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VATUSA Reference & Study Guides


Tower Operations



An Intro to Local Control

Runway Selection

Coordination

Initial Contact and Position Determination

Advisories and Traffic Information

Airspace Restrictions

Wake Turbulence

Departure Release

Departure Procedures

Departure and Dep/Arr Separation

Arrival Procedures

The Traffic Pattern

Closed Traffic

Arrival and Arr/Dep Separation




An Intro to Local Control


Tower, better known as the Local Controller is responsible for the active runway surfaces. Local control clears aircraft for take off or landing and ensures the runway is clear for these aircraft.
To accomplish this, local control controllers are normally given 2 to 5 nautical miles (4 to 9 km) of airspace around the airport, allowing them to give the
clearances necessary for airport safety. If the local controller detects any unsafe condition, a landing aircraft will be told to "go around" and will be
re-sequenced into the landing pattern by the terminal area controller.


A highly disciplined communications process between local and ground control is an absolute necessity. Ground control must request and gain approval from
local control to cross any runway with any aircraft or vehicle. Likewise, local control must ensure ground control is aware of any operations that impact the
taxiways and must work with the arrival radar controllers to ensure "separation" of arrival traffic is created and most importantly, maintained (where necessary)
to allow taxiing traffic to cross runways and to allow departures aircraft to take off.


In real-life Tower controllers control aircraft based primarily on what they see out the windows.
All separation standards depend on seeing the aircraft and other visible landmarks. Tower radar displays are only an aid. Here on VATSIM it's a bit different. You can't see out the windows
so your radar display, supplemented by pilot reports, becomes your primary tool. Therefore some accommodations have to be made. These will be discussed as the need arises.


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Runway Selection (7110.65, 3-5-1)


Normally Tower selects the runway in use. However, at some locations due to the close proximity of other airports or other factors, Approach Control will select the runway
in use. You should remain flexible and consider the impact on other controllers when selecting and coordinating a runway in use.


When deciding runways in use, first refer to any R20;runway use,R21; runway selection programs, or calm wind designation that an airport has in effect. These may be located in Letters of Agreement,
Facility Directives, or Standard Operating Procedures. If there is no selection program, then use the runway most aligned with the winds when speed is greater than 5 knots. If winds are less than 5 knots, use a
designated R20;calm windR21; runway, or a runway of your choice or pilot choice.


It should be noted that the "calm wind runway" does not mean that the winds are calm. As stated in the Basic Study Guide, when the winds are less than three knots, it is considered "calm." Therefore, "Calm Winds" and "Calm Wind Runway" are two separate terms.
On the radio, you may state R20;Calm WindsR21; only when winds are less than 3 knots, from any direction. Examples:


Wind is 25005: R20;November 2-6-1 Papa Delta, Winds are 2-5-0 at 4, runway 2-1-Left, cleared to land."


Wind is 29003: R20;Northwest 2-2-1, Winds are Calm, runway 8, cleared to land."


Sometimes operational factors will make another runway less aligned with the wind more suitable. Reasons for selecting a different runway could be the availability of instrument approaches, length, noise abatement, or other locally unique reasons.
You may use a runway other than the runway in use if it will be operationally advantageous or is requested by the pilot. Some examples would be: Assigning large aircraft to the runway in use and smaller aircraft to another runway, or a pilot requesting a
straight-in approach to a different runway instead of flying a complete pattern to the runway in use, or requesting a runway that is closer to his parking area.


State the runway in use when using another runway e.g. "RUNWAY 36 IN USE, RUNWAY 28L CLEARED TO LAND."


Parts of this section were contributed by Steve Ogrodowski of the Cleveland ARTCC.


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Coordination (7110.65, 3-1-4)


In addition to the general coordination concepts you learned in the Basic Study Guide, and built upon in the Ground Control Study Guide, Local Control has its own unique coordination requirements. For instance, when you authorize Ground Control to
cross an active runway, you should use the word "CROSS" and the runway number, e.g. "CROSS RUNWAY 36." In real-life each individual crossing must be coordinated. On VATSIM, to reduce the amount of coordination, blanket approval is sometimes
given to GND to cross active runways when he sees it is safe to do so. You should inform GND of the type of crossing coordination you wish to use. Before you use any runway not previously designated as active you must coordinate with GND to make sure he
doesnR17;t have any aircraft taxiing on it


You should also coordinate with the Approach Controller to determine what type instrument approach arrivals will be making, handoff points, unplanned missed approach instructions, Class B or C Airspace procedures, and any other locally unique requirements.
Finally, you should coordinate with the controller doing the departure function (DEP, APP, or CTR) to determine the initial vector or routing for departures, IFR release procedures (individual or automatic), and initial separation for successive departures.


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Initial Contact and Position Determination
(7110.65, 3-1-7)



When working Local Control, as when working Ground, you should provide airport traffic control service on the basis of known or observed conditions. This is more difficult on VATSIM than in real-life.
You cannot simply look out the window. You must rely on your radar display, pilot reports, and your own common sense.


Before you begin controlling an aircraft, you must know where it is. Again, just as in Ground Control, issuing control instructions without being sure of an aircraftR17;s position could easily create a conflict. While aircraft positions on radar are generally
accurate enough, pilots may be unsure of their exact location. Use caution when relying on aircraft position reports alone.


