Figure 2-62. Minimum crossing altitude (MCA).
or above the MTA until joining the centerline of the ATS
route following the turn. Once established on the centerline
following the turning fix, the MEA/MOCA determines the
minimum altitude available for assignment.
An MTA may also preclude the use of a specific altitude or
a range of altitudes during a turn. For example, the MTA
may restrict the use of 10,000 through 11,000 feet MSL.
In this case, any altitude greater than 11,000 feet MSL is
unrestricted, as are altitudes less than 10,000 feet MSL
provided MEA/MOCA requirements are satisfied.
All MTA information associated with the airway/route
inbound to the turn fix/facility is put in the remarks section
of FAA Form 8260-16, Transmittal of Airways/Route Data,
using the following format [Figure 2-61]:
#CHART: MTA V330 E TO V520 W 16000
(Document on V330 FAA Form 8260-16)
#CHART: MTA V465 NE TO V330 W OR V520 W 16000
(Document on V465 FAA Form 8260-16)
When an MTA is required by FAA Order 8260.3, paragraph
15-1-5c, enter the MTA information in the REMARKS section
of FAA Form 8260-2, Radio Fix and Holding Data Record, as
specified on the appropriate FAA Form 8260-16, Transmittal
of Airways/Route Data, using the following format:
MTA: V330 E TO V520 W 16000
700'
3200'
2000'
6 NM
4620' MSL
120' per NM required
Multiply by 6 NM −720 feet
Maximum Displacement
MSL
MEA 5200'
MCA 5900' E
Obstruction height 4,620'
Required clearance +2000'
MOCA at obstruction =6,620'
Climb value* −720'
MCA required =5,900'
* Based upon 6 NM @ 120 feet per NM
Obstacle Line
2000'
Figure 2-63. Minimum crossing altitude (MCA) determination point.
MTA: V465 NE TO V330 W OR V520 W 16000
Minimum Crossing Altitude (MCA)
An MCA is the lowest altitude at certain fixes at which the
aircraft must cross when proceeding in the direction of a
higher minimum en route IFR altitude. [Figure 2-62] When
applicable, MCAs are depicted on the en route chart. [Figure
2-59] MCAs are established in all cases where obstacles
intervene to prevent pilots from maintaining obstacle
clearance during a normal climb to a higher MEA after
passing a point beyond which the higher MEA applies. The
same protected en route area vertical obstacle clearance
requirements for the primary and secondary areas are
considered in the determination of the MCA. The standard
for determining the MCA is based upon the following climb
gradients and is computed from the flight altitude:
• Sea level through 5,000 feet MSL—150 feet per NM
• 5000 feet through 10,000 feet MSL—120 feet per
NM
• 10,000 feet MSL and over—100 feet per NM
To determine the MCA seen on an en route chart, the
distance from the obstacle to the fix is computed from
the point where the centerline of the en route course in
the direction of flight intersects the farthest displacement
from the fix. [Figure 2-63] When a change of altitude is
involved with a course change, course guidance must be
provided if the change of altitude is more than 1,500 feet
and/or if the course change is more than 45°, although
there is an exception to this rule. In some cases, course
changes of up to 90° may be approved without course
guidance provided that no obstacles penetrate the
established MEA requirement of the previous airway or
route segment. Outside United States airspace, pilots may
encounter different flight procedures regarding MCA and
transitioning from one MEA to a higher MEA. In this case,
pilots are expected to be at the higher MEA crossing the
fix, similar to an MCA. Pilots must thoroughly review flight
procedure differences when flying outside United States
airspace. On IFR en route low altitude charts, routes and
associated data outside the conterminous United States
are shown for transitional purposes only and are not part
of the high altitude jet route and RNAV route systems.
[Figure 2-64]
Minimum IFR Altitude (MIA)
The MIA for operations is prescribed in 14 CFR Part 91. These
MIAs are published on aeronautical charts and prescribed
in 14 CFR Part 95 for airways and routes, and in
14 CFR Part 97 for standard instrument approach
procedures. If no applicable minimum altitude is prescribed
NOT FOR NAVIGATION
IN CANADA CROSS EACH FIX AT OR
ABOVE THE HIGHER MINIMUM EN ROUTE
IFR ALTITUDE APPLICABLE TO FLIGHT .
