LANDING DISTANCE COMPUTATION

FOM 2.4.7

(1) On FAR 135 flights, the 15% additional

runway required for landing on a "wet or

slippery" runway, and the 15% addition

when visibility / RVR is less than 3/4 statues

mile/4000 feet, are not cumulative.

FOM 2.4.7

FAR 135 Flight: In accordance with

FAR 135.385 (d) the landing distance that

meets the 60% of effective runway length

required by 135.385 (d), or the landing

distance that meets the 80% effective runway

length allowed by 135.385 (f) (i.e., when flight

meets requirements for use of DAAP

provisions shall be in increased

by a minimum of 15% for landing on a wet

runway. 

FAR 135.385 (d)

. . . "would allow a full stop landing a the

intended destination airport within 60 percent

of the effective length . . .

Actual Landing Distance

The "unfactored" certified landing distance"

for a given weight / temperature / altitude, that

is corrected for the applicable factors of; reported meteorological and runway surface conditions; runway slope; airplane configuration; approach

speed, and; other factors required by the

applicable AFM for normal operations.

Factored Landing Distance

The "unfactored certified landing distance"

increased by the preflight planning safety

margin (i.e., 60% or 80%) and other factors

required by the applicable operating rules

(i.e., "135" of "91K")

If the surface of the planned landing runway

is forecast or expected to be wet, the landing

distance computed in accordance with the

reduced planning requirement shall be

increased by 15% minimum.

Note: Two landing distance computations

are required to release a flight under the r

educed landing distance planning requirement

if the planned landing runway is forecast or

expected to be "wet"

(per definition in FOM 2.4.7)

(1) Determine the 80% "Factored Landing

Distance" and increase by 15%.

(2) Then determine the "Actual Landing

Distance" from the AFM (approved or

advisory data, as appropriate) for a "wet"

runway.

(3) Compare the two "planned" landing

distances from (1) and (2); the longer of

the distances shall be used to determine

the planned maximum allowable takeoff

weight for release of the flight.

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In the example on the Web Site, I used the

60% computation but the calculations are

the same for the 80% as listed in the FOM.

Available Runway                    6,200'

  

:  Required Landing Distance IAW AFM  = 2,840’

                        Available Runway Length = 6,200’

                       Adjusted Runway Length  = 4,733’

                                      (2840 ÷ 0.6)

WET RUNWAY

AFM Planned Landing Distance 3,000

Factored Landing Distance (Non-DAAP) 5,000'          

                                   [3000 ÷ 0.6]

           

\Multiply Factored Landing Distance by 1.15  (15%)

Result:   Adjusted Runway Required 5,750’

CONTAMINATED RUNWAY

Longer of the two

Adjusted    

Actual (for conditions IAW AFM Charts)