Pilots are required to establish communications before entering the Class D airspace. If you respond to a radio call with "(CALLSIGN) STANDBY" communications have been established and the pilot may enter the Class D. If you want the aircraft to remain outside
the Class D you must say so eg "(CALLSIGN) REMAIN OUTSIDE DELTA AIRSPACE AND STANDBY."


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Advisories and Traffic Information
(7110.65, 2-1-21)


Issue information about the airport necessary for an aircraft's safe operation in time for it to be useful to the pilot. While not likely to be encountered
on VATSIM, this would include information on construction,
less than normal braking action, or other pertinent airport conditions. When describing any observed abnormal aircraft condition always use the term "APPEARS", e.g. "IT APPEARS YOU HAVE LANDED ON THE WRONG RUNWAY."
This is especially useful on VATSIM because what the pilot sees on his computer may not exactly match what you see on yours.


All vehicles, equipment, and personnel must be off the runway before a departing aircraft starts takeoff roll or a landing aircraft crosses the landing threshold. The only positive way to ensure this is by requiring these vehicles, etc to maintain radio contact with the control
tower at all times. They may only enter the runway with permission from the tower and must exit and report off when instructed. When vehicles, equipment, or personnel are on the runway, aircraft may still make low approaches to that runway if they are restricted to at least 500 feet
above the airport elevation, eg airport elevation 300MSL "CLEARED FOR LOW APPROACH AT OR ABOVE 800 VEHICLE ON THE RUNWAY."


Vehicles, equipment, and personnel in direct communications with the control tower may be authorized to operate up to the edge of the runway, but not actually on it, if you issue an advisory to the aircraft, eg "MEN AND EQUIPMENT RIGHT SIDE OF RUNWAY."
Advise other aircraft of the runway braking action when reports are received from pilots. While reduced braking action is not currently modeled in Flight Simulator you should know how to handle any reports you may receive from pilots or observe in the REMARKS section of a METAR.
Describe the quality of braking action using the terms "GOOD" "FAIR" "POOR" or "NIL" and include type of aircraft e.g. "BRAKING ACTION POOR, REPORTED BY A 727." If the pilot report uses different words, ask him to restate braking action in these terms.


A wet runway surface or USAF Runway Condition Reading may sometimes be shown in the REMARKS section of the METAR as "//WR" or "RCR05P." If available provide it to all USAF aircraft and other aircraft upon pilot request, "WET RUNWAY" or "RCR ZERO FIVE, PATCHY."
Describe traffic in an easy to understand manner, such as "TO YOUR RIGHT" or "AHEAD OF YOU" e.g. "TRAFFIC, MD-80 ON DOWNWIND TO YOUR LEFT." Avoid using cardinal directions (north, south, etc) or referring to landmarks such as "past the fire station" or similar objects the pilot may not be familiar with or may not be included in his scenery.


You may also issue traffic in the standard radar traffic advisory format. This consists of:



  • 12-hour clock position or cardinal direction (N, S, E, W).

  • Distance in miles.

  • Direction of movement.

  • Type and altitude if known

"TRAFFIC, 11 O'CLOCK, 10 MILES, SOUTHBOUND, BOEING 737, 17,000."
TRAFFIC, 12 O'CLOCK, 15 MILES, OPPOSITE DIRECTION, ALTITUDE UNKNOWN

When the traffic is no longer a factor or depicted on radar inform the pilot eg "TRAFFIC NO FACTOR/NO LONGER OBSERVED."

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Airspace Restrictions (AIM, 4-3-5)

If an aircraft requests to takeoff, land, or touch-and-go on a closed or unsafe runway, inform the pilot the runway is closed or unsafe, and inform him that a clearance cannot be issued. If the pilot persists in his request and traffic is not a factor, inform him that the operation will be at his own risk e.g. "RUNWAY 36 CLOSED. UNABLE TO ISSUE CLEARANCE. DEPARTURE/LANDING/TOUCH-AND-GO WILL BE AT YOUR OWN RISK."

Do not approve a speed in excess of 250 knots within Class C or D airspace unless the pilot informs you the higher speed is required by the aircraft flight manual or military procedures. Do not approve unusual maneuvers such as "buzz jobs" where a flight is conducted at a low altitude or high speed for thrill purposes within Class B, C, or D airspace if they are not essential to the performance of the flight unless covered in a local Standard Operating Procedure or Letter of Agreement.

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Wake Turbulence (7110.65, 2-1-19)

Wake turbulence is generated by the passage of an aircraft through the atmosphere. Generally speaking the heavier the aircraft the more wake turbulence. The term also includes vortices, thrust stream turbulence, jet blast, jet wash, propeller wash, and rotor wash both on the ground and in the air. Wake turbulence may be encountered by aircraft on the ground as well as in flight. Because wake turbulence is unpredictable, controllers are not responsible for anticipating its existence or effects. Wake turbulence isnR17;t modeled by FS so pilots wonR17;t experience its effects but as a controller you are still required to provide the appropriate wake turbulence separation.

For the purposes of Wake Turbulence Separation aircraft are classified as Heavy, Large, or Small. For a detailed listing of aircraft weight classifications click here.

