Updated: Dec 8, 2020

IFR En-Route Procedures Lesson by wifiCFI

En-Route Procedures

In this lesson we will cover IFR En-Route Procedures to include:

IFR Low En-Route Chart Symbology

Instrument En-Route Altitudes

Flying on Victor Airways

Waypoints and Changeover Points

“Cruise” Clearances

VFR on Top Procedures

Reporting Points and Radio Procedures

IFR Low En-Route Charts

IFR Low En-Route Charts contain all of the necessary information pilots need while flying En-Route below 18,000’ MSL.

Charts are established for altitudes above 18,000’ MSL but are called “High En-Route Charts.”

Low En-Route Chart Symbology

See the full En-Route Chart Symbology in your wifiCFI Lesson.

Selecting the Cruise Altitude

A pilot should select an IFR Cruising Altitude based on his/her magnetic course with the following criteria:

If your Magnetic Course is between 000-179 = Odd Altitudes (ex. 3,000, 5,000, 7,000’).

If your Magnetic Course is between 180-359 = Even Altitudes (ex. 4,000, 6.000, 8,000’).

Instrument En-Route Altitudes

There are different instrument altitudes pilots need to be aware of when operating on an IFR Flight. We will discuss each one in detail.









MEA stands for “Minimum En-Route Altitude.”

They are depicted along Victor Airways as seen below.

An MEA Altitude Guarantees a pilot 2 things:

First, Obstacle Clearance:

1,000’ in Non-Mountainous Areas

4 NM either side of course centerline

2,000’ in Mountainous Areas

4 NM either side of course centerline

Second, suitable Navigation Coverage throughout the entire route segment.

Its important for pilots to know when an MEA changes along their route of flight.

That way, the pilot can climb or descend to the new MEA Altitude and maintain obstacle clearance and navigation coverage.

Changes in MEA altitudes are depicted on the Low En-Route Charts.


MOCA stands for “Minimum Obstacle Clearance Altitude.”

They are depicted under MEA’s with an Asterisk.

A MOCA Altitude Guarantees a pilot 2 things:

First, Obstacle Clearance:

1,000’ in Non-Mountainous Areas

4 NM either side of course centerline

2,000’ in Mountainous Areas

4 NM either side of course centerline

Second, suitable Navigation Coverage for 22 NM from each VOR.


MAA stands for “Maximum Authorized Altitude.”

They are depicted as shown below.

An MAA may be established for many reasons:

Keep pilots below other airplanes on approach.

So a pilot does not pick up 2 VOR’s of the same frequency.


MRA stands for “Minimum Reception Altitude.”

They are depicted as shown on wifiCFI.

They are established to pick up off-route VOR’s.

Off-route VOR’s  can be used to identify waypoints along a route.

In our example we can see…

The pilot will need to be at an MRA Altitude of 11,000’

To pick up the 180 Radial off of VOR C

The pilot will use radial 180 from VOR C and Radial 090 from VOR A to identify “Waypoint A”


MCA stands for “Minimum Crossing Altitude.”

They are depicted as shown on wifiCFI.

MCA’s are specific to the direction of flight being flown.

MCA are established to allow terrain clearance along a route.

Pilots should always check for MCA symbols along their route of flight.

In our example we can see…

The Pilot will need to cross VOR B at a minimum of 12,000’

This will ensure terrain clearance as he/she continues climb to the new MEA of 14,000’


OROCA stands for “Off-Route Obstacle Clearance Altitude.”

This altitude should be maintained when flying off victor airways.

These altitudes are broken into map sections.

It will provide terrain clearance:

Non-Mountainous Areas: 1,000’

Mountainous Areas: 2,000’


MSA stands for “Minimum Sector Altitudes.”

These altitudes are commonly found on Instrument Approach Procedure Charts.

They will be covered in the Approach Lesson in more detail.

However, MSA’s provide the pilot with a safe emergency altitude to climb to.

They provide 1,000’ terrain clearance in both mountainous and non-mountainous areas.