Figure 2-64. En route chart minimum crossing altitude data (outside of the U.S.).
SAMPLE NOT
FOR ACTUAL USE
Figure 2-65. MVA chart.
in 14 CFR Parts 95 or 97, the following MIA applies: In
designated mountainous areas, 2,000 feet above the
highest obstacle within a horizontal distance of 4 NM
from the course to be flown; or other than mountainous
areas, 1,000 feet above the highest obstacle within a
horizontal distance of 4 NM from the course to be flown; or
as otherwise authorized by the Administrator or assigned
by ATC. MIAs are not flight checked for communication.
Minimum Vectoring Altitudes (MVA)
MVAs are established for use by ATC when radar ATC is
exercised. The MVA provides 1,000 feet of clearance above
the highest obstacle in non-mountainous areas and 2,000
RKS 160
RKS 080
KS 003
RKS 269
RKS 325
10,000
RIW
15,800
14,500
12,000
13,700
10,700
11,000
12,40012,000
15,500
14,200
11,000
13,800
13,300
12,300
14,500
CKW
VEL
FBR
RKS
feet above the highest obstacle in designated mountainous
areas. Because of the ability to isolate specific obstacles,
some MVAs may be lower than MEAs, MOCAs, or other
minimum altitudes depicted on charts for a given location.
While being radar vectored, IFR altitude assignments by
ATC are normally at or above the MVA.
Air traffic controllers use MVAs only when they are assured
an adequate radar return is being received from the aircraft.
Charts depicting MVAs are available to controllers and have
recently become available to pilots. They can be found
at http://www.faa.gov/air_traffic/flight_info/aeronav/
digital_products/mva_mia/ Situational Awareness is
IFR
EVEN
2,000'
Intervals
begin at
18,000' MSL
VFR or
VFR-ON-TOP
EVEN
2,000'
Intervals
begin at
FL 185
IFR
ODD
2,000'
Intervals
begin at
FL 190
VFR or
VFR-ON-TOP
ODD
2,000'
Intervals
begin at
FL 195
359°M
180°
0°
179°M
18,000' MSL to flight level 290
IFR
EVEN
4,000'
Intervals
begin at
FL 310
VFR or
VFR-ON-TOP
4,000'
Intervals
begin at
FL 320
IFR
4,000'
Intervals
begin at
FL 290
VFR or
VFR-ON-TOP
4,000'
Intervals
begin at
FL 300
359°M
180°
0°
179°M
Flight level 290 and above
IFR
EVEN
thousands
VFR or
ON-TOP
EVEN
thousands
plus
500'
IFR
ODD
thousands
VFR or
ON-TOP
ODD
thousands
plus
500'
359°M
180°
0°
179°M
Cruising altitudes - U.S.
IFR within controlled airspace as assigned by ATC
For additional symbol information
refer to the chart user’s guide.
VFR above 3000' AGL unless otherwise
authorized by ATC IFR outside controlled
airspace all courses are magnetic
NO VFR FLIGHTS WITHIN
CLASS A AIRSPACE
CRUISING ALTITUDES
IFR within controlled airspace as assigned by ATC
VFR above 3,000' AGL unless otherwise
authorized by ATC IFR outside controlled
airspace all courses are magnetic
Figure 2-66. Cruising altitude or flight level.