  1. Heavy aircraft are capable of takeoff weights of 255,000 pounds or more whether or not they are operating at this weight during a particular phase of flight. Some examples are most 707/C-135, all 747, 767, DC-10, L-1011, A-300, C-5, C-141, C-17, and B-52.
  2. Large aircraft are aircraft of more than 41,000 pounds but less than 255,000 pounds maximum takeoff weight. Most military, Air Carrier, and other non-General Aviation aircraft are Large.
  3. Small aircraft are aircraft of 41,000 pounds or less maximum takeoff weight. Most General Aviation aircraft are Small and most weigh 12,500 lb or less.

Apply wake turbulence procedures to aircraft operating behind Heavy jets and, where indicated, to Small aircraft behind Large aircraft. Specific separations are listed in the appropriate sections. Separation shall continue to touchdown for all IFR aircraft not making a visual approach or maintaining visual separation.

Issue wake turbulence cautionary advisories, e.g. "CAUTION WAKE TURBULENCE" to:

  • VFR aircraft behind a Heavy or B757.
  • IFR aircraft that accept a visual approach or visual separation behind a Heavy or B757.
  • Any aircraft if in your opinion wake turbulence may have an adverse effect on it.

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Departure Releases (7110.65, 4-3-4)

Departure Procedure

An IFR departure clearance is not valid until the aircraft is released by Departure Control. In real-life and in many VATUSA ARTCCs departure releases are covered in a local SOP. Without an SOP the Departure controller must inform the Tower if they are to obtain a release for each departure or grant them "automatic" releases. If an automatic release is in effect the Departure controller must specify the separation he or she desires between successive departures.

Clearance Void Time

A pilot may receive a clearance, when operating from an airport without a control tower, which contains a provision for the clearance to be void if not airborne by a specific time. A pilot who does not depart prior to the clearance void time must advise ATC as soon as possible of their intentions. ATC will normally advise the pilot of the time allotted to notify ATC that the aircraft did not depart prior to the clearance void time. This time cannot exceed 30 minutes. Failure of an aircraft to contact ATC within 30 minutes after the clearance void time will result in the aircraft being considered overdue.

Note: In the real-world, other IFR traffic for the airport where the clearance is issued is suspended until the aircraft has contacted ATC or until 30 minutes after the clearance void time or 30 minutes after the clearance release time if no clearance void time is issued. Confirm with your local SOP before suspending other IFR traffic. Use the following example as a general and acceptable phraseology.

Clearance void if not off by (clearance void time) and, if required, if not off by (clearance void time) advise (facility) not later than (time) of intentions.

Hold For Release

ATC may issue "hold for release" instructions in a clearance to delay an aircraft's departure for traffic management reasons (i.e., weather, traffic volume, etc.). When ATC states in the clearance, "hold for release," the pilot may not depart utilizing that IFR clearance until a release time or additional instructions are issued by ATC. In addition, ATC will include departure delay information in conjunction with "hold for release" instructions. The ATC instruction, "hold for release," applies to the IFR clearance and does not prevent the pilot from departing under VFR. However, prior to takeoff the pilot should cancel the IFR flight plan and operate the transponder on the appropriate VFR code. An IFR clearance may not be available after departure. Use the following example as a general and acceptable phraseology.

"Aircraft identification) cleared to (destination) airport as filed, maintain (altitude), and, if required (additional instructions or information), hold for release, expect (time in hours and/or minutes) departure delay."

Release Times

A "release time" is a departure restriction issued to a pilot by ATC, specifying the earliest time an aircraft may depart. ATC will use "release times" in conjunction with traffic management procedures and/or to separate a departing aircraft from other traffic. Use the following example as a general and acceptable phraseology.

(Aircraft identification) released for departure at (time in hours and/or minutes).

Expect Departure Clearance Time

The EDCT is the runway release time assigned to an aircraft in a ground delay program. Aircraft are expected to depart no earlier than 5 minutes before, and no later than 5 minutes after the EDCT.

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Departure Procedures (7110.65, 3-9-9) (7110.65, 5-8-1)

When the aircraft calls ready and traffic permits, issue takeoff clearance. When more than one runway is active, first state the runway number followed by the takeoff clearance, e.g. "RUNWAY 27L, CLEARED FOR TAKEOFF."

You may taxi aircraft into position and hold when takeoff clearance cannot be issued because of traffic, e.g. "RUNWAY 36, POSITION AND HOLD." The most common use for this is when waiting for a preceding arrival to exit the runway or while waiting for successive departure separation. It should not be used routinely with every departure. Whenever possible aircraft should be issued takeoff clearance when still holding short of the runway. Position and hold does not allow you to conduct operations (low approach, touch-and-go, etc) by landing one aircraft over another aircraft holding in position.

When you taxi an aircraft into position inform it of the closest traffic on approach to the same runway, e.g. "RUNWAY 18, POSITION AND HOLD. TRAFFIC A 737 SIX MILE FINAL." Do not use conditional phrases such as "BEHIND LANDING TRAFFIC" or "AFTER THE DEPARTING AIRCRAFT" when taxiing aircraft into position. Wait until the other aircraft is no longer a conflict before issuing instructions to taxi into position. Do not taxi aircraft into position at an intersection at night. You should be flexible when applying this rule on VATSIM. The reason behind it is the visual problems encountered by real-life controllers when looking out the windows at night. This isnR17;t yet a problem on VATSIM plus many pilots operate on a "simulator time" which may be different from the actual time. Your "night" may be his "day."

