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ItsAjob
4th Mar 2010, 09:16
A question for perfomance engineers.

Assuming engine failure at V1 with no published EO sid, you climb straight ahead to 1500ft, clean up and begin to climb to msa which is significantly higher than 1500ft

I understand runway performance figures cover us until 1500ft.
What ensures terrain clearance between 1500 and msa?

When operators establish if they need an EO sid do they take into account the distance between 1500 and msa?

Thanks!

Nubboy
4th Mar 2010, 09:50
I think you are confusing several things here.


The 1500' is in respect of airfield elevation, not amsl. Hence this can be quite limiting in itself at high elevation airfields.

With no obstacles present, at for example EGLL, london Heathrow,, elevation about 80' amsl my company go straight ahead, tell ATC when we have time to do so, use a standard acceleration cleanup of 1580' qnh, clean up as required, and expect to turn towards an appropiate holding point and climb to 2300' qnh which is the local area msa. We don't expect any performance issues or need to go so far frfom the field we're in danger of hitting any fixed obstacles.

Have a look at north west departures from somewhere like geneva. These SIDS have minimum gradients and minimum altitudes to be attained at specific waypoints before you can continue, otherwise you have to tell ATC and climb in a holding pattern. If you follow the routing and the profile then you should keep out of trouble.

Other places have an engine out procedure which requires you to keep the speed back, V2+10, turn the aeroplane away from the obstacle and point it towards a clearer area to climb to acceleration altitude before it's safe to accelerate. Loads of examples, but runway 04R at Nice (LFMN?) is one that springs to mind, although I've not been there for a while. Good fun and spectular enough on 2 engines, the thought of struggling on one toward the mountains would concentrate the mind wonderfully. Addis Abbaba, Bole International on 25L can combine high elevation, high temperatures, huge difference between indicated and true airspeeds, with a dirty great hill (baby mountain?) at the far end.

Places like this it's important to have a very good idea of what you intend to do if it goes all exciting at an innopportune moment, and understand why the procedure is laid down as it is.

Hope this helps.

ItsAjob
4th Mar 2010, 10:22
my company go straight ahead, tell ATC when we have time to do so, use a standard acceleration cleanup of 1580' qnh, clean up as required, and expect to turn towards an appropiate holding point and climb to 2300' qnh which is the local area msa.

But once you turn towards your holding fix you are not on any specific published track, I know its not a lot between 1580 and 2300 but what terain guarantee have you got whilst under the msa?

Im just thinking if there was a significant difference, say an msa of 7000ft all round.

Whatever direction you choose to turn you will be under the msa, off track whilst you climb.
If you choose to continue climb straight ahead because there was no EO sid you will easily end up further than 25 miles.

Nubboy
4th Mar 2010, 10:38
Sorry, should have expanded.

All of planned departure airfields have been approved by operations, to one of 3 catergories. (A B or C ).

The take off performance data is listed for each of these, with data listed for each runway and intersection which we are permitted to use. This gives us all the normal information for temperature, flex, head or tailwind, low qnh corrections etc. At the bottom of each page is a description of what we should do in the event of engine failure, which is where I've extracted the description of what we do for LHR. This has been provided by our performance department and has taken all the airfield obstacles into account. Each airport has an obstacle chart for each runway.
Therefore in following the procedure, we are relying on our performance people to have number crunched it on our behalf.

To get a gross overview of what high bits are where, as the SID charts don't normally show terrain, then the final approach (eg ILS or VOR plates) charts, as well as a radar/terrain chart if published enables you to see if what's proposed is sensible. Hope this clears it up.

ItsAjob
4th Mar 2010, 10:57
Ah ok thanks.

I wasn't aware of the specific emergency procedure details for every runway that you fly to.

Checkboard
4th Mar 2010, 11:47
I understand runway performance figures cover us until 1500ft.
What ensures terrain clearance between 1500 and msa?
All performance calculations I have used have a survey area of 30 nm around the airport, in order to allow an aircraft to clean up, and then return to the airport. Any obstacle which would be a problem is taken care of in the Engine out procedure. Failures in the climb are covered by either a direct turn back to the airport, or (where necessary) with a procedure (which is usually back-tracking the SID).

Nubboy
4th Mar 2010, 11:47
Yep its listed either as standard, in which case ahed to 1500'agl, then turn to a suggested fix, or NON standard, which then gives details of required turn and height before you can accelerate and clean up.

A37575
4th Mar 2010, 12:06
herefore in following the procedure, we are relying on our performance people to have number crunched it on our behalf.


Careful about relying 100 percent on anyone including your performance engineers. I flew for one airline who had an engine failure procedure published for a Greek island. The procedure published was simple enough in that it said turn left and fly heading 020 - flap retract height 800 feet. On departure from that runway on a sunny day I noticed another small island with a 1500 ft spot height feet dead ahead on track 020 and 10 miles away from the departure airport. There was little doubt in my mind that the level acceleration with one engine inoperative would have put us smack into terrain below the spot height.

When asked how far ahead on 020 was the flight path surveyed for obstacles, the company performance section replied 50,000 feet and that after that distance, it was pilot responsibility to calculate own terrain clearance. Furthermore, the performance section had obtained this information from Greek authorities who had provided the obstacle clearance charts from which our runway analysis had been calculated.

