Very interesting thread, there is a bit of a debate going on in our company at the moment about this very question. The two sides of the debate are: 1) If there is no engine out SID, obstacle turn etc. then follow the normal SID and 2). Go straight ahead UNLESS there is an EO SID or obstacle turn. Assuming the worst case of failure at V1 then
in my opinion the second option, straight ahead, is the ONLY safe option for the following reasons.
Firstly consider how Perf A. (or whatever it's called under JAA) calculates obstacle clearance. At the end of the TODA an area begins that is 100m + a wing span wide. This expands at a rate of 12.5% of distance out to a maximum of 1800m. This area extends unitl the a/c reaches 1500ft agl. This area has been surveyed and any obstacles in it are noted, following an engine failure at V1 these obstacles must be cleared by 35ft. If the a/c will not achieve this you must reduce weight or increase VR (runway length permitting) to improve the climb gradient. If the resulting weight is very low it is also possible to fly a procedure that takes the a/c on a flight path that allows the 35ft clearance to be achieved, again this is based on survey data of the area, the max weight that can be lifted will be lower however because as we know on one engine the a/c will climb more slowly during turning flight than wings level. At high weights it probably not possible to turn, climb and accelerate at the same time which why many procedures tell you to ignore accel. height until a certain point during the turn.
It seems to me that there are a few vital implications that come out of the above.
If you do not fly straight ahead you are turning out of the flight path funnel in which your obstacle clearance in assured. You are on your own now, nobody has surveyed the area you are climbing in. You may or may not clear any obstructions that are in the way. 35ft is not much clearance and even in day VMC you will not be able to eyeball it. The rules of course only consider IMC. Outside the funnel something like a power pylon, tall building or gently rising ground could be right in your flighpath and you may not clear it. These obstacles may be present within the funnel but your RTOW will have taken account of them. If you do turn you are also reducing your climb performance and it is likely that at high weights you will not achieve the required gradient. If you are flying an obstacle clearance turn then your RTOW will have taken account of the fact that you will not climb as well during the turn.
Engine out performance planning is a very complex subject and just after a engine failure is not the time to start messing with it. In an airline, someone has done the work for you. (not sure what the biz. jet drivers do)
Look out of the window now and imagine an airliner, on one engine, clearing the house next door by 35ft. Scary isn't it, and that would be legal!
So I reckon that unless there is a published engine out turn you MUST climb straight ahead to 1500ft. If you do anything else you are not doing a Perf A. take-off, you are making it up as you go along and may put yourself in a very dangerous situation.
[ 20 July 2001: Message edited by: Max Angle ]