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appropriate weight and altitude) used in along an intended track except under calculating the airplane's flight path the conditions of either paragraph (a) shall be diminished by an amount, in or paragraph (b) of this section. feet per minute, equal to
(a) No place along the intended track
shall be more than 90 minutes away 0.08 0.06
from an available landing area at which N
a landing can be made in accordance (when N is the number of engines in- with the requirements of $ 40.78, assumstalled and V8, is expressed in miles per ing all engines to be operating at cruishour) for airplanes certificated under ing power. Part 4b of this subchapter and by (b) The take-off weight shall not be 0.02 Vs for airplanes certificated under
greater than that which would permit Part 4a of this subchapter.
the airplane, with the two critical en(2) The all-engine-operating altitude gines inoperative, to have a rate of shall be such that, in the event the climb in feet per minute equal to 0.01 critical engine becomes inoperative at V8' (Vs, being expressed in miles per any point along the route, the flight will hour) along all points of the route, be capable of proceeding to a predeter- from the point where the two engines mined alternate airport by use of this are assumed to fail simultaneously to procedure. For the purpose of deter- the landing area, either at an altitude mining the take-off weight, the airplane of 1,000 feet above the elevation of the shall be assumed to pass over the critical highest ground or obstruction within obstruction following engine failure at 10 miles on either side of the intended a point no closer to the critical obstruc- track or at an altitude of 5,000 feet, tion than the nearest approved radio
whichever is higher. The point where navigational fix: Provided, That the Ad- the two engines are assumed to fail ministrator may authorize a procedure shall be that point along the route which established on a different basis where is most critical with respect to the takeadequate operational safeguards are
off weight. In showing compliance found to exist.
with this prescribed rate of climb, the (3) The airplane shall meet the pro
following shall apply: visions of paragraph (a) of this section (1) It shall be permissible to consider at 1,000 feet above the airport used as
that the weight of the airplane as it proan alternate in this procedure.
ceeds along its intended track is (4) The procedure shall include an
progressively reduced by normal conapproved method of accounting for winds
sumption of fuel and oil with all engines and temperatures which would other
operating up to the point where the two wise adversely affect the flight path.
engines are assumed to fail and with two
engines operating beyond that point. (5) In complying with this procedure fuel jettisoning shall be permitted if the
(2) Where the engines are assumed to Administrator finds that the air carrier
fail at an altitude above the prescribed has an adequate training program,
minimum altitude, compliance with the proper instructions are given to the flight
prescribed rate of climb at the prescribed crew, and all other precautions are
minimum altitude need not be shown taken to insure a safe procedure.
during the descent from the cruising (6) The alternate airport shall be
altitude to an altitude at which the rate specified in the dispatch release and shall
of descent becomes zero, if the latter is meet the provisions of $ 40.390.
sufficiently above the prescribed mini(c) For the purposes of this section
mum altitude to assure compliance with it shall be assumed that the weight of
the prescribed rate of climb at the prethe airplane as it proceeds along its in
scribed minimum altitudes during the tended track is progressively reduced by
subsequent portion of the flight. normal consumption of fuel and oil.
(3) If fuel jettisoning is provided, the $ 40.75 En route limitations; two en
airplane's weight at the point where the gines inoperative. The provisions of
two engines are assumed to fail shall be this section shall apply only to airplanes
considered to be not less than that which certificated in accordance with the per
would include sufficient fuel to proceed formance requirements of Part 4b of to an available landing area at which a this subchapter. No airplane having landing can be made in accordance with four or more engines shall be fiown the requirements of $ 40.78 and to arrive
there at an altitude of at least 1,000 feet istics of the airplane type involved and directly over the landing area.
other conditions (e. g., landing aids, ter
rain, etc.) and allowing for the effect $ 40.76 Special en route limitations.
