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When to Descend. ATC requirements probably have more influence over when to begin the descent than
any other single factor. Other items to consider before starting an enroute descent are range, desired
descent rate, weather, terrain, and low altitude fuel consumption. For planning purposes, various
techniques are acceptable to determine the point at which descent is desired. A simple technique is to use
three times the altitude to lose in thousands of feet as the distance from destination in nautical miles to
begin descent (3 X altitude to lose = miles). Another rule of thumb is [2 X (altitude to lose)]+10=miles.
Other techniques compare a desired rate of descent to altitude to lose to determine the time; time and
groundspeed then gives distance. Ensure you use a descent gradient/descent rate appropriate to the
technique you are using (reference 60-to-1 rules in section 412). In other words, know what pitch to use
and VSI to hold during the descent so that you arrive at your target altitude at the desired point over the
ground. The big picture is the closer you get, the more descent rate is required, and any technique used to
The use of radar vectors is the simplest and most convenient way to position an aircraft for an approach.
Using radar, air traffic controllers can position an aircraft at almost any desired point, provide obstacle
clearance by the use of minimum vectoring altitudes, and ensure traffic separation. This flexibility allows an
aircraft to be vectored to any segment of a published routing shown on the IAP or to a radar final. Radar
controllers use minimum vectoring altitude (MVA) charts providing minimum altitudes of 1000 or 2000 feet in
designated mountainous areas; MVAs may be lower than non-radar MEAs/MOCAs. They may also be below
emergency safe or minimum sector altitudes. However, while being radar vectored, IFR altitude assignments
will be at or above MVA. While being radar vectored, repeat all headings, altitudes and assigned),
and altimeter settings; and comply with controller instructions.
Descent. If at any time there is doubt as to whether adequate obstacle clearance is provided or controller
instructions are unclear, query the controller. The controller should inform you if radar contact is lost and
provide you with a new clearance or additional instructions. If advised radar contact is lost while in IFR
conditions and there is a delay in receiving new instructions, ask the controller for a new clearance or advise
the controller of your intentions. (This is particularly important if below minimum safe, sector, or emergency
safe altitude.)
Vectors for Approach. The controller may vector the aircraft to any segment of an IAP prior to the FAF
and clear an aircraft for an approach from that point. Normally maintain 150 KIAS while being radar
vectored, although 170 KIAS or other airspeeds may be flown at the pilot's discretion or as directed by
ATC. The controller will issue an approach clearance only after you are established on a segment of the
IAP; or you will be assigned an altitude to maintain until you are established on a segment of the IAP.
Orientation. Remain oriented in relation to the FAF by using all available navigation aids. Have the IAP
available for the approach to be flown along with a backup procedure to be used if available. Complete the
Approach Checklist and be prepared to fly the approach when cleared by the controller. Once cleared for
the approach, maintain the last assigned altitude and heading until established on a segment of a published
route or IAP. Use normal lead points to roll out on course. From that point, comply with all course and
altitude restrictions as depicted on the approach procedure except you must not climb above the last
assigned altitude to comply with published altitude restrictions unless so instructed by the controlling
agency. Configure, slow, and complete the Landing Checklist prior to the FAF.
D. Low Altitude Procedures.
Terminal routings. Terminal routings from enroute or feeder facilities are considered segments of the IAP
and normally provide a course, range in nautical miles (not DME), and minimum altitude to the IAF. The
altitudes published on terminal routings are minimum altitudes and provide the same protection as an
airway MEA. Terminal routings may take the aircraft to a point other than the IAF if it is operationally