How do you determine Effective Runway Length?
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How do you determine Effective Runway Length?
§ 135.361:
(b) For the purpose of this subpart, "effective length of the runway," for landing means the distance from the point at which the obstruction clearance plane associated with the approach end of the runway intersects the centerline of the runway to the far end of the runway.
(c) For the purpose of this subpart, "obstruction clearance plane" means a plane sloping upward from the runway at a slope of 1:20 to the horizontal, and tangent to or clearing all obstructions within a specified area surrounding the runway as shown in a profile view of that area…
§ 135.385:
(b) Except as provided in paragraph (c), (d), or (e) of this section, no person operating a turbine engine powered large transport category airplane may takeoff that airplane unless its weight on arrival, allowing for normal consumption of fuel and oil in flight (in accordance with the landing distance in the Airplane Flight Manual for the elevation of the destination airport and the wind conditions anticipated there at the time of landing), would allow a full stop landing at the intended destination airport within 60 percent of the “effective length of each runway” described below from a point 50 feet above the intersection of the obstruction clearance plane and the runway.
The Question is:
If the only information available is the information given on an approach chart or the A/FD, how does a (normal) pilot determine the effective runway length at various different airports for practical day-to-day operations?
Effective runway length is absolutely essential for calculating the 60% (destination) or 70% (alternate) landing distance requirement, but there does not seem to be any way of calculating it from the information available.
Thanks
(b) For the purpose of this subpart, "effective length of the runway," for landing means the distance from the point at which the obstruction clearance plane associated with the approach end of the runway intersects the centerline of the runway to the far end of the runway.
(c) For the purpose of this subpart, "obstruction clearance plane" means a plane sloping upward from the runway at a slope of 1:20 to the horizontal, and tangent to or clearing all obstructions within a specified area surrounding the runway as shown in a profile view of that area…
§ 135.385:
(b) Except as provided in paragraph (c), (d), or (e) of this section, no person operating a turbine engine powered large transport category airplane may takeoff that airplane unless its weight on arrival, allowing for normal consumption of fuel and oil in flight (in accordance with the landing distance in the Airplane Flight Manual for the elevation of the destination airport and the wind conditions anticipated there at the time of landing), would allow a full stop landing at the intended destination airport within 60 percent of the “effective length of each runway” described below from a point 50 feet above the intersection of the obstruction clearance plane and the runway.
The Question is:
If the only information available is the information given on an approach chart or the A/FD, how does a (normal) pilot determine the effective runway length at various different airports for practical day-to-day operations?
Effective runway length is absolutely essential for calculating the 60% (destination) or 70% (alternate) landing distance requirement, but there does not seem to be any way of calculating it from the information available.
Thanks
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Our FAR121 OPS SPECS require the duty dispatchers to make runway analysis for departure, arrival and alternate airports. We carry a Runway Analysis Manual aboard to double check the figures. We never get involved in "computing" "effective runway length." The RAM includes data for each runway with varying temperatures, wind, slope, wet/dry, Anti Skid, QNH corrections, second segment climb limits, and respective max or reduced (assumed temperature) power settings.
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R2-
As GB says, your dispatch section must have this information available to them to legally dispatch the flight. For a quick reference, you can check the runway length for landing on the Jepp 10-9A.
The rules are quite similar for 121 and 135 operations in this regard, but are often misunderstood by even the most experienced flight crews.
You will note that 135.385 states that "no person operating"....."may TAKEOFF that airplane at a weight".......(emphasis mine). It does NOT say ......no person may takeoff or LAND that airplane.
135.385 (and 121.195) are FARs that govern dispatch of the flight, although the compliance with the FAR rests with the PIC, because the dispatcher has no control over how much fuel is actually burned during taxi, etc.
It's also important to note that flights are dispatched to AIRPORTS, not runways. Although the airport must have runways that meet the requirements of 135.385 (b)(1) and (2)...and 121.195 (b) (1) and (2), there is no legal requirement to land on any particular runway. Once again, "no person may takeoff".....etc.
Now the questions is: What do I do if there is a runway change at the destionation,...or....what if I find there was less headwind enroute (which makes me heavier for landing),....or less headwind on landing which will increase my landing distance, etc. If you took off at or close to your MTOW for landing, you may find that you aren't within the 60% any longer.
There is no legal requirement to use only 60% of the runway for landing. You are legal to use all of it.
(Disclaimer- I speak to the US rules only, your state may differ.)
As GB says, your dispatch section must have this information available to them to legally dispatch the flight. For a quick reference, you can check the runway length for landing on the Jepp 10-9A.
The rules are quite similar for 121 and 135 operations in this regard, but are often misunderstood by even the most experienced flight crews.
You will note that 135.385 states that "no person operating"....."may TAKEOFF that airplane at a weight".......(emphasis mine). It does NOT say ......no person may takeoff or LAND that airplane.
135.385 (and 121.195) are FARs that govern dispatch of the flight, although the compliance with the FAR rests with the PIC, because the dispatcher has no control over how much fuel is actually burned during taxi, etc.
It's also important to note that flights are dispatched to AIRPORTS, not runways. Although the airport must have runways that meet the requirements of 135.385 (b)(1) and (2)...and 121.195 (b) (1) and (2), there is no legal requirement to land on any particular runway. Once again, "no person may takeoff".....etc.
Now the questions is: What do I do if there is a runway change at the destionation,...or....what if I find there was less headwind enroute (which makes me heavier for landing),....or less headwind on landing which will increase my landing distance, etc. If you took off at or close to your MTOW for landing, you may find that you aren't within the 60% any longer.
There is no legal requirement to use only 60% of the runway for landing. You are legal to use all of it.
(Disclaimer- I speak to the US rules only, your state may differ.)
