR for Los Banos ~ 2,500,’
“San Francisco Clearance Delivery, helicopter 7532D, Signature with Delta, VFR to Watsonville @ 2,500’,
request present position departure”.
Class C Airspace Scenario
You are twenty-five miles north of SNS @ 1,500, information Juliet is current. You want to land at the helipad and stay for about an hour.
ARRIVAL
• NorCal approach, helicopter 694DC. Helicopter 694DC, NorCal approach, go ahead.
• Helicopter 694DC is 20 miles north @ 1,500, landing with Juliet. Helicopter 4DC, squawk 4217.
• 4DC,squawk42l7.
Helicopter 4DC, radar contact 20 miles north @ 1,500.
• 4DC.
4DC, traffic 3 o’clock, 2 miles, altitude readout indicates 2,200.
• 4DC, looking. OR
• 4DC has traffic.
Helicopter 4DC, where would you like to go on the airport?
• 4DC would like the helipad.
4DC, traffic 12 o’clock, 4 miles, is a United Express Metroliner climbing through 1,100 for 8,000.
• 4DC has the Metroliner. 4DC, what type helicopter are you?
• 4DC, Robinson R22 4SH, traffic no longer a factor.
• 4DC.
4DC, contact tower 119.4
THEN:
• Tower 119.4.
• Salinas tower, helicopter 694DC inbound @ 1,500 with Juliet.
Helicopter 694DC, wind 320 © 10, altimeter 29.98. Confirm you’d like to go to the Helipad?
4DC, cleared to land on the Helipad, traffic on short final 31 is a National Guard F16, wind 310 @ 09.
• 4DC, cleared to land Helipad, have the F16.
DEPARTURE
You are departing for Los Banos @ 1,500. You would like to depart directly from your present position at the big H. Current ATIS is Kilo.
• Fresno ground, helicopter 694DC adjacent big H with Kilo, VFR to Los Banos @ 1,500, request present position departure.
Helicopter 694DC, Fresno ground, after takeoff maintain VFR at or below 2,000 on course for Los Banos, squawk 3514, Fresno departure on 119.6.
THEN:
• Helicopter 694DC, maintain VFR at or below 2,000 on course for Los Banos, squawk 3514, departure 119.6.
• Fresno tower, helicopter 694DC ready for takeoff, big H.
Helicopter 694DC, Fresno tower, cleared for takeoff from present position, avoid overflying parked aircraft. Caution, wake turbulence from departing UPS 757.
• 694DC cleared for takeoff present position, avoid overflying parked aircraft.
4DC, contact departure. Have a good flight.
THEN:
• 4DC, contact departure. Thanks.
• Fresno departure, helicopter 694DC climbing through 1,300 for 1,500. Helicopter 5545H, Fresno departure, radar contact 3 miles west of the airport @ 1,300’.
• 694DC.
Helicopter 694DC, traffic 10 o’clock, 1 mile, altitude readout indicates 900’, appears to be maneuvering.
• 4DC, looking. 4DC, traffic no longer a factor.
• 4DC.
4DC, leaving my airspace to the west, radar service terminated, squawk VFR, frequency change approved. Good day.
• 4DC, squawk VFR, frequency change approved. Good day.
Salinas Valley Airport
RADIO ARRIVAL PROCEDURES
PRIOR TO CONTACTING SALINAS TOWER GET ATIS ON 124.85
PRIOR TO ENTERING SALINAS CLASS D, CONTACT TOWER ON 119.4 (7-10 MILES OUT)
PILOT “SALINAS TOWER CESSNA SIX FIVE SIX FIVE JULIET TEN MILES SOUTHEAST INBOUND FOR LANDING WITH (INFORMATION) XRAY”
OR
“SALINAS TOWER. CESSNA SIX FIVE SIX FIVE JULIET, TEN MILES SOUTHEAST.INBOUND FOR PATTERN WORK WITH (INFORMATION) XRAY”
TOWER “CESSNA SIX FIVE SIX FIVE JULIET, MAKE STRAIGHT IN RUNWAY THREE ONE, REPORT TWO MILES”
PILOT “SIX FIVE JULIET STRAIGHT IN RUNWAY THREE ONE, REPORT TWO MILES”
AT TWO MILES
PILOT “SALINAS TOWER, SIX FIVE JULIET TWO MILES’~
EXPECT
TOWER “CESSNA SIX FIVE SIX FIVE JULIET, CLEARED TO LAND RUNWAY THREE ONE”
PILOT “SIX FIVE JULIET. CLEARED TO LAND, RUNWAY THREE ONE
OR
TOWER “CESSNA SIX FIVE SIX FIVE JULIET, CLEARED FOR THE OPTION, RUNWAY THREE ONE”
PILOT “CESSNA SIX FIVE JULIET. CLEARED FOR THE OPTION, RUNWAY THREE ONE”
RADIO DEPARTURE PROCEDURES
AFTER ENGINE START CONTACT ATIS ON 124.85
AFTER TAXI CHECKLIST. CONTACT GROUND ON 121.7
PILOT “SALINAS GROUND, CESSNA SIX FIVE SIX FIVE JULIET AT AIR TRAILS. READY TO TAXI WITH ALPHA”
GROUND “CESSNA SIX FIVE SIX FIVE JULIET, TAXI TO RUNWAY THREE ONE”
PILOT “SIX FIVE JULIET TAXI TO RUNWAY THREE ONE”
AFTER TAXI AND RUN UP, TAXI UP TO AND HOLD SHORT OF THE HOLD SHORT LINE, CONTACT TOWER ON 119.4
PILOT “SALINAS TOWER CESSNA SIX FIVE SIX FIVE JULIET. READY FOR TAKE OFF RUNWAY THREE ONE. DOWNWIND DEPARTURE”