Handoff all departing IFR aircraft to the controller performing the departure control function (DEP, APP, or CTR) when further communication with you is not required. You may start the handoff when the aircraft is still on the runway. Normally you should complete it when the aircraft is approximately 1/2NM off the departure end. VFR departures in Class B and C Airspace and Special VFR departures are handled the same as IFR departures. Do not request departing military aircraft to make radio frequency or transponder changes before the aircraft reaches 2500 AGL.

There are two ways to handle VFR departures in Class D airspace:

  1. Instruct the aircraft to depart in a cardinal direction (N, S, E, W) e.g. "NORTHEAST DEPARTURE APPROVED."
  2. Instruct the aircraft to depart via a leg of the traffic pattern, e.g. "MAKE RIGHT DOWNWIND DEPARTURE."

Cancel takeoff clearance if circumstances require, e.g. "CANCEL TAKEOFF CLEARANCE." Once an aircraft has started takeoff roll, cancel takeoff clearance only for safety reasons.

When a helicopter requests to depart from any point on the movement area issue takeoff clearance "CLEARED FOR TAKEOFF." When a helicopter requests to depart from a non-movement area use the term "PROCEED AS REQUESTED." When a helicopter requests to depart from an area not authorized for helicopter use or an area off the airport use the term "DEPARTURE WILL BE AT YOUR OWN RISK." Unless requested by the helicopter pilot, do not issue downwind takeoffs if the tailwind exceeds 5 knots

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Departure and Dep/Arr Separation (7110.65, 3-9-1)(7110.65, 3-10-1)

Separation of IFR departures in the air is the responsibility of the controller performing the departure function (DEP, APP, or CTR). Tower must obtain a release from the DEP controller for each departure or provide the separation specified by the departure controller in addition to applying runway separation. Many ARTCCs have SOPs or LOAs which cover departure releases and separations. If there is no SOP or LOA or the departure controller doesnR17;t specify any required separation, you should ensure at least 5NM between successive IFR departures.

Runway separation in real-life is based on looking out the windows at the aircraft in relation to other landmarks such as taxiways or the runway ends. Since this is not practical on VATSIM work-arounds must be used. Watch the aircraftR17;s altitude readout compared to the field elevation to determine when an aircraft has landed or is airborne. Compare aircraft positions to each other and the runways on the radar map to determine when an aircraft is at the appropriate points.

  • Separate a departure from a preceding departure on the same runway by ensuring it does not begin takeoff roll until the first aircraft is airborne and past the runway end or turned to avert any conflict.
  • Use 2 minutes separation when any aircraft departs from the same or parallel runways separated by less than 2500 feet behind a Heavy or B757. This separation may not be waived by the pilot.
  • Use 2 minutes when any aircraft departs behind a departing Heavy or B757 on an intersecting runway or parallel runways separated by more than 2500 feet if the projected flight paths will cross.
  • Use 2 minutes when any aircraft departs after a Heavy or B757 lands if the departure will fly through the airborne path of the arrival.
  • Use 3 minutes separation when any aircraft departs from an intersection behind a heavy jet or B757 or if it departs in the opposite direction from the Heavy or B757 on the same runway. This separation may not be waived by the pilot.
  • Use 3 minutes separation when a Small aircraft departs from an intersection behind a Large aircraft. This separation is not required if the pilot has specifically requested to waive the separation. A simple request for takeoff is not a request for a waiver. Issue a wake turbulence cautionary advisory before clearing the Small aircraft for takeoff.

Aircraft conducting multiple touch-and-go or stop-and-go operations in the VFR pattern are considered to be departing from an intersection. However, 3 minutes separation is not required unless ATC takes action to reduce the visual separation being applied by the pilot. For example, if you simply instruct the touch-and-go aircraft to "FOLLOW" the Heavy the 3 minutes are not required but if you tell it to "MAKE SHORT APPROACH" or "TURN BASE NOW" the 3 minutes are required.

Do not taxi Small aircraft into position and hold behind a departing Heavy or B757. Separate a departure from a preceding arrival on the same runway by ensuring it does not begin takeoff roll until the arriving aircraft is off of the runway. Separate a departure from a preceding departure on an intersecting runway by ensuring it does not begin takeoff roll until the first departure has passed the runway intersection or is turning to avert any conflict. Separate a departure from a preceding arrival on an intersecting runway by ensuring it does not begin takeoff roll until the arrival has passed the runway intersection or has completed landing roll and will hold short of the runway intersection.

When the second aircraft is a helicopter you may instruct it to "MAINTAIN VISUAL SEPARATION" instead of applying runway separation. When both aircraft are helicopters ensure the second helicopter does not depart until the first helicopter has left the take off area or taxied off the landing area.

