B737 Single Engine Go Around - Flap Retraction Altitude?

[The Mad Russian]

My Companies SOP with regard to Single Engine Go-Around Flap Retraction Altitude is the lowest of three possibilities:

• End of missed approach altitude

• Minimum holding altitude, if the missed approach contains a hold

• MSA

Having just converted to the B737 this seems to involve long periods of G/A Thrust on the good engine, the 5 min limit is a consideration. At somewhere like GVA Max Con would need to be set at some point during the missed approach.

Apparently this is the only procedure that complies with JAR requirements for an Engine Out Missed Approach? 2.5% Gradient.

Just wondered what other European 737 (or any other type for that matter?) operators do in this circumstance?

[dusk2dawn]

I like the option to start retracting at MSA - allways thought that was sensible.
In our company we are struck with "End of missed approach altitude".

[Rainboe]

In BA it is a standard 1000' above airport altitude, rounded up to the next whole 100'. Unless there are exceptional terrain problems, it seems to do the trick.

[BOAC]

I think the Boeing 'minimum' is 400 AGL but it is up to individual airlines to dictate when. Analysis of each airport/runway will decide the required climb gradient and if a turn or modified retraction is required, it will/should be published. in the case of GVA R23, yes, if you delay flap retraction, say, until 'turn complete' you will need to take max continuous.

[Techman]

My company also uses 1000' above field elevation, unless the surrounding terrain dictates otherwise. Then a new altitude/procedure will be described in the airport analysis.

[RoyHudd]

In the event of a GA at GVA, off r/w 23 in icing conditions, (not inconceivable) should one attempt to retract flaps/slats expeditiously, or should one simply climb at G/A thrust to the recommended time limits for the a/c and powerplant, and then re-configure? The 10600 foot MSA within 10nm of the field rules out a single-engine climb at GA thrust to the MSA.

There would appear to be a need to compromise between climb angle and re-configuring, and I wonder if anyone has some guidelines for this type of case.

[BOAC]

Roy - it is simple! Follow your company's SOPs and performance brief for R23 GVA.
The g/a (IIRC) goes ahead to PAS, then left to SPR? It keeps you clear of terrain. It is just a matter of:-

1) at what speed YOUR company asks you to fly the turn
2) when YOUR company asks you to retract the flap
3) when you should select Max Cont while climbing to 7000'.

[RoyHudd]

Thanks, BOAC.

Speed is max 185 kts in the turn, bank angle 25 degrees.

The company has no laid down policy for flap retraction and MCT specific to GVA, and it's an up-coming sim detail. I was hoping to tell the examiner, in preference to asking him.

Given that, I guess pilot's discretion/common sense applies, i.e. retract at 1500 aal, and MCT straight after that. I wouldn't want to prolong a climb in icing conds with flaps/slats out, and not making use of MCT.

[BOAC]

Speed is max 185 kts in the turn, bank angle 25 degrees. - that sounds familiar to me. In my last company (737 Classic) IIRC we flew the turn at F1/185 (<63T, considered a 'safe' speed) but there was no 'policy' on power so my brief was retract to F1 at 'normal' height, take max cont when at Flap 1/185 and clean up when pointing at SPR/above 5000' which seemed to satisfy terrain/engine aspects? At 185kts the published turn was well above terrain. I'm sure if you went round the turn at Flap 5 it would be fine too

If there is no 'guidance' on power then one would hope the examiner would apply 'common-sense'!:D

[Winston]

The boeing 400' AGL is for take off. The GA requires 2.5% min (sometimes more if written on the chart) If you look in the performance section of the ops manual there is a chart with pressure altitude and weight which will give you the expected SE GAclimb gradient. If you cannot achieve 2.5% you will need either a visual escape manoeuvre or a higher minima. If the climb gradient chart gives you higher than 2.5% you know that you can fly the standard missed approach HOWEVER if you accelerate before MSA or missed appr alt you now do not know what the average climb gradient has been so you are no longer safe. My answer 9sorry its been a bit dragged out) is on a single engine Ga you must not accelerate until you reach MSA or missed appr alt. Hope that helps

[R8TED THRUST]

I fly the 737 for a Canadian company and our SOP uses FRA at 800 feet AGL! Hope this helps.

Cheers

[RoyHudd]

Hmmmm. OK Winston, understood, but this case has an MSA of 10,600 ft, and missed approach alt of 7000 Long climb on one engine at GA thrust. When to go MCT? (Apart from powerplant manufacturer's time limit that is). Genuine enquiry, just seeking an "official" standpoint.

[BOAC]

Roy - I think there is confusion here. To me, 'MSA' here means exactly that, not 'CHART' MSA, but ACTUAL MSA for where you are and where you are going - ie TRACK related, not 'general'. Eg in the case of GVA, when you are on the procedure and either above 5000' or pointing safely at SPR. Take INN, CMF and many others - OEI acceleration takes place WELL before SSA, 'MSA' and missed approach altitude.

[outofsynch]

ezy s/e FRA is same as two engine - 1000' AAL unless otherwise specified

[Bumblebee]

Rainboe:

sorry mate but I think you'll find that our B737 SOP flap retraction is at 1500'aal minimum on both one or two engines except when promulgated differently by the Perf manual (usually places like INN or CBY where you're final segment climb limited and clean up higher).
cheers BB

[Cough]

Bumble...Just for your info, I believe that we are the only BA fleet to clean at 1500', the rest being 1000'...But I know we are on about 737's.

GVA...Interestingly enough, our SOP's are now to clean up at 1500' (aka alt 2900') and turn at min clean (210/220kt). Apparently the state turn requirement of 185kt/25 AOB doesn't apply to single engine stuff.

[Bumblebee]

Bumble...Just for your info, I believe that we are the only BA fleet to clean at 1500', the rest being 1000'...But I know we are on about 737's.

yep.. i know.... I was wondering...is it another hang-over from the -200? (from when the original noise abatement stuff started?)

[Cough]

I guess so...Given that we have A320's with CFM56's on that accel at 1000' then I presume that its not a noise issue...

[Blip]

There's a thread on a related topic started by LOKE regarding the tracking requirements during a single engine go-around when the climb gradient may be less than that required for the published missed approach procedure.

Just imagine you are in the take-off position on the same runway you are approaching. What procedure would you follow if you had an engine failure at V1? If you imagine starting from a standstill at the threshold of the runway and getting away with an engine failure at V1, suffering an engine failure during a missed approach, at approach speed, at some point before or at the threshold during a landing to the same runway should be a breeze shouldn't it?

Answer these questions and you will be OK:
What are the tracking requirements for an engine failure at V1 from this runway?
At what altitude is acceleration to commence? This altitude is always calculated and written somewhere on your take-off charts aren't they? If not, the standard acceleration altitude nominated by your company would be appropriate.


For example, departing RWY34 in Wellington, NZ. We take-off over the bay. There is a significant ridge along the northern edge of the bay. The normal two engine departure has us accelerating on two engines at 1300ft. With an engine failure on take-off, the acceleration altitude is 2100ft.

So I do the RWY 34 ILS approach with these figures in mind incase I should have to do a missed approach. If there were no procedure specified for the runway during take-off, then the standard altitudes would apply to the go-around (1000 ft AGL two engines, 800 ft AGL one engine inoperative).

Makes sense really. The thing is though, you have to ask the question. If you haven't asked the question, the scenario hasn't occured to you, and so if the day comes that it happens to you (engine failure during a go-around) it's just dumb luck that you don't suffer contolled flight into terrain. It's great that you are asking the question. There are many that don't! :)

[RoyHudd]

Than k you Winston, 100% correct.