TOWER “CESSNA SIX FIVE SIX FIVE JULIET HOLD SHORT” (LANDlNG AIRCRAFT)
TAXI INTO POSITION AND HOLD” (AIRCRAFT ON RUNWAY) CLEARED FOR TAKEOFF, RIGHT DOWNWIND DEPARTURE APPROVED”
NOTE: TRAFFIC MAY CAUSE TOWER TO USE A LEFT DOWNWIND DEPARTURE
PILOT “SIX FIVE JULIET. CLEARED FOR TAKEOFF. RIGHT DOWNWIND DEPARTURE”
OTHER DEPARTURES
Monterey
Departing Monterey (any runway in use) Watsonville
From rnwy 31 request “straight out departure” From rnwy 26 request “right 45 departure”
Hollister
From rnwy 26 or 31 request “departing Hollister”
Flying from Salinas (KSNS) to Monterey (KMRY)
Typical Best Case Scenario-Expect Minor and Major Variations
Frequencies KMRY
Atis 119.25
Norcal Approach 133.0 (127.15)* Monterey Tower 118.4
Monterey Ground 121.9
1. Tell Salinas Tower at departure Salinas Tower, Cessna 6565 Juliet, ready for takeoff, departing to Monterey”… this will normally provide you with a quick frequency change, normally as you cross the Freeway… if you don’t hear from the tower by the time you cross the freeway, ASK for a frequency change.
2. Have Monterey Atis set on one of your radios with the Com panel Com switch on both, ATIS volume turned down so you can just hear it without blocking out the Tower or Norcal Approach. With the frequency change approval, switch from Salinas Tower to Norcal Approach.
3. The following call to Norcal Approach is a departure from obtaining flight following for a cross country or the Salinas Valley practice area… “Norcal Approach Cessna 6565 Juliet departing Salinas, Landing Monterey”
4. Expect “Cessna 6565 Juliet, Squawk. 0325, make straight in runway 28 (Left/ Right) say” NOTE: expect the unexpected when dealing with Norcal Approach. Do NOT ENTER Monterey Airspace if they do not acknowledge you with your tail number. For instance if they say “Aircraft calling from Salinas say again” you are NOT cleared to enter Monterey airspace. If they say “6565 Juliet, standby” you are cleared to enter their airspace (although I recommend circling at Highway 68 and the Salinas River until Radar Contact is established. Also, 2000 feet is plenty of altitude for the trip, 1500 will do if you follow Highway 69 until aligned with the extended runway centerline), If the wind favors Runways 10 L/R you can expect “Cessna 6565 Juliet, Squawk. 0325, make left traffic for runway 10 Left”
5. Repeat the clearance “65Juliet squawk 0325, straight in runway 28 (Left/Right)
6. Approach will then come back with “65 Juliet, radar contact, say altitude”
7. Respond with “65 Juliet climbing through 800 for 2000”,
8. Expect a handoff to Monterey Tower... “6 5 Juliet, contact tower, 118.4”.
9. Do NOT change frequency without acknowledging the handoff.. “65 Juliet contact tower 118.4”
10. Contact tower .Monterey tower, 6565 Juliet with you”
11. Tower knows your location and will instruct you ‘65 Juliet cleared too land runway Note: if cleared to land 28 right, you may request 28 left, and providing there is no incoming traffic on the parallel runway, you will usually get your request.
12. After landing promptly taxi clear of the runway, and unless otherwise instructed by tower, contact Ground,
121.9 and announce… “Monterey Ground, Cessna 6565 Juliet, clear of runway going to _” or “taxiing back for takeoff to Salinas” (or other destination).
* 127.15 normally reserved for off the shoreline (see sectional), but often there is only one controller who can be on either 133.0 or 127.15.
NOTE: Normal Departure instructions to Salinas from runways 10 from Ground are.., “Cessna 6565 Juliet after
takeoff fly runway heading to 900 feet then left turn to 060 degrees, departure frequency 133.0, squawk. 0436” similarly from the 28 runways except... “climb on runway heading until past the freeway, then right turn to 060.”
REID-HILLVIEW AIRPORT
Downwind Departure From Reid-Hillview Airport
1. Contact Atis. Write down altimeter setting, wind direction and speed, atis code.
2. Initial callup to ground from tie down: (Southbound departure, runway 31 in use, Atis code for these examples
= Romeo).
Pilot: “Reid-Hillview ground, Cessna (call sign) at transient parking, ready to taxi with Romeo, downwind departure.”
