Accelleration during SID Turns

[longobard]

Since i have no airline operations flying general operation experience i was wondering if assuming:

ALL ENGINE OPERATING TAKEOFF CLIMB IN A TURNING SID

Can the pilot satisfy himself on obstacle clearence and SID track e gradient compliance side if FLAP RETRACTION AND ACCELERATION TO FINAL TAKEOFF SPEED IS PERFORMED DURING THE TURN?

My doubt is also that he may not have enough stick shacker protection during that phase and not enough gradient to clear obstacles and Minimum SID gradiend.

Please advise on commmon airline practises.

Thanks

Flavio

[blueloo]

Turns should be ok, assuming you remain above the Take Off Safety Speed. Different aircraft have different profiles and limits of course - In the 737 with takeoff flaps a maximum bank angle of 30 degrees is permitted at v2+15.

When following the recommended speed schedule there is adequate margin to stick shaker for at least an inadvertant 15 degree overshoot beyond the normal 25 degrees angle of bank.

Alternatively Adequate manoevre margin is retained at a speed 20knots below the recommended speed for all bank angles up to 30 degrees.

[J0N0]

Longobard
Since you mentioned no Airline experience I am gonna assume (big mistake I know) your talking about Aircraft above 5700kg so talking about CAO 20.7.1.B
Venturing out of my depth of understanding here but for the Dash8 its not an issue. V2 (1.2vs for Dash8) is to be achieved by 35 feet and then company policy is to hold 125kts to 1000ft. Plateau height (Flap retraction) is generally 500 AGL and in my limited experience the Dash is at 125kts before then so if V2 for a Dash8-100 at max weight is 104kts VS would be about 87kts so thats about a 38kt buffer above VS or slightly more than 1.4vs. Cant remember how much to increase stall speed by in a 25deg turn but plenty of margin there. Hope that helps
:confused:
:D

[longobard]

ok thanks blueloo,

i understand about stall protection margins but i'm still not sure about

SID tracking (i'm not sure a 747 accellerating to clean configuration manouvering speed durring a SID turn can stay within PANOPS SID buffer area);

OBSTACLE CLEARANCE (acceleration means also lower climb gradient and during turn we even have higher gradiend loss due to decrease of vertical lift compenent)

Please help me.....

[Captain Sand Dune]

SIDs have minimum gradients published. The pilot is responsible for determining whether or not the aircraft can achieve or exceed these minimum gradients until the aircraft is established above MSA/LSALT. The fact that the aircraft is accelerating and retracting flap is of no interest to the procedure designer.
An older PANS/OPS variant ('71 I believe) used to have an acceleration segent to cater for flap retraction, however the current PANS/OPS86 do not.
Therefore it is encumbent on the crew to examine the relevant performance charts to ensure the aircraft will meet or exceed the required gradients.
If the aircraft maintains IAS below the maximum stated on the SID chart (or in the relevant AIP if it is not published directly on the chart) then it will be contained within the surveyed area. Go above this speed - especially during a turning departure - then you risk flying outside the surveyed area.

[longobard]

So in my understanding,
it's up to the cpt determine if he can accelerate during SID turns according to the aircraft performance. Should the pilot know the MAX IAS a SID is designed for, if it's not specified in the SID chart/aip, in order to remain within the survey area?

thanks again

[fugitive]

Normal procedure in the advent of an engine failure on T/O, is to fly straight ahead to eng out accn ht, clean up,then acc to Vmcl and advise intentions.
ATC will give you priority when you declare an emergency.
You can follow a SID and the normal procedure would be to continue climbing thru the SID until you achieve your initial HDG.With a max of 15 degrees of bank eng out,you can retact flaps,providing you have achieved min flap retract speed.In an EFIS cockpit ,this will be indicated on your primary flight display with an F.
The usual procedure,is to climb in the turn at between V2+10 to V2+ 20 with climb flaps extended until you reach your HDG and min ht for flap retract.You would not normally be accelerating in the turn.
Retracting flaps in the turn is not necessary and just adds another control problem when you least need it.
Some companies do it,but in my experience,it is silly..
regards

[OzExpat]

longobard... if there's no speed restriction shown on the chart, or in the relevant State AIP, then the SID design gradient rules. If this is not shown on the chart (and not stated otherwise in the AIP), the standard climb gradient is 3.3%. The crew must know whether or not they can meet this gradient in the specific conditions of weight, runway and other environmental aspects.