Takeoff clearance need not be withheld until the required separation exists if you are sure it will exist when the aircraft starts takeoff roll. For example, the first departure is airborne but has not crossed the runway end and the second departure has called ready. The first departure will almost certainly cross the runway end before the second departure actually starts rolling so you may issue takeoff clearance to the second departure without waiting. This is called "anticipating separation."

Parts of this section were contributed by Justin McElvaney of the Houston ARTCC.

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Arrival Procedures (7110.65, 3-10-5)

IFR Arrivals will be separated, sequenced, and cleared for approach by the Approach Control. Tower need only issue landing clearance. VFR arrivals in Class B and C Airspace are handled the same as IFR arrivals. You must issue current landing information to VFR arrivals not handed off to you by APP.

  • Runway in use.
  • Wind.
  • Altimeter Setting
  • Ceiling and visibility if below VFR.
  • Low level windshear advisories when available.
  • Braking action reports when available and the braking action is reported as "POOR" or "NIL."

Landing information contained in the ATIS broadcast may be omitted if the pilot states the appropriate ATIS code.

Issue landing clearance. Restate the landing runway whenever more than one runway is active, or an instrument approach is being conducted to a closed runway.

"CLEARED TO LAND"

"RUNWAY (designator) CLEARED TO LAND"

Inform the closest aircraft that is cleared to land, touch-and-go, stop-and-go, or unrestricted low approaches when there is traffic holding on the same runway.

"AAL116, cleared to land. Traffic holding in position"
or
"AAL116, runway one eight, cleared to land. Traffic holding in position"

Most VATUSA facilities require their Tower controllers to issue the current winds with ALL landing clearances, regardless if the aircraft is on an IFR or VFR flightplan.

"WIND (surface wind direction and velocity), CLEARED TO LAND"
or
"WIND (surface wind direction and velocity), RUNWAY (designator) CLEARED TO LAND"

Landing Clearance With Traffic On Final
3-10-6. ANTICIPATING SEPARATION

Landing clearance to succeeding aircraft in a landing sequence need not be withheld if you observe the positions of the aircraft and determine that prescribed runway separation will exist when the aircraft cross the landing threshold. Issue traffic information to the succeeding aircraft if not previously reported and appropriate traffic holding in position or departing prior to their arrival. Here are three examples.

  1. "American Two Forty-Five cleared to land, number two following United Boeing Seven-Thirty-Seven two mile final, traffic will depart prior to your arrival."
  2. "American Two Forty-Five cleared to land, number two following United Boeing Seven-Thirty-Seven two mile final, traffic will be an MD 88 holding in position."
  3. "American Two Forty-Five cleared to land, following United Boeing Seven-Thirty-Seven two mile final, traffic will depart prior to your arrival."

Note - Landing sequence number is optional at tower facilities where arrivals are sequenced by the approach control.

Landing Clearance Without Visual Observation

When an arriving aircraft reports at a position where he/she should be seen but has not been visually observed, advise the aircraft as a part of the landing clearance that it is not in sight and restate the landing runway.

"NOT IN SIGHT, RUNWAY (number) CLEARED TO LAND"

Side-step Landing Clearances

Sometimes when a facility has parallel runways, such as inner and outer, a pilot may request to land on the opposite runway he or she is currently established on. This practice is known as a side-step landing and is usually requested to save taxi distance. If traffic permits and your local operating procedures approve the use of these landings, issue them in the following format.

RUNWAY (designator) IN USE, WIND (surface wind direction and velocity), RUNWAY (designator) CLEARED TO LAND"

Note - Notice the use of an advisory as to

  1. which runway is in use,
  2. a repeat of the winds information, and
  3. clearance to land on the alternate runway

Missed Approach / Go Arround Procedures

A pilot on an IFR flight plan making an instrument approach may execute a missed approach if they are unable to safely descend to the runway due to weather or other factors. The Tower controller must check the local procedures of the facility he or she is working at to see how a missed approach should be handled. In general, the controller will advise the pilot that they copy the missed approach, instruct the aircraft to fly runway heading, climb them to pattern altitude, and hand the pilot over to approach control for re-sequencing.

"COPY MISSED APPROACH, FLY RUNWAY HEADING, CLIMB AND MAINTAIN (altitude). CONTACT APPROACH ON (frequency)."

To instruct a pilot to abandon his approach use the term "GO AROUND." The most common reasons is another aircraft still on the runway or a runway incursion will result otherwise. Less common are unauthorized vehicles or personnel on the runway. Normally you should not issue go around instructions for approaches that look "unsafe." The pilot is usually in the best position to determine if he is able to make a safe landing.

A pilot on a VFR flight or IFR flight performing a visual approach may initiate a Go-Around procedure if they are unable to safely descend to the runway. Unless you issue other instructions a VFR aircraft will overfly the runway while climbing to traffic pattern altitude and an IFR aircraft will execute the published missed approach.

Handoff any IFR aircraft executing a go around or missed approach back to approach control unless the aircraft requests to remain in the VFR traffic pattern or cancels IFR. VFR aircraft will normally remain in closed traffic for another pattern.

