The normal slow-flight procedure is useful either following a go around or
when entering a standard traffic pattern for landing. A second type of slow
flight, flown during NDB or VOR instrument approaches, is described a little
further down the page.
The situation immediately following a go around illustrates the procedures for normal slow flight.
Level off at 1500 ft AGL, reduce the M.P. to 22 in.—throttles— and reduce the props to 2050 RPM. Adjust as necessary for 105 kts and the aircraft should maintain 1500 ft. Do not change your heading following a go-around until the slow-flight configuration has stabilized, except when the missed approach procedure requires immediate action, or ATC assigns you a new heading, or you are headed directly into a mountain or the Empire State Building—both unlikely at Cape Cod.
Other slow-flight circumstances will dictate the flight altitude.
NDB and VOR instrument approaches, often called "Dive and Drive" approaches,
require a second type of slow flight. As the aircraft proceeds inbound to
the field, once it reaches the FAF, the Final Approach Fix, it descends as
rapidly as possible, "Dives," to the MDA, the Minimum Descent Altitude. From
that point on it maintains the MDA, "Drives," until either the runway is
sighted or the clock tells you that you have missed the field and must do a
This slow-flight configuration differs from that previously described in that the aircraft is near the landing configuration: half flaps are down, the gear has been lowered, and the props are in High RPM. Everything is controlled with the throttle. At this point you are really dragging in; approach speed will be the same 85 kts for any other type of landing.
The level approach permits the pilot to concentrate solely on flying the
aircraft, a particularly desirable situation when the ceiling and visibility
are near minimums for landing.
Note the headings in this NDB approach panel-photo. The approach is to Provincetown's Runway 7, which has a 075° alignment, but the aircraft heading is 093°, requiring an 18° jog to the left to line up with the runway on sighting the threshold. In this instrument approach, the NDB is located on the field, and obviously must be located a safe distance to side of the runway rather than directly in front of the runway, hence the angular approach. If the NDB (or VOR) were located off the field, usually about 5 NM distant, it is almost always directly aligned with the runway heading, simplifying the approach.
Many of DC-3 Airways flights require either an NDB approach or a VOR approach. Refer to the Navigation Tutorial for full information on how to fly those sort of approaches. In many ways, they are more fun to fly than a standard ILS approach. Don't pass them up.