Ground: “Cessna (call sign), taxi to 31 right via Zulu”
-or-
Ground: “Cessna (call sign), taxi to 31 right via inner ramp to hotel then Zulu.”
Pilot: Repeat ground instructions
3. Callup to tower at hold short line, after taxi from runup area:
Pilot: “Reid-Hillview tower, Cessna (call sign) ready for takeoff, 31 right”
Tower: “(call sign) hold short” (landing aircraft)
“(call sign) taxi into position and hold” (aircraft on runway)
“(call sign) cleared for departure, 31 right, downwind departure.”
“(call sign) taxi across 31 right, cleared fro takeoff runway 31 left, left downwind departure approved
“(call sign) cross 31 right to 31 left, taxi into position and hold.” (aircraft on runway) – to be followed by: “(call sign) cleared for takeoff runway 31 left, downwind departure approved.” “(call sign) taxi into position and hold.” (aircraft on runway) – to be followed by:
“(call sign) cleared for takeoff.” Repeat tower instructions.
Landing at Reid-Hillview Airport from Southeast
1. Get atis code at 2500 ft. or greater. (At or before Anderson Reservoir). Atis will advise wind, altimeter, runways in use, and to contact tower on 119.8 or if busy and occasionally on weekends 126.1. If 126.1 is in use, plan on a straight in approach to 31L or right downwind for 13R
2. At UTC:
Pilot: “Reid-Hillview tower, Cessna (call sign) at UTC, descending through 3500 ft, inbound for landing with Romeo.”
Tower: “(call sign) (optional: wind 330 at 12) fly straight in for runway 31 left (or 31 right), report 2 (or
3) miles.”
Pilot: Repeat Tower instructions.
3. At 2 (or 3) mile mark:
Pilot: “Reid-Hillview tower, (call sign) 2 (or 3) miles.
Tower: “(Call sign) cleared for landing, runway 31 left (31 right).”
4. After landing:
(Note: move quickly to leave runway at nearest exit without hard brake use, taxi clear of old short line and contact ground after coming to a full stop. Before proceeding, apply “After Landing” checklist). While on rollout on the active runway, tower may say to taxi to parking after landing.
Tower: (While rolling to a stop on 31 right) “(call sign) turn off runway at exit Delta (or other) and contact
ground at point 65’
(From 31 left While rolling to a stop) “(call sign) cross 31 right at exit Delta (or other) and
Non-Tower Airports
Making self-announced reports when operating at non-tower airports
Pilot: “Watsonville traffic, Helicopter (call sign) five miles out (direction), at 1200 ft.(or other altitude) Inbound for landing, runway 20, Watsonville”
Pilot: “Watsonville traffic, Helicopter (call sign) at the river and the freeway (or direction) for a left forty five downwind entry, 20, Watsonville”
Pilot: “Watsonville traffic, Helicopter (call sign) taking off parallel taxiway 20 (taxiway alpha) left closed pattern, Watsonville”
Pilot: “Watsonville traffic, Helicopter (call sign) turning left crosswind, 20, Watsonville”
Pilot: “Watsonville traffic, Helicopter (call sign) entering left downwind, 20, Watsonville”
Pilot: “Watsonville traffic, Helicopter (call sign) turning left base, parallel taxiway 20, Watsonville”
Pilot: “Watsonville traffic, Helicopter (call sign) on final, parallel taxiway 20, Watsonville”
- if you land on runway 16 and have cleared runway 16.
Pilot: “Watsonville Traffic, Helicopter (call sign) clear runway 20.”
