| Home | Privacy | Contact |

Instrument Flying Handbook
The National Airspace System
IFR En Route Charts

| First | Previous | Next | Last |

Instrument Flying


Table of Contents

Chapter 1. Human Factors
Chapter 2. Aerodynamic Factors
Chapter 3. Flight Instruments
Chapter 4. Section I
Airplane Attitude Instrument
Using Analog Instrumentation
Chapter 4. Section II
Airplane Attitude Instrument
Using an Electronic Flight

Chapter 5. Section I
Airplane Basic
Flight Maneuvers
Using Analog Instrumentation
Chapter 5. Section II
Airplane Basic
Flight Maneuvers
Using an Electronic Flight

Chapter 6. Helicopter
Attitude Instrument Flying

Chapter 7. Navigation Systems
Chapter 8. The National
Airspace System

Chapter 9. The Air Traffic
Control System

Chapter 10. IFR Flight
Chapter 11. Emergency

En Route Airport Legend
Figure 8-3. En Route Airport Legend

The minimum crossing altitude (MCA) will be charted when
a higher MEA route segment is approached. The MCA is
usually indicated when a pilot is approaching steeply rising
terrain, and obstacle clearance and/or signal reception is
compromised. In this case, the pilot is required to initiate
a climb so the MCA is reached by the time the intersection
is crossed. On NACG charts, the MCA is indicated by the
symbol , and the Victor airway number, altitude, and
the direction to which it applies (e.g. "V24 8000 SE").

The maximum authorized altitude (MAA) is the highest
altitude at which the airway can be flown with assurance
of receiving adequate navigation signals. Chart depictions
appear as "MAA-15000."

When an MEA, MOCA, and/or MAA change on a segment
other than at a NAVAID, a sideways "T" is depicted
on the chart. If there is an airway break without the symbol,
one can assume the altitudes have not changed (see the upper
left area of Figure 8-2). When a change of MEA to a higher
MEA is required, the climb may commence at the break,
ensuring obstacle clearance. [Figure 8-4]

Navigation Features
Types of NAVAIDs
Very high frequency omnidirectional ranges (VORs) are the
principal NAVAIDs that support the Victor and Jet airways.
Many other navigation tools are also available to the pilot.
For example, nondirectional beacons (NDBs) can broadcast
signals accurate enough to provide stand-alone approaches,
and DME allows the pilot to pinpoint a reporting point on the
airway. Though primarily navigation tools, these NAVAIDs
can also transmit voice broadcasts.

Tactical air navigation (TACAN) channels are represented
as the two or three-digit numbers following the three-letter
identifier in the NAVAID boxes. The NACG terminal
procedures provide a frequency-pairing table for the
TACAN-only sites. On NACG charts, very-high frequencies
and ultra-high frequencies (VHF/UHF) NAVAIDs (e.g.,
VORs) are depicted in black, while low frequencies and
medium frequencies (LF/MF) are depicted as brown.
[Figure 8-5]

Identifying Intersections
Intersections along the airway route are established by a
variety of NAVAIDs. An open triangle indicates the
location of an ATC reporting point at an intersection. If the
triangle is solid, a report is compulsory. [Figure 8-4]