on the landing path and roll of not more The 10-mile lateral distance specified in
than 50 percent of the wind component $$ 40.73 through 40.75 may, for a dis
along the landing path if opposite to the tance of no more than 20 miles, be re
direction of landing, or not less than duced to 5 miles, if operating VFR, or if
150 percent of the wind component if in air navigational facilities are so located
the direction of landing. as to provide a reliable and accurate identification of any high ground or ob- (c) If the airport of intended destinastruction located outside of such 5-mile tion will not permit full compliance with lateral distance but within the 10-mile paragraph (b) of this section, the airdistance.
plane may be taken off if an alternate
airport is designated which permits § 40.76–1 Special en route limitations
compliance with $ 40.78. (CAA policies which apply to $ 40.76). No attempt is made to classify specific § 40.77-1 Landing distance limitatypes of navigational facilities as ac- tions; airport of destination (CAA policeptable or unacceptable for the purposes
cies which apply to $ 40,77). (a) Section of $ 40.76, but each case will be examined 40.77 establishes two major consideraon its own merits. In general, however,
tions in determining the permissible the facility should be of a type that
landing weight at the airport of destigives the pilot a continuous fix of his nation, The first is that the aircraft position with an error of not more than weight will be such on arrival that it two miles, or a continuous on-course in
can be landed within 60 percent of the dication with an error of not more than effective landing length of the most fatwo miles, or a continuous indication of
vorable (normally the longest) runway the bearing and distance of the obstacle
in still air. This maximum weight for from the airplane, with an accuracy ade
an airport/aircraft configuration, once quate to allow the pilot to turn away
established, remains constant and canfrom the obstacle with ample clearance.
not be exceeded, regardless of wind Any mechanical or electrical facilities
conditions. that are to be acceptable should be thor- (b) The second is that consideration oughly reliable regardless of weather or be given to the maximum weight that other operating conditions. Such con- will be permitted due to the necessity of siderations apply only for IFR operations. using another runway because of the [Supp. 2, 18 F. R. 7164, Nov. 11, 1953)
probable wind condition, ground han
dling characteristics of the aircraft, § 40.77 Landing distance limitations;
landing aids, etc. This consideration airport of destination. No airplane
may result in a lower gross weight than shall be taken off at a weight in excess of
permitted in paragraph (a) of this secthat which, under the conditions stated
tion, in which case, dispatch must be in this part would permit the airplane to based on this lesser weight. be brought to rest at the field of intended
(c) The probable wind referred to in destination within 60 percent of the effective length of the runway from a
paragraph (b) of this section, is the wind
forecasted to exist at the time of arrival. point 50 feet directly above the intersec
(d) If the forecast conditions are such tion of the obstruction clearance plane
that consideration of the requirements and the runway. For the purpose of this section it shall be assumed that the take
in $ 40.77 (b) would preclude a landing
at the intended destination, the airoff weight of the airplane is reduced by the weight of the fuel and oil expected
craft may be dispatched if an alternate
airport is designated which permits comto be consumed in flight to the field of intended destination.
pliance with $ 40.78.
(e) (1) If a flight has been properly (a) It shall be assumed that the air
dispatched, but arrives at the destinaplane is landed on the most favorable
tion with a weight higher than anticirunway and direction in still air.
pated due to unexpected wind condi(b) It shall be assumed, considering tions or fuel consumption, $ 40.77 (b) the probable wind velocity and direc- should not be construed as prohibiting tion, that the airplane is landed on the a landing at the overweight condition, most suitable runway, taking due ac- provided the crosswind and/or tailwind count of the ground handling character- operating limitations are not exceeded,
(2) If conditions are such that the For the purpose of determining percrosswind and/or tailwind limitations formance data, figures 1, 3, and 6, “paved will be exceeded, the flight must proceed runway" shall mean paved with asphalt to its alternate, if one has been named or concrete, Figures 2, 4, and 7 shall be to meet the requirements of $ 40.77 (b). used for all other runway surfaces, exHowever, if an alternate was not pro- cept in individual cases where the Advided, and upon arrival the wind condi- ministrator finds that a particular runtions were such that the crosswind and/ way surface justifies the use of the paved or tailwind limitations would be ex
runway data or a specific correction facceeded, the pilot should exercise the au
tor. Data based on flight tests conductthority granted him in § 40.360 (a).