Fly-By Waypoints

Fly-By waypoints are depicted as shown below.

It means the pilot can “cut-the-corner” in a manner of speaking.

He/she does not need to fly-over the waypoint before making a course change.

Fly-Over Waypoints

Fly-Over waypoints are depicted as shown below.

He/she must fly over the waypoint before making the course change.

Changeover Points

Changeover points let a pilot know when he/she should switch from tracking one VOR to the next.

There are 3 types of changeover points on En-Route Charts.

First, when no changeover point is published, the pilot should changeover halfway between VOR’s.

Some Victor Airways have depicted changeover points.

They look as shown below.

They tell the pilot, in NM, when to switch from one VOR to the next.

The third changeover point is whenever there is a bend in an airway.

Sometimes, bends in airways are very noticeable.

Other times they aren’t so noticeable.

When the bend is not super apparent they are depicted with an “X”

ATC Reporting Points

There are 2 types of reporting points in the IFR Flight Environment.


“Compulsory” means mandatory.

Compulsory reporting points must be reported to ATC when NOT in Radar Contact.


These points are NOT mandatory reporting points.

However, ATC can request pilots make reports at these points in the interest of safety.

These two reporting point types are depicted on charts as shown on wifiCFI.

Cruise Clearances (AIM PCG)

At times, ATC can issue a “Cruise” Clearance to pilots.

A Cruise Clearance allows a pilot to “cruise” at any altitude from the MEA to the Cruise Altitude given in the clearance en-route to the destination. 

Climbs and descents made within this “block” of airspace may be made at the pilot’s discretion.

However, once a pilot commences descent and informs ATC of the descent, he/she may not return to the vacated altitude without an additional ATC clearance.

Lastly, a Cruise Clearance allows a pilot to select any desired instrument approach at the Destination Airport.

Example Clearance:

“N736TB Cruise 10,000’ to Wendover Airport”

VFR On Top (AIM 5-5-13)

A VFR On Top Clearance can be granted to pilots that wish to fly IFR through a layer a clouds and then operate VFR On Top of the cloud layer.

Requested in conjunction with an IFR Clearance.

They allow the pilot to operate at VFR altitudes in lieu of an assigned VFR altitude.

A pilot on a VFR On Top Clearance Must:

Be responsible for his/her own traffic clearance (see and avoid)

Maintain the regulated VFR Altitudes

Comply with all Instrument Flight Rules applicable to the route of flight (minimum IFR altitudes, position reporting, ATC Clearances, etc.)

Comply with VFR Visibility and Cloud Clearance Requirements applicable to the class of airspace (VFR on Top is never allowed in Class A airspace)

Advise ATC of any altitude changes.

ATC Reporting Procedures

Below is a list of all the Mandatory Reporting Scenarios with ATC:

Remember acronym “MATHCALLS”

M: Missed Approach

A: Altitude Changes when VFR on Top

T: True Airspeed Change of +/- 10 KIAS or 5%

H: Holding

Time and altitude when entering/exiting the holding fix

C: Cannot maintain 500 FPM climb or descent

A: Altitude and time at a holding fix

L: Leaving an assigned altitude

L: Lost Communication or Navigation Equipment

S: Safety of Flight Issues

C: Clearance Limit Arrival

Below is a list of Compulsory Reporting Calls when NOT in Radar Contact:

Depicted Compulsory Reporting Points

Inbound at the FAF (Final Approach Fix)

Inbound at the OM (Outer Marker)

ETA difference of 3 minutes or more

ATC Reporting Calls

When making position reports to ATC, the pilot should include the following in the radio call:

Remember acronym “IPTANES”

I: ID (tail number)

P: Position

T: Time

A: Altitude

N: Next fix

E: ETA at next fix

S: Supplemental Information (anything else pertinent)

FAA Sources Used for This Lesson

Federal Aviation Regulations Part 91

Aeronautical Information Manual Chapter 5

Pilot Controller Glossary

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