Things to Keep in Mind When Reporting
• Use common sense when making reports
• Observe the amount of traffic in the pattern
• Consider making fewer radio calls if there is no one around to avoid cluttering the UNICOM frequency
Favorite Aviation Internet Addresses
AOPA
ASF
www.aopa.org/asf/taxi
Taxi Diagrams
www.aopa.org/asf/runway_safety/
Interactive runway safety course
EAA
Flying Start (EAA learn to fly)
www.eaa.org www.eaa.org/chopters/flyinq_start.html
WEATHER
AOPA Weather Brief (members only)
Briefing from DUATS
EAA Weather Brief (Members only)
Flight planning and legal weather briefing ~
members.eaa.org/home/flightbrief www.enflight.com
Goes Imagery and Satellite Tutorials:
Naval Research Laboratory Colorado State University
www.nrlmry.navy.mil/sat products.html
National Weather Service Weather website
Nexrad:
www.cira.colostate.edu/ramm/advimgry/toc
www.nws.noaa.gov adds.awc–kc.noaa. gov/
The Weather Channel
-Intellicast
ASOS/AWOS
Real time weather
Prides itself on being most complete
www.intellicast.com/weather/usa/others
www.faa.gov/asos/asos.html www.rap.ucar.edu/weather/index.html www.aviationweather.com/
INSTRUMENT FLYING
Airport approach plates
www.aeroplanner.com/flightplanning/
approachplates.cfm
Jep IFR clinic reviews
www.jeppesen.com/onlinepubs/aopa.phtml
Articles from IFR Refresher magazine
FAA
Home Page
Civil Aeromedical Institute (CAMI)
FSDO Offices
FAA Forms, pilot/maint. Schools/#’s
faa-gov/avr/afs/fsdo/fsdornaphome.htm
Library and FARs AIM
www.av-info.faa.gov
faa.gov/atpubs/aim/index.htm
Advisory Circ. Chkist
www.faa.gov/aba/htmI_policies/
files_pdf/ac_ckist-all.pdf
Judgment Training Manual
www-cyberair.com/tower/faa/index.html
GPS
www.gps.faa.gov
FAA Accident database
nasdac.faa.gov/main. htm
Flight data (FAR access, N Registry)
Changing CFI#’s & Forms
registry.faa.gov
Miscellaneous
Links for CFIs, including AIM
www.TheCfi com
GA Pilot Info
www.dot.state.tx.us “AVIATION”, then
bottom of page GA PILOT INFO-Info for VFR, IFR and huge list of Web sites
Many web sites www.landings.com
Trip ideas www.100dollarhamburger.com
Rod Machado www.rodmachado.com
Aviation Speakers www.aviationspeakers.com
Learn to fly and marketing for CFIs www.beapilot.com 1-888-232-7456
Flying Start (EAA learn to fly) www.flyinqstart.org
Source for students/instructors www.whittsflying. corn
Air foil simulator FM www.lerc.nasa.gov/WWW/K-12/aerosim
Flight planning for Cheapest gas www.airnav.com
Women in Aviation, International www-wiai.com
Airport Remote Radio Access System www.arinc.com/
AVWeb-Aviation News Service www.avweb.com
General Aviation Manufactures www.qeneralaviation.org
National Air & Space Museum www.nasm.edu
Nat’l. Trans. Safety Board www.ntsb-gov
USAF Museum www.wpafb.af.mil
Aero Planner for charts www.aeroplanner.com
Noise reduction headset for $44.90 total www.avshop.com/560208001.html Thunderstorm internet class www.nwas.org/committees/avnwxcourse
/course.htm
Runway Safety Web site runwaysafety.foa.gov
Decision Making flysafe.faa.qov/Flysafe/home.htm
Ben Hinkle’s BLM TFR airspace.blm.gov/ av-info.faa.gov/data/640otherfaqlpt61-18.doc
Radio Calls specific to Watsonville Airport
When you need a little training on how to use the radio or just want to freshen up your radio phrasology.
Radio Calls, Watsonville, CA
WT = Watsonville Traffic W = Watsonville H = Helicopter L = Left R = Right *Substitute “2-0” for any of the other runways (8, 2, 2-6)
Sample Departure Radio Calls:
WT
H 0SH on the go Alpha taxiway, parallel 2-0
L closed traffic (or “staying in the pattern”)
W
WT
H 0SH departing south end of Alpha taxiway, parallel 2-0
Straight out departure
W
WT
H 0SH departing grass area, between Alpha taxiway and 2-0
L closed traffic
W
WT
H 0SH on the go, Alpha taxiway, parallel 2-0
Left crosswind departure
W
WT
H 0SH departing Alpha taxiway, parallel 2-0, have the landing traffic in sight
L closed traffic
W
Sample Traffic Pattern Radio Calls:
WT
H 0SH L crosswind 2-0
W
WT
H 0SH L crosswind 2-0, departing the pattern
W
WT
H 0SH L downwind 2-0 (can add location such as “midfield” or “abeam the numbers 2-0” or “abeam the number 2”)
W
WT
H 0SH L downwind 2-0, number 2 (if you are following an aircraft in the pattern. Could also be “number 3” if multiple aircraft are in the pattern)
W
WT
H 0SH L downwind 2-0, number 2 behind the Cessna (substitute type of aircraft you are following if known. This lets the aircraft you are following know that you have them in sight.)
W
WT
H 0SH L base 2-0
W
WT
H 0SH L base 2-0, number 2
W
WT
H 0SH L base over runway 2-6 for 2-0
W
WT
H 0SH L base over home depot runway 2-0
W
WT
H 0SH final Alpha taxiway, parallel 2-0
W
WT
H 0SH final 2-0, number 2
W
WT
H 0SH L base to final runway 2-0, simulated engine failure (if doing a straight-in autorotation)
W
WT
H 0SH R downwind to final runway 2-0, simulated engine failure (if doing a 180° autorotation)
W
WT
H 0SH L base to final Alpha taxiway, remaining east of 2-0 at all times
W
Miscellaneous Airport Radio Calls:
WT
H 0SH clear of 2-0
W
WT
H 0SH air taxiing from north to south end of Alpha taxiway, parallel 2-0
W
Sample Position Reports When in the Vicinity of the Airport:
WT
H 0SH 1 mile to the southeast, climbing through one thousand for two thousand five hundred
Southeast bound
W
WT
H 0SH abeam Moss Landing at one thousand five hundred, inbound for landing
W
WT
H 0SH over the river and the freeway, L 45 entry 2-0
W
WT
H 0SH on a 3 mile 45 runway 2-0
W
WT
H 0SH 3 miles east, at one thousand two hundred, will be making an extended L base runway 2-0
W
WT
H 0SH on a 2 mile R base runway 2-0
W
WT
H 0SH short final runway 2-6
W
WT
H 0SH 6 miles to the northeast over the quarry at three thousand two hundred, northeast bound, last call,
W
Sample Calls to Find Out What Other Aircraft Are Up to:
Aircraft on final, will you be making a full stop, or touch and go?