It is wise to check with your own performance engineers responsible for individual runway analysis charts, to exactly what distance are the charts valid. Depending on aircraft weight, met conditions, density altitude etc a loaded 737 could be as far as 14 miles after lift off on one engine and still be at 800 feet before flaps are up and MCT selected.

Ideally, the published engine failure terrain clearance flight path procedure, should provide the pilot with safe terrain clearance and associated data, to a height where an instrument approach may be commenced.

Old Smokey
4th Mar 2010, 15:54
BEWARE! - A lot of Performance Engineers and subcontractors DON'T take care of flight from 1500' to MSA, I do, I sleep better that way.

PE's techniques vary, the procedures that I create take the pilot from the runway to the MSA, after which PANS-OPS or TERPS apply. It aint so hard, but the rocks that a willy nilly return from 1500' to the airport at pilot discretion are very very hard, and invariably fatal.

Not an ego trip, but my procedures take the pilot, with appropriate tracking out to MAA, and then onwards at at least MAA to a "Safe Climb Holding Pattern" within the MSA coverage for continued climb to MSA.

Interestingly, in Australia, the OEI climb to 1500' (or more if required) is covered by the Civil Aviation Order (CAO 20.7.1B), whereas the REQUIREMENT for a safe tracking procedure for onwards flight to MSA is covered in the AIP...... Interesting cross reading.

A certain well known Performance Provider beginning with a J takes you out to 30 miles.....and then what? NOTHING!!!!:eek:. (J DOES NOT include the venerable John_Tullamarine who takes these things very seriously).

Regards,

Old Smokey

9.G
4th Mar 2010, 16:46
EOSID design criterion at least known to me as follows:
Flight Path with Engine Failure at V1
When an engine failure occurs during take-off, the obstacle clearance is based on the “Engine-Out Standard Instrument Departure (EOSID)” or “Special EOSID”. Engine failure procedures are based on engine failure at V1 (or after, but before initial turn on to SID), to avoid obstacles that have not been considered in the analysis, and which would reduce the Regulated Take-off Mass, or flex temperature if they were to be considered. If engine failure occurs after initial turn onto SID, continue following the SID. At airfields where such performance is not guaranteed, a SID specific decision point procedure is developed. The heights of obstructions are modified to reflect the climb gradient loss due to banking the aircraft. No gradient degradation is applied to turn with a magnetic heading change less than 15 deg.
The procedures provide a min terrain clearance of 35ft in level flight, and 50ft during a turn. It is imperative that the turn be commenced at the proper time, distance or location as specified in the instruction for each turn procedure. Turning too early, with the subsequent reduction in the climb gradient, may well leave no clearance over close-in obstacles in the vicinity of the airfield, and turning too late may take the aircraft outside the area over which the terrain clearance performance has been calculated.
Constructing this kind of procedure whole range of take off weights along with utmost unfavorable temperatures and winds are to be taken into account. The Engine-out SID Procedure (EOSID) guarantees obstacle clearance over the whole flight path, provided the airplane continues climbing after flap/slat retraction for at least one round in the holding pattern (unless above MSA). It's pretty clear to me that as long as one follows the EOSID even being below MSA it's safe. :ok:

Old Smokey
4th Mar 2010, 17:10
9.G,

There are many Normal (all engines) procedures designers on these forums who will categorically verify that normal SIDs DO NOT consider engine failure. As OzExpat has stated, there's just too many variations between aircraft types to consider such a thing.

Your Remark -"At airfields where such performance is not guaranteed, a SID specific decision point procedure is developed" is very sound indeed. Being already commited to the SID and suffering engine failure is nightmare stuff.......unless a Performance Engineer worth his salt has indeed developed such a break-off point with subsequent OEI tracking. Many PEs do not, I do.

Your final remark -"It's pretty clear to me that as long as one follows the EOSID even being below MSA it's safe", yep, that's OK IF the PE has developed the EOSID ALL of the way to a Safe Climb Holding Area for further climb to MSA. As said before, many PEs do not, I do. Big "J" just gets you out to 30 miles (outside MSA coverage), and then you're on your own. (Big "J" has a much bigger litigation budget than I do).

No criticism of your excellent post, none at all, perhaps you fly for a reputable operator whose PEs take the care to ensure your safety all of the way to MSA, but sadly, many many pilots do not work for such companys.

Regards,

Old Smokey

9.G
4th Mar 2010, 17:54
O.S, thanks. I'm not a performance guru just a driver endeavoring to gain a bit deeper understanding of backgrounds. I just take it for granted with a healthy portion of skepticism, of course, what the performance layout says. All I can tell is that those EO procedures are designed for all the fleets from 320 till 346. for each and every RWY. So yeah, it's all about how serious the operator is about those things, I suppose. :ok:

john_tullamarine
5th Mar 2010, 12:01
What OS infers, and with which I agree, is that ops engineers who periodically frighten themselves in row 0 (as opposed to straight engineering types) probably, in generally, are a conservative lot given to a rabid desire to live through until retiring age ....