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The Traffic Pattern (AIM, Chapter 4)

Traffic patterns can be defined as left-hand or right-hand, according to which way the turns in the pattern lie. They are usually left-hand because most small airplanes are piloted from the left seat (or the senior pilot or pilot in command sits in the left seat), and so the pilot has better visibility out the left window. Right-hand patterns will be set up for parallel runways for noise abatement or because of ground features (such as terrain, towers, etc.). Helicopters are encouraged, but not required, to use an opposite pattern from fixed wing traffic due to their slower speed and greater maneuverability. Because the active runway is chosen to meet the wind at the nearest angle (upwind), the circuit orientation also depends on wind direction.

Patterns are typically rectangular in basic shape, and include the runway along one long side of the rectangle. Each leg of the pattern has a particular name:

  • Upwind Leg - A flight path parallel to the landing runway in the direction of landing.
  • Crosswind Leg - A flight path at right angles to the landing runway off its takeoff end.
  • Downwind Leg - A flight path parallel to the landing runway in the opposite direction of landing.
  • Base Leg - A flight path at right angles to the landing runway off its approach end and extending from the downwind leg tothe intersection of the extended runway centerline.
  • Final Leg - A flight path in the direction of landing along the extended runway centerline from the base leg to the runway.
  • Departure Leg - The flight path which begins after takeoff and continues straight ahead along the runway centerline. The departureclimb continues until reaching a point at least 1/2 mile beyond the departure end of the runway and within 300feet of the traffic pattern altitude.

Pattern Altitude

A facility will define a pattern altitude, that is, a nominal altitude above the field at which pilots are required to fly while in the pattern. Unless otherwise specified, the standard pattern height is 1000 ft AGL although many small airports within VATUSA operate with a pattern height of 800 feet AGL. Helicopters usually fly their pattern at 500 feet AGL.

Entering the Pattern

Aircraft landing at an airport within Class B or Class C airspace are required to contact the appropriate ATC before entering the airspace. Usually, if the plane is small and coming in under the airspace, they will contact TWR first. The TWR controller should assign a VFR squawk code (anything in the 1200 range EXCEPT 1200) and then advise the pilot how to approach the airport (usually similar to Class D arrivals, such as "left downwind"). The only difference is that usually you donR17;t want them on a long final approach to the runway, since youR17;ll probably have high-speed IFR aircraft coming down that approach path. A close-in base turn is almost always preferable.

Arriving aircraft will normally contact the Tower when they are 5 to 10 miles from the airport, and they should give you their position and intentions (such as, "11 miles northwest, inbound for landing," or "over Mayflower, inbound for touch and goR17;s"). You wonR17;t be able to tell who is who, because all aircraft squawking 1200 are just identified with a box on the ASRC/VRC screen, along with their Mode C altitude. ThatR17;s why you need to know where they are.

Based on their position, you should give instructions on how enter the traffic pattern and when to call again. Something like "Enter left traffic for Runway 18, report midfield downwind," or "Make straight-in to Runway 18, report 2-mile final." Refer to the following table on issuing pattern entry instructions. For reference purposes we're simulating runway 18 in the examples.

Inbound Flight Direction

Arrival Procedure Phraseology

From the east R20;Cross the airport midfield at XXX feet or above (at least 500 above traffic pattern) and then make a 45-degree entry, report on the 45.R21;
From the north R20;Make straight-in to Runway 18; report on a two mile final.R21;
From the west R20;Make mid-field 45-degree entry, report on the 45R21;
From the south R20;Enter left downwind traffic, report midfield on the downwind.R21;

Again, you donR17;t tell the pilot what heading to fly, or exactly what altitude. You just tell them what "route" to get into the pattern. Your job is to plan sufficient spacing between each plane to make safe landings. If necessary, help a pilot spot another plane to follow: "Traffic is 10 oR17;clock and 2 miles, a Cessna, follow that traffic on downwind." That way, it is the pilotR17;s job to maintain good separation.

Exiting the Pattern

You already know that a VFR flight doesn't get a route clearance, so the first controller the pilot will call is Ground (if available) or Tower, and will declare that they are ready to taxi. With ASRC/VRC you wonR17;t see their callsign next to the target. In fact, when theyR17;re on the ground, they should be squawking standby, so all youR17;ll see is the primary target dot. Try to keep track of planes by writing down the call sign as they call in. The pilot will call the Tower and say they are ready for takeoff. If they donR17;t mention it, ask which direction they are departing (or if they are "staying in the pattern" to practice landings and takeoffs). Again, write down which plane called and what order they are lined up, because you canR17;t tell from the ASRC/VRC screen who is who.

Refer to the following table on how to issue pattern exiting instructions. For reference purposes we're simulating runway 18 in the examples.

Outbound Flight Direction

Departure Procedure Phraseology

Eastbound

R20;Make straight-out departureR21;

Northbound

R20;Make left cross-wind departureR21;

Westbound

R20;Make left down-wind departureR21;

*Southbound

R20;Fly straight-out until X miles from the fieldR21;

Remaining in pattern

R20;Make left closed trafficR21;


* With this procedure you as the controller will need to determine how many miles are safe.

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Closed Traffic (7110.65, 3-10-11) (AIM, Section 3)

In the previous lesson we looked at the traffic pattern and how aircraft sucessfully enter it and depart from it. But it's important to also know what to do and how to control those aircraft that wish to remain in the pattern, which is commonly referred to as "Closed Traffic". A lot of times VATSIM aircraft will request to remain in the pattern to practice their takeoff and landing procedures or sometimes to test out new panels and modules in the aircraft they are flying. Military aircraft will from time to time remain in the pattern usually for training purposes. But whatever the reason, you should know how to control closed traffic, as it is always the responsibility of the Tower to oversee these operations.