Aircraft in run up area for 2-0, please hold short for landing traffic.
Aircraft on downwind, I do not have you in sight. Please say your position.
Aircraft rolling on 2-0, will you be making a left or right turn out?
Helicopter Flight Training Tips
Helicopter tips are just as important to safe learning in the cockpit as having a flight instructor with you. Take a few minutes and try these next time you fly.
- Keep your scan moving
- As needed for your particular mission
- Scan RPM’s = Green
- On hover
- On takeoff roll
- During all phases of cruise flight
- On approach
- During practice emergency procedures
- Watch your needles
- Where are they going?
- Watch for trends
- Autos
- Communicate
i. Explain task on ground with student
ii. Initial simulated emergency without warning is dangerous
iii. Eliminate surprises
iv. During autos always roll on throttle prior to raising collective
- A/S, RPM, descent rate = stable prior to 300 AGL level
i. A/S, RPM, rate of descent must be stable before starting auto and before 300 AGL
ii. If above is not met, do go around
iii. Practice go around anyway
iv. Scan instruments = RPM, A/S, rate of descent
- Have a plan in case of a problem/failure
i. In case of problem comes up you can do a full down successfully
ii. Practice autos should be to runways or taxiways, not too rolling hills or grass
Practice autorotations are similar to firearms training for law enforcement officers. Pilots spend a lot of time preparing for a situation that they will likely never encounter during their flying careers.
Each year, there are very few mechanical failures that require the use of emergency procedures to safely land a helicopter. Due to the risk involved, both to pilot careers and personal safety, it is imperative that pilots and CFI’s clearly communicate, stabilize cockpit indications, and identify a safe touchdown zone when conducting practice autorotations.
Unlike a bullet fired from a gun, a poorly executed autorotation can be turned into a go-around and attempted again.
Helicopter Overspeeds - What to do!
OOPS- you overspead the rotor and now what do you need to know...
Helicopter Overspeeds
One of the most costly incidents that we experience is an Overspeed. It is imperative that we, as a helicopter community avoid any more such incidents in the future. Despite frequent discussions and reminders during continuation training, overspeeds occur far too often. Consequently, here is a reminder of how they can occur and how they can be avoided.
Definition:
An overspeed occurs when either ERPM or RRPM or both exceed the red lines on the RPM tachometer.
Types of Overspeed
- Engine RPM overspeed on start up
- Engine & Rotor RPM during lift into the hover
- Engine & Rotor RPM during flight
- High Rotor RPM in auto rotation
Let’s look at each type individually and how they can occur and how to prevent them.
Engine RPM overspeed on start up
Cause
Engine is started – either by turning the key or pressing the starter button – without the throttle being in the fully closed position.
Effect
ERPM rises rapidly to exceed 104 %; governor does not have sufficient information to intervene before overspeed occurs.
Potential Damage
Scoring of cylinders, damage to push rods and piston seals and crankshaft. Damage to magnetos misalignment of the cooling fan.
Prevention
Follow the Company start up check list properly. Do not rush and do not skip steps.
The throttle must always be fully closed before and during the start process. Always ensure that the throttle is fully closed before you start the engine. If the engine is reluctant to start you may prime by opening the throttle then closing it fully again before a second attempt in an R22 or using the key in an R44. On no account should the engine be encouraged to start by cracking the throttle open whilst cranking the starter.
Engine & Rotor RPM during lift into the hover
Cause
Lifting without the governor switched on / governor faulty or non operational.
Effect
Without the governor switched on ERPM & RRPM will rise as the lever is raised. The mechanical system of Correlation does not work outside the range of 17-21” MAP. Consequently the needles will both continue to rise above 104% as the lever is raised. Whilst this may be counter-intuitive, it is nevertheless fact and will cause significant damage.
Potential Damage
Scoring of cylinders, damage to push rods and piston seals and crankshaft. Damage to magnetos, Brinelling (crushing spherical bearings into egg shapes) of feathering bearings in the rotor head.
If the helicopter is flown in this condition for any length of time, overstressing of journals, rotor head and rotor blades, damage to drive shafts and main rotor and tail rotor gearboxes & hydraulic systems may also occur.
Prevention
Follow the Company check list properly;
Switch the governor on before start as directed;
Allow governor to set RPM to 104 % during wind up;
Allow governor to recover RPM after Low RPM warning horn check;
Check both sets of Warning Lights are out when directed.
