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2,000 feet. “Four miles
from LIMA. Turn right
heading three four zero.
Maintain two thousand
until established on the
localizer. Cleared ILS
runway three six
approach.”
There are many times
when it is desirable to
position an aircraft onto
the final approach course
prior to a published,
charted segment of an
instrument approach procedure (IAP). Sometimes
IAPs have no initial segment and require vectors.
“RADAR REQUIRED”
will be charted in the
planview. Sometimes a
route will intersect an
extended final approach
course making a long
intercept desirable.
When ATC issues a vector or clearance to the
final approach course
beyond the published
segment, controllers
assign an altitude to
maintain until the aircraft
is established on a segment of a published route
or IAP. This ensures that
both the pilot and controller know precisely
what altitude is to be
flown and precisely
where descent to appropriate minimum altitudes
or step-down altitudes can begin.
Most aircraft are vectored onto a localizer or final
approach course between an intermediate fix and the
approach gate. These aircraft normally are told to maintain an altitude until established on a segment of the
approach.
When an aircraft is assigned a route that will establish the
aircraft on a published segment of an approach, the controller must issue an altitude to maintain until the aircraft
is established on a published segment of the approach.
Aircraft 4 is established on the final approach course
beyond the approach segments, 8 NM from Alpha at
6,000 feet. The minimum vectoring altitude for this area
Figure 4-7. Cleared for the Palm Beach ILS Approach.
is 4,000 feet. “Eight miles from Alpha. Cross Alpha at
or above four thousand. Cleared ILS runway three six
approach.”
If an aircraft is not established on a segment of a published approach and is not conducting a radar approach,
ATC will assign an altitude to maintain until the aircraft is established on a segment of a published route
or instrument approach procedure, as depicted in
Figure 4-9.
The aircraft is being vectored to a published segment of
the ILS final approach course, 3 NM from Alpha at
4,000 feet. The minimum vectoring altitude for this area
is 4,000 feet. “Three miles from Alpha. Turn left heading
two one zero. Maintain four thousand until established
on the localizer. Cleared ILS runway one eight
approach.”
The ATC assigned altitude ensures IFR obstruction
clearance from the point at which the approach clearance is issued until established on a segment of a
published route or instrument approach procedure.
ATC tries to make frequency changes prior to passing
the FAF, although when radar is used to establish the
FAF, ATC informs the pilot to contact the tower on the
local control frequency after being advised that the aircraft is over the fix. For example, “Three miles from
final approach fix. Turn left heading zero one zero.
Maintain two thousand until established on the localizer. Cleared ILS runway three six approach. I will
advise when over the fix.”
“Over final approach fix. Contact tower one one eight
point one.”
Where a terminal arrival area (TAA) has been established to support RNAV approaches, as depicted in
LIMA
LOM
1500
6 DME
X-RAY
INT
1300
12 DME
4000
20 DME
ALPHA
INT
IAF IAF
Figure 4-8. Arrival Instructions When Established.
4000
12 DME
ALPHA
IAF
FAF
Straight-In ILS
Figure 4-9. Arrival Instructions When Not Established.
4-9
Figure 4-10, ATC informs the aircraft of its position
relative to the appropriate IAF and issues the approach
clearance, as shown in the following examples:
Aircraft 1 is in the straight-in area of the TAA. “Seven
miles from CENTR, Cleared RNAV Runway One Eight
Approach.’’
Aircraft 2 is in the left base area of the TAA. “Fifteen
miles from LEFTT, Cleared RNAV Runway One Eight
Approach.’’
Aircraft 3 is in the right base area of the TAA. “Four
miles from WRITE, Cleared RNAV Runway One Eight
Approach.”
IFR en route descent procedures should include a
review of minimum, maximum, mandatory, and recommended altitudes that normally precede the fix or
NAVAID facility to which they apply. The initial descent
gradient for a low altitude instrument approach procedure does not exceed 500 feet per NM (approximately 5
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Instrument Procedures Handbook (IPH)仪表程序手册下(88)
