SIDS for Noise Abatement

[JetPilo007]

Hi Guys.

I just encountered a small situation where I couldn't meet the Climb gradient of any SID of a certain airport on a single engine. Now, the airport is surrounding flat land, so I am confident its not an Obstacle avoidance climb gradient, but a Noise abatement climb gradient?

Does this really restrict me from taking off because I can't meet a climb gradient on single engine, that its sole purpose was to ensure noise abatement?

Looking forward to hearing what you think.

[Icenor]

Do they really have a noise abatement procedure incase of engine failure... If there was one situation where we could disregard noise abatement, I would think it was during an engine failure

What airport is this?

[JetPilo007]

No. You misunderstood.,

EGBB

This airport required a minimum climb gradient of 4.5% . All the sids are either that gradient or higher.

Looking at the topography, the airport is surrounded by flat land. Therefore, I am assuming the required climb gradient is for noise abatement. Maybe some towers around the airport area...

If I can't meet that gradient with 1 engine (Departing full of fuel for a long haul flight), does that really restrict me to depart from that airport? There is no ODP on the airport chart.. So, I am in a loss here...

Thanks

[Cough]

The min climb gradients can also be for atc purposes in terms of avoiding conflicts with other dep/arr/local traffic. Single engine, if you choose to, the SID is out the window anyway... Along with that goes its climb gradient so worry not, just make sure you tell them though!

[JetPilo007]

So in other words. Before takeoff let them know that we won't meet the gradient if we loose an engine?

[Piltdown Man]

As long as you have sufficient performance to 1. Make the minimum climb two engines operating and 2. Climb to a safe height and land somewhere following EFATO, there's no need to say anything.

PM

[JetPilo007]

That makes sense.

Any reg or AC that can prove this fact?

Thanks!

JP

[HEATHROW DIRECTOR]

Maybe for noise abatement..... but maybe for separation from aircraft flying under the climb-out?

[kenparry]

Looking at the topography, the airport is surrounded by flat land. Therefore, I am assuming the required climb gradient is for noise abatement. Maybe some towers around the airport area...

For a twin especially, there can be close-in obstacles which are significant in the engine-out case, even though they do not look to be much above the surrounding general level of things. Also, look about 8 nm N of the field, there is a TV tower at 1501 ft amsl. In the days when I flew B737/757 out of BHX, we had a 2-stage emergency turn procedure to follow for engine failure after V1 when using RW 33. The first stage was to go about 15 degrees right to avoid some close-in obstacles, the details of which I forget. The second stage was to miss the TV mast.

Back to your original question, noise abate does not apply to engine-out ops, as I recall, though I am not able to quote a specific regulation.

[Cough]

007,

Just meant that you should tell ATC if the engine fails, via the normal calls.

Nobody will care about noise in the engine failure case, unless you make lots by crashing so please avoid that. Climb gradients to meet ATC requirements I believe become null and void, as ATC will probably get everything out of your way anyway so no issue there. And how long will you remain on the sid, or will an emergency turn/EO Sid take over? In which case, the min climb gradient no longer applies as you aren't conforming to the sid.

Trust me, it's the last thing you will be criticised for if you bring your craft home safely after an engine failure...

[5LY]

SID's are designed for a climb gradient of 3.3% or greater. The standard is 3.3%. If higher is required it will be noted on the SID chart.

I assume that you are flying a twin engine a/c. The climb gradient you are required to meet on one engine is 2.4%. (That's what you are looking at in the climb section of your runway analysis chart.)

You have no business following a SID on one engine unless your performance dept. has assessed that particular departure and confirmed that 2.4% will keep you safe.

Depending who does your charting, it is generally assumed that you will fly straight ahead on one engine or follow an escape route if 2.4% gradient isn't safe on runway track.

It may be that the higher gradient that you refer to is for ATC seperation and not for terrain, but without doing some engineering work you won't know.

In any case, ATC does not necessarily expect you to follow your assigned SID if you've lost an engine. That's why you give them the Pan or Mayday call.

Talk to your performance dept. You really need to know what they've based their performance calculations on. They've made certain assumptions about what you will do in the event of an engine failure. Make sure you're on the same page they are.

[PukinDog]

SIDs climb gradient requirements (standard or higher) are based on all-engines operating. There is no requirement to let ATC know beforehand if you can't meet the gradient of a published SID in the event of an engine failure. Some SIDs have crossing restrictions well into the Flight Levels and almost no engine-out civil aircraft could ever meet them. Southeast-bound SID out of Geneve with winter tailwinds, for example.

The regulatory gradient requirement you must meet for every takeoff whether VFR or IFR regardless of terrain or the existence of published SIDs (assuming you're flying a 2-engine aircraft) are those required for certification, and usually the most restrictive in terms of adjusting weight to meet it is the 2.4% 2nd-segment climb gradient after the loss an engine (not taking into consideration approach and landing climb gradient requirements at your destination, which may be more limiting as far as your takeoff weight is concerned).

That being said, if you're departing in IMC conditions and you know you can't make the published SID climb requirements to the airway MEA or at least the MSA, what do you do if you lose an engine?

If you're a commercial operator you'll have an approved engine-out procedure for that aircraft type that may involve turns (taking into consideration 15 degrees of bank) and an acceleration altitude (where the 2nd segment ends). They're escape procedures designed around known obstacles and terrain. The result of having these procedures available is being legal for far greater takeoff weights at many airports.

If you're a non-commercial operator and it's IMC (or virtual IMC in CAVOK darkness) and you can't see to avoid terrain or obstacles, if you can't make a published procedure to at least the MSA by the end of 2nd segment as determined by engine time limits or lack of performance numbers to altitudes that high above the departure runway, a big flag should go up if you don't subscribe to a service that can provide an engine-out turn procedure for that runway that's been approved for your aircraft. Don't blindly rely on ATC to keep you out of the dirt, and never assume you can fly-straight out forever clawing for altitute even if you think terrain isn't an issue.

Also remember, very few aircraft manufacturers provide single-engine climb performance numbers based on anything other than a max 15 degree banked turn. Where terrain is an issue, to achieve a contained-area turn many SIDs require not only a max speed but also require minimum bank (say, 25 degrees) to acheive desired, small-radius ground track. In those cases, you really don't have any gradient numbers that take into account the degradation in climb performance for an engine-out, V2 climb, 25 degree-banked condition.

[mutt]

very few aircraft manufacturers provide single-engine climb performance numbers based on anything other than a max 15 degree banked turn

Another way of doing this is to take the gradient loss for the 25 degree bank turn and increase the obstacle height accordingly, then your performance figures will work

Mutt