Perform pre takeoff checks properly every time you lift. Things may have changed since you trained, our recommended mantra is now:
- Upper Warning Lights Out
- RPM 104% & governed
- MAP
- Lower Warning Lights Out (INCLUDING GOVERNOR)
- T’s, P’s & Keys (set to both magnetos)
- Fuel (Sufficient for flight)
- Carb Heat Set
- (R44 Hydraulics On)
- Hatches & Harnesses
- Area Clear, Left, Right & Above
Take off technique
When raising the collective to lift, pause at 17” MAP to check RPM is holding at 104%. If it is not, then the governor is not doing its job but you will have spotted it before you exceed limits and cause damage.
Engine & Rotor RPM during flight
Cause
Governor failure, inadvertent switching off of governor, mis-handling of throttle, poor re-engagement technique following recovery from auto.
Effect
ERPM & RRPM do not remain within the Power On range: R22: 97 – 104%, R44: 98 – 102%
Potential Damage
Scoring of cylinders, damage to push rods and piston seals and crankshaft. Damage to magnetos, Brinelling (crushing spherical bearings into egg shapes) of feathering bearings in the rotor head, tail rotor drive shaft failure followed by loss of tailcone.
Prevention
Regular scan of instruments must include RPM tachometer and warning lights.
Governor usually ensures RPM is correctly maintained. Pilot must still monitor that the governor is working correctly.
Low RPM: Warning horn sounds indicating governor has failed to maintain RPM;
High RPM: No such warning received. Pilot must spot and gently roll off throttle till RPM back in the permitted range.
If RPM correctly set prior to take-off, governor failure is unlikely to take RPM far enough outside limits to cause significant damage. Use manual throttle to correct RPM gently.
NB: During auto recovery, ensure needles joined in the power-on range before raising lever.
High Rotor RPM in auto rotation
Cause
Insufficient check up on lever to contain RRPM rises due to disc loading / airspeed changes.
Effect
As rate of descent increases, updrafting air increases RRPM. Failure to raise lever to contain RRPM rise may lead to RRPM needle exceeding Power Off Limit of 110%.
Potential Damage
Brinelling (crushing spherical bearings into egg shapes) of feathering bearings in the rotor head, over-stressing of journals and rotor blades, damage to drive shafts and main rotor and tail rotor gearboxes may also occur.
Prevention
Having entered autorotation, never forget to check up on collective to contain RRPM rise.
Avoid aggressive cyclic inputs during auto – fly smoothly & monitor RRPM throughout exercise.
Feel for increasing pressure on your backside signalling increasing disc load and check up again if necessary. Monitor needle re-engagement carefully during recover to climb.
Do not fly a helicopter above its maximum permitted all up weight.
What to do if you do over speed a helicopter.
You must get RPM back within normal limits as soon as possible, land & shut down immediately.
Whilst the helicopter can probably continue flying, after damage has occurred, there is no guarantee, so be safe and make a sensible controlled precautionary landing.
You are legally required to report any unserviceability to the operator, so you must tell us what has occurred:-
- Certain engineering checks have to made to ensure helicopter is airworthy.
- Providing we can tell the insurance company what has happened and that it is Pilot Error, it is an insured risk and will usually be covered by the underwriters.
- No other pilot will be put at risk by your error.
If you do not report an overspeed:
- Repairs will not be covered by insurance and the owner will have to bear the costs, making them unlikely to hire out helicopters in the future;
- An un-airworthy helicopter could remain in operation which could suffer a catastrophic failure at any time causing injury or even a DEATH for which you would be responsible.
It is therefore vital that any incident is reported. We always try to address such matters positively and retrain pilots when errors occur and are admitted. That makes for better pilots. You won’t be popular but providing you engage with us in rectifying the problems it need not affect your flying in the future.
Transponder Codes
What in the world does this transponder really do and how do you operate it.
Transponder modes
Several different RF communication protocols have been standardized for aviation transponders:
§ Mode 1 – provides 2-digit 5-bit mission code. (military only – cockpit selectable)
§ Mode 2 – provides 4-digit octal unit code. (military only – set on ground for fighters, can be changed in flight by transport aircraft)
§ Mode 3/A – provides a 4-digit octal identification code for the aircraft, assigned by the air traffic controller. (military and civilian)
§ Mode 4 – provides a 3-pulse reply to crypto coded challenge. (military only)
§ Mode 5 – provides a cryptographically secured version of Mode S and ADS-B GPS position. (military only)
§ Mode C – provides 4-digit octal code for aircraft's pressure altitude. (military and civilian)
§ Mode S – provides multiple information formats to a selective interrogation. Each aircraft is assigned a fixed 24-bit address. (military and civilian)
Mode A and Mode C
When the transponder receives a radar signal it sends back a transponder code (or "squawk code"). This is referred to as "Mode 3A" or more commonly "Mode A". A transponder code can be paired with pressure altitude information, which is called "Mode C".
Mode 3A and C are used to help air traffic controllers to identify the aircraft and to maintain separation.
Mode S
See also: Air traffic control radar beacon system#Mode S
Another mode called Mode S (Selective) is designed to help avoiding overinterrogation of the transponder (having many radars in busy areas) and to allow automatic collision avoidance. Mode S transponders are compatible with Modes A & C. This is the type of transponder that makes the ACAS II (Airborne Collision Avoidance System) and the ADS-B (Automatic dependent surveillance-broadcast) systems function.
