B737 go around sequence

[LEM]

If I take off with flaps 15 and have an eng failure I'll wait till the established altitude to retract flaps on schedule.

Now, let's say I go around, set flaps 15 and THEN have an eng failure: shall I retract immediately the flaps to 1 or shall I wait till the acceleration altitude?:confused:

[PifPaf]

In my opinion, you must maintain the flaps until the level off altitude. After the go around procedure was initiated, we could consider as we were taking off.
So, if you chose to takeoff with flaps 15, you would wait. In the same way, if you already began the go around, you must procced with the selected flaps.
Any contrary opinions?
Regards,

PP

[CI54]

Hello,

I agree with you Piff Paff. In fact the Boeing FCTM specifically mentions it as such; In case of engine failure during go-around, treat it as a flaps 15 takeoff.

The reasons could be numerous but one which I can think of is the speed. The Vref for 2 engine approach is either Vref flaps 30 or 40 (this is B737) + 5. If one is on single engine approach, the Vref is Vref 15 + 5. The difference in speed is quite significant. In a single engine go around, the higher speed is used to compensate the loss of lift through the flap retraction. On a two engine go-around, if one loses an engine, it may be that he has not reached the 160kts ias the flight director is asking him to maintain with flaps 15. So, if flaps is further retracted to flaps 1, the resultant decrease in lift will be, I believe, significant. You may not be able to even achieve a positive climb gradient, let alone the required climb gradient.

I hope this helps. As usual, I stand corrected...

[Bokomoko]

...In case of poor climb perfomance increase speed to Vref + 15 and retract flaps to 1. That speed is approximately equal to V2 for flaps 1 and must be used in case of engine failure prior to go around.

[LEM]

That's the information I had, Bokomoko!
But After a few years I can't find the source for that information:
In case of eng failure in final, if you decide to go around, retract the flaps to 1 !!!
Can you tell the source of that information?

LEM

[timzsta]

If I remember back to my ATPL PoF and Perf exam in Feb this year, is it not the case that the more flap you have out the lower the climb gradient will be. So by going to Flap 1 we will increase the climb gradient and hence better obstacle clearance and meet the required climb gradient on go-around (seem to remember its about 2.4%). Stand corrected, as I am still only a student!!

[Aviation Trainer too]

edited for error in judgement: flaps 1 is the one!!

[Bokomoko]

LEM,
Information describing procedures in case of "Engine Failure In The Landing Configuration" was in the old 737 Operations Manual, Volume 1, Non-Normal Procedures section (expanded information), page 03.05.07. Anyway, there's no mention about Engine Failure after starting a G/A, but a maneuver in the event of a G/A with an E/O before the decision point (in my point of view even more restricted)
When the new 737 manuals edition arrived, all information concerning that maneuver is in the FCTM, but without an explanation about Vref + 15 and V2 for F1...Well, my manual can be outdated, since I've not been flying 737 lately.
Regards,
Bkmk

[pancho]

Engine failure procedure in the G/A is as mentioned, deal with it as a F15 T/O.

Engine failure on approach can be a subtle and dangerous event. However, there are essentially two ways to deal with it. In IMC it is a mandatory G/A. At normal landing weights Vref F30/40 is more or less equal to V2 F15, therefore treat it as a F15 T/O for accel. In VMC some companies (and Boeing) allow the approach to be continued. In this event you must set G/A power, select F15 and accelerate to at least Vref +15 (sometimes known as the "High White Bug") +5. If at a later stage on the approach you decide to G/A, now the call will be for F1 as in the 1 ENG INOP approach and accelerate as per sched. Hope it never happens! ;)

[LEM]

Thanks, Bokomoko! I found it!
So, let's sum up:
In case of ENGINE FAILURE IN THE LANDING CONFIGURATION Boeing says: " ...In the event of a go around, maintain VREF+15, retract flaps to position 1 (!) ..."
So that's what I'll do. We know it takes a lot of time for the flaps to move from 30 to one, so no danger of stalling while accelerating while pulling up!
Thanks everybody!
LEM
:cool:

[Pickle]

Yes, but the first priority is to select Flaps 15 and increase the thrust and get to Vref 30/40 + 15 (which = Vref 15).

Then, unless you are stabilized (above approx 1000' RA) or very close to the runway (below approx 100' RA), it is advisable to GA.

Maintain the Vref 30/40 + 15 speed and select Flaps 1 for GA.

(On some models the additional speed is ref +20 knots).

If an engine failure occurs during a GA, use normal GA procedures (select Flaps 15) and verify max GA N1 is set.

[LEM]

I like your idea, Pickle, to split the sequence in two: first, increase to vref+15 and flaps 15 on the glide, and THEN pull up retracting the flaps to 1!
:ok:

[Pickle]

Yes LEM,

I think it is OK to initiate the GA as soon as required (selecting Flaps to 15), especially if you are getting low on altitude. I think with max GA N1 selected you will find the speed still increasing while you slowly pitch up. We all know the aircraft will climb with Flaps 15 on one engine no trouble at all.

What I meant is not to select Flaps 1 until you have the required speed. I don't recommend selecting Flaps 1 straight from Flaps 30/40. Something may happen in between or distraction, and then you find you are below your safe speed margin.

[john_tullamarine]

A couple of considerations -

(a) standardisation is extremely important for such high workload but non-routine operations

(b) the underlying consideration is matching speed to configuration. Easiest way to check out this aspect is to look at the QRH and compare V2 and Vref data. The standard procedures then fall into place quite easily.

[Popolama]

now let s say you made a go around and you had an engine failure after the go around while climbing.what procedure should you follow? the normal missed approach procedure on the approach chart or should you go for the one engine inop compagnie procedure (exp:Rwy hdg ctc atc) ?

[Thinair]

Vref F40 + 15kt ~ VMan F15 ~ V2 F1

Situation: bugs set for F40, go around, retract flaps to F15 Then engine failure...
So If you:

-need climb performance: New target speed=outer bug (Vref F40 + 15kts) , then retract flaps to F1.
You are now flying V2, so your max bank angle is limited to 15deg.(plus 'overbank')
The turn radius however will be large due to the shallow bank angle.(As during an engine failure on take-off)

-need turn radius : New target speed is (again) outer bug, keep flaps 15.
Your are flying Vman F15, so you can use normal bank, which gives you a good turn radius, but reduced climb performance due to the drag being greater for F15 than for F1, AND the greater bank.

So for a close-by obstacle that you cannot avoid by turn (e.g. a low hill range), I would choose climb performance (F1).
And for a high obstacle that can be avoided by turn, a better turn radius seems appropriate (F15)

Hope this helps (Hope I didn't mix up the numbers)