Flap retraction after Single eng go around

[LeftHeadingNorth]

Hi!

Topic says it all really. Minimum missed approach gradient is 2.5% if I'm not mistaken. However, if you start retracting flaps when flying with one engine you are most likely not going to make the 2.5%. So question is should you wait with flaps retraction until reaching missed approach altitude?

Regards,
LHN

[parkfell]

So we are dealing with a single engine go-around, as oppose to a loss of power etc on take-off where the emergency turn procedure is used

Mr Boeing says retract the flap normally 1000ft above airfield elevation for a B.737

Additional information : FCOM PD 32.6 for % climb gradient SE

[Piltdown Man]

LHN: You are right. I can' answer for Mr. Boeing or other companies, but we deal with flap retraction on our N-1 (to use the current parlance) missed approaches in exactly the same way as we would with all engines operating. We retract our flaps at Missed Approach Altitude.

Depending on the fleet and where the go-around starts, we have two methods of tracking where we have a non-standard N-1 take-off path. Our Jet jockies follow the Standard Missed Approach but the Turbrop guys take a different route. If they go-around below DA, they follow the Non-Std N-1 Take-off path.

But as ever, when things are looking marginal, Airmanship and SCD come into play.

PM

[flyburg]

You are correct, you might not make the 2.5 climb requirement. This is why the procedure designers incorporate a level acceleration segment in the missed approach procedure. It starts at a minimum of 800'', 300 feet of obstacle clearance is provided and it is a minimum of 6nm long. If local conditions require a higher acceleration hight it will be indicated on the chart.

Hope this answers your question.

p.s. as the previous poster mentioned 800 is the minimum build in the procedure, nothing precludes you from doing it higher, Boeing indeed recommends 1000' as a minimum. My own company uses the missed approach altitude

greetings

edited for typing errors, mini laptop's are a b#@%

[Rainboe]

but we deal with flap retraction on our N-1 (to use the current parlance) missed approaches in exactly the same way as we would with all engines operating. We retract our flaps at Missed Approach Altitude.

Who says this N-1 nonsense is 'current'? Not here it ain't! For a start, it is fixing a number in your head (1) when you might have lost Nos 2, 3 or 4. I suggest we leave it across the channel where it belongs!

As far as possible, your OEI procedure should be as similar as normal procedure- fighting a failure is not the time to start remembering 'special' procedures.

[flyburg]

Uhh....feel better now?

[Rainboe]

Very well thank you! Not that one was unwell in the first place. And may one enquire of your health? Is one interested?

[Old Smokey]

You should no more think about flap retraction during an OEI Go-Around below Acceleration Altitude, than you would think of doing so for an engine failure after Takeoff. Doing so would "consume" all of your obstacle protection!. END OF CASE STUDY.

A pox on N-1, bloody silly idea, what's wrong with OEI?

Regards,

Old Smokey

[Capn Bloggs]

We use PANS-OPS approach charts and as far as I am aware there is no level segment built into the Missed Approach Procedure. It's 100ft clearance plus 2.5° to the MSA.

If you can't make 2.5° to the MSA for whatever reason, then you have to raise your MDA/DA until you can. Some approaches from our ANSP have exactly that: two different minimas for different missed approach gradients.

[Henry VIII]

In this case my company SOP requires to accelerate reaching missed approach altitude.

[jersey145]

on the ERJ145 its a climb with the flight director up to Aa with flap 9 then accelerate to VFS cleaning up at V2 + 15. If its a moderate weight during go-around no level off will be required as the performance is still pretty good single eng.

[Todders]

Interesting topic thanks guys.

In my old company using Jeppy plates derived by pans ops and certainly for a couple of airfields we operated into we had different minima for minimum achievable climb gradient as worked out by you from the performance dispatch section.

Never had I considered modifying our standard single eng go around profile which for your info included acc at 800ft agl. Thankfully I cant recall ever having to use the procedure in anger at any of these "limiting" airfields but it certainly poses an interesting thought process. Gonna get the old books out and have a check me thinks.

[A Very Civil Pilot]

In my company SE GA acceleration is lowest of MSA, MHA or missed approach alt.

[galaxy flyer]

A Civil Pilot

I do hope there is some allowance for OEI climb gradient achieved in that OEI procedural height.

Do you have runway analysis done?

GF

[A Very Civil Pilot]

Higher minimas if you can't make the standard 2.5%.

[CJ Driver]

Very short sectors?

Whilst it is an interesting academic discussion, in reality only people flying very short sectors are likely to be limited on a OEI missed approach. After all, you were able to meet the OEI departure requirements when you departed some time ago, you are now definitely below max LANDING weight (rather than MTOW), so even if you lose an engine it's not going to be a crisis.

Even our modest steed will make more than 10% climb gradients at typical landing W/A/T on one engine - in most cases it will even accelerate through flap retract speed whilst doing it.

[Capn Bloggs]

CJ Driver,

Whilst it is an interesting academic discussion, in reality only people flying very short sectors are likely to be limited on a OEI missed approach.

I beg to differ. Try taking off at sea level, flying for an hour, then landing at 1700ft AMSL at 40°C at max landing weight. This issue then becomes bigger than Ben Hur.

If you're doing 10% OEI (~1200fpm?), then you either don't have much fuel, don't have many pax, it's bluddy cold, or your engines are too big!