Most airlines that I'm aware of have SOPs to deal with SIDs that are non-standard in any respect.

fugitive... As far as I'm aware, this topic relates to the AEO case, not the OEI situation. However, since you have raised it, I can think of many places where the use of a so-called "normal procedure" will result in a CFIT. Rather than go too far off the topic on this, all I'll say is that many airlines employ their own "escape procedure" to account for a OEI emergency.

Captain Sand Dune... spot on! :ok: The only variation - and it's most inconsequential anyway, is that there was a level acceleration segment in Pans Ops 86, but it was removed somewhere around 1992, I think.

[fugitive]

Hi OzExpat; I thought he was talking about the OEI case and was just giving a couple of examples of how different airlines handle an engine failure procedure.
You are right of course, about possible CFIT,but this is discussed in the T/O briefing and when operating out of certain airports, this would be one of the many considerations.In some cases,following the SID is the best option.
During the PRE T/O emergency briefing ,you would consider the best course of action and terrain is the responsibility of the PIC.
You are correct again with respect to speed restrictions on the charts,minimum rates and gradients of climb etc.
With a restriction of 250 KTS below A100,speed is generally not a problem during normal departure.
Anyway,it is a good to discuss the way different airlines handle the SID and your options in both normal and emergency situations.
Cheers,have a happy New Year.

[OzExpat]

Agreed fugitive, in the real world, one must consider the OEI case prior to each take-off. In that sense, it can't be overlooked in a topic such as this. I had simply been thinking about this topic in the sense that the crew has not encountered the OEI case at the time of the turn and therefore, the AEO case continues to apply until some later time when the crapola hits the proverbial fan.

I guess that I'd also been thinking about the many places where a major turn has to be made at a reduced speed, fairly soon after take-off. An example of this would be the RWY 15 SID for Cairns, but there are many other of course.

Happy new year. :ok:

[longobard]

so as conclusion it's NOT a normal procedure during an AEO takeoff accellerate during a turn, but it can be done if the captain satisfy himself about climb performance and SID tracking.

Thanks Guys!

[fugitive]

Hi Longo,I think OzExpat and others have coverered what you asked.
In both OEI as in AEO,you may follow the SID,but terrain clearance has not been assessed for climb gradients of less than 3.3%.The min required net gradients of climb for 2,3 and 4 engine A/C with OEI are less than this,so you would need to assess the surrounding terrain during your briefing.You can then decide on your best option .There may be no terrain problems and you may choose as PIC to follow the SID following an engine failure.
Major airlines will cover all situations , but some of the smaller or less reputable outfits will leave everything up to the PIC.At the end of the day,you are responsible for the safety of the aircraft and passengers.
The SID departure is based on an average 15 degrees of bank and a maximum speed of 290 Kts,so the OEI speed of roughly 120-160 Kts up to 290 Kts,gives a fairly wide speed band.
Anyway,you have made me start to think about again,so good luck in the future.

[Chris Higgins]

Vs New= Vs Old multiplied by the square root of the load factor

Load Factor = 1 divided by the cosine of the angle of bank.

eg: cosine of 60 degrees equals .5

1 divided by .5 = 1.41

That's where we get an increase in stall speed of 41 percent in a 60 degree steep turn.

The typical stall identification system of a turbojet aircraft triggers at 1.07 vs.

V2 must guarantee 1.2 Vs and 1.1 of VMCa as part of SFAR 25 certification.

The bottom line is that if you held V2 or better, you would be guaranteed stall protection for any manouvering at a rate one turn.