ed under the supervision of CAA Aircraft (f) For application of the wind com- Engineering Division and approved by ponents as allowed in § 40.77 (b), refer
the Administrator may be used in lieu to $ 40.72–1 (f).
of the published data. An application [Supp. 2, 18 F. R. 7164, Nov. 11, 1953]
for any deviation shall include all sup§ 40.78 Landing distance limitations;
and wind angle relative to the runway. (In alternate airports. No airport shall be
the example illustrated in figure 8, for Rundesignated as an alternate airport in a
way 27, and a wind from WNW at 25 m. p. b., dispatch release unless the airplane at the relative wind angle is 22o.) the weight anticipated at the time of ar- (b) Enter the chart with the above inrival at such airport can comply with formation at point A. the requirements of $ 40.77: Provided,
(c) Enter chart at point B using the existThat the airplane can be brought to
ing effective runway length and project &
line horizontally. rest within 70 percent of the effective
(d) Project a vertical line from point A length of the runway.
to intersect line from point B.
(e) At point C, the intersection of these AIRPLANE PERFORMANCE OPERATING LIMI
two lines, read the effective runway length TATIONS; NONTRANSPORT CATEGORY
available for zero wind. This figure, after § 40.90 Nontransport category air
being corrected for runway gradient, is used plane operating limitations. In operat
with the appropriate take-off or landing
chart to determine the maximum permissible ing any large, nontransport category
gross weight. It should be noted that a reairplane in passenger service, the provi
verse of this procedure will furnish informasions of $ $ 40.91 through 40.94 shall be tion on the actual runway required if the complied with, unless deviations there- zero wind runway required is known for a from are specifically authorized by the given gross weight. Administrator on the ground that the
(1) By projecting a line horizontally from special circumstances of a particular case
point A to point D, the crosswind component
can be determined. make a literal observance of the require
Example 2. Operating conditions for ments unnecessary for safety. Per- take-off: formance data published or approved by Aircraft=DC-3 S1C3G. the Administrator for each such non- Airport =Elevation=4,000'. transport category airplane shall be used
Effective runway length=3,300 feet in determining compliance with the pro
(paved). visions of $ $ 40.91 through 40.94.
Runway gradient=+1.2 percent.
The equivalent runway length due to $ 40.90—1 Performance data (CAA gradient= rules which apply to $ 40.90). Perform
SG ance data published by the Administrator
SG92 sin a to determine performance requirements in relation to the airports to be used and
3,300 the areas to be traversed are set forth in
(3,300 X 32.2X2X.012) figures 1 through 10 % and § 40.91-1 (b).
(98 X 1.467)?
= 2,938 feet. * The charts are presented in graph form for selected values. Other values may be
Due to the positive, or uphill, gradient efdetermined by interpolation or extrapolation,
fect, the zero gradient runway length is 2.938
feet. This figure, versus the airport elevaprovided the operating and structural limita
tion is used with figure 3 to determine the tions are not exceeded. The following ex- allowable gross weight for take-off. It will amples are given to explain the use of figures
be noted that this runway length/alrport 1 through 10:
elevation combination is outside the range of Example 1. Figure 8 is used in the follow
values plotted on the chart. Therefore, Ing manner: (a) Determine the wind velocity under a zero wind condition, operations from
porting data and shall be forwarded to power-off stalling speed in the take-off the CAA Aviation Safety District Office configuration, whichever is the greater. charged with the over-all inspection In applying the requirements of this of the air carriers' operations.
section: [Supp. 3, 18 F. R. 8678, Dec. 24, 1953; 19 F. R.
(a) It may be assumed that take-off 747, Feb. 2, 1954)
power is used on all engines during the § 40.91 Take-off limitations. No acceleration; take-off shall be made at a weight in (b) Account may be taken of not more excess of that which will permit the air
than 50 percent of the reported wind plane to be brought to a safe stop within component along the take-off path if opthe effective length of the runway from
posite to the direction of take-off, and any point during the take-off up to the account shall be taken of not less than time of attaining 105 percent of mini- 150 percent of the reported wind commum control speed or 115 percent of the
ponent if in the direction of the take-off;
(c) Account shall be taken of the avthe runway in question would be impracti
erage runway gradient when the average cable due to the weight restriction.
gradient is greater than 12 percent. If a 25 m. p. h. headwind component exists,
The average runway gradient is the difthe use of figure 8 indicates a zero wind runway length of 3,800 feet. This figure is
ference between the elevations of the predicated on 1.05V mc=92 m. p. h. Since end points of the runway divided by the figure 10 indicates 1.05V mc(92 m. p. h. total length; TIAS) =97.6 m. p. h. TAS (use 98) at an
(d) It shall be assumed that the airelevation of 4,000 feet, the distance of 3,800
plane is operating in the standard feet must be multiplied by a correction factor from figure 9. The factor in this atmosphere. example, (25 m. p. h. headwind component
$ 40.91-1 Take-off limitations (CAA and 1.05V =98 m. p. h. TAS), is 1.018 giving
rules which apply to $ 40.91). (a) Fig& corrected zero wind runway distance of
ures 1, 2, 3, 4, 8, 9, and 10 shall be used in 3,800 feet x 1.018=3,868 feet. By referring to figure 3, it is found that this zero wind run
determining take-off limitations. The way length will permit a take-off at a weight
weight of de-icing equipment, when inof 24,200 pounds.
stalled, must be included in the compuIf the take-off was to be made in the op- tations of allowable take-off weights. posite direction, the benefit of the downhill
(b) If the gradient of the runway exgradient on the accelerate distance would result in a zero gradient runway length of 3,770
ceeds 12 percent, the effect of the total feet. This would permit a take-off at a
average gradient shall be accounted for. weight of 24,200 pounds, with zero wind. The effect of gradient shall be calculated Figure 3 indicates that 3,970 feet of runway is as shown in figure 11 or by any other required to permit take-off at a maximum method by which the effect of gradient gross weight of 25,200 pounds. Figure 8 in
may be accurately or conservatively dicates that & beadwind component of 3 m. p. h. will give the desired zero wind run
computed. way length of 3,970 feet to permit take-off (c) The maximum allowable take-off at the maximum gross weight.
weight from sod runways shall be the Example 3. Operating conditions for land
lesser gross weight as determined by aping: Same as in example 2, except that $ 40.93 does not require consideration of
plication of the effective length to the gradient in detailing the landing limitations. appropriate take-off table (fig. 1 or 3)
Referring to figure 6, we find that a 3,300- and by application of the actual runway foot paved runway at an elevation of 4,000
length to the corresponding take-off feet, permits a landing gross weight of 22,600 pounds, in a zero wind condition.
table (fig. 2 or 4). Figures 1 and 3 are
If a 25 m. p. h. headwind component is forecast, we
used to determine the maximum allowfind by reference to figure 8 that the zero able gross weight which will permit the wind runway length becomes 4,300 feet. In
aircraft to take off within the effective this example, the distance of 4,300 feet is predicated on 1.3V.. =92 m. p. h. Therefore,
runway length, while figures 2 and 4 are 80
used to determine the maximum allowby reference, figure 10, 1.3Vs, is found to be
able gross weight which will permit the 98 m. p. h. at 4,000 feet and by reference to figure 9, it is found that the correction factor
particular aircraft to be accelerated and is 1.018, resulting in a zero wind runway
brought to a full stop within the actual length of 4,300 x 1.018=4,377 feet. Figure 6
length of available runway. indicates that this zero wind runway length [Supp. 3, 18 F. R. 8679, Dec. 24, 1953, as will permit landing at the maximum gross amended by Supp. 11, 19 F. R. 5658, Sept. 8, weight.