about B737 flaps setting when missed approach

[CleoB737NG]

Dear ALL,

Question: when pass the DH and can not see runway, then we miss approach, hit TO/GA flaps 15 then go around thrust, positive rate gear up, 400HDG SEL.... but at this time, we lost one Engine. we need single engine miss approach use flaps 1, well at this situation, the speed not reach the speed (170) knots to move the flaps, Can we move flaps up to position flaps 1 immediately or not?

question 2:
when flaps at 1 position, is drag larger than pull? so what about flaps 5,15, 30 ,40's ? I remember when flaps at 1, and 5. the drag <pull. when flaps at position 15 to 40, the pull> drag. :confused:


THanks

[B737MRG]

Q1 : V2 Flaps 1 = Vref Flaps 40 + 15 knots

So as soon as you are "outerbug" (classic) - "top bug" (NG) you have enough speed to select Flaps 1

[Centaurus]

FCTM "If an engine fails during GA, perform normal GA and Missed Approach procedures. Verify max GA thrust is set. Maintain flaps 15, Vref 30 or 40 +wind correction speed and limit bank angle to 15 deg until initial maneuvring is complete and a safe altitude reached. Accelerate to flap retraction speed by repositioning the command speed to the maneuvring speed for the desired flap setting and adjusting pitch. Retract flaps on the normal flap/speed schedule".

The operative phrase is "maintain flap 15" and this assumes you have just set Flap 15 as part of the all engines GA procedure. Nothing about going to flap 1.

[CleoB737NG]

I am a little unsure of the exact situation that you put forth in your question.

First of all, what aircraft are you in? Is it a 300 or is it a New Generation - - 800 or 900?
The reason I ask is because you are referencing 300 procedures by attaining certain
speeds for flap retraction in contrast to using MASI speed(s) for flap retraction.

Also, what is the airport elevation, approximate temperature, and your gross weight?

Perhaps more importantly, what is the obstacle situation? Are there any obstacles
that you must consider for the missed approach. Our airports with non-standard
obstacle consideration(s) have special engine out procedures. For example the Reno
engine out procedure - - which is published - - If you are flying the one engine inoperative
approach to Reno at flaps 15 and subsequently go missed you would call for flaps
one and maintain your approach target speed - - this will now be your missed approach
target speed at flaps 1. Reno requires tracking out the localizer to 2.4 miles DME and
then making a "non-standard" twenty degree turn to the left until you have completed
the turn back to a heading that has you returning to the NO locater outer marker. Only
then - - when you are wings level, can you accelerate and retract the flaps on schedule.

If you know in advance from your calculations that you are going to be climb limited
at your destination (based on the possibility of a single engine go around) - - that will
determine you weight at departure in order to not arrive at a destination (high density
altitude - - for example high altitude and hot). Knowing this in advance, you know that
a single engine missed will require you to go to flaps 1. Another consideration would be
to plan on a bleeds off approach (start the APU and use it for pressurization / air conditioning)
then if you have to go around single engine, you will immediately have more thrust available for
the missed approach performance.

I realize that the exact scenario that you described is not exactly the question I am
answering. Please consider this - - it is sometimes better to use this old pilot axiom /
proverb. A superior pilot is a pilot that uses his superior knowledge and planning to
avoid getting into a scenario from which he must demonstrate his superior skills and abilities
in order to survive. In other words - - IF this airport that is your destination is one that
results in your aircraft being climb limited (single engine) - - - then it may be better to
plan your departure weight (ie. less weight) in order to ensure a safe one engine missed
approach / single engine climb performance. Another consideration is to plan the
approach with the engine bleeds off as I alluded to in the above paragraph. Certainly
if you suddenly and unexpectedly could not climb at flaps 15 you may have to in this
emergency situation just turn both bleeds off immediately without waiting for the APU
in order to improve your climb.

Part of your scenario (again without knowing the specifics) is something that we do not
specifically train for - - - BUT, if you suddenly found yourself in this situation, you would
have to quicky analyze the situation. First, are you climbing at flaps 15? If so, then
continue to climb - - once you have attained sufficient altitude - - then you could either
level off and accelerate or maybe even trade off a little altitude in order to gain airspeed.

Second, - - if you are not climbing at flaps 15 - - then you HAVE TO DO SOMETHING - -
if the bleeds are on - - IMMEDIATELY turn them OFF. Next you may have to retract
the flaps from 15 to 10 - - analyze that step - - if you gain a little - - then maybe bring
the flaps to 5 - - (you may lose some lift, but in the trade off you may gain some speed)
then when your speed increases - - you can retract the flaps to 2 - - then 1 and you are
on your way.

I realize that the above answers are somewhat non commital - - but please realize you
didn't give me all of the conditions existing at the time. My best answer is to (1) compute
the performance in advance, (2) if the aircraft weight is close to the approach climb weigh,
then plan and fly a BLEEDS OFF landing - - by limiting your weight at takeoff, and flying
a bleeds off approach - - you will be in a much better situation to deal with your scenario
in the event you go missed approach and then suddenly find yourself with only one engine.

As to the second question, are you discussing various flap positions for takeoff - - in other
words are you looking at the advantages and/or disadvantages of taking off with the
different flap settings? Again I'm not quite sure what your question is.

There are pro's and con's for the different flaps settings - - flaps 15 may be better for a
shorter runway or snow covered runway.

[Empty Cruise]

Hi Cleo,

Well, that's why you check your Approach Climb limiting mass with F15 before you go anywhere near the runway - right?

If you go-around and then loose an engine, you will still fly F15, and the aircraft will climb away nicely at top bug.

If you for some reason are limited not by max. landing mass vs. LDA, but by Approach climb limiting mass, you might find that you can increase your allowable landing mass by using F15 for landing. In that case, the max. mass vs. LDA will drop, but your max. mass vs. approach climb will increase. However, I fail to see how F15 will help you land on a short or contaminated runway?

Best regards,
Empty