Bank Angle maximum 15° till 1500 AGL - Why? This is mostly seen in E/O Departures.

Increasing bank angle increases load factor, reducing the margin to stall. A larger bank angle would require a faster speed to be flown, reducing E/O climb performance.

I can think of 3 reasons:

1. Regulation: The amount of manouvering during the initial stages of a SID is limited by procedure design recommendations to reduce workload & errors during that critical transition phase.

2. Performance based obstacle clearance: If you are already at a maximum performance airspeed, climb rate (and therefore gradient) reduces as bank angle increases.

3. Navigation based obstacle clearance: Turn radius (and therefore ground path radius) reduces as angle of bank increases.

Certainly not a recommended procedure by the manufacturer.

Bank angle equals load factor increase which is essentially similar to increased weight for performance .. not a really good idea OEI.

Presumably you are aware that the AFM specifies a gradient reduction for climb calculations for turns ?

15 degrees is more than enough to create difficulties with terrain critical departures OEI.

I notice that you have a similar thread in another forum. Against site rules, I'm afraid. I'll leave this one run as it is appropriate to Tech Log. However, please don't run multiple threads as that is a good way to end up in the sin bin.

I have always thought the limitation was there to control track deviations at low altitude. Also a wing down on a transport size aircraft will reduce your obstacle clearance by 20-30 feet, depending on span and bank angle.

I have always thought the limitation was there to control track deviations at low altitude.

Not to my knowledge. It is presumed that the pilot can manipulate with a reasonable modicum of skill so track locus is reasonably well controlled. The track splay is intended to take care of minor tracking errors.

Also a wing down on a transport size aircraft will reduce your obstacle clearance by 20-30 feet, depending on span and bank angle.

If you scale, say, B707/DC8 at 15 degrees, you will find that the loss is around 15 ft .. hence the 35/50 delta for straight/turning departures.

It much depends upon performance legislation, i.e. the State in which the aircraft is registered and compliance with the local authority. For example, the UK TriStar (RIP), had flight manoeuvre limits of 15 degrees of bank, whereas in the USA (for an FAA registered aeroplane) the limit was 30 degrees of bank. Min Manoeuvre speeds for retracting the flap are predicated upon the bank angle, hence, should there be an engine failure after take-off you're within the speed bracket; erring upon the safe side.

V2 min is only 1.15 or 1.2 Vs (depending on aircraft certification). Coupled with the other problems brought on by unexpected engine failure, this is not much of a margin above stall, so is probably the main reason for the 15 degree bank angle limit.
If a V2 overspeed is permitted ('improved climb'), although the close proximity to stall is then not such an issue, the takeoff analysis should still assume any turn below 1500 feet will be at 15 degrees bank angle and take into account the greater turn radius.
Some SIDs which require a low level turn after take off may state minimum bank angle greater than 15 degrees. V2 should be increased in the analysis to cover this.

- Please state your reference for this and cut and paste the words here so we can make head or taii of this. What is your standard company acceleration height?

Bank angle maximum 15 degrees is not an operating limitation. It is a limitation for the regulatory demonstration of E/O obstacle clearance. For that demonstration it must be assumed that the bank angle does not exceed 15 degrees. It applies until clear of obstacles, which may be higher than 1500 AGL.

Ref B737 family. 15 Bank Angle is likely only required if flying < V2 +15. This a manoeuvre margin certification issue reflective to Vs. It applies to any time time you are below this speed for the flap configuration. This will apply with an engine failure on takeoff and when an 'emergency turn' is required. It should be required until the first turn is completed and above MFRA. The 1500' consideration could come from obstacle clearance only being considered up to 1500' above the airfield. It is true that less bank angle = better climb performance, but that comes into the obstacle clearance calculation and any emergency turn routing and MFRA requirement.

