Enroute Syllabus

From ZOA Training Wiki

Contents 1 Separation 1.1 Lateral Separation 1.2 Vertical Separation 2 Altitudes and Flight Levels 3 VFR on Top 3.1 Introduction 3.2 Procedure 4 Special Use Airspace 4.1 Introduction 4.2 Alert Areas 4.3 Military Operations Areas (MOAs) 4.4 National Security Areas 4.5 Prohibited Areas 4.6 Restricted Areas 4.7 Warning Areas 5 Speed Restrictions 6 Route Amendments 7 Descents 8 Holds 9 Oceanic Clearances and Transfers

Separation

Lateral Separation

For the enroute controller, radar separation rules are fairly straightforward.

• There is no visual separation allowed in Class A airspace.
• 5 nm separation below FL600
• 10 nm separation at or above FL600

Note that local SOPs or LOAs may dictate other separation requirements that you must adhere to. For example, two aircraft on the same route to the same airport in an adjoining ARTCC may require a minimum of 10 nm in trail, sometimes regardless of vertical separation.

For oceanic flights at the same cruise altitude, the minimum lateral separation may be 20 nm in trail.

Vertical Separation

Here is the minimum vertical separation between aircraft. This should be a review of what you already know from Approach Control.

• Below FL290 - 1000 ft
• FL300 to FL410 with RVSM - 1000 ft
• FL300 to FL410 with no RVSM - 2000 ft
• Above FL410 for all aircraft - 2000 ft
• FL600 and above - 5000 ft
• Oceanic aircraft above FL450 - 4000 ft

Altitudes and Flight Levels

Recall that when an aircraft climbs up to the transition altitude (the first usable flight level) the pilot sets the altimeter to standard pressure, 29.92. Many VATSIM pilots probably assume that the first usable flight level is always FL180. However that is not always the case.

When the barometric pressure falls below standard pressure (29.92 in Hg) this has an impact on usable flight levels. How does that happen?

Let's say that you are flying in an aircraft that is level at FL180 with altimeter set to 29.92. As the barometric pressure in the environment around you falls lower and lower -- and even though it appears to you that you are in level flight at the same altitude above the ground -- in fact your aircraft is getting closer and closer to the ground!

Or to put it another way,

1. When the barometric pressure is at exactly 29.92 in Hg, FL180 happens to be exactly the same as 18000 MSL.
2. When the pressure is higher than 29.92, then FL180 is actually above 18000 MSL.
3. When the pressure falls below 29.92, then FL180 is below 18000 MSL.

With me so far? Good.

Now let's consider vertical separation of aircraft -- something very important to an air traffic controller. In cases 1 and 2 above, you can be assured that an aircraft flying at FL180 is separated by at least 1000 ft above any other IFR aircraft at 17000 MSL (assuming the latter has his altimeter correctly set). However in case 3 an aircraft that is flying at FL180 may very well be separated by LESS THAN 1000 ft from other aircraft at 17000 MSL. So that means we cannot use FL180 as a safe cruise altitude. BUT WAIT... there's more. If the barometric pressure gets low enough, you also cannot use FL190. Maybe not even FL200!

So here are the exact guidelines to follow.

Barometric pressure below 29.92 – FL180 is unavailable

Barometric pressure below 28.91 – FL190 is unavailable

Barometric pressure below 27.92 – FL200 is unavailable

VFR on Top

Introduction

VFR on Top allows a pilot with an IFR flight plan to fly under visual flight rules, as long as he remains clear (or "on top") of clouds, fog, haze, smoke, or other visual constraints that may have required flying under IFR earlier in the flight, such as during departure and climb-out.

• VFR on Top is not allowed in class A airspace
• The aircraft must fly at the appropriate altitude + 500
• Pilot is responsible for his own separation from other traffic, and his own separation from weather

Procedure

1. Pilot requests VFR on Top
2. "N2581K, climb to and report VFR-on-top. Tops reported 12000." (or) "... no tops reported."
3. "If not on top at FL180, maintain FL180 and advise."
4. (when pilot reports): "N2581K, maintain VFR-on-top."

Special Use Airspace

Introduction

Alert Areas

Military Operations Areas (MOAs)

National Security Areas

Prohibited Areas

Restricted Areas

Warning Areas

Speed Restrictions

Route Amendments

Often it may be necessary to amend a clearance route. For example, an aircraft that you just took control of, where the flight plan does not include an appropriate arrival procedure or equivalent routing. Or perhaps there is an arrival procedure that currently is not valid to use due to winds, time of day, or other conditions.

Note that local SOPs may specify that if a pilot cannot accept a preferred arrival procedure (for example does not have the chart), the aircraft will then be cleared via the equivalent routing using fixes.

Here are examples of route amendment phraseology:

"Cleared via MOD3 arrival OAL transition, rest of route unchanged."

"Cleared direct BSR, BSR2 arrival."

"Cleared direct PYE, direct SFO."

Descents

To issue descents you have two options: either you decide when the aircraft should start down, or let the pilot do it.

• Option 1: specific descent instruction

Let's start with the less common option. If you want to tell the pilot when to start his descent, determine the point to begin descent by multiplying the net altitude decrease, in 1000’s of feet, by 4. The result is how many miles away from the destination (or the completion of the descent) to start down.

Example:

You are controlling an aircraft at FL320 on BSR2 arrival, that needs to descend to FL200 prior to handoff to MRY_APP. This aircraft will have a crossing restriction for SKUNK at or below 12000. So the net altitude decrease to SKUNK is 20000 (FL320 - 120000). Divide to the nearest thousands, then multiply by four: 20 x 4 = 80. The aircraft should begin its descent to FL200 approximately 80 nm away from SKUNK (about 26 nm prior to BSR).

• Option 2: pilot's discretion

Now let's talk about the simpler way to do it. Assuming the pilot knows how to do the above calculations himself (or rely on his FMC to do it!) You can give the intruction, "Descend pilot’s discretion, maintain FL200" early enough so the pilot can determine for himself when to start his descent. In many cases the pilot will want to refer to refer to "Vertical Planning Information" in the arrival chart. If you have doubts about the ability of the pilot you are talking to, better to play it safe and give the explicit instruction to start the descent as described above.

Holds

Holding instructions usually consist of the following five (5) items. Some of these items may be omitted if using a published hold on a chart.

1. Holding Fix and cardinal direction (N, S, E, W, etc.).
2. Holding course, radial, bearing, or airway on which the aircraft is to hold.
3. Leg length in miles or minutes (standard hold is 1-minute legs at or below 14000 ft, or 1½ minute legs above 14000 ft).
4. Direction of turns (although standard hold is right turns, be sure to specify).
5. Expect Further Clearance time (EFC).

Examples:

"Cleared to PYE, hold northwest on the 325 radial, 1-minute legs, right turns, expect further clearance 0115 zulu."

"Cleared to BSR, hold south on V-27, 10 mile legs, left turns, expect further clearance 1920 zulu."

If the holding pattern is published and the pilot has the chart you only need to include the direction, the term "AS PUBLISHED" and an Expect Further Clearance (EFC):

Example:

"Cleared to MOD, hold east as published, expect further clearance 2345 zulu."

You must use your best judgment when computing EFCs. They should be as accurate and realistic as possible. Consider these factors:

• The number of aircraft in the approach sequence ahead of the holding aircraft.
• The distance from the holding fix to the destination.
• Each complete holding pattern takes a minimum of 4 minutes.

You may also use a visual fix if the pilot can see it and is familiar with it. For example:

"Hold at Angel Island until further advised."

Remember that maximum airspeed in a hold is 210 kts.

Oceanic Clearances and Transfers