always important, especially when being radar vectored
during a climb into an area with progressively higher MVA
sectors, similar to the concept of MCA. Except where diverse
vector areas have been established, when climbing, pilots
should not be vectored into a sector with a higher MVA
unless at or above the next sector’s MVA. Where lower
MVAs are required in designated mountainous areas to
achieve compatibility with terminal routes or to permit
vectoring to an instrument approach procedure, 1,000 feet
of obstacle clearance may be authorized with the use of
Airport Surveillance Radar (ASR). The MVA provides at least
300 feet above the floor of controlled airspace. The MVA
charts are developed to the maximum radar range. Sectors
provide separation from terrain and obstructions. Each MVA
chart has sectors large enough to accommodate vectoring
of aircraft within the sector at the MVA. [Figure 2-65]
IFR Cruising Altitude or Flight Level
In controlled airspace, pilots must maintain the altitude or
flight level assigned by ATC, although if the ATC clearance
assigns “VFR conditions on-top, ” an altitude or flight level as
prescribed by 14 CFR Part 91, § 91.159 must be maintained.
In uncontrolled airspace (except while in a holding pattern
of two minutes or less or while turning) if operating an
aircraft under IFR in level cruising flight, an appropriate
altitude as depicted in the legend of IFR en route high
and low altitude charts must be maintained. [Figure 2-66]
When operating on an IFR flight plan below 18,000 feet
MSL in accordance with a VFR-on-top clearance, any VFR
cruising altitude appropriate to the direction of flight
between the MEA and 18,000 feet MSL may be selected that
allows the flight to remain in VFR conditions. Any change in
altitude must be reported to ATC, and pilots must comply
with all other IFR reporting procedures. VFR-on-top is not
authorized in Class A airspace. When cruising below 18,000
feet MSL, the altimeter must be adjusted to the current
setting, as reported by a station within 100 NM of your
position. In areas where weather-reporting stations are
more than 100 NM from the route, the altimeter setting of
a station that is closest may be used.
During IFR flight, ATC advises flights periodically of the
current altimeter setting, but it remains the responsibility
of the pilot or flight crew to update altimeter settings in a
timely manner. Altimeter settings and weather information
are available from weather reporting facilities operated or
approved by the U.S. National Weather Service, or a source
approved by the FAA. Some commercial operators have
the authority to act as a government-approved source of
weather information, including altimeter settings, through
certification under the FAA’s Enhanced Weather Information
System.
Flight level operations at or above 18,000 feet MSL require
the altimeter to be set to 29.92 inches of mercury (" Hg). A
flight level (FL) is defined as a level of constant atmospheric
pressure related to a reference datum of 29.92 " Hg. Each
flight level is stated in three digits that represent hundreds of
feet. For example, FL 250 represents an altimeter indication
of 25,000 feet. Conflicts with traffic operating below 18,000
feet MSL may arise when actual altimeter settings along the
route of flight are lower than 29.92 " Hg. Therefore, 14 CFR
Part 91, § 91.121 specifies the lowest usable flight levels for
a given altimeter setting range.
Reduced Vertical Separation Minimums (RSVM)
Reduced vertical separation minimums (RVSM) is a term
used to describe the reduction of the standard vertical
separation required between aircraft flying at levels
between FL 290 (29,000 feet) and FL 410 (41,000 feet)
from 2,000 feet to 1,000 feet. The purpose; therefore,
increases the number of aircraft that can safely fly in a
particular volume of airspace. Historically, standard vertical
separation was 1,000 feet from the surface to FL 290, 2,000
feet from FL 290 to FL 410 and 4,000 feet above this. This
was because the accuracy of the pressure altimeter (used
to determine altitude) decreases with height. Over time,
air data computers (ADCs) combined with altimeters have
become more accurate and autopilots more adept at
maintaining a set level; therefore, it became apparent that
for many modern aircraft, the 2,000-foot separation was not
required . It was, therefore, proposed by ICAO that this be
reduced to 1,000 feet.
Between 1997 and 2005, RVSM was implemented in all of
Europe, North Africa, Southeast Asia, North America, South
America, and over the North Atlantic, South Atlantic, and
Pacific Oceans. The North Atlantic implemented initially in
March 1997, at FL 330 through FL 370. The entire western
hemisphere implemented RVSM FL 290–FL 410 on January
20, 2005.