Mode S is mandatory in controlled airspace in many countries. Some countries require that all aircraft be equipped with Mode S, even in uncontrolled airspace. However in the field of general aviation, there have been objections to these moves, because of the cost, size, limited benefit to the users in uncontrolled airspace, and, in the case of balloons and gliders, the power requirements for these aircraft that have limited electrical power.
Mode S features
Mode S transponders broadcast information about the aircraft to the Secondary Surveillance Radar (SSR) system, TCAS receivers on board aircraft and to theADS-B SSR system. This information includes the call sign of the aircraft and/or the transponder's permanent ICAO 24-bit address in the form of a hex code.
ICAO 24-bit address
All modern aircraft are assigned a unique ICAO 24-bit address or (informally) Mode-S "hex code" upon national registration and this address becomes a part of the aircraft's Certificate of Registration. Normally, the address is never changed, however, the transponders are reprogrammable and, occasionally, are moved from one aircraft to another (presumably for operational or cost purposes), either by maintenance or by changing the appropriate entry in the aircraft's FMS system.
There are 16,777,214 unique ICAO 24-bit addresses (hex codes) available. The ICAO 24-bit address can be represented in three digital formats:hexadecimal, octal, and binary. These addresses can be decoded and converted amongst each other online using tools such as those at Airframes.org andKloth.net to obtain the aircraft's tail number. Whichever format is used, the same information is carried through the signal.
Example of an ICAO 24-bit address:
§ Hexadecimal: AC82EC
§ Decimal: 11305708 (Note: rarely used format)
§ Octal: 53101354
§ Binary: 101011001000001011101100 (Note: occasionally, spaces are added for visual clarity, thus 10101100 10000010 11101100)
(These all correlate to the same aircraft registration, N905NA.)
Other features
Mode S TIS Secondary surveillance radar (SSR), or Traffic Information Service, allows a radar installation to send information about nearby traffic back to aircraft, which then displays it on the moving map. Mode S TIS is only available when the aircraft is within radar range of a radar installation that supports it. A Mode S TIS installation combines a Mode S transponder that sends TIS data to a display device – usually a GPS device or Multi Function Display (MFD). Examples of such pairings are a Garmin GTX330D transponder and a GNS530 GPS, and the Garmin G1000 avionics suite.
Mode S capable transponders are also a building block for next generation air traffic control systems, as they can be used to transmit location information forADS-B and potentially other air traffic control communications. Currently the FAA is deactivating several Mode S TIS equipped stations.
Issues with Mode S transponders
One major issue with Mode S transponders is that pilots have frequently been entering the wrong "flight identity" (i.e. call sign) into their Mode S transponders. In this case, the capabilities of ACAS II and Mode S SSR can be degraded
Operation
A pilot may be requested to squawk a given code by the air traffic controller via the radio, using a phrase such as "Cessna 123AB, squawk 0363". The pilot then selects the 0363 code on their transponder and the track on the radar screen of the air traffic controller will become correctly associated with their identity.
Because primary radar generally gives bearing and range position information, but lacks altitude information, mode C and mode S transponders also report pressure altitude. Around busy airspace there is often a regulatory requirement that all aircraft be equipped with an altitude-reporting mode C or mode S transponders. In the United States, this is known as a Mode C veil. Mode S transponders are compatible with transmitting the mode C signal, and have the capability to report in 25 foot increments. Without the pressure altitude reporting, the air traffic controller has no display of accurate altitude information, and must rely on the altitude reported by the pilot via radio. This limitation has resulted in at least one accident. On 31 August 1986, a Piper Archer with a pilot and two passengers had inadvertently penetrated the 6,000-foot floor of controlled airspace without a clearance and collided with Aeromexico Flight 498, a DC-9 with 58 passengers and 6 crew at an altitude of 6,650 feet. The Archer had only a mode A squawk reporting capability and the air traffic controller assumed it was below the controlled airspace.
Ident
All mode A, C, and S transponders include an "ident" button, which activates a special "thirteenth" bit on the mode A reply known as Ident, short for Identify. When radar equipment receives the Ident bit, it results in the aircraft's blip "blossoming" on the radar scope. This is often used by the controller to locate the aircraft amongst others by requesting the ident function from the pilot (i.e. "Cessna 123AB, squawk 0363 and ident").
Ident can also be used in case of a reported or suspected radio failure to determine if the failure is only one way and whether the pilot can still transmit or receive but not both (i.e. "Cessna 123AB, if you read, squawk ident").
Transponder codes
Transponder codes are four digit numbers transmitted by the transponder in an aircraft in response to a secondary surveillance radar interrogation signal to assist air traffic controllers in traffic separation. A discrete transponder code (often called a squawk code) is assigned by air traffic controllers to uniquely identify an aircraft. This allows easy identity of the aircraft on radar.
