View Full Version : Acceleration altitude and engine-out acceleration altitude

3rd Aug 2015, 13:34

Let's assume that we are establishing NADP 2 as 1000/1000 AAL and aerodrome elevation is 200ft. So we enter 1200/1200ft on the PERF TO page as THR RED / ACC altitude and we leave the EO ACC which is on the right side 1500ft as default.

Let's think that we've checked the RTOW chart and realised that Min Acc Alt is 1700ft so we updated the EO ACC as 1700ft.

For example lets say that we had a CONF 2 takeoff. And after 1200 ft with the first flap retraction we pulled the THR LVR to CLB detent and started acceleration to full retraction of flaps and at that time we had engine failure and we were still below 1700ft

Shall we also update -1200/1200- as 1700/1700 or 1200/1700 in order to guarantee the 2nd segment obstacle clearance if we encounter engine failure during second segment?

Thanks for your interest

4th Aug 2015, 04:50
Your company should give you a procedure for that, as it is not covered in the Airbus SOPs.

When the engine failure occurs after acceleration but before the airplane is clean, you should go TOGA again (SRS will activate and also GA TRK) and you should pull speed and go back to V2 plus until reaching 1,700 ft in your example, then you can resume normal acceleration.

However! If you didn't, most likely the outcome is going to be the same and the take off safe, because you already climbed 1,200 ft on two engines, so you are quite good if you compare with a failure at V1.

4th Aug 2015, 09:32
A two engined jet is climbing seven times better on two engines than on one. You will be way above your OEI profile and the second segment is history, so as long as you won't fall out of the sky you can't do anything wrong.

4th Aug 2015, 10:52
Little bit off topic but also related to EO acc altitude.

As is known AB RTOW provides min acc altitude limited by OBS clearance and max acc alt limited by 10min TOGA.
There are some airports/rwys in our network that for unknown reason do not provide this min/max, ****** is shown on RTOW.
We have check on Airbus documentation such as " getting the grips with...performance" and the explanation is not clear. ***** is provided when min alt is higher than the max alt ?????

Anybody out there can help?

Best regards.

4th Aug 2015, 13:05
FlyH and alatriste
Since THR RED/ACC ALT both are 1200ft. When you reach THR RED ALT LVR CLB will flash and simultaneously SRS will change to CLB. You would reduce first to CLB thrust and then retract flaps to one. At this stage if engine quits you don't want to accelerate so pull speed and you would continue to climb at that speed. You may not go to V2 since that was for CONF2 and you are in CONF1+F now. Thrust can be put in MCT. Obstacle clearance will not be an issue as suggested because you would have reached there earlier on two engines and you need to climb another 500 feet.
According Airbus explanation of MIN ACC ALT, it is highest of the altitudes for the whole chart and MAX ACC ALT is minimum on the chart. This can give rise to MIN being higher than MAX. In that case it is dashed.

4th Aug 2015, 16:54
Vilas, thanks for your cooperation.
Maybe, because of my limited understanding, it is not clear to me yet.
As far as I know:

Min acc alt is limited by 35 feet obs clearance of the net climb flight path. Understood that all OTOW are calculated accepting the EOSID procedure will be flown. So, only one track per runway. How can we talk about the max of the minimun if only one track is prescribed? There will be always the same limiting obstacle.

Max acc alt is limited for 10 min TOGA until aircraft is clean up (F 0) and MCT is selected. This altitude depends on factors such as ATOW, Flex temp, TO CONF etc. Max altitude will be the one most restrictive ( lowest or MIn of the max) taking account all this parameters.Only one EOSID track is considered as well.

If we found a ***** What are we supposed to do?
I found this weird *** in airports without any complicated EOSID procedures limited by surrounding high terrain. LAX, HND, CSX. Not in ZRH.

Thanks again

4th Aug 2015, 17:13

For what it is worth, the company I work for had our performance technical group look at this. Their answer was if the SE accel Alt is higher than 2 engine accel alt, raise the 2 engine to equal the single engine.

In your example this would be



4th Aug 2015, 19:20
Our company procedures are the same as Toms :ok:

5th Aug 2015, 05:17
That is a beautiful solution. I totally love it

5th Aug 2015, 16:43

Hahn: If MIN EO ACC ALT is increased by obstacle it could well be after the 2nd segment climb is finished, further from the field, depends on the EO routeing.

[hairsplitting on]
For those with RTOW charts, do not forget to apply cold temeprature correction to min EO ACC ALT if limited by obstacles and with OAT less than what is printed. Applies also for PEP/OCTOPUS if true cold OAT is not inserted (aka wet equivalent runway limited to -5 deg C).


6th Aug 2015, 08:37
Thr mct ,pull speed v2 , secure the engine than speed up .. Carry out eosid forsure ;)

6th Aug 2015, 09:00
Considered you climb with 2000 fpm before the engine fails, you will travel the required 500 ft while saying " Oh, look at that, an engine failed ". By the way: the biggest hairsplitters / beancounters I fly with will watch the "LVR CLB" message flash five to seven times before slowly and carefully bringind back the thrust levers, starting to accelerate at acc. alt. plus 500 to 800. The whole problem is more of a theorethical nature.

6th Aug 2015, 14:38
From our side we go back to TOGA and leave the SRS take care of the speed. Fly the EFP if it is feasible, meaning that if the SID goes on the opposite direction of the EFP, don't hit anything in trying to rejoin the EFP. Start the ECAM actions till engine secure which is going to be way above the EO ACC ALT anyway since the engine failure occurred during the flaps retraction. The Max ENG OUT ACC ALT for the 10 minutes of take off thrust is not applicable anymore as CLB thrust was already selected before, therefore the 10 minutes are starting again from the new application of TOGA.

6th Aug 2015, 15:39
According airbus explanation if for any where on the chart the MAX ACC ALT is lower than MIN ACC ALT any where (they have displayed a chart) then these values are dashed at the usual bottom place. In such a case you need to check these values in a specific chart.

6th Aug 2015, 17:00
On a side note another interesting exercise is an engine fire occurring just before the normal acceleration altitude. By the time the engine will be shutdown the airplane will be in CLB already with a very similar sequence of events as described in this thread.

8th Aug 2015, 07:57
Vilas, could you please give me a reference that min acc is the the highest and max acc is the minimum. I'm trying to find it on the Airbus docs for four days but I couldn't. Thanks

8th Aug 2015, 16:17
You won't find it in any manuals. It was explained in Fight Operations Web Conference 05May2009 RTOW Charts Frequently Asked Questions.