Takeoff Separation

According to the 7110.65, here is minimum seperation needed for aircraft taking off and landing:

  1. When only Category I aircraft are involved- 3,000 feet.
  2. When a Category I aircraft is preceded by a Category II aircraft- 3,000 feet.
  3. When either the succeeding or both are Category II aircraft- 4,500 feet.
  4. When either is a Category III aircraft- 6,000 feet.

Here is what defines each category

  • CATEGORY I- small aircraft weighing 12,500 lbs. or less, with a single propeller driven engine, and all helicopters.
  • CATEGORY II- small aircraft weighing 12,500 lbs. or less, with propeller driven twin-engines.
  • CATEGORY III- all other aircraft.

For your takeoff clearance, make sure you have proper phraseology as you would any other IFR aircraft, the only differences are depending on weather the aircraft is leaving the pattern or staying in the pattern. When you have 2 parallel runways, youR17;ll have to remember the fact that you canR17;t have both of the runways doing left traffic patterns, as aircraft could collide. So, what you need to do is issue right and left traffic patterns as per the runway number. For instance, if you have a runway 28L and 28R, runway 28L traffic would be left hand patterns while 28R would be right hand patterns. LetR17;s look at the proper phraseology for aircraft remaining in the pattern:

"(Callsign), Runway (XXX), winds XXX@XX, cleared for takeoff, make (left/right) closed traffic."

What about traffic departing out of the pattern? When they first call you, they will say ready for takeoff, (North/South/East/West) departure. When you hear that, you will use that in their clearance:

"(Callsign), Runway (XXX), winds XXX@XX, cleared for takeoff,(North/South/East/West) departure approved."

Upwind Sequencing (7110.65, 3-8-1)

The first way you can sequence an aircraft into the pattern is by simply extending his upwind in order to allow more room for traffic to arrive later in the pattern. There are two ways to do this. The first way is by giving the pilots a specific mileage to fly or extend their upwind before they turn. Proper phraseology is:

"(Callsign), Extend upwind (X) mile(s)".

Another way you can extend a pilot's upwind, which is preferred by most General Aviation pilots, is to inform the pilot when they can turn. Proper phraseology is:

"(Callsign), Extend upwind, IR17;ll call your crosswind".

When you are ready to turn the aircraft for their cross wind:

"(Callsign), turn crosswind now."
"(Callsign), crosswind approved."

It is at this point that you can start your sequencing even though it is the least preferred method (to extend upwind) it can become a valuable tool when you have numerous aircraft and multiple aircraft types in the pattern. Just remember, donR17;t forget about your aircraft as they have a tendency to leave your airspace before you know what happened to them.

Downwind Leg

he downwind leg can be one of the hardest legs to control when youR17;re working VFR traffic in the pattern. You have aircraft joining the pattern, flying in the pattern and departing the pattern all on one leg. It can be quite confusing trying to keep it all straight, so youR17;ll have to keep on your toes especially during this leg. First, letR17;s talk about having traffic join the pattern for the runway on the downwind leg. Most traffic will enter your airspace and call you up for a certain type of landing. When you want them to enter the pattern, simply state:

"(Callsign), enter (left/right) downwind runway (XXX)"

The pilot will then proceed to join the traffic pattern at the downwind leg. Now, if you are busy, and need the aircraft to fly outside the pattern before you sequence him in, simply state:

"(Callsign), fly (North/South/East/West) bound outside the pattern."

For aircraft that you need to sequence on final, there are, just like the upwind, two ways to sequence aircraft on the downwind to give you your necessary room. You can either have the traffic extend their downwind for a specified amount of miles, or you can tell them when to turn.

"(Callsign), Extend downwind (X) mile(s)."
"(Callsign), Extend downwind, IR17;ll call your base."

When you are ready for them to turn base, use the following phraseology:

"(Callsign), turn base now."
"(Callsign), base approved."

Outside of the Upwind and Downwind leg, sequencing in the traffic pattern rarely occurs. Most of the sequencing should be done if at all possible on the downwind leg, and if you are really far behind, the upwind leg. Just remember, as a tower controller, your airspace is only about 4NM from the airport, so make sure you keep the aircraft INSIDE your airspace when sequencing traffic in the traffic pattern.

Approach / Landing Clearances

When doing pattern work, there are multiple types of approaches and landings that you can do while in the pattern, here's an explanation of each.