It matters not whether it's the B737 family or any other family. It's a regulatory requirement which, as previously stated, is governed by each country's aviation authority. A UKCAA or a USA FAA regulated (identical) aeroplane will each have a different bank angle limit; 15 or 30 respectively.

I believe it's about accommodation
 

Considering different classes of aircraft will require varying degrees of bank angle to alter their track a similar amount, this makes sense. Thank you Sir John. Also understand and agree how the maths clearly illustrate the vertical clearance reduction by having a wing down on a large aircraft - we know this is the key factor driving AFM bank angle limitations under 50 feet AGL.

Perhaps in designing the SID procedures, bank angle limitations are a regulatory accommodation that allows for different aircraft performance characteristics. Stay within the guidelines, and all aircraft will be able to safely navigate the prescribed course, including aircraft with an engine out.

There are no public criteria obstacle surfaces, nor public criteria, which takes into account engine out.

If you are following an EO SID procedure, you would need to verify that your aircraft can follow the procedure min climb gradient, and with enough speed so as to not exceed the bank limit.

If you cannot, you cannot use the procedure.

If I remember correctly, there are many aircraft which are bank limited even further than this below certain altitudes. (arent 747/777 limited to 8 degrees below 1000 ft?)



Also, per the FAA procedure design guidelines: 8260.58 (this should really clear it all up!)

Basic information.

Except as limited by the rules below, the standard design bank angle is assumed
to be 18 degrees (14 degrees for CAT A-only procedures).

The maximum bank angle is:

Fly-by turn rule: One-half the magnitude of track change for turns less than 50 degrees; 25 degrees for turns equal to or greater than 50 degrees (20 for RNP/ATT less than 1.0). Maximum bank angle below 500 ft above airport is 3 degrees.

Fly-over turn rule: Determine the OEA outer boundary radius based on standard bank angle. For segment length calculation, maximum bank angle is 25 degrees.
Maximum bank angle below 500 ft above airport is 3 degrees.

RF turn rule: Calculated RF bank angle based on the design radius is not to exceed 25* degrees (20* for RNP/ATT values less than 1.0). Maximum bank angle below 500 ft above airport is 3 degrees.
*15 degrees for CAT A and B-only procedures

A good reference is Getting to Grips with Aircraft Performance.
Available here:Getting to Grips With Aircraft Performance


Read pages 62-74 and note the difference between the regulatory requirements of FAR and EU-OPS

Reading the OP. Is he saying the FD bank angle selector is required by his company SOP to be set at 15 degrees on all take off's (in case an engine failure occurs in the climb to 1500 ft) and not changed until above 1500 ft? The 737 has a bank angle selector for the flight director. Most operators I know of have it set at 25-30 degrees for normal flight. If the departure requires a curve after engine failure at V1 then it is a simple movement to switch the angle of bank limitation on the FD selector to 15 degrees. As the gradient of climb varies only a slight amount between V2 and V2 +20, then even if an engine failure occurs seconds after lifting off, the aircraft will have already accelerated during the rotation sequence to V2 + 15-25 and a 30 degree angle of bank is quite legal and safe.

It is unnecessary and proves nothing, to limit the angle of bank to 15 degrees on all engines until reaching 1500 feet - just in case an engine should fail before 1500 ft.
However I may have misunderstood the full meaning of the original post

underfire:

Those are design criteria for RNAV instrument approach procedures. They have nothing to do with departures, much less OEI departures.

This is used for RNAV DEP and RNP 1 DEP. I would suspect that SID DEP would be similar.

Yes, there is nothing in any criteria for EO anything.

there is nothing in any criteria for EO anything

Generally an operator/commander consideration in the application.

The basic certification/AFM data is used to match RTOW against runway distances and departure terrain clearances to cover the takeoff failure case.

Indeed, the AFM consideration is driven by the OEI case.

Considering that EVERY heavy takeoff considers and calculates OEI requirements ... to suggest that there is no EO criteria is somewhat fatuous, I suggest ...