737 Flight Crew Training Manual
Precision Approach Path Indicator (PAPI)
The PAPI uses lights which are normally on the left side of the runway. They are
similar to the VASI, but are installed in a single row of light units. When the airplane is on a normal 3° glide path, the pilot sees two white lights on the left and two red lights on the right. The PAPI may be safely used with respect to threshold height, but may result in landing further down the runway. The PAPI is normally aligned to intersect the runway 1,000 to 1,500 feet down the runway.
PAPI Landing Geometry
Landing Geometry Visual Aim Point
During visual approaches many techniques and methods are used to ensure main landing gear touchdown at the desired point on the runway. One of the most common methods used is to aim at the desired gear touchdown point on the runway, then adjust the final approach glide path until the selected point appears stationary in relation to the airplane (the point does not move up or down in the pilot’s field of view during the approach).
Visual aim points versus gear touchdown point differences increase as glide path angle decreases as in a flat approach. For a particular visual approach, the difference between gear path and eye level path must be accounted for by the pilot.
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FCT 737 (TM) October 31, 2006
Runway Markings (Typical)
The following runway markings are for runways served by a precision approach.
MARKINGS
30m (98’) to
60m (197’)
by
4m (13’) to
10m (33’)
STRIPES
1.8m (6’) WIDTH
1.5m (5’) SPACING
22.5m (74’) MIM
LENGTH
United States ICAO
737 Flight Crew Training Manual
Threshold Height
Threshold height is a function of glide path angle and landing gear touchdown target. Threshold height for main gear and pilot eye level is shown in the Two Bar/Three Bar VASI Landing Geometry tables on a previous page. Special attention must be given to establishing a final approach that assures safe threshold clearance and gear touchdown at least 1,000 feet down the runway. If automatic callouts are not available, the radio altimeter should be used to assist the pilot in judging terrain clearance, threshold height and flare initiation height.
Flare and Touchdown
The techniques discussed here are applicable to all landings including one engine inoperative landings, crosswind landings and landings on slippery runways. Unless an unexpected or sudden event occurs, such as windshear or collision avoidance situation, it is not appropriate to use sudden, violent or abrupt control inputs during landing. Begin with a stabilized approach on speed, in trim and on glide path.
When the threshold passes under the airplane nose and out of sight, shift the visual sighting point to approximately 3/4 the runway length. Shifting the visual sighting point assists in controlling the pitch attitude during the flare. Maintaining a constant airspeed and descent rate assists in determining the flare point. Initiate the flare when the main gear is approximately 15 feet above the runway by increasing pitch attitude approximately 2° - 3°. This slows the rate of descent.
After the flare is initiated, smoothly retard the thrust levers to idle, and make small pitch attitude adjustments to maintain the desired descent rate to the runway. Ideally, main gear touchdown should occur simultaneously with thrust levers reaching idle. A smooth power reduction to idle also assists in controlling the natural nose-down pitch change associated with thrust reduction. Hold sufficient back pressure on the control column to keep the pitch attitude constant. A touchdown attitude as depicted in the figure below is normal with an airspeed of approximately VREF plus any gust correction.
Note: Do not trim during the flare or after touchdown. Trimming in the flare increases the possibility of a tailstrike.
Landing Flare Profile
The following diagrams use these conditions:
.
3° approach glide path
.
flare distance is approximately 1,000 to 2,000 feet beyond the threshold
Copyright . The Boeing Company. See title page for details.
6.10 FCT 737 (TM) October 31, 2006
737 Flight Crew Training Manual
.
typical landing flare times range from 4 to 8 seconds and are a function of approach speed
.
airplane body attitudes are based upon typical landing weights, flaps 30, VREF 30 + 5 (approach) and VREF 30 + 0 (landing), and should be reduced by 1° for each 5 knots above this speed.
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