Squawk codes are four-digit octal numbers; the dials on a transponder read from zero to seven inclusive. Thus the lowest possible squawk is 0000 and the highest is 7777. There are 4096 combinations of these four digit codes, which is why they are often called "4096 code transponders." Because these squawks are sensitive, care must be taken not to squawk any emergency code during a code change. For example, when changing from 1200 to 6501 (an assigned ATC squawk), one might turn the second wheel to a 5 (thus 1500), and then rotate the first wheel backwards in the sequence 1-0-7-6 to get to 6. This would momentarily have the transponder squawking a hijack code (7500), which might lead to more attention than one desires. Pilots are instructed not to place the transponder in "standby mode" while changing the codes as it causes the loss of target information on the ATC radar screen, but instead to carefully change codes to avoid inadvertently selecting an emergency code. Additionally, modern digital transponders are operated by buttons to avoid this problem
There are other codes known as 'conspicuity codes' which are not necessarily unique to a particular aircraft, but may have their own meaning and are used to convey information about the aircraft to ATC, possibly when the aircraft is not in radio contact.
The use of the word "squawk" comes from the system's origin in the World War II Identification Friend or Foe (IFF) system, which was code-named "Parrot". Parrot today generally refers to IFF only. The parrot check is generally done as part of the last-chance inspection at the runway, or after becoming airborne. Parrot sweet, and parrot sour are given, and the aircraft will have to abort in a real-world mission when sour, or face being attacked by friendly forces. Modern use of the word Parrot refers to a test transponder located at a fixed location off the radar facility. The parrot verifies range and direction accuracy of the radar facility.
Routine codes
§ 0000:
§ military intercept code (in the US)
§ mode C or other SSR failure (in the UK).
§ shall not be used – is a non-discrete mode A code (Europe)
§ 0001: Military code for high speed uncontrolled (non-ATC directed) flight (US)
§ 0033: Parachute dropping in progress (UK)
§ 1000:
§ Instrument Flight Rules (IFR) flight below 18,000' when no other code has been assigned (Canada)
§ non-discrete mode A code reserved for future use in Mode S radar environment where the aircraft identification will be used to correlate the flight plan instead of the mode A code
§ 1200: Visual flight rules (VFR) flight, this is the standard squawk code used in Australian and North American airspace when no other has been assigned.
§ 1400: VFR flight above 12,500'ASL when no other code has been assigned (Canada)
§ 2000: The code to be squawked when entering a secondary surveillance radar (SSR) area from a non-SSR area (used as Uncontrolled IFR flight squawk code in ICAO countries and in Canada for uncontrolled IFR at or above 18,000')
§ 4000: Aircraft on a VFR Military Training Route or requiring frequent or rapid changes in altitude (US)
§ 4400 to 4477: Reserved for use by SR-71, YF-12, U-2 and B-57, pressure suit flights, and aircraft operations above FL600 (USA only).
§ 7000:
§ VFR standard squawk code when no other code has been assigned (ICAO)
§ UK: this code does not imply VFR; 7000 is used as a general conspicuity squawk.)
§ 7001:
§ Sudden military climb out from low-level operations (UK)
§ Used in some countries to identify VFR traffic (France, ...)
§ 7004: Aerobatic and display code in some countries.
§ 7010: VFR circuit traffic code in the UK
§ 707X: Paradrop activities in France (7070, 7071, 7072...)
§ 7777:
§ military interception (US) ("Under no circumstances should a pilot of a civil aircraft operate the transponder on Code 7777. This code is reserved for military interceptor operations.")
§ non-discrete code used by fixed test transponders (RABMs) to check correctness of radar stations (BITE). (US, Germany, Netherlands, Belgium, ...)
In Belgium following codes are assigned for VFR traffic under Flight Information Services (BXL FIC)
§ series from 0041 till 0057
In Germany the following codes have been used:
§ 0021: VFR squawk code for German airspace (5000 feet and below)
§ 0022: VFR squawk code for German airspace (above 5000 feet)
As from 15 March 2007 these have been replaced by the international 7000 code for VFR traffic.
Emergency codes
§ 7700: General Emergency
§ 7600: Lost Communications
§ 7500: Unlawful Interference (Hijack)
Codes assigned by ATC
Most codes above can be selected by aircraft if and when the situation requires or allows it, without permission from ATC. Other codes are generally assigned by ATC units. For IFR flights, the squawk code is typically assigned as part of the departure clearance and stays the same throughout the flight. VFR flights, when in uncontrolled airspace, will "squawk VFR" (1200 in the US, 7000 in Europe). Upon contact with an ATC unit, they will be told to squawk a certain unique code. When changing frequency, for instance because the VFR flight leaves controlled airspace or changes to another ATC unit, the VFR flight will be told to "squawk VFR" again.
In order to avoid confusion over assigned squawk codes, ATC units will typically be allocated blocks of squawk codes, not overlapping with the blocks of nearby ATC units, to assign at their discretion.
Not all ATC units will use radar to identify aircraft, but they assign squawk codes nevertheless. As an example, London Information – the Flight Information Service station that covers the lower half of the UK – does not have access to radar images, but does assign squawk code 0027 to all aircraft that receive an FIS from them. This tells other radar equipped ATC units that that specific aircraft is listening on the London Information radio frequency, in case they need to get hold of that aircraft.