Net Take-off Flight Path CARs

[triplese7en]

I need some expert interpretation in regards to CAR 704.47(2)(b).

For a standard IFR departure there are no turns below 400', however, under this regulation you are allowed to bank up to 15 degrees below 400' to avoid obstacles by the required distances - 35' vertically and 200' or 300' horizontally.

After all the calculations are done, you end up with a maximum weight that you can takeoff at for a specific runway - but there is no mention that you might have to do a shallow turn right after liftoff to avoid an obstacle!

Am I interpreting this correctly?

[AOW]

Refer to AC 700-016 for all the juicy details...

Normal IFR departure requires no turns below 400', yes; but it also requires a climb gradient of 200 ft/nm. One engine inop climb gradient (for a twin) is only 2.4%, or 146 ft/nm, so you won't be able to meet the normal obstacle clearance. Some companies have specific engine out departure procedures for certain airports for this very reason.

[triplese7en]

Thanks AOW! That's what I'm looking for.

[triplese7en]

So reading through it I have a couple questions.

1) This seems like a very obvious question but if the performance numbers (max takeoff weight charts [includes compensation for airport altitude, temp and head/tailwinds]) that my company is using were relying on a specific Engine Out Departure Procedure (EODP) that deviated from the standard departure (1/2sm), that EODP would need to be included in the COM? I don't believe we have any specific EODP published for our normal destinations. All our sched operations are in the Prairies so I'm guessing we don't need them but there are still some airports where I wonder if deviations from a standard departure might be necessary to achieve sufficient obstacle clearance should you lose an engine at some point past V1.

2) The AC says that air operators should have a EODPs that take into account an engine failure at any point on the takeoff until the airplane reaches an enroute altitude where enroute obstacle clearance would be appropriate. Is my understanding correct that you should follow the standard departure (1/2sm) or SID until you have an engine failure and then follow the EODP if it deviates from the standard departure or SID?

[floatplanepilot]

So reading through it I have a couple questions.

1) This seems like a very obvious question but if the performance numbers (max takeoff weight charts [includes compensation for airport altitude, temp and head/tailwinds]) that my company is using were relying on a specific Engine Out Departure Procedure (EODP) that deviated from the standard departure (1/2sm), that EODP would need to be included in the COM? I don't believe we have any specific EODP published for our normal destinations. All our sched operations are in the Prairies so I'm guessing we don't need them but there are still some airports where I wonder if deviations from a standard departure might be necessary to achieve sufficient obstacle clearance should you lose an engine at some point past V1.

2) The AC says that air operators should have a EODPs that take into account an engine failure at any point on the takeoff until the airplane reaches an enroute altitude where enroute obstacle clearance would be appropriate. Is my understanding correct that you should follow the standard departure (1/2sm) or SID until you have an engine failure and then follow the EODP if it deviates from the standard departure or SID?

http://apg.aero

Generates EODP's based on aircraft performance and obstacles

A few good videos.
http://www.youtube.com/watch?v=OSSdkGguDLU
http://www.youtube.com/watch?v=iEULv-3LCEo
http://www.youtube.com/watch?v=jj_IAjtE81A

[pelmet]

Refer to AC 700-016 for all the juicy details...

Normal IFR departure requires no turns below 400', yes; but it also requires a climb gradient of 200 ft/nm. One engine inop climb gradient (for a twin) is only 2.4%, or 146 ft/nm, so you won't be able to meet the normal obstacle clearance. Some companies have specific engine out departure procedures for certain airports for this very reason.

A departure procedure can have a turn below 400 feet for normal operations. At least internationally such as runway 34 at Macao..

[Gino Under]

Your AFM should provide weight limits for a variety of conditions. The Second Segment Climb and Obstacle Clearance charts are usually based on net performance rather than gross. Some airports are located in an environment of penalizing obstacles, which may necessitate turning to follow a specific departure procedure. Turning departures are subject to conditions.

The turn conditions differ between regulations.

JAR-OPS 1.495 Subpart G
(c) (1) Track changes shall not be allowed up to the point at which the net take-off flight path has achieved a height equal to one half the wingspan but not less than 50 feet above the elevation of the end of the take-off run available.
Thereafter, up to a height of 400 ft it is assumed that the airplane is banked by no more than 15 degrees. Above 400 ft height bank angles greater than 15 degrees, but no more than 25 degrees may be scheduled.
An operator must use special procedures, subject to the approval of the Authority, to apply increased bank angles of not more than 20 degrees between 200 ft and 400 ft, or not more than 30 degrees above 400 ft.

FAR 121.189 Subpart I
(f) For the purpose of this section, it is assumed that the airplane is not banked before reaching a height of 50 ft, [...] and thereafter that the maximum bank is not more than 15 degrees.