  • "Cleared touch-and-go" - When authorized by the Tower, the touch-and-go procedure allows the pilot to land on the runway, reconfigure the aircraft and perform a takeoff to re-enter the traffic pattern. If requesting this approach, the pilot should do so upon establishing a downwind.
  • "Cleared low approach" - A low approach clearance allows the pilot to perform a simulated emergency landing or normal landing down to the runway enviroment (1000 ft AGL) and then perform a go-around to re-enter or depart the pattern. If requesting this approach the pilot should do so upon establishing a downwind on the traffic pattern.
  • "Cleared stop-and-go" - A stop-and-go clearance allows the pilot to land on the runway, come to a full stop, and then takeoff on the remaining length of the runway. The pilot must be aware of runway lengths and takeoff distance requirements. If requesting this clearance, the pilot should do so upon establishing a downwind on the traffic pattern.
  • "Cleared to land" (full stop) - When given this clearance, the Tower has authorized the pilot to land on the runway in use. The phrase "cleared to land" gives the pilot immediate use of that runway, unless the Tower advises the pilot that they are in sequence for landing.
  • "Cleared for the option" - When a pilot is cleared for the option, Tower is giving them permission to either do a touch-and-go, make a low approach, missed approach, stop-and-go, or a full stop landing. If requesting this clearance, the pilot should do so upon establishing a downwind on the pattern.

"(Callsign), runway (XX), cleared for the option."
"(Callsign), runway (XX), cleared (Low Approach/Touch-and-Go/Stop-and-Go/ to Land)."

Using the above only authorizes the pilot to do that specific thing, unless there is a lot of traffic, clear the pilot for the option and let him do what he wants to do. If the pilot requests to do a short approach, verify that it will not conflict with other aircraft in the pattern, and if he can do it, then after you say the R20;clearedR30;.R21; Above, state:

"Short Approach Approved"

Traffic Calls and Information

Unlike radar, since tower is all visual work, most traffic calls are relaxed and simpler to give out then radar traffic calls. The easiest way to call traffic in a tower, is say the aircraft type and where the aircraft is in comparison to his aircraft:

"(Callsign), traffic is a piper warrior off your (left/right) wing."
"(Callsign), traffic is a piper warrior off your nose."

If saying their location in comparison is difficult, you can give their position in the traffic pattern:

"(Callsign), traffic is a Cessna skylane, midfield downwind runway (XX)"
"(Callsign), traffic is a Cessna skylane, 1 mile base runway (XX)"
"(Callsign), traffic is a Cessna skylane, turning base to final runway (XX)"

If an aircraft reports that he has the traffic in sight, you can use that to sequence aircraft on final. Make sure if the aircraft is following another for final, you give him his number to land when there is multiple aircraft for the runway:

"(Callsign), follow the traffic, runway (XX), cleared for the option, number (2/3/4)"

While having traffic in the pattern, it can also cause some problems on the occasion where you may need to revoke landing or takeoff clearance. Should you have to do this, make it clear that the pilot understands you:

"(Callsign), go around, traffic on the runway"
"(Callsign), cancel takeoff clearance, traffic overhead the runway"

Parts of this section were contributed by Marko Savatic of the Chicago ARTCC.

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Arrival and Arr/Dep Separation (7110.65, 3-10-1)

Separation of IFR arrivals on the same final approach course is the responsibility of the Approach Control. Tower applies runway separation. Separate an arrival from a preceding arrival on the same runway by ensuring it does not cross the landing threshold until the first aircraft has landed and taxied off the runway. Separate an arrival from a preceding departure on the same runway by ensuring it does not cross the landing threshold until the first aircraft is airborne and past the runway end.

Separate an arrival from a preceding arrival on an intersecting runway by ensuring it does not cross the landing threshold until the arrival has passed the runway intersection or has completed landing roll and will hold short of the runway intersection. Separate an arrival from a preceding departure on an intersecting runway by ensuring it does not cross the landing threshold until the departure has passed the runway intersection or is turning to avert any conflict.

Use 2 minutes separation when any aircraft will land behind a Heavy or B-757 departing on a crossing runway if the arrival and departure airborne paths will cross. Simultaneous takeoffs and landings or simultaneous landings on intersecting runways involving Land And Hold Short Operations (LAHSO) require approval from the ARTCC ATM. He must make available to pilots and controllers the conditions under which these operations may be conducted and the procedures to be used. When the second aircraft is a helicopter you may instruct it to "MAINTAIN VISUAL SEPARATION" instead of applying runway separation. When both aircraft are helicopters ensure the second helicopter does not land until the first helicopter has taxied off the landing area or left the take off area.

Issue wake turbulence cautionary advisories to any aircraft landing behind a Heavy or B757:

  1. On the same or parallel runways separated by less than 2,500 feet, eg "RUNWAY 27L CLEARED TO LAND, CAUTION WAKE TURBULENCE, HEAVY 747 DEPARTING RUNWAY 27R."
  2. On crossing runways if the arrivalR17;s flight path will cross behind the departureR17;s path and rotation point, eg "RUNWAY 36 CLEARED TO LAND, CAUTION WAKE TURBULENCE, 757 DEPARTING RUNWAY 27."

Landing clearance need not be withheld until the required separation exists if you are sure it will exist when the second aircraft crosses the landing threshold. For example, the first arrival is landing roll and the second arrival is 5 mile final. The first arrival is virtually certain to be off the runway before the second arrival flies those 5 miles. Therefore, you may issue landing clearance to the second aircraft even though the required separation doesnR17;t currently exist. This is called "anticipating separation." Issue traffic information to the second aircraft, e.g. "RUNWAY 36 CLEARED TO LAND. TRAFFIC IS A LEAR 45 OVER THE APPROACH LIGHTS."

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