Only aircraft with specially certified altimeters and
autopilots may fly in RVSM airspace, otherwise the aircraft
must fly lower or higher than the airspace, or seek special
exemption from the requirements. Additionally, aircraft
operators (airlines or corporate operators) must receive
specific approval from the aircraft’s state of registry in
order to conduct operations in RVSM airspace. Non-RVSM
approved aircraft may transit through RVSM airspace
provided they are given continuous climb throughout the
designated airspace, and 2,000 feet vertical separation is
provided at all times between the non-RVSM flight and all
others for the duration of the climb/descent.
Critics of the change were concerned that by reducing
the space between aircraft, RVSM may increase the
number of mid-air collisions and conflicts. In the ten
years since RVSM was first implemented, not one
collision has been attributed to RVSM. In the United
States, this program was known as the Domestic
Reduced Vertical Separation Minimum (DRVSM).
Cruise Clearance
The term “cruise” may be used instead of “maintain” to
assign a block of airspace to an aircraft. The block extends
from the minimum IFR altitude up to and including the
altitude that is specified in the cruise clearance. On a cruise
clearance, you may level off at any intermediate altitude
within this block of airspace. You are allowed to climb or
descend within the block at your own discretion. However,
once you start descent and verbally report leaving an
altitude in the block to ATC, you may not return to that
altitude without an additional ATC clearance. A cruise
clearance also authorizes you to execute an approach at
the destination airport.
Lowest Usable Flight Level
When the barometric pressure is 31.00 " Hg or less and
pilots are flying below 18,000 feet MSL, use the current
reported altimeter setting. When an aircraft is en route
on an instrument flight plan, air traffic controllers furnish
this information at least once while the aircraft is in the
controller’s area of jurisdiction. When the barometric
pressure exceeds 31.00 " Hg, the following procedures are
placed in effect by NOTAM defining the geographic area
affected: Set 31.00 " Hg for en route operations below
18,000 feet MSL and maintain this setting until beyond
the affected area. ATC issues actual altimeter settings and
advises pilots to set 31.00 " Hg in their altimeter, for en route
operations below 18,000 feet MSL in affected areas. If an
aircraft has the capability of setting the current altimeter
setting and operating into airports with the capability of
measuring the current altimeter setting, no additional
restrictions apply. At or above 18,000 feet MSL, altimeters
should be set to 29.92 " Hg (standard setting). Additional
procedures exist beyond the en route phase of flight.
The lowest usable flight level is determined by the
atmospheric pressure in the area of operation. As local
altimeter settings fall below 29.92 " Hg, pilots operating
in Class A airspace must cruise at progressively higher
indicated altitudes to ensure separation from aircraft
FAA AIR SERVICE OUTSIDE U.S. AIRSPACE
IS PROVIDED IN ACCORDANCE WITH
ARTICLE 12 AND ANNEX 11 OF ICAO
CONVENTION. ICAO CONVENTION NOT
APPLICABLE TO STATE AIRCRAFT BUT
COMPLIANCE WITH ICAO STANDARDS
AND PRACTICES IS ENCOURAGED.
NOT FOR NAVIGATION
MONCTON FIRCZQM
ALTIMETERQNH QNE
CRABB
N42°13.00´
W65°44.00´
Figure 2-67. Altimeter setting changes.
operating in the low altitude structure as follows:
Current Altimeter Setting Lowest Usable Flight Level
29.92 or higher 180
29.91 to 29.42 185
29.41 to 28.92 190
28.91 to 28.42 195
28.41 to 27.91 200
When the minimum altitude, as prescribed in 14 CFR Part
91, § 91.159 and 91.177, is above 18,000 feet MSL, the
lowest usable flight level is the flight level equivalent of
the minimum altitude plus the number of feet specified
according to the lowest flight level correction factor as
follows:
Altimeter Setting Correction Factor
29.92 or higher —
29.91 to 29.42 500 feet
Altimeter Setting Correction Factor
29.41 to 28.92 1,000 feet
28.91 to 28.42 1,500 feet
28.41 to 27.91 2,000 feet
27.91 to 27.42 2,500 feet
Operations in Other Countries
When flight crews transition from the U.S. NAS to another
country’s airspace, they should be aware of differences not
only in procedures but also airspace. For example, when
flying into Canada as depicted in Figure 2-67, notice the
change from transition level (QNE) to transition altitude
(QNH) when flying north-bound into the Moncton flight
information region (FIR).
Operations in international airspace demand that pilots
are aware of, and understand the use of, the three types
of altimeter settings. Most overseas airports give altimeter
RADAR/NON-RADAR REPORTS
These reports should be made at all times without a specific ATC request.
Leaving one assigned flight altitude or flight level for another
VFR-on-top change in altitude
Leaving any assigned holding fix or point
Missed approach
Unable to climb or descend at least 500 fpm
TAS variation from filed speed of 5% or 10 knots, whichever
is greater
Time and altitude or flight level upon reaching a holding fix
or clearance limit
Loss of Nav/Comm capability (required by Part 91.187)
Unforecast weather conditions or other information relating
to the safety of flight (required by Part 91.183)
"Marathon 564, leaving 8,000, climb to 10,000. "
"Marathon 564, VFR-on-top, climbing to 10,500. "
"Marathon 564, leaving FARGO Intersection. "
"Marathon 564, missed approach, request clearance to Chicago. "
"Marathon 564, maximum climb rate 400 feet per minute. "
"Marathon 564, advises TAS decrease to140 knots. "
"Marathon 564, FARGO Intersection at 05, 10,000, holding east. "
"Marathon 564, ILS receiver inoperative. "
"Marathon 564, experiencing moderate turbulence at 10,000. "
NON-RADAR REPORTS
When you are not in radar contact, these reports should be made without a specific request from ATC.
Leaving FAF or OM inbound on final approach
Revised ETA of more than three minutes
"Marathon 564, outer marker inbound, leaving 2,000. "
"Marathon 564, revising SCURRY estimate to 55. "
REPORTS EXAMPLE
REPORTS EXAMPLE
Figure 2-68. ATC reporting procedures.
settings in hectopascals (hPa) (millibars). Therefore, it is
imperative that pilots or on-board equipment are able
to accurately convert inches of mercury to hPa, or hPa to
inches of mercury.
Altitude Above Ground (QFE)
A local altimeter setting equivalent to the barometric
pressure measured at an airport altimeter datum, usually
signifying the approach end of the runway is in use. At the
airport altimeter datum, an altimeter set to QFE indicates
zero altitude. If required to use QFE altimetry, altimeters
are set to QFE while operating at or below the transition
altitude and below the transition level. On the airport, the
altimeter will read “0” feet.
Barometric Pressure for Standard Altimeter
Setting (QNE)
Use the altimeter setting (en route) at or above the
transition altitude (FL 180 in the United States). The
altimeter setting is always 29.92 inches of mercury/1013.2
hPa for a QNE altitude. Transition levels differ from country
to country and pilots should be particularly alert when
making a climb or descent in a foreign area.
Barometric Pressure for Local Altimeter Setting
(QNH)
A local altimeter setting equivalent to the barometric
pressure measured at an airport altimeter datum and
corrected to sea level pressure. At the airport altimeter
datum, an altimeter set to QNH indicates airport elevation
above mean sea level (MSL). Altimeters are set to QNH
while operating at and below the transition altitude and
below the transition level.
For flights in the vicinity of airports, express the vertical
position of aircraft in terms of QNH or QFE at or below the
transition altitude and in terms of QNE at or above the
transition level. While passing through the transition layer,
express vertical position in terms of FLs when ascending
and in terms of altitudes when descending.
When an aircraft that receives a clearance as number one
to land completes its approach using QFE, express the
vertical position of the aircraft in terms of height above
the airport elevation during that portion of its flight for
which you may use QFE.
It is important to remember that most pressure altimeters
are subject to mechanical, elastic, temperature, and
installation errors. In addition, extremely cold temperature
differences may also require altimeter correction factors
as appropriate.