The FAA rule is similar to the ICAO annex 6 recommendations.

"One engine inop climb gradient (for a twin) is only 2.4%, or 146 ft/nm, so you won't be able to meet the normal obstacle clearance. "
What if there is a minimum climb gradient published that you can meet EVEN on one engine. You WOULD be able to meet the normal obstacle clearance, wouldn't you? Remember, the 2.4% only applies to the second segment which ends at 400 ft. Above that, 400 ft, the available gradient of climb must not be less than 1.2% for a two-engined airplane.
So, below 400 ft, the speed must be maintained constant to a minimum of V2. Above 400 ft, the aircraft must fulfill a minimum climb gradient, which can be transformed into an acceleration capability in level flight. The regulatory minimum acceleration height is fixed to 400 feet above the takeoff surface.

Gino Under

[doorhandle27]

Gino is right. 2.4 to 400' is a standard departure when know other gradient is specified. Don't forget, a departure above the min vis and ceiling doesn't require you to meet a gradient as it's considered a visual climb.

[triplese7en]

Gino...

"One engine inop climb gradient (for a twin) is only 2.4%, or 146 ft/nm, so you won't be able to meet the normal obstacle clearance. "
What if there is a minimum climb gradient published that you can meet EVEN on one engine. You WOULD be able to meet the normal obstacle clearance, wouldn't you? Remember, the 2.4% only applies to the second segment which ends at 400 ft. Above that, 400 ft, the available gradient of climb must not be less than 1.2% for a two-engined airplane.

Everything there seems to be correct except for the 2.4%. Under Canadian rules (CAR 523.67(c)) the second segment requirement is 2.0%.

Also, the 2.0% (2.4% for transport category) requirement for second segment climb (two engines) is only at the point of 35' above the Departure End Runway (DER) - it does not extend for the entire second segment. You need to take into account the reduction in climb rate due to, 1) loss of thrust, and 2) increase in TAS, as you increase altitude.

(c) For commuter category aeroplanes, the following apply:

(1) Takeoff; landing gear extended. The steady gradient of climb at the altitude of the takeoff surface must be measurably positive for two-engine aeroplanes, not less than 0.3 percent for three-engine aeroplanes, or 0.5 percent for four-engine aeroplanes with:

(i) The critical engine inoperative and its propeller in the position it rapidly and automatically assumes;

(ii) The remaining engine(s) at takeoff power;

(iii) The landing gear extended, and all landing gear doors open;

(iv) The wing flaps in the takeoff position(s);

(v) The wings level; and

(vi) A climb speed equal to V2.

(2) Takeoff; landing gear retracted. The steady gradient of climb at an altitude of 400 feet above the takeoff surface must be not less than 2.0 percent for two-engine aeroplanes, 2.3 percent for three-engine aeroplanes, and 2.6 percent for four-engine aeroplanes with:

(i) The critical engine inoperative and its propeller in the position it rapidly and automatically assumes;

(ii) The remaining engine(s) at takeoff power;

(iii) The landing gear retracted;

(iv) The wing flaps in the takeoff position(s);

(v) A climb speed equal to V2.

(3) Enroute. The steady gradient of climb at an altitude of 1,500 feet above the take-off or landing surface, as appropriate, must be not less than 1.2 percent for two-engine aeroplanes, 1.5 percent for three-engine aeroplanes, and 1.7 percent for four-engine aeroplanes with:

(i) The critical engine inoperative and its propeller in the minimum drag position;

(ii) The remaining engine(s) at not more than maximum continuous power;

(iii) The landing gear retracted;

(iv) The wing flaps retracted; and

(v) A climb speed not less than 1.2 VS1.

(4) Discontinued approach. The steady gradient of climb at an altitude of 400 feet above the landing surface must be not less than 2.1 percent for two-engine aeroplanes, 2.4 percent for three-engine aeroplanes, and 2.7 percent for four-engine aeroplanes, with:

(i) The critical engine inoperative and its propeller in the minimum drag position;

(ii) The remaining engine(s) at takeoff power;

(iii) Landing gear retracted;

(iv) Wing flaps in the approach position(s) in which VS1 for these position(s) does not exceed 110 percent of the VS1 for the related all-engines-operated landing position(s); and

(v) A climb speed established in connection with normal landing procedures but not exceeding 1.5 VS1.

[Gino Under]

Triplese7en

Thanks for the info. Always nice to compare performance.
I'm not that familiar with CARs and I haven't flown in commuter ops since the 80s. It sounds to me like a close tie in to UK Performance B. I'll have a look when I have